Fix an error that could occur if the first transaction executed by a connection configured to use blocking locks is a write-transaction for which the WRITER lock cannot be obtained.

FossilOrigin-Name: 49e4dc72f7a4b28e4b49d7b91030bc986aea3ff44dac38cb6e68305800cd1de5
Merge trunk changes into this branch.
2020-05-07 14:26:40 +00:00 · 2020-05-07 14:05:08 +00:00 · 2020-05-07 01:56:57 +00:00 · 2020-05-06 21:25:39 +00:00 · 2020-05-06 21:24:29 +00:00 · 2020-05-06 20:55:38 +00:00
35 changed files with 1360 additions and 515 deletions
@@ -190,7 +190,8 @@ LIBOBJS0 = alter.lo analyze.lo attach.lo auth.lo \
         table.lo threads.lo tokenize.lo treeview.lo trigger.lo \
         update.lo userauth.lo upsert.lo util.lo vacuum.lo \
         vdbe.lo vdbeapi.lo vdbeaux.lo vdbeblob.lo vdbemem.lo vdbesort.lo \
-         vdbetrace.lo wal.lo walker.lo where.lo wherecode.lo whereexpr.lo \
+         vdbetrace.lo vdbevtab.lo \
+         wal.lo walker.lo where.lo wherecode.lo whereexpr.lo \
         window.lo utf.lo vtab.lo

 # Object files for the amalgamation.
@@ -296,6 +297,7 @@ SRC = \
  $(TOP)/src/vdbemem.c \
  $(TOP)/src/vdbesort.c \
  $(TOP)/src/vdbetrace.c \
+  $(TOP)/src/vdbevtab.c \
  $(TOP)/src/vdbeInt.h \
  $(TOP)/src/vtab.c \
  $(TOP)/src/vxworks.h \
@@ -502,6 +504,7 @@ TESTSRC2 = \
  $(TOP)/src/vdbe.c \
  $(TOP)/src/vdbemem.c \
  $(TOP)/src/vdbetrace.c \
+  $(TOP)/src/vdbevtab.c \
  $(TOP)/src/where.c \
  $(TOP)/src/wherecode.c \
  $(TOP)/src/whereexpr.c \
@@ -607,6 +610,7 @@ SHELL_OPT += -DSQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
 SHELL_OPT += -DSQLITE_ENABLE_STMTVTAB
 SHELL_OPT += -DSQLITE_ENABLE_DBPAGE_VTAB
 SHELL_OPT += -DSQLITE_ENABLE_DBSTAT_VTAB
+SHELL_OPT += -DSQLITE_ENABLE_BYTECODE_VTAB
 SHELL_OPT += -DSQLITE_ENABLE_OFFSET_SQL_FUNC
 SHELL_OPT += -DSQLITE_ENABLE_DESERIALIZE
 FUZZERSHELL_OPT = -DSQLITE_ENABLE_JSON1
@@ -619,6 +623,7 @@ FUZZCHECK_OPT += -DSQLITE_ENABLE_FTS4
 FUZZCHECK_OPT += -DSQLITE_ENABLE_RTREE
 FUZZCHECK_OPT += -DSQLITE_ENABLE_GEOPOLY
 FUZZCHECK_OPT += -DSQLITE_ENABLE_DBSTAT_VTAB
+FUZZCHECK_OPT += -DSQLITE_ENABLE_BYTECODE_VTAB
 FUZZCHECK_SRC = $(TOP)/test/fuzzcheck.c $(TOP)/test/ossfuzz.c
 DBFUZZ_OPT =

@@ -688,6 +693,7 @@ DBFUZZ2_OPTS = \
  -DSQLITE_ENABLE_DESERIALIZE \
  -DSQLITE_DEBUG \
  -DSQLITE_ENABLE_DBSTAT_VTAB \
+  -DSQLITE_ENABLE_BYTECODE_VTAB \
  -DSQLITE_ENABLE_RTREE \
  -DSQLITE_ENABLE_FTS4 \
  -DSQLITE_ENABLE_FTS5
@@ -1004,6 +1010,9 @@ vdbesort.lo:	$(TOP)/src/vdbesort.c $(HDR)
 vdbetrace.lo:	$(TOP)/src/vdbetrace.c $(HDR)
 	$(LTCOMPILE) $(TEMP_STORE) -c $(TOP)/src/vdbetrace.c

+vdbevtab.lo:	$(TOP)/src/vdbevtab.c $(HDR)
+	$(LTCOMPILE) $(TEMP_STORE) -c $(TOP)/src/vdbevtab.c
+
 vtab.lo:	$(TOP)/src/vtab.c $(HDR)
 	$(LTCOMPILE) $(TEMP_STORE) -c $(TOP)/src/vtab.c

@@ -1211,6 +1220,7 @@ TESTFIXTURE_FLAGS += -DSQLITE_SERIES_CONSTRAINT_VERIFY=1
 TESTFIXTURE_FLAGS += -DSQLITE_DEFAULT_PAGE_SIZE=1024
 TESTFIXTURE_FLAGS += -DSQLITE_ENABLE_STMTVTAB
 TESTFIXTURE_FLAGS += -DSQLITE_ENABLE_DBPAGE_VTAB
+TESTFIXTURE_FLAGS += -DSQLITE_ENABLE_BYTECODE_VTAB
 TESTFIXTURE_FLAGS += -DSQLITE_ENABLE_DESERIALIZE

 TESTFIXTURE_SRC0 = $(TESTSRC2) libsqlite3.la
@@ -357,6 +357,7 @@ OPT_FEATURE_FLAGS = $(OPT_FEATURE_FLAGS) -DSQLITE_ENABLE_JSON1=1
 OPT_FEATURE_FLAGS = $(OPT_FEATURE_FLAGS) -DSQLITE_ENABLE_STMTVTAB=1
 OPT_FEATURE_FLAGS = $(OPT_FEATURE_FLAGS) -DSQLITE_ENABLE_DBPAGE_VTAB=1
 OPT_FEATURE_FLAGS = $(OPT_FEATURE_FLAGS) -DSQLITE_ENABLE_DBSTAT_VTAB=1
+OPT_FEATURE_FLAGS = $(OPT_FEATURE_FLAGS) -DSQLITE_ENABLE_BYTECODE_VTAB=1
 OPT_FEATURE_FLAGS = $(OPT_FEATURE_FLAGS) -DSQLITE_ENABLE_DESERIALIZE=1
 !ENDIF
 OPT_FEATURE_FLAGS = $(OPT_FEATURE_FLAGS) -DSQLITE_ENABLE_COLUMN_METADATA=1
@@ -1353,6 +1354,7 @@ SRC01 = \
  $(TOP)\src\vdbemem.c \
  $(TOP)\src\vdbesort.c \
  $(TOP)\src\vdbetrace.c \
+  $(TOP)\src\vdbevtab.c \
  $(TOP)\src\vtab.c \
  $(TOP)\src\wal.c \
  $(TOP)\src\walker.c \
@@ -1684,6 +1686,7 @@ FUZZCHECK_OPTS = $(FUZZCHECK_OPTS) -DSQLITE_ENABLE_FTS4
 FUZZCHECK_OPTS = $(FUZZCHECK_OPTS) -DSQLITE_ENABLE_RTREE
 FUZZCHECK_OPTS = $(FUZZCHECK_OPTS) -DSQLITE_ENABLE_GEOPOLY
 FUZZCHECK_OPTS = $(FUZZCHECK_OPTS) -DSQLITE_ENABLE_DBSTAT_VTAB
+FUZZCHECK_OPTS = $(FUZZCHECK_OPTS) -DSQLITE_ENABLE_BYTECODE_VTAB

 FUZZCHECK_SRC = $(TOP)\test\fuzzcheck.c $(TOP)\test\ossfuzz.c
 OSSSHELL_SRC = $(TOP)\test\ossshell.c $(TOP)\test\ossfuzz.c
@@ -2109,6 +2112,9 @@ vdbesort.lo:	$(TOP)\src\vdbesort.c $(HDR)
 vdbetrace.lo:	$(TOP)\src\vdbetrace.c $(HDR)
 	$(LTCOMPILE) $(CORE_COMPILE_OPTS) -c $(TOP)\src\vdbetrace.c

+vdbevtab.lo:	$(TOP)\src\vdbevtab.c $(HDR)
+	$(LTCOMPILE) $(CORE_COMPILE_OPTS) -c $(TOP)\src\vdbevtab.c
+
 vtab.lo:	$(TOP)\src\vtab.c $(HDR)
 	$(LTCOMPILE) $(CORE_COMPILE_OPTS) -c $(TOP)\src\vtab.c

@@ -2353,6 +2359,7 @@ TESTFIXTURE_FLAGS = $(TESTFIXTURE_FLAGS) -DSQLITE_SERIES_CONSTRAINT_VERIFY=1
 TESTFIXTURE_FLAGS = $(TESTFIXTURE_FLAGS) -DSQLITE_DEFAULT_PAGE_SIZE=1024
 TESTFIXTURE_FLAGS = $(TESTFIXTURE_FLAGS) -DSQLITE_ENABLE_STMTVTAB=1
 TESTFIXTURE_FLAGS = $(TESTFIXTURE_FLAGS) -DSQLITE_ENABLE_DBPAGE_VTAB=1
+TESTFIXTURE_FLAGS = $(TESTFIXTURE_FLAGS) -DSQLITE_ENABLE_BYTECODE_VTAB=1
 TESTFIXTURE_FLAGS = $(TESTFIXTURE_FLAGS) -DSQLITE_ENABLE_JSON1=1
 TESTFIXTURE_FLAGS = $(TESTFIXTURE_FLAGS) -DSQLITE_ENABLE_DESERIALIZE=1
 TESTFIXTURE_FLAGS = $(TESTFIXTURE_FLAGS) $(TEST_CCONV_OPTS)
@@ -195,6 +195,7 @@ struct CksmFile {
                        ** Always true if reserve size is 8. */
  char verifyCksm;      /* True to verify checksums */
  char isWal;           /* True if processing a WAL file */
+  char inCkpt;          /* Currently doing a checkpoint */
  CksmFile *pPartner;   /* Ptr from WAL to main-db, or from main-db to WAL */
 };

@@ -366,6 +367,20 @@ static int cksmClose(sqlite3_file *pFile){
  return pFile->pMethods->xClose(pFile);
 }

+/*
+** Set the computeCkSm and verifyCksm flags, if they need to be
+** changed.
+*/
+static void cksmSetFlags(CksmFile *p, int hasCorrectReserveSize){
+  if( hasCorrectReserveSize!=p->computeCksm ){
+    p->computeCksm = p->verifyCksm = hasCorrectReserveSize;
+    if( p->pPartner ){
+      p->pPartner->verifyCksm = hasCorrectReserveSize;
+      p->pPartner->computeCksm = hasCorrectReserveSize;
+    }
+  }
+}
+
 /*
 ** Read data from a cksm-file.
 */
@@ -383,22 +398,21 @@ static int cksmRead(
    if( iOfst==0 && iAmt>=100 && memcmp(zBuf,"SQLite format 3",16)==0 ){
      u8 *d = (u8*)zBuf;
      char hasCorrectReserveSize = (d[20]==8);
-      if( hasCorrectReserveSize!=p->computeCksm ){
-        p->computeCksm = p->verifyCksm = hasCorrectReserveSize;
-      }
+      cksmSetFlags(p, hasCorrectReserveSize);
    }
-    /* Verify the checksum if (1) the size seems appropriate for a database
-    ** page, and if (2) checksum verification is enabled.  But (3) do not 
-    ** verify the checksums on a WAL page if the main database file
-    ** has subsequently turned off checksums.
+    /* Verify the checksum if
+    **    (1) the size indicates that we are dealing with a complete
+    **        database page
+    **    (2) checksum verification is enabled
+    **    (3) we are not in the middle of checkpoint
    */
    if( iAmt>=512           /* (1) */
     && p->verifyCksm       /* (2) */
-     && (!p->isWal || (p->pPartner!=0 && p->pPartner->verifyCksm))  /* (3) */
+     && !p->inCkpt          /* (3) */
    ){
      u8 cksum[8];
      cksmCompute((u8*)zBuf, iAmt-8, cksum);
-      if( memcmp(zBuf+iAmt-8, cksum, 8)!=0 ){
+      if( memcmp((u8*)zBuf+iAmt-8, cksum, 8)!=0 ){
        sqlite3_log(SQLITE_IOERR_DATA,
           "checksum fault offset %lld of \"%s\"",
           iOfst, p->zFName);
@@ -423,9 +437,7 @@ static int cksmWrite(
  if( iOfst==0 && iAmt>=100 && memcmp(zBuf,"SQLite format 3",16)==0 ){
    u8 *d = (u8*)zBuf;
    char hasCorrectReserveSize = (d[20]==8);
-    if( hasCorrectReserveSize!=p->computeCksm ){
-      p->computeCksm = p->verifyCksm = hasCorrectReserveSize;
-    }
+    cksmSetFlags(p, hasCorrectReserveSize);
  }
  /* If the write size is appropriate for a database page and if
  ** checksums where ever enabled, then it will be safe to compute
@@ -433,7 +445,10 @@ static int cksmWrite(
  ** it will never decrease.  And because it cannot decrease, the
  ** checksum will not overwrite anything.
  */
-  if( iAmt>=512 && p->computeCksm ){
+  if( iAmt>=512
+   && p->computeCksm
+   && !p->inCkpt
+  ){
    cksmCompute((u8*)zBuf, iAmt-8, ((u8*)zBuf)+iAmt-8);
  }
  return pFile->pMethods->xWrite(pFile, zBuf, iAmt, iOfst);
@@ -510,6 +525,7 @@ static int cksmFileControl(sqlite3_file *pFile, int op, void *pArg){
        }else{
          p->verifyCksm = 0;
        }
+        if( p->pPartner ) p->pPartner->verifyCksm = p->verifyCksm;
      }
      azArg[0] = sqlite3_mprintf("%d",p->verifyCksm);
      return SQLITE_OK;
@@ -518,6 +534,9 @@ static int cksmFileControl(sqlite3_file *pFile, int op, void *pArg){
      /* Do not allow page size changes on a checksum database */
      return SQLITE_OK;
    }
+  }else if( op==SQLITE_FCNTL_CKPT_START || op==SQLITE_FCNTL_CKPT_DONE ){
+    p->inCkpt = op==SQLITE_FCNTL_CKPT_START;
+    if( p->pPartner ) p->pPartner->inCkpt = p->inCkpt;
  }
  rc = pFile->pMethods->xFileControl(pFile, op, pArg);
  if( rc==SQLITE_OK && op==SQLITE_FCNTL_VFSNAME ){
@@ -168,7 +168,8 @@ static int stmtColumn(
      sqlite3_result_int(ctx, sqlite3_stmt_busy(pCur->pStmt));
      break;
    }
-    case STMT_COLUMN_MEM: {
+    default: {
+      assert( i==STMT_COLUMN_MEM );
      i = SQLITE_STMTSTATUS_MEMUSED + 
            STMT_COLUMN_NSCAN - SQLITE_STMTSTATUS_FULLSCAN_STEP;
      /* Fall thru */
@@ -45,6 +45,7 @@ static int uintCollFunc(
  const unsigned char *zA = (const unsigned char*)pKey1;
  const unsigned char *zB = (const unsigned char*)pKey2;
  int i=0, j=0, x;
+  (void)notUsed;
  while( i<nKey1 && j<nKey2 ){
    x = zA[i] - zB[j];
    if( isdigit(zA[i]) ){
@@ -74,7 +74,8 @@ LIBOBJ+= vdbe.o parse.o \
         table.o threads.o tokenize.o treeview.o trigger.o \
         update.o upsert.o userauth.o util.o vacuum.o \
         vdbeapi.o vdbeaux.o vdbeblob.o vdbemem.o vdbesort.o \
-	 vdbetrace.o wal.o walker.o where.o wherecode.o whereexpr.o \
+	 vdbetrace.o vdbevtab.o \
+         wal.o walker.o where.o wherecode.o whereexpr.o \
         utf.o vtab.o window.o

 LIBOBJ += sqlite3session.o
@@ -173,6 +174,7 @@ SRC = \
  $(TOP)/src/vdbemem.c \
  $(TOP)/src/vdbesort.c \
  $(TOP)/src/vdbetrace.c \
+  $(TOP)/src/vdbevtab.c \
  $(TOP)/src/vdbeInt.h \
  $(TOP)/src/vtab.c \
  $(TOP)/src/vxworks.h \
@@ -421,6 +423,7 @@ TESTSRC2 = \
  $(TOP)/src/vdbeaux.c \
  $(TOP)/src/vdbe.c \
  $(TOP)/src/vdbemem.c \
+  $(TOP)/src/vdbevtab.c \
  $(TOP)/src/where.c \
  $(TOP)/src/wherecode.c \
  $(TOP)/src/whereexpr.c \
@@ -526,6 +529,7 @@ SHELL_OPT += -DSQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
 SHELL_OPT += -DSQLITE_ENABLE_STMTVTAB
 SHELL_OPT += -DSQLITE_ENABLE_DBPAGE_VTAB
 SHELL_OPT += -DSQLITE_ENABLE_DBSTAT_VTAB
+SHELL_OPT += -DSQLITE_ENABLE_BYTECODE_VTAB
 SHELL_OPT += -DSQLITE_ENABLE_OFFSET_SQL_FUNC
 FUZZERSHELL_OPT = -DSQLITE_ENABLE_JSON1
 FUZZCHECK_OPT = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_MEMSYS5
@@ -536,6 +540,7 @@ FUZZCHECK_OPT += -DSQLITE_ENABLE_FTS4
 FUZZCHECK_OPT += -DSQLITE_ENABLE_RTREE
 FUZZCHECK_OPT += -DSQLITE_ENABLE_GEOPOLY
 FUZZCHECK_OPT += -DSQLITE_ENABLE_DBSTAT_VTAB
+FUZZCHECK_OPT += -DSQLITE_ENABLE_BYTECODE_VTAB
 DBFUZZ_OPT =
 KV_OPT = -DSQLITE_THREADSAFE=0 -DSQLITE_DIRECT_OVERFLOW_READ
 ST_OPT = -DSQLITE_THREADSAFE=0
@@ -586,6 +591,7 @@ DBFUZZ2_OPTS = \
  -DSQLITE_ENABLE_DESERIALIZE \
  -DSQLITE_DEBUG \
  -DSQLITE_ENABLE_DBSTAT_VTAB \
+  -DSQLITE_ENABLE_BYTECODE_VTAB \
  -DSQLITE_ENABLE_RTREE \
  -DSQLITE_ENABLE_FTS4 \
  -DSQLITE_ENABLE_FTS5
@@ -895,6 +901,7 @@ TESTFIXTURE_FLAGS += -DSQLITE_SERIES_CONSTRAINT_VERIFY=1
 TESTFIXTURE_FLAGS += -DSQLITE_DEFAULT_PAGE_SIZE=1024
 TESTFIXTURE_FLAGS += -DSQLITE_ENABLE_STMTVTAB
 TESTFIXTURE_FLAGS += -DSQLITE_ENABLE_DBPAGE_VTAB
+TESTFIXTURE_FLAGS += -DSQLITE_ENABLE_BYTECODE_VTAB
 TESTFIXTURE_FLAGS += -DTCLSH_INIT_PROC=sqlite3TestInit

 testfixture$(EXE): $(TESTSRC2) libsqlite3.a $(TESTSRC) $(TOP)/src/tclsqlite.c
@@ -1,11 +1,11 @@
-C Add\sa\smissing\sVdbeCoverage()\smacro.
-D 2020-05-02T03:29:21.137
+C Fix\san\serror\sthat\scould\soccur\sif\sthe\sfirst\stransaction\sexecuted\sby\sa\sconnection\sconfigured\sto\suse\sblocking\slocks\sis\sa\swrite-transaction\sfor\swhich\sthe\sWRITER\slock\scannot\sbe\sobtained.
+D 2020-05-07T14:26:40.925
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
-F Makefile.in f6ab6e307d31e09d82aa4eca87ccb21ce66f486279e204b54b3149ff0d71616f
+F Makefile.in 280cf54350738dfd567bd97ae1bff1bf68c64658c4d5ff21be9cae117e92f063
 F Makefile.linux-gcc f609543700659711fbd230eced1f01353117621dccae7b9fb70daa64236c5241
-F Makefile.msc 46c338b1151fbeed42c82416c6bc4da7ff9a10f851bf379f8592280fd53d6efa
+F Makefile.msc d9232f9339da7d2b82611cb148734d36be4cc90e17a968882e71d9bf75e512df
 F README.md 1514a365ffca3c138e00c5cc839906108a01011a6b082bad19b09781e3aa498a
 F VERSION 980d78a2ce04a1fd0ebefbaabd665f7f9186563820629ee29c6e350e96f19b52
 F aclocal.m4 a5c22d164aff7ed549d53a90fa56d56955281f50
@@ -285,7 +285,7 @@ F ext/misc/appendvfs.c 3777f22ec1057dc4e5fd89f2fbddcc7a29fbeef1ad038c736c54411bb
 F ext/misc/blobio.c a867c4c4617f6ec223a307ebfe0eabb45e0992f74dd47722b96f3e631c0edb2a
 F ext/misc/btreeinfo.c 26004b7a6be320ec08fc20ca8d0f01fccb00a98cbe0f3197446794ff2a506aa3
 F ext/misc/carray.c 91e9a7f512fda934894bed30464552fffa7d3073b5be04189ae0bd0c59f26bfd
-F ext/misc/cksumvfs.c 755627c9112a000bc89653cb5038e080e69c58fa0a5c8e9ebd747f24e5fc01c9
+F ext/misc/cksumvfs.c b0d07f2e1bb08f8b6f311f4e454360b6a7f0021912c326428d74900020f29c31
 F ext/misc/closure.c dbfd8543b2a017ae6b1a5843986b22ddf99ff126ec9634a2f4047cd14c85c243
 F ext/misc/completion.c a0efe03edfdc4f717c61e6c9b0bfe2708ff7878010dae3174980a68fdf76aabc
 F ext/misc/compress.c 3354c77a7c8e86e07d849916000cdac451ed96500bfb5bd83b20eb61eee012c9
@@ -318,10 +318,10 @@ F ext/misc/shathree.c 135b7c145db4a09b1650c3e7aff9cb538763a9a361e834c015dd1aaf8d
 F ext/misc/showauth.c 732578f0fe4ce42d577e1c86dc89dd14a006ab52
 F ext/misc/spellfix.c 94df9bbfa514a563c1484f684a2df3d128a2f7209a84ca3ca100c68a0163e29f
 F ext/misc/sqlar.c c9e5d58544e1506135806a1e0f525f92d4bb6bb125348dce469d778fb334fbce
-F ext/misc/stmt.c 8a8dc4675042e4551e4afe99b8d0cc7a4a2fc1a8dacc0a9ce1b1bbff145da93d
+F ext/misc/stmt.c 35063044a388ead95557e4b84b89c1b93accc2f1c6ddea3f9710e8486a7af94a
 F ext/misc/templatevtab.c 8a16a91a5ceaccfcbd6aaaa56d46828806e460dd194965b3f77bf38f14b942c4
 F ext/misc/totype.c fa4aedeb07f66169005dffa8de3b0a2b621779fd44f85c103228a42afa71853b
-F ext/misc/uint.c 5870865fb5f6153db18db443f3ecdcdb17a06567ee47ecd9fd26e3ec7e5f6ce8
+F ext/misc/uint.c 053fed3bce2e89583afcd4bf804d75d659879bbcedac74d0fa9ed548839a030b
 F ext/misc/unionvtab.c 36237f0607ca954ac13a4a0e2d2ac40c33bc6e032a5f55f431713061ef1625f9
 F ext/misc/urifuncs.c f71360d14fa9e7626b563f1f781c6148109462741c5235ac63ae0f8917b9c751
 F ext/misc/uuid.c 5bb2264c1b64d163efa46509544fd7500cb8769cb7c16dd52052da8d961505cf
@@ -455,7 +455,7 @@ F ext/userauth/userauth.c 7f00cded7dcaa5d47f54539b290a43d2e59f4b1eb5f447545fa865
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F magic.txt 8273bf49ba3b0c8559cb2774495390c31fd61c60
-F main.mk f3a972451ed68fa1101d81606a2a1b0a2600b85547059fe89ccb2380b983e50c
+F main.mk addd0a300e90ad090dc4a934df8a6f1b6c52c057a1aebb93682aed29fb68a345
 F mkso.sh fd21c06b063bb16a5d25deea1752c2da6ac3ed83
 F mptest/config01.test 3c6adcbc50b991866855f1977ff172eb6d901271
 F mptest/config02.test 4415dfe36c48785f751e16e32c20b077c28ae504
@@ -468,23 +468,23 @@ F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
 F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
 F src/alter.c fa2c3be9b0ebecfafb7062072a0ae6eda126d3e5a9fd51b2eded5acd95dc783c
-F src/analyze.c f71fb976b1bc8e62320e4932f979e56f535237b1579e07b392b22f9a1ccbba42
+F src/analyze.c 953a6c43870ccaf080597244e1eeb4dc2ff6cb84f9501b24e46323de36970b61
 F src/attach.c ff2daea0fe62080192e3f262670e4f61f5a86c1e7bea9cec34e960fe79852aa1
 F src/auth.c a3d5bfdba83d25abed1013a8c7a5f204e2e29b0c25242a56bc02bb0c07bf1e06
-F src/backup.c 5e617c087f1c2d6005c2ec694ce80d6e16bc68d906e1b1c556d7c7c2228b636b
+F src/backup.c b1c90cd4110248c8e1273ff4578d3a84c0c34725e1b96dacd4a6294a908702de
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c 3383ad76753193c3529318ba30db41747663639428d2f6cb7cbcd8034d4a99cd
+F src/btree.c f14e415fcfd0b52b4e4ebd193ba5fadac5e8252c30f023389af682813af44025
 F src/btree.h 989ef3c33413549e3e148f3dcb46c030f317dac130dc86809ba6b9aa4b16c72a
-F src/btreeInt.h 887cdd2ea7f4a65143074a8a7c8928b0546f8c18dda3c06a408ce7992cbab0c0
-F src/build.c ec6c0bda1e43ef55e5f5121a77ba19fac51fc6585f95ce2da795bcedcf6e8f36
+F src/btreeInt.h 5c8b8749805787313ecf49eb5be3ced1e94bbf8ef54bb01470ce6bd0d5185c67
+F src/build.c 5566b570435d3511a0fd57388c124491b1f74e59561f0c1679fabe74c4c54b7a
 F src/callback.c d0b853dd413255d2e337b34545e54d888ea02f20da5ad0e63585b389624c4a6c
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
-F src/ctime.c 060c9bc1c8a848a942326c6e73fff449e54e8e98487f555e49e7b897639db270
+F src/ctime.c e98518d2d3d4029a13c805e07313fb60c877be56db76e90dd5f3af73085d0ce6
 F src/date.c b29b349d277e3d579dcc295b24c0a2caed83fd8f090a9f7cbe6070c0fd662384
 F src/dbpage.c 8a01e865bf8bc6d7b1844b4314443a6436c07c3efe1d488ed89e81719047833a
 F src/dbstat.c 793deaf88a0904f88285d93d6713c636d55ede0ffd9f08d10f4ea825531d367f
-F src/delete.c 11000121c4281c0bce4e41db29addfaea0038eaa127ece02557c9207bc3e541d
+F src/delete.c 88047c8e59878c920fce14582bc1dde4d81157d1ca5ffdf36c2907e6d41996c4
 F src/expr.c d1e1d42cbdec08bb867a1ab43a59b401d82ff2bc88bdcb4af20e479a5facb6d8
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 4b575423b0a5d4898b1a7868ce985cf1a8ad91c741c9abbb108ff02536d20f41
@@ -497,7 +497,7 @@ F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 8e4211d04eb460c0694d486c6ba1c068d468c6f653c3f237869a802ad82854de
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 421310045bd78afefb772294a99e50f37d87ae578786a6169074e6291e30d969
-F src/main.c 652a782cd7b6c6ddf7419fcaf06b8aa9440b7c815857241171c9bdf03ab6544c
+F src/main.c 266393c10ff58d0919941f3187b54c0144b27d2f3fab8ae849eefbb89c48c451
 F src/malloc.c a3e13b001f988ecec6bdb90c0ea8912c8c786e623724d7098da623d8d01d19b1
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
@@ -517,16 +517,16 @@ F src/os.c 669cc3839cc35d20f81faf0be1ab6d4581cea35e9d8f3a9d48a98d6571f7c285
 F src/os.h 48388821692e87da174ea198bf96b1b2d9d83be5dfc908f673ee21fafbe0d432
 F src/os_common.h b2f4707a603e36811d9b1a13278bffd757857b85
 F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
-F src/os_unix.c 7ef8b60222558a373d89c18d0c3bc44365b45273a528183d40bec5bb76ce23fc
+F src/os_unix.c 13f983da988b6460ef3c4c22099c67ab0938291e543644ac4d99eccc8ba604f1
 F src/os_win.c 035a813cbd17f355bdcad7ab894af214a9c13a1db8aeac902365350b98cd45a7
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
-F src/pager.c 52cee2f72710be47b5b13ff66b339ca3855e5bc48e92a94114d2affedc70041f
-F src/pager.h 3b33619a90180e0874c7eca31d6f6ceb464d9322c6fb4e9a7bbb318c8a17bdb3
+F src/pager.c 96436cb1920074d4ade120a1a8a9d0ae3f52df06651e21b7eccc5eae2f02b111
+F src/pager.h 8d1dc9a2c3fc5eb6eeed75f48a076f425e77706f8935f05817fa05a308f587b5
 F src/parse.y c8eff38606f443d5ba245263fa7abc05e4116d95656e050c4b78e9bfbf931add
 F src/pcache.c 385ff064bca69789d199a98e2169445dc16e4291fa807babd61d4890c3b34177
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c 6596e10baf3d8f84cc1585d226cf1ab26564a5f5caf85a15757a281ff977d51a
-F src/pragma.c 85f763714b192cc26a236e3ec020a9155fe8da248af21eae86c0d1f0f49a0753
+F src/pragma.c 1b0db48177e52b256c003b8dc6ac708b1079a82cded944a23820574586a4731f
 F src/pragma.h 8168e588536bffd95319451f34e9a754dc37d205ebe433031a7813c5b286beae
 F src/prepare.c 8d4d6c8aa6afefc48027c54b41cdf134b4d6bc2fc4badbe483ad7fd9e1728a28
 F src/printf.c 9be6945837c839ba57837b4bc3af349eba630920fa5532aa518816defe42a7d4
@@ -534,11 +534,11 @@ F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
 F src/resolve.c d36a2b1639e1c33d7b508abfd3452a63e7fd81737f6f3940bfef085fca6f21f4
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
 F src/select.c 1720bff2168491ca79af81a03bd18c0383f61d845c6e17caff9d25aabc4ab435
-F src/shell.c.in 86cd0f0412b9739b769fafdfcad28f731882d522042a95c30ab033a5eba68b03
-F src/sqlite.h.in b20d5dc52765ff82f3701395a7e670611ddf138ee0ae84482452ad3a0b5f24b5
+F src/shell.c.in cf2d24f54412c06e5fb34af7fabc748651125e1dceac29b740e91f06d23447b6
+F src/sqlite.h.in a42bae930f462294801f24468dd56832b09de01072a26dc0df60ddc3c5602210
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 2d1af80082edffd71c6f96f70ad1ce6a4fb46615ad10291fc77fe0dea9ff0197
-F src/sqliteInt.h 1f6909cd268d1cda2f04914d150997b17afd8ff7e5cf1930cc1f88d337a49f74
+F src/sqliteInt.h 9d2caeaee7a317af536a60fcd828425da5d64c4f26aac5356f13dce1de3cb066
 F src/sqliteLimit.h 95cb8479ca459496d9c1c6a9f76b38aee12203a56ce1092fe13e50ae2454c032
 F src/status.c 9ff2210207c6c3b4d9631a8241a7d45ab1b26a0e9c84cb07a9b5ce2de9a3b278
 F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@ -604,20 +604,21 @@ F src/update.c 3eb778c42155d944377a4ee5e440b04520f07094804ed6ce63d2528f619614d9
 F src/upsert.c 2920de71b20f04fe25eb00b655d086f0ba60ea133c59d7fa3325c49838818e78
 F src/utf.c 95fb6e03a5ca679045c5adccd05380f0addccabef5911abddcb06af069500ab7
 F src/util.c 3b6cedf7a0c69bd6e1acce832873952d416212d6293b18d03064e07d7a9b5118
-F src/vacuum.c f25d3b39681595e321a8a4e7fca3e5971cb14a401213d0742c9bf7d4ce8c2a1a
-F src/vdbe.c f55fe7dbffae72e1cd5861e9ea3b55d50b70d863eebce3aebf11e1271ceae796
-F src/vdbe.h 51282fbe819ee0e8eeeaab176240860d334c20a12b14f3b363e7f1a4e05d60b9
-F src/vdbeInt.h 0b728ee662862a38b1912af741e2ac64f524de3c77aa86cf4306c42bdcd9de59
+F src/vacuum.c de9780b89fa4ee74c3534f60b94820e3179aca759ffc1338ee53cb4ea7693dd3
+F src/vdbe.c e3dba0dee25bc92e871c13cac655260912b3be4abcc85b439259c9934b208da3
+F src/vdbe.h 07b8c636a87df8b6e58f29d6badd7f10d5844353deff1d7c88ed1c2bfe3bbd35
+F src/vdbeInt.h 571413068b5ac07e2ed8ca7a02fa529622fd5455ae6981498376e5e492d2e5ef
 F src/vdbeapi.c d176ee7251d5344de7bb2a0d2dd0fe536834e5843d9bc2389e0f5cdcd5374141
-F src/vdbeaux.c 8349559e72bf0cfa2258b1159b004ec4d1717a054d2e1829c8cc897c32da8752
+F src/vdbeaux.c ee65c810ec97acce013e3024e5b8f3f767459b5d1499a8d379232059eb9aea03
 F src/vdbeblob.c 253ed82894924c362a7fa3079551d3554cd1cdace39aa833da77d3bc67e7c1b1
 F src/vdbemem.c 39b942ecca179f4f30a32b54579a85d74ccaefa5af2a0ad2700abe5ef0768b22
 F src/vdbesort.c 2be76d26998ce2b3324cdcc9f6443728e54b6c7677c553ad909c7d7cfab587df
 F src/vdbetrace.c fa3bf238002f0bbbdfb66cc8afb0cea284ff9f148d6439bc1f6f2b4c3b7143f0
+F src/vdbevtab.c 8094dfc28dad82d60a1c832020a1b201a5381dc185c14638affc6d4e9d54c653
 F src/vtab.c 7b704a90515a239c6cdba6a66b1bb3a385e62326cceb5ecb05ec7a091d6b8515
 F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
-F src/wal.c ea8dad28bb0e2b85ac1ab7618968687ff5fd522af8a1a38d6960ec176ebc8ee6
-F src/wal.h 606292549f5a7be50b6227bd685fa76e3a4affad71bb8ac5ce4cb5c79f6a176a
+F src/wal.c fdbf7641be6fa6e57f86484e8b5ffe816dffae176c4fd72a9b76e5e0b99bf6dd
+F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
 F src/walker.c 7c429c694abd12413a5c17aec9f47cfe9eba6807e6b0a32df883e8e3a14835ed
 F src/where.c 9546c82056e8cdb27291f98cf1adca5d271240b399bb97b32f77fc2bea6146c9
 F src/whereInt.h 6b874aa15f94e43a2cec1080be64d955b04deeafeac90ffb5d6975c0d511be3c
@@ -822,7 +823,7 @@ F test/descidx1.test edc8adee58d491b06c7157c50364eaf1c3605c9c19f8093cb1ea2b6184f
 F test/descidx2.test a0ba347037ff3b811f4c6ceca5fd0f9d5d72e74e59f2d9de346a9d2f6ad78298
 F test/descidx3.test 953c831df7ea219c73826dfbf2f6ee02d95040725aa88ccb4fa43d1a1999b926
 F test/diskfull.test 106391384780753ea6896b7b4f005d10e9866b6e
-F test/distinct.test 8b6c652f0b2d477f0830884736f2a1cd2e8f7fc10a04aa6d571a401fa13ed88b
+F test/distinct.test e7d0cf371944dd0cbedff86420744e2f1ea2b528156451c97eb6ff41a99b9236
 F test/distinct2.test 11b0594c932098e969d084ba45ab81d5040f4d4e766db65d49146705a305ed98
 F test/distinctagg.test 1a6ef9c87a58669438fc771450d7a72577417376
 F test/e_blobbytes.test 439a945953b35cb6948a552edaec4dc31fd70a05
@@ -1657,7 +1658,7 @@ F test/vtab_alter.test 736e66fb5ec7b4fee58229aa3ada2f27ec58bc58c00edae4836890c37
 F test/vtab_err.test dcc8b7b9cb67522b3fe7a272c73856829dae4ab7fdb30399aea1b6981bda2b65
 F test/vtab_shared.test 5253bff2355a9a3f014c15337da7e177ab0ef8ad
 F test/vtabdrop.test 65d4cf6722972e5499bdaf0c0d70ee3b8133944a4e4bc31862563f32a7edca12
-F test/wal.test cdf0ca6cc0447520d19ef1c83287824ebeb3e82d75af856511ba96841a79fc9b
+F test/wal.test 16180bc4becda176428ad02eaea437b4b8f5ae099314de443a4e12b2dcc007a2
 F test/wal2.test 537f59e5c5932e3b45bf3591ae3e48a2601360c2e52821b633e222fe6ebd5b09
 F test/wal3.test 2a93004bc0fb2b5c29888964024695bade278ab2
 F test/wal4.test 4744e155cd6299c6bd99d3eab1c82f77db9cdb3c
@@ -1688,6 +1689,7 @@ F test/walprotocol2.test 7d3b6b4bf0b12f8007121b1e6ef714bc99101fb3b48e46371df1db8
 F test/walro.test cb438d05ba0d191f10b688e39c4f0cd5b71569a1d1f4440e5bdf3c6880e08c20
 F test/walro2.test 0e79dd15cbdb4f482c01ea248373669c732414a726b357d04846a816afafb768
 F test/walrofault.test c70cb6e308c443867701856cce92ad8288cd99488fa52afab77cca6cfd51af68
+F test/walsetlk.test 11f7fe792fdce54cf09874dab824e0627f2eedecfb9f7983e325606ec5184e0c
 F test/walshared.test 0befc811dcf0b287efae21612304d15576e35417
 F test/walslow.test c05c68d4dc2700a982f89133ce103a1a84cc285f
 F test/walthread.test 14b20fcfa6ae152f5d8e12f5dc8a8a724b7ef189f5d8ef1e2ceab79f2af51747
@@ -1800,7 +1802,7 @@ F tool/mkshellc.tcl 70a9978e363b0f3280ca9ce1c46d72563ff479c1930a12a7375e3881b732
 F tool/mksourceid.c 36aa8020014aed0836fd13c51d6dc9219b0df1761d6b5f58ff5b616211b079b9
 F tool/mkspeedsql.tcl a1a334d288f7adfe6e996f2e712becf076745c97
 F tool/mksqlite3c-noext.tcl 4f7cfef5152b0c91920355cbfc1d608a4ad242cb819f1aea07f6d0274f584a7f
-F tool/mksqlite3c.tcl 5fed3d75069d8f66f202d3b5200b0cea4aa7108481acd06732a06fdd42eb83a2
+F tool/mksqlite3c.tcl 3ab95bcf7b765f9d6d99cbeb8c4f150b38b0bb1f001ffac688f2ad02ebce2123
 F tool/mksqlite3h.tcl 080873e3856eceb9d289a08a00c4b30f875ea3feadcbece796bd509b1532792c
 F tool/mksqlite3internalh.tcl eb994013e833359137eb53a55acdad0b5ae1049b
 F tool/mkvsix.tcl b9e0777a213c23156b6542842c238479e496ebf5
@@ -1862,7 +1864,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 2100b2c8f339e9778723fa0c91e479bab8675cf6fbea1664b6af49f40db6d27b
-R 90bb2d279dfaf51c661d9433e0108281
-U drh
-Z fa6729d909d64e1004093dfe525b2a80
+P ac4ee69664278a828e0a64c5be3b96fdb6eb6acc95646a9425c667aea328791c
+R 22b4478e3cf3c244a4ab3e6943ce3c12
+U dan
+Z e85493d3ac63dab3b3e9ea5cdd9d6a6e
@@ -1 +1 @@
-77a55c394d2c313a5710229bee9262457dcfc6620e6500f9f526c5f6acf87cef
+49e4dc72f7a4b28e4b49d7b91030bc986aea3ff44dac38cb6e68305800cd1de5
@@ -768,7 +768,7 @@ static void statPush(
    }
  }else
 #endif
-  if( p->nLimit && p->nRow>p->nLimit*(p->nSkipAhead+1) ){
+  if( p->nLimit && p->nRow>(tRowcnt)p->nLimit*(p->nSkipAhead+1) ){
    p->nSkipAhead++;
    sqlite3_result_int(context, p->current.anDLt[0]>0);
  }
@@ -112,7 +112,7 @@ static Btree *findBtree(sqlite3 *pErrorDb, sqlite3 *pDb, const char *zDb){
 */
 static int setDestPgsz(sqlite3_backup *p){
  int rc;
-  rc = sqlite3BtreeSetPageSize(p->pDest,sqlite3BtreeGetPageSize(p->pSrc),-1,0);
+  rc = sqlite3BtreeSetPageSize(p->pDest,sqlite3BtreeGetPageSize(p->pSrc),0,0);
  return rc;
 }

@@ -2304,8 +2304,7 @@ static int btreeInvokeBusyHandler(void *pArg){
  BtShared *pBt = (BtShared*)pArg;
  assert( pBt->db );
  assert( sqlite3_mutex_held(pBt->db->mutex) );
-  return sqlite3InvokeBusyHandler(&pBt->db->busyHandler,
-                                  sqlite3PagerFile(pBt->pPager));
+  return sqlite3InvokeBusyHandler(&pBt->db->busyHandler);
 }

 /*
@@ -2856,19 +2855,17 @@ int sqlite3BtreeSetPagerFlags(
 */
 int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve, int iFix){
  int rc = SQLITE_OK;
+  int x;
  BtShared *pBt = p->pBt;
-  assert( nReserve>=-1 && nReserve<=254 );
+  assert( nReserve>=0 && nReserve<=255 );
  sqlite3BtreeEnter(p);
-  if( nReserve>=0 ){
-    pBt->nReserveWanted = nReserve + 1;
-  }
+  pBt->nReserveWanted = nReserve;
+  x = pBt->pageSize - pBt->usableSize;
+  if( nReserve<x ) nReserve = x;
  if( pBt->btsFlags & BTS_PAGESIZE_FIXED ){
    sqlite3BtreeLeave(p);
    return SQLITE_READONLY;
  }
-  if( nReserve<0 ){
-    nReserve = pBt->pageSize - pBt->usableSize;
-  }
  assert( nReserve>=0 && nReserve<=255 );
  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
        ((pageSize-1)&pageSize)==0 ){
@@ -2919,12 +2916,12 @@ int sqlite3BtreeGetReserveNoMutex(Btree *p){
 ** The amount of reserve can only grow - never shrink.
 */
 int sqlite3BtreeGetRequestedReserve(Btree *p){
-  int n;
+  int n1, n2;
  sqlite3BtreeEnter(p);
-  n = ((int)p->pBt->nReserveWanted) - 1;
-  if( n<0 ) n = sqlite3BtreeGetReserveNoMutex(p);
+  n1 = (int)p->pBt->nReserveWanted;
+  n2 = sqlite3BtreeGetReserveNoMutex(p);
  sqlite3BtreeLeave(p);
-  return n;
+  return n1>n2 ? n1 : n2;
 }


@@ -3374,6 +3371,7 @@ int sqlite3BtreeNewDb(Btree *p){
 */
 int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
  BtShared *pBt = p->pBt;
+  Pager *pPager = pBt->pPager;
  int rc = SQLITE_OK;

  sqlite3BtreeEnter(p);
@@ -3389,7 +3387,7 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
  assert( pBt->inTransaction==TRANS_WRITE || IfNotOmitAV(pBt->bDoTruncate)==0 );

  if( (p->db->flags & SQLITE_ResetDatabase) 
-   && sqlite3PagerIsreadonly(pBt->pPager)==0 
+   && sqlite3PagerIsreadonly(pPager)==0 
  ){
    pBt->btsFlags &= ~BTS_READ_ONLY;
  }
@@ -3437,6 +3435,18 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
  pBt->btsFlags &= ~BTS_INITIALLY_EMPTY;
  if( pBt->nPage==0 ) pBt->btsFlags |= BTS_INITIALLY_EMPTY;
  do {
+    sqlite3PagerWalDb(pPager, p->db);
+
+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+    /* If transitioning from no transaction directly to a write transaction,
+    ** block for the WRITER lock first if possible. */
+    if( pBt->pPage1==0 && wrflag ){
+      assert( pBt->inTransaction==TRANS_NONE );
+      rc = sqlite3PagerWalWriteLock(pPager, 1);
+      if( rc!=SQLITE_BUSY && rc!=SQLITE_OK ) break;
+    }
+#endif
+
    /* Call lockBtree() until either pBt->pPage1 is populated or
    ** lockBtree() returns something other than SQLITE_OK. lockBtree()
    ** may return SQLITE_OK but leave pBt->pPage1 set to 0 if after
@@ -3450,7 +3460,7 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
      if( (pBt->btsFlags & BTS_READ_ONLY)!=0 ){
        rc = SQLITE_READONLY;
      }else{
-        rc = sqlite3PagerBegin(pBt->pPager,wrflag>1,sqlite3TempInMemory(p->db));
+        rc = sqlite3PagerBegin(pPager, wrflag>1, sqlite3TempInMemory(p->db));
        if( rc==SQLITE_OK ){
          rc = newDatabase(pBt);
        }else if( rc==SQLITE_BUSY_SNAPSHOT && pBt->inTransaction==TRANS_NONE ){
@@ -3463,11 +3473,15 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
    }
  
    if( rc!=SQLITE_OK ){
+      (void)sqlite3PagerWalWriteLock(pPager, 0);
      unlockBtreeIfUnused(pBt);
    }
  }while( (rc&0xFF)==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
          btreeInvokeBusyHandler(pBt) );
-  sqlite3PagerResetLockTimeout(pBt->pPager);
+  sqlite3PagerWalDb(pPager, 0);
+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+  if( rc==SQLITE_BUSY_TIMEOUT ) rc = SQLITE_BUSY;
+#endif

  if( rc==SQLITE_OK ){
    if( p->inTrans==TRANS_NONE ){
@@ -3519,7 +3533,7 @@ trans_begun:
      ** open savepoints. If the second parameter is greater than 0 and
      ** the sub-journal is not already open, then it will be opened here.
      */
-      rc = sqlite3PagerOpenSavepoint(pBt->pPager, p->db->nSavepoint);
+      rc = sqlite3PagerOpenSavepoint(pPager, p->db->nSavepoint);
    }
  }

@@ -7155,7 +7169,7 @@ static int editPage(
  assert( nCell>=0 );
  if( iOld<iNew ){
    int nShift = pageFreeArray(pPg, iOld, iNew-iOld, pCArray);
-    if( nShift>nCell ) return SQLITE_CORRUPT_BKPT;
+    if( NEVER(nShift>nCell) ) return SQLITE_CORRUPT_BKPT;
    memmove(pPg->aCellIdx, &pPg->aCellIdx[nShift*2], nCell*2);
    nCell -= nShift;
  }
@@ -417,7 +417,7 @@ struct BtShared {
 #endif
  u8 inTransaction;     /* Transaction state */
  u8 max1bytePayload;   /* Maximum first byte of cell for a 1-byte payload */
-  u8 nReserveWanted;    /* 1 more than desired number of extra bytes per page */
+  u8 nReserveWanted;    /* Desired number of extra bytes per page */
  u16 btsFlags;         /* Boolean parameters.  See BTS_* macros below */
  u16 maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
  u16 minLocal;         /* Minimum local payload in non-LEAFDATA tables */
@@ -4630,7 +4630,7 @@ int sqlite3OpenTempDatabase(Parse *pParse){
    }
    db->aDb[1].pBt = pBt;
    assert( db->aDb[1].pSchema );
-    if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize, -1, 0) ){
+    if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize, 0, 0) ){
      sqlite3OomFault(db);
      return 1;
    }
@@ -193,6 +193,9 @@ static const char * const sqlite3azCompileOpt[] = {
 #if SQLITE_ENABLE_BATCH_ATOMIC_WRITE
  "ENABLE_BATCH_ATOMIC_WRITE",
 #endif
+#if SQLITE_ENABLE_BYTECODE_VTAB
+  "ENABLE_BYTECODE_VTAB",
+#endif
 #if SQLITE_ENABLE_CEROD
  "ENABLE_CEROD=" CTIMEOPT_VAL(SQLITE_ENABLE_CEROD),
 #endif
@@ -858,6 +858,7 @@ void sqlite3GenerateRowIndexDelete(
        &iPartIdxLabel, pPrior, r1);
    sqlite3VdbeAddOp3(v, OP_IdxDelete, iIdxCur+i, r1,
        pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
+    sqlite3VdbeChangeP5(v, 1);  /* Cause IdxDelete to error if no entry found */
    sqlite3ResolvePartIdxLabel(pParse, iPartIdxLabel);
    pPrior = pIdx;
  }
@@ -25,15 +25,78 @@
 #if defined(SQLITE_ENABLE_ICU) || defined(SQLITE_ENABLE_ICU_COLLATIONS)
 # include "sqliteicu.h"
 #endif
+
+/*
+** This is an extension initializer that is a no-op and always
+** succeeds, except that it fails if the fault-simulation is set
+** to 500.
+*/
+static int sqlite3TestExtInit(sqlite3 *db){
+  (void)db;
+  return sqlite3FaultSim(500);
+}
+
+
+/*
+** Forward declarations of external module initializer functions
+** for modules that need them.
+*/
+#ifdef SQLITE_ENABLE_FTS1
+int sqlite3Fts1Init(sqlite3*);
+#endif
+#ifdef SQLITE_ENABLE_FTS2
+int sqlite3Fts2Init(sqlite3*);
+#endif
+#ifdef SQLITE_ENABLE_FTS5
+int sqlite3Fts5Init(sqlite3*);
+#endif
 #ifdef SQLITE_ENABLE_JSON1
 int sqlite3Json1Init(sqlite3*);
 #endif
 #ifdef SQLITE_ENABLE_STMTVTAB
 int sqlite3StmtVtabInit(sqlite3*);
 #endif
-#ifdef SQLITE_ENABLE_FTS5
-int sqlite3Fts5Init(sqlite3*);
+
+/*
+** An array of pointers to extension initializer functions for
+** built-in extensions.
+*/
+static int (*const sqlite3BuiltinExtensions[])(sqlite3*) = {
+#ifdef SQLITE_ENABLE_FTS1
+  sqlite3Fts1Init,
 #endif
+#ifdef SQLITE_ENABLE_FTS2
+  sqlite3Fts2Init,
+#endif
+#ifdef SQLITE_ENABLE_FTS3
+  sqlite3Fts3Init,
+#endif
+#ifdef SQLITE_ENABLE_FTS5
+  sqlite3Fts5Init,
+#endif
+#if defined(SQLITE_ENABLE_ICU) || defined(SQLITE_ENABLE_ICU_COLLATIONS)
+  sqlite3IcuInit,
+#endif
+#ifdef SQLITE_ENABLE_RTREE
+  sqlite3RtreeInit,
+#endif
+#ifdef SQLITE_ENABLE_DBPAGE_VTAB
+  sqlite3DbpageRegister,
+#endif
+#ifdef SQLITE_ENABLE_DBSTAT_VTAB
+  sqlite3DbstatRegister,
+#endif
+  sqlite3TestExtInit,
+#ifdef SQLITE_ENABLE_JSON1
+  sqlite3Json1Init,
+#endif
+#ifdef SQLITE_ENABLE_STMTVTAB
+  sqlite3StmtVtabInit,
+#endif
+#ifdef SQLITE_ENABLE_BYTECODE_VTAB
+  sqlite3VdbeBytecodeVtabInit,
+#endif
+};

 #ifndef SQLITE_AMALGAMATION
 /* IMPLEMENTATION-OF: R-46656-45156 The sqlite3_version[] string constant
@@ -1551,8 +1614,7 @@ const char *sqlite3ErrStr(int rc){
 */
 static int sqliteDefaultBusyCallback(
  void *ptr,               /* Database connection */
-  int count,               /* Number of times table has been busy */
-  sqlite3_file *pFile      /* The file on which the lock occurred */
+  int count                /* Number of times table has been busy */
 ){
 #if SQLITE_OS_WIN || HAVE_USLEEP
  /* This case is for systems that have support for sleeping for fractions of
@@ -1566,31 +1628,6 @@ static int sqliteDefaultBusyCallback(
  int tmout = db->busyTimeout;
  int delay, prior;

-#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
-  if( sqlite3OsFileControl(pFile,SQLITE_FCNTL_LOCK_TIMEOUT,&tmout)==SQLITE_OK ){
-    if( count ){
-      /* If this is the second or later invocation of the busy-handler,
-      ** but tmout==0, then code in wal.c must have disabled the blocking
-      ** lock before the SQLITE_BUSY error was hit. In this case, no delay
-      ** occurred while waiting for the lock, so fall through to the xSleep()
-      ** code below to delay a while before retrying the lock.  
-      **
-      ** Alternatively, if tmout!=0, then SQLite has already waited 
-      ** sqlite3.busyTimeout ms for a lock. In this case, return 0 to 
-      ** indicate that the lock should not be retried and the SQLITE_BUSY 
-      ** error returned to the application.  */
-      if( tmout ){
-        tmout = 0;
-        sqlite3OsFileControl(pFile, SQLITE_FCNTL_LOCK_TIMEOUT, &tmout);
-        return 0;
-      }
-    }else{
-      return 1;
-    }
-  }
-#else
-  UNUSED_PARAMETER(pFile);
-#endif
  assert( count>=0 );
  if( count < NDELAY ){
    delay = delays[count];
@@ -1610,7 +1647,6 @@ static int sqliteDefaultBusyCallback(
  ** must be done in increments of whole seconds */
  sqlite3 *db = (sqlite3 *)ptr;
  int tmout = ((sqlite3 *)ptr)->busyTimeout;
-  UNUSED_PARAMETER(pFile);
  if( (count+1)*1000 > tmout ){
    return 0;
  }
@@ -1628,19 +1664,10 @@ static int sqliteDefaultBusyCallback(
 ** If this routine returns non-zero, the lock is retried.  If it
 ** returns 0, the operation aborts with an SQLITE_BUSY error.
 */
-int sqlite3InvokeBusyHandler(BusyHandler *p, sqlite3_file *pFile){
+int sqlite3InvokeBusyHandler(BusyHandler *p){
  int rc;
  if( p->xBusyHandler==0 || p->nBusy<0 ) return 0;
-  if( p->bExtraFileArg ){
-    /* Add an extra parameter with the pFile pointer to the end of the
-    ** callback argument list */
-    int (*xTra)(void*,int,sqlite3_file*);
-    xTra = (int(*)(void*,int,sqlite3_file*))p->xBusyHandler;
-    rc = xTra(p->pBusyArg, p->nBusy, pFile);
-  }else{
-    /* Legacy style busy handler callback */
-    rc = p->xBusyHandler(p->pBusyArg, p->nBusy);
-  }
+  rc = p->xBusyHandler(p->pBusyArg, p->nBusy);
  if( rc==0 ){
    p->nBusy = -1;
  }else{
@@ -1665,7 +1692,6 @@ int sqlite3_busy_handler(
  db->busyHandler.xBusyHandler = xBusy;
  db->busyHandler.pBusyArg = pArg;
  db->busyHandler.nBusy = 0;
-  db->busyHandler.bExtraFileArg = 0;
  db->busyTimeout = 0;
  sqlite3_mutex_leave(db->mutex);
  return SQLITE_OK;
@@ -1716,7 +1742,6 @@ int sqlite3_busy_timeout(sqlite3 *db, int ms){
    sqlite3_busy_handler(db, (int(*)(void*,int))sqliteDefaultBusyCallback,
                             (void*)db);
    db->busyTimeout = ms;
-    db->busyHandler.bExtraFileArg = 1;
  }else{
    sqlite3_busy_handler(db, 0, 0);
  }
@@ -3042,6 +3067,7 @@ static int openDatabase(
  int isThreadsafe;               /* True for threadsafe connections */
  char *zOpen = 0;                /* Filename argument to pass to BtreeOpen() */
  char *zErrMsg = 0;              /* Error message from sqlite3ParseUri() */
+  int i;                          /* Loop counter */

 #ifdef SQLITE_ENABLE_API_ARMOR
  if( ppDb==0 ) return SQLITE_MISUSE_BKPT;
@@ -3189,6 +3215,9 @@ static int openDatabase(
 #endif
 #if defined(SQLITE_DEFAULT_DEFENSIVE)
                 | SQLITE_Defensive
+#endif
+#if defined(SQLITE_DEFAULT_LEGACY_ALTER_TABLE)
+                 | SQLITE_LegacyAlter
 #endif
      ;
  sqlite3HashInit(&db->aCollSeq);
@@ -3282,14 +3311,11 @@ static int openDatabase(
  sqlite3RegisterPerConnectionBuiltinFunctions(db);
  rc = sqlite3_errcode(db);

-#ifdef SQLITE_ENABLE_FTS5
-  /* Register any built-in FTS5 module before loading the automatic
-  ** extensions. This allows automatic extensions to register FTS5 
-  ** tokenizers and auxiliary functions.  */
-  if( !db->mallocFailed && rc==SQLITE_OK ){
-    rc = sqlite3Fts5Init(db);
+
+  /* Load compiled-in extensions */
+  for(i=0; rc==SQLITE_OK && i<ArraySize(sqlite3BuiltinExtensions); i++){
+    rc = sqlite3BuiltinExtensions[i](db);
  }
-#endif

  /* Load automatic extensions - extensions that have been registered
  ** using the sqlite3_automatic_extension() API.
@@ -3302,62 +3328,6 @@ static int openDatabase(
    }
  }

-#ifdef SQLITE_ENABLE_FTS1
-  if( !db->mallocFailed ){
-    extern int sqlite3Fts1Init(sqlite3*);
-    rc = sqlite3Fts1Init(db);
-  }
-#endif
-
-#ifdef SQLITE_ENABLE_FTS2
-  if( !db->mallocFailed && rc==SQLITE_OK ){
-    extern int sqlite3Fts2Init(sqlite3*);
-    rc = sqlite3Fts2Init(db);
-  }
-#endif
-
-#ifdef SQLITE_ENABLE_FTS3 /* automatically defined by SQLITE_ENABLE_FTS4 */
-  if( !db->mallocFailed && rc==SQLITE_OK ){
-    rc = sqlite3Fts3Init(db);
-  }
-#endif
-
-#if defined(SQLITE_ENABLE_ICU) || defined(SQLITE_ENABLE_ICU_COLLATIONS)
-  if( !db->mallocFailed && rc==SQLITE_OK ){
-    rc = sqlite3IcuInit(db);
-  }
-#endif
-
-#ifdef SQLITE_ENABLE_RTREE
-  if( !db->mallocFailed && rc==SQLITE_OK){
-    rc = sqlite3RtreeInit(db);
-  }
-#endif
-
-#ifdef SQLITE_ENABLE_DBPAGE_VTAB
-  if( !db->mallocFailed && rc==SQLITE_OK){
-    rc = sqlite3DbpageRegister(db);
-  }
-#endif
-
-#ifdef SQLITE_ENABLE_DBSTAT_VTAB
-  if( !db->mallocFailed && rc==SQLITE_OK){
-    rc = sqlite3DbstatRegister(db);
-  }
-#endif
-
-#ifdef SQLITE_ENABLE_JSON1
-  if( !db->mallocFailed && rc==SQLITE_OK){
-    rc = sqlite3Json1Init(db);
-  }
-#endif
-
-#ifdef SQLITE_ENABLE_STMTVTAB
-  if( !db->mallocFailed && rc==SQLITE_OK){
-    rc = sqlite3StmtVtabInit(db);
-  }
-#endif
-
 #ifdef SQLITE_ENABLE_INTERNAL_FUNCTIONS
  /* Testing use only!!! The -DSQLITE_ENABLE_INTERNAL_FUNCTIONS=1 compile-time
  ** option gives access to internal functions by default.  
@@ -3846,7 +3816,7 @@ int sqlite3_file_control(sqlite3 *db, const char *zDbName, int op, void *pArg){
    }else if( op==SQLITE_FCNTL_RESERVE_BYTES ){
      int iNew = *(int*)pArg;
      *(int*)pArg = sqlite3BtreeGetRequestedReserve(pBtree);
-      if( iNew>=0 && iNew<=254 ){
+      if( iNew>=0 && iNew<=255 ){
        sqlite3BtreeSetPageSize(pBtree, 0, iNew, 0);
      }
      rc = SQLITE_OK;
@@ -1565,8 +1565,9 @@ static int osSetPosixAdvisoryLock(
  struct flock *pLock,  /* The description of the lock */
  unixFile *pFile       /* Structure holding timeout value */
 ){
+  int tm = pFile->iBusyTimeout;
  int rc = osFcntl(h,F_SETLK,pLock);
-  while( rc<0 && pFile->iBusyTimeout>0 ){
+  while( rc<0 && tm>0 ){
    /* On systems that support some kind of blocking file lock with a timeout,
    ** make appropriate changes here to invoke that blocking file lock.  On
    ** generic posix, however, there is no such API.  So we simply try the
@@ -1574,7 +1575,7 @@ static int osSetPosixAdvisoryLock(
    ** the lock is obtained. */
    usleep(1000);
    rc = osFcntl(h,F_SETLK,pLock);
-    pFile->iBusyTimeout--;
+    tm--;
  }
  return rc;
 }
@@ -4316,13 +4317,20 @@ static int unixShmSystemLock(
  assert( n>=1 && n<=SQLITE_SHM_NLOCK );

  if( pShmNode->hShm>=0 ){
+    int res;
    /* Initialize the locking parameters */
    f.l_type = lockType;
    f.l_whence = SEEK_SET;
    f.l_start = ofst;
    f.l_len = n;
-    rc = osSetPosixAdvisoryLock(pShmNode->hShm, &f, pFile);
-    rc = (rc!=(-1)) ? SQLITE_OK : SQLITE_BUSY;
+    res = osSetPosixAdvisoryLock(pShmNode->hShm, &f, pFile);
+    if( res==-1 ){
+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+      rc = (pFile->iBusyTimeout ? SQLITE_BUSY_TIMEOUT : SQLITE_BUSY);
+#else
+      rc = SQLITE_BUSY;
+#endif
+    }
  }

  /* Update the global lock state and do debug tracing */
@@ -4819,22 +4827,23 @@ static int unixShmLock(
  assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 );
  assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 );

-  /* Check that, if this to be a blocking lock, that locks have been
-  ** obtained in the following order.
+  /* Check that, if this to be a blocking lock, no locks that occur later
+  ** in the following list than the lock being obtained are already held:
  **
  **   1. Checkpointer lock (ofst==1).
-  **   2. Recover lock (ofst==2).
+  **   2. Write lock (ofst==0).
  **   3. Read locks (ofst>=3 && ofst<SQLITE_SHM_NLOCK).
-  **   4. Write lock (ofst==0).
  **
  ** In other words, if this is a blocking lock, none of the locks that
  ** occur later in the above list than the lock being obtained may be
  ** held.  */
 #ifdef SQLITE_ENABLE_SETLK_TIMEOUT
-  assert( pDbFd->iBusyTimeout==0 
-       || (flags & SQLITE_SHM_UNLOCK) || ofst==0
-       || ((p->exclMask|p->sharedMask)&~((1<<ofst)-2))==0
-  );
+  assert( (flags & SQLITE_SHM_UNLOCK) || pDbFd->iBusyTimeout==0 || (
+         (ofst!=2)                                   /* not RECOVER */
+      && (ofst!=1 || (p->exclMask|p->sharedMask)==0)
+      && (ofst!=0 || (p->exclMask|p->sharedMask)<3)
+      && (ofst<3  || (p->exclMask|p->sharedMask)<(1<<ofst))
+  ));
 #endif

  mask = (1<<(ofst+n)) - (1<<ofst);
@@ -5705,7 +5705,6 @@ void sqlite3PagerUnrefPageOne(DbPage *pPg){
  assert( pPg->pgno==1 );
  assert( (pPg->flags & PGHDR_MMAP)==0 ); /* Page1 is never memory mapped */
  pPager = pPg->pPager;
-  sqlite3PagerResetLockTimeout(pPager);
  sqlite3PcacheRelease(pPg);
  pagerUnlockIfUnused(pPager);
 }
@@ -6998,16 +6997,6 @@ sqlite3_file *sqlite3PagerFile(Pager *pPager){
  return pPager->fd;
 }

-#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
-/*
-** Reset the lock timeout for pager.
-*/
-void sqlite3PagerResetLockTimeout(Pager *pPager){
-  int x = 0;
-  sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_LOCK_TIMEOUT, &x);
-}
-#endif
-
 /*
 ** Return the file handle for the journal file (if it exists).
 ** This will be either the rollback journal or the WAL file.
@@ -7421,7 +7410,6 @@ int sqlite3PagerCheckpoint(
        pPager->walSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
        pnLog, pnCkpt
    );
-    sqlite3PagerResetLockTimeout(pPager);
  }
  return rc;
 }
@@ -7586,7 +7574,31 @@ int sqlite3PagerCloseWal(Pager *pPager, sqlite3 *db){
  return rc;
 }

+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+/*
+** If pager pPager is a wal-mode database not in exclusive locking mode,
+** invoke the sqlite3WalWriteLock() function on the associated Wal object 
+** with the same db and bLock parameters as were passed to this function.
+** Return an SQLite error code if an error occurs, or SQLITE_OK otherwise.
+*/
+int sqlite3PagerWalWriteLock(Pager *pPager, int bLock){
+  int rc = SQLITE_OK;
+  if( pagerUseWal(pPager) && pPager->exclusiveMode==0 ){
+    rc = sqlite3WalWriteLock(pPager->pWal, bLock);
+  }
+  return rc;
+}

+/*
+** Set the database handle used by the wal layer to determine if 
+** blocking locks are required.
+*/
+void sqlite3PagerWalDb(Pager *pPager, sqlite3 *db){
+  if( pagerUseWal(pPager) ){
+    sqlite3WalDb(pPager->pWal, db);
+  }
+}
+#endif

 #ifdef SQLITE_ENABLE_SNAPSHOT
 /*
@@ -7606,7 +7618,10 @@ int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot){
 ** read transaction is opened, attempt to read from the snapshot it 
 ** identifies. If this is not a WAL database, return an error.
 */
-int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot){
+int sqlite3PagerSnapshotOpen(
+  Pager *pPager, 
+  sqlite3_snapshot *pSnapshot
+){
  int rc = SQLITE_OK;
  if( pPager->pWal ){
    sqlite3WalSnapshotOpen(pPager->pWal, pSnapshot);
@@ -177,14 +177,22 @@ int sqlite3PagerSharedLock(Pager *pPager);
  int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
  int sqlite3PagerCloseWal(Pager *pPager, sqlite3*);
 # ifdef SQLITE_ENABLE_SNAPSHOT
-  int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot);
-  int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot);
+  int sqlite3PagerSnapshotGet(Pager*, sqlite3_snapshot **ppSnapshot);
+  int sqlite3PagerSnapshotOpen(Pager*, sqlite3_snapshot *pSnapshot);
  int sqlite3PagerSnapshotRecover(Pager *pPager);
  int sqlite3PagerSnapshotCheck(Pager *pPager, sqlite3_snapshot *pSnapshot);
  void sqlite3PagerSnapshotUnlock(Pager *pPager);
 # endif
 #endif

+#if !defined(SQLITE_OMIT_WAL) && defined(SQLITE_ENABLE_SETLK_TIMEOUT)
+  int sqlite3PagerWalWriteLock(Pager*, int);
+  void sqlite3PagerWalDb(Pager*, sqlite3*);
+#else
+# define sqlite3PagerWalWriteLock(y,z) SQLITE_OK
+# define sqlite3PagerWalDb(x,y)
+#endif
+
 #ifdef SQLITE_DIRECT_OVERFLOW_READ
  int sqlite3PagerDirectReadOk(Pager *pPager, Pgno pgno);
 #endif
@@ -210,11 +218,6 @@ int sqlite3PagerIsMemdb(Pager*);
 void sqlite3PagerCacheStat(Pager *, int, int, int *);
 void sqlite3PagerClearCache(Pager*);
 int sqlite3SectorSize(sqlite3_file *);
-#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
-void sqlite3PagerResetLockTimeout(Pager *pPager);
-#else
-# define sqlite3PagerResetLockTimeout(X)
-#endif

 /* Functions used to truncate the database file. */
 void sqlite3PagerTruncateImage(Pager*,Pgno);
@@ -555,7 +555,7 @@ void sqlite3Pragma(
      ** buffer that the pager module resizes using sqlite3_realloc().
      */
      db->nextPagesize = sqlite3Atoi(zRight);
-      if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize,-1,0) ){
+      if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize,0,0) ){
        sqlite3OomFault(db);
      }
    }
@@ -3158,6 +3158,7 @@ static int shell_exec(
            const char *zEQPLine = (const char*)sqlite3_column_text(pExplain,3);
            int iEqpId = sqlite3_column_int(pExplain, 0);
            int iParentId = sqlite3_column_int(pExplain, 1);
+            if( zEQPLine==0 ) zEQPLine = "";
            if( zEQPLine[0]=='-' ) eqp_render(pArg);
            eqp_append(pArg, iEqpId, iParentId, zEQPLine);
          }
@@ -508,6 +508,7 @@ int sqlite3_exec(
 #define SQLITE_LOCKED_VTAB             (SQLITE_LOCKED |  (2<<8))
 #define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
 #define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
+#define SQLITE_BUSY_TIMEOUT            (SQLITE_BUSY   |  (3<<8))
 #define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
 #define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
 #define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
@@ -516,6 +517,7 @@ int sqlite3_exec(
 #define SQLITE_CANTOPEN_SYMLINK        (SQLITE_CANTOPEN | (6<<8))
 #define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
 #define SQLITE_CORRUPT_SEQUENCE        (SQLITE_CORRUPT | (2<<8))
+#define SQLITE_CORRUPT_INDEX           (SQLITE_CORRUPT | (3<<8))
 #define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
 #define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
 #define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
@@ -1111,6 +1113,11 @@ struct sqlite3_io_methods {
 ** happen either internally or externally and that are associated with
 ** a particular attached database.
 **
+** <li>[[SQLITE_FCNTL_CKPT_START]]
+** The [SQLITE_FCNTL_CKPT_START] opcode is invoked from within a checkpoint
+** in wal mode before the client starts to copy pages from the wal
+** file to the database file.
+**
 ** <li>[[SQLITE_FCNTL_CKPT_DONE]]
 ** The [SQLITE_FCNTL_CKPT_DONE] opcode is invoked from within a checkpoint
 ** in wal mode after the client has finished copying pages from the wal
@@ -1155,6 +1162,7 @@ struct sqlite3_io_methods {
 #define SQLITE_FCNTL_SIZE_LIMIT             36
 #define SQLITE_FCNTL_CKPT_DONE              37
 #define SQLITE_FCNTL_RESERVE_BYTES          38
+#define SQLITE_FCNTL_CKPT_START             39

 /* deprecated names */
 #define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
@@ -994,7 +994,6 @@ struct BusyHandler {
  int (*xBusyHandler)(void *,int);  /* The busy callback */
  void *pBusyArg;                   /* First arg to busy callback */
  int nBusy;                        /* Incremented with each busy call */
-  u8 bExtraFileArg;                 /* Include sqlite3_file as callback arg */
 };

 /*
@@ -4585,7 +4584,7 @@ void sqlite3RenameExprlistUnmap(Parse*, ExprList*);
 CollSeq *sqlite3GetCollSeq(Parse*, u8, CollSeq *, const char*);
 char sqlite3AffinityType(const char*, Column*);
 void sqlite3Analyze(Parse*, Token*, Token*);
-int sqlite3InvokeBusyHandler(BusyHandler*, sqlite3_file*);
+int sqlite3InvokeBusyHandler(BusyHandler*);
 int sqlite3FindDb(sqlite3*, Token*);
 int sqlite3FindDbName(sqlite3 *, const char *);
 int sqlite3AnalysisLoad(sqlite3*,int iDB);
@@ -377,7 +377,7 @@ end_of_vacuum:
  db->nChange = saved_nChange;
  db->nTotalChange = saved_nTotalChange;
  db->mTrace = saved_mTrace;
-  sqlite3BtreeSetPageSize(pMain, -1, -1, 1);
+  sqlite3BtreeSetPageSize(pMain, -1, 0, 1);

  /* Currently there is an SQL level transaction open on the vacuum
  ** database. No locks are held on any other files (since the main file
@@ -5652,12 +5652,19 @@ case OP_SorterInsert: {     /* in2 */
  break;
 }

-/* Opcode: IdxDelete P1 P2 P3 * *
+/* Opcode: IdxDelete P1 P2 P3 * P5
 ** Synopsis: key=r[P2@P3]
 **
 ** The content of P3 registers starting at register P2 form
 ** an unpacked index key. This opcode removes that entry from the 
 ** index opened by cursor P1.
+**
+** If P5 is not zero, then raise an SQLITE_CORRUPT_INDEX error
+** if no matching index entry is found.  This happens when running
+** an UPDATE or DELETE statement and the index entry to be updated
+** or deleted is not found.  For some uses of IdxDelete
+** (example:  the EXCEPT operator) it does not matter that no matching
+** entry is found.  For those cases, P5 is zero.
 */
 case OP_IdxDelete: {
  VdbeCursor *pC;
@@ -5674,7 +5681,6 @@ case OP_IdxDelete: {
  sqlite3VdbeIncrWriteCounter(p, pC);
  pCrsr = pC->uc.pCursor;
  assert( pCrsr!=0 );
-  assert( pOp->p5==0 );
  r.pKeyInfo = pC->pKeyInfo;
  r.nField = (u16)pOp->p3;
  r.default_rc = 0;
@@ -5684,6 +5690,9 @@ case OP_IdxDelete: {
  if( res==0 ){
    rc = sqlite3BtreeDelete(pCrsr, BTREE_AUXDELETE);
    if( rc ) goto abort_due_to_error;
+  }else if( pOp->p5 ){
+    rc = SQLITE_CORRUPT_INDEX;
+    goto abort_due_to_error;
  }
  assert( pC->deferredMoveto==0 );
  pC->cacheStatus = CACHE_STALE;
@@ -290,6 +290,9 @@ void sqlite3VdbeLinkSubProgram(Vdbe *, SubProgram *);
 int sqlite3VdbeHasSubProgram(Vdbe*);

 int sqlite3NotPureFunc(sqlite3_context*);
+#ifdef SQLITE_ENABLE_BYTECODE_VTAB
+int sqlite3VdbeBytecodeVtabInit(sqlite3*);
+#endif

 /* Use SQLITE_ENABLE_COMMENTS to enable generation of extra comments on
 ** each VDBE opcode.
@@ -31,7 +31,8 @@
 ** "explain" P4 display logic is enabled.
 */
 #if !defined(SQLITE_OMIT_EXPLAIN) || !defined(NDEBUG) \
-     || defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
+     || defined(VDBE_PROFILE) || defined(SQLITE_DEBUG) \
+     || defined(SQLITE_ENABLE_BYTECODE_VTAB)
 # define VDBE_DISPLAY_P4 1
 #else
 # define VDBE_DISPLAY_P4 0
@@ -496,7 +497,14 @@ int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
 int sqlite3VdbeIdxKeyCompare(sqlite3*,VdbeCursor*,UnpackedRecord*,int*);
 int sqlite3VdbeIdxRowid(sqlite3*, BtCursor*, i64*);
 int sqlite3VdbeExec(Vdbe*);
-#ifndef SQLITE_OMIT_EXPLAIN
+#if !defined(SQLITE_OMIT_EXPLAIN) || defined(SQLITE_ENABLE_BYTECODE_VTAB)
+int sqlite3VdbeNextOpcode(Vdbe*,Mem*,int,int*,int*,Op**);
+char *sqlite3VdbeDisplayP4(sqlite3*,Op*);
+#endif
+#if defined(SQLITE_ENABLE_EXPLAIN_COMMENTS)
+char *sqlite3VdbeDisplayComment(sqlite3*,const Op*,const char*);
+#endif
+#if !defined(SQLITE_OMIT_EXPLAIN)
 int sqlite3VdbeList(Vdbe*);
 #endif
 int sqlite3VdbeHalt(Vdbe*);
@@ -538,7 +546,7 @@ int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
 #ifndef SQLITE_OMIT_WINDOWFUNC
 int sqlite3VdbeMemAggValue(Mem*, Mem*, FuncDef*);
 #endif
-#ifndef SQLITE_OMIT_EXPLAIN
+#if !defined(SQLITE_OMIT_EXPLAIN) || defined(SQLITE_ENABLE_BYTECODE_VTAB)
 const char *sqlite3OpcodeName(int);
 #endif
 int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
@@ -1464,11 +1464,10 @@ static int translateP(char c, const Op *pOp){
 **       "PX@PY+1" ->  "r[X..X+Y]"    or "r[x]" if y is 0
 **       "PY..PY"  ->  "r[X..Y]"      or "r[x]" if y<=x
 */
-static int displayComment(
+char *sqlite3VdbeDisplayComment(
+  sqlite3 *db,       /* Optional - Oom error reporting only */
  const Op *pOp,     /* The opcode to be commented */
-  const char *zP4,   /* Previously obtained value for P4 */
-  char *zTemp,       /* Write result here */
-  int nTemp          /* Space available in zTemp[] */
+  const char *zP4    /* Previously obtained value for P4 */
 ){
  const char *zOpName;
  const char *zSynopsis;
@@ -1476,8 +1475,8 @@ static int displayComment(
  int ii;
  char zAlt[50];
  StrAccum x;
-  sqlite3StrAccumInit(&x, 0, zTemp, nTemp, 0);

+  sqlite3StrAccumInit(&x, 0, 0, 0, SQLITE_MAX_LENGTH);
  zOpName = sqlite3OpcodeName(pOp->opcode);
  nOpName = sqlite3Strlen30(zOpName);
  if( zOpName[nOpName+1] ){
@@ -1544,10 +1543,12 @@ static int displayComment(
  }else if( pOp->zComment ){
    sqlite3_str_appendall(&x, pOp->zComment);
  }
-  sqlite3StrAccumFinish(&x);
-  return x.nChar;
+  if( (x.accError & SQLITE_NOMEM)!=0 && db!=0 ){
+    sqlite3OomFault(db);
+  }
+  return sqlite3StrAccumFinish(&x);
 }
-#endif /* SQLITE_DEBUG */
+#endif /* SQLITE_ENABLE_EXPLAIN_COMMENTS */

 #if VDBE_DISPLAY_P4 && defined(SQLITE_ENABLE_CURSOR_HINTS)
 /*
@@ -1628,11 +1629,11 @@ static void displayP4Expr(StrAccum *p, Expr *pExpr){
 ** Compute a string that describes the P4 parameter for an opcode.
 ** Use zTemp for any required temporary buffer space.
 */
-static char *displayP4(Op *pOp, char *zTemp, int nTemp){
-  char *zP4 = zTemp;
+char *sqlite3VdbeDisplayP4(sqlite3 *db, Op *pOp){
+  char *zP4 = 0;
  StrAccum x;
-  assert( nTemp>=20 );
-  sqlite3StrAccumInit(&x, 0, zTemp, nTemp, 0);
+
+  sqlite3StrAccumInit(&x, 0, 0, 0, SQLITE_MAX_LENGTH);
  switch( pOp->p4type ){
    case P4_KEYINFO: {
      int j;
@@ -1716,36 +1717,32 @@ static char *displayP4(Op *pOp, char *zTemp, int nTemp){
      int n = ai[0];   /* The first element of an INTARRAY is always the
                       ** count of the number of elements to follow */
      for(i=1; i<=n; i++){
-        sqlite3_str_appendf(&x, ",%d", ai[i]);
+        sqlite3_str_appendf(&x, "%c%d", (i==1 ? '[' : ','), ai[i]);
      }
-      zTemp[0] = '[';
      sqlite3_str_append(&x, "]", 1);
      break;
    }
    case P4_SUBPROGRAM: {
-      sqlite3_str_appendf(&x, "program");
+      zP4 = "program";
      break;
    }
    case P4_DYNBLOB:
    case P4_ADVANCE: {
-      zTemp[0] = 0;
      break;
    }
    case P4_TABLE: {
-      sqlite3_str_appendf(&x, "%s", pOp->p4.pTab->zName);
+      zP4 = pOp->p4.pTab->zName;
      break;
    }
    default: {
      zP4 = pOp->p4.z;
-      if( zP4==0 ){
-        zP4 = zTemp;
-        zTemp[0] = 0;
-      }
    }
  }
-  sqlite3StrAccumFinish(&x);
-  assert( zP4!=0 );
-  return zP4;
+  if( zP4 ) sqlite3_str_appendall(&x, zP4);
+  if( (x.accError & SQLITE_NOMEM)!=0 ){
+    sqlite3OomFault(db);
+  }
+  return sqlite3StrAccumFinish(&x);
 }
 #endif /* VDBE_DISPLAY_P4 */

@@ -1835,24 +1832,28 @@ void sqlite3VdbeLeave(Vdbe *p){
 */
 void sqlite3VdbePrintOp(FILE *pOut, int pc, VdbeOp *pOp){
  char *zP4;
-  char zPtr[50];
-  char zCom[100];
+  char *zCom;
+  sqlite3 dummyDb;
  static const char *zFormat1 = "%4d %-13s %4d %4d %4d %-13s %.2X %s\n";
  if( pOut==0 ) pOut = stdout;
-  zP4 = displayP4(pOp, zPtr, sizeof(zPtr));
+  dummyDb.mallocFailed = 1;
+  zP4 = sqlite3VdbeDisplayP4(&dummyDb, pOp);
 #ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
-  displayComment(pOp, zP4, zCom, sizeof(zCom));
+  zCom = sqlite3VdbeDisplayComment(0, pOp, zP4);
 #else
-  zCom[0] = 0;
+  zCom = 0;
 #endif
  /* NB:  The sqlite3OpcodeName() function is implemented by code created
  ** by the mkopcodeh.awk and mkopcodec.awk scripts which extract the
  ** information from the vdbe.c source text */
  fprintf(pOut, zFormat1, pc, 
-      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, zP4, pOp->p5,
-      zCom
+      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, 
+      zP4 ? zP4 : "", pOp->p5,
+      zCom ? zCom : ""
  );
  fflush(pOut);
+  sqlite3_free(zP4);
+  sqlite3_free(zCom);
 }
 #endif

@@ -1943,6 +1944,121 @@ void sqlite3VdbeFrameMemDel(void *pArg){
  pFrame->v->pDelFrame = pFrame;
 }

+#if defined(SQLITE_ENABLE_BYTECODE_VTAB) || !defined(SQLITE_OMIT_EXPLAIN)
+/*
+** Locate the next opcode to be displayed in EXPLAIN or EXPLAIN
+** QUERY PLAN output.
+**
+** Return SQLITE_ROW on success.  Return SQLITE_DONE if there are no
+** more opcodes to be displayed.
+*/
+int sqlite3VdbeNextOpcode(
+  Vdbe *p,         /* The statement being explained */
+  Mem *pSub,       /* Storage for keeping track of subprogram nesting */
+  int eMode,       /* 0: normal.  1: EQP.  2:  TablesUsed */
+  int *piPc,       /* IN/OUT: Current rowid.  Overwritten with next rowid */
+  int *piAddr,     /* OUT: Write index into (*paOp)[] here */
+  Op **paOp        /* OUT: Write the opcode array here */
+){
+  int nRow;                            /* Stop when row count reaches this */
+  int nSub = 0;                        /* Number of sub-vdbes seen so far */
+  SubProgram **apSub = 0;              /* Array of sub-vdbes */
+  int i;                               /* Next instruction address */
+  int rc = SQLITE_OK;                  /* Result code */
+  Op *aOp = 0;                         /* Opcode array */
+  int iPc;                             /* Rowid.  Copy of value in *piPc */
+
+  /* When the number of output rows reaches nRow, that means the
+  ** listing has finished and sqlite3_step() should return SQLITE_DONE.
+  ** nRow is the sum of the number of rows in the main program, plus
+  ** the sum of the number of rows in all trigger subprograms encountered
+  ** so far.  The nRow value will increase as new trigger subprograms are
+  ** encountered, but p->pc will eventually catch up to nRow.
+  */
+  nRow = p->nOp;
+  if( pSub!=0 ){
+    if( pSub->flags&MEM_Blob ){
+      /* pSub is initiallly NULL.  It is initialized to a BLOB by
+      ** the P4_SUBPROGRAM processing logic below */
+      nSub = pSub->n/sizeof(Vdbe*);
+      apSub = (SubProgram **)pSub->z;
+    }
+    for(i=0; i<nSub; i++){
+      nRow += apSub[i]->nOp;
+    }
+  }
+  iPc = *piPc;
+  while(1){  /* Loop exits via break */
+    i = iPc++;
+    if( i>=nRow ){
+      p->rc = SQLITE_OK;
+      rc = SQLITE_DONE;
+      break;
+    }
+    if( i<p->nOp ){
+      /* The rowid is small enough that we are still in the
+      ** main program. */
+      aOp = p->aOp;
+    }else{
+      /* We are currently listing subprograms.  Figure out which one and
+      ** pick up the appropriate opcode. */
+      int j;
+      i -= p->nOp;
+      assert( apSub!=0 );
+      assert( nSub>0 );
+      for(j=0; i>=apSub[j]->nOp; j++){
+        i -= apSub[j]->nOp;
+        assert( i<apSub[j]->nOp || j+1<nSub );
+      }
+      aOp = apSub[j]->aOp;
+    }
+
+    /* When an OP_Program opcode is encounter (the only opcode that has
+    ** a P4_SUBPROGRAM argument), expand the size of the array of subprograms
+    ** kept in p->aMem[9].z to hold the new program - assuming this subprogram
+    ** has not already been seen.
+    */
+    if( pSub!=0 && aOp[i].p4type==P4_SUBPROGRAM ){
+      int nByte = (nSub+1)*sizeof(SubProgram*);
+      int j;
+      for(j=0; j<nSub; j++){
+        if( apSub[j]==aOp[i].p4.pProgram ) break;
+      }
+      if( j==nSub ){
+        p->rc = sqlite3VdbeMemGrow(pSub, nByte, nSub!=0);
+        if( p->rc!=SQLITE_OK ){
+          rc = SQLITE_ERROR;
+          break;
+        }
+        apSub = (SubProgram **)pSub->z;
+        apSub[nSub++] = aOp[i].p4.pProgram;
+        MemSetTypeFlag(pSub, MEM_Blob);
+        pSub->n = nSub*sizeof(SubProgram*);
+        nRow += aOp[i].p4.pProgram->nOp;
+      }
+    }
+    if( eMode==0 ) break;
+#ifdef SQLITE_ENABLE_BYTECODE_VTAB
+    if( eMode==2 ){
+      Op *pOp = aOp + i;
+      if( pOp->opcode==OP_OpenRead ) break;
+      if( pOp->opcode==OP_OpenWrite && (pOp->p5 & OPFLAG_P2ISREG)==0 ) break;
+      if( pOp->opcode==OP_ReopenIdx ) break;      
+    }else
+#endif
+    {
+      assert( eMode==1 );
+      if( aOp[i].opcode==OP_Explain ) break;
+      if( aOp[i].opcode==OP_Init && iPc>1 ) break;
+    }
+  }
+  *piPc = iPc;
+  *piAddr = i;
+  *paOp = aOp;
+  return rc;
+}
+#endif /* SQLITE_ENABLE_BYTECODE_VTAB || !SQLITE_OMIT_EXPLAIN */
+

 /*
 ** Delete a VdbeFrame object and its contents. VdbeFrame objects are
@@ -1983,16 +2099,14 @@ void sqlite3VdbeFrameDelete(VdbeFrame *p){
 int sqlite3VdbeList(
  Vdbe *p                   /* The VDBE */
 ){
-  int nRow;                            /* Stop when row count reaches this */
-  int nSub = 0;                        /* Number of sub-vdbes seen so far */
-  SubProgram **apSub = 0;              /* Array of sub-vdbes */
  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
  sqlite3 *db = p->db;                 /* The database connection */
  int i;                               /* Loop counter */
  int rc = SQLITE_OK;                  /* Return code */
  Mem *pMem = &p->aMem[1];             /* First Mem of result set */
  int bListSubprogs = (p->explain==1 || (db->flags & SQLITE_TriggerEQP)!=0);
-  Op *pOp = 0;
+  Op *aOp;                             /* Array of opcodes */
+  Op *pOp;                             /* Current opcode */

  assert( p->explain );
  assert( p->magic==VDBE_MAGIC_RUN );
@@ -2012,14 +2126,6 @@ int sqlite3VdbeList(
    return SQLITE_ERROR;
  }

-  /* When the number of output rows reaches nRow, that means the
-  ** listing has finished and sqlite3_step() should return SQLITE_DONE.
-  ** nRow is the sum of the number of rows in the main program, plus
-  ** the sum of the number of rows in all trigger subprograms encountered
-  ** so far.  The nRow value will increase as new trigger subprograms are
-  ** encountered, but p->pc will eventually catch up to nRow.
-  */
-  nRow = p->nOp;
  if( bListSubprogs ){
    /* The first 8 memory cells are used for the result set.  So we will
    ** commandeer the 9th cell to use as storage for an array of pointers
@@ -2027,147 +2133,55 @@ int sqlite3VdbeList(
    ** cells.  */
    assert( p->nMem>9 );
    pSub = &p->aMem[9];
-    if( pSub->flags&MEM_Blob ){
-      /* On the first call to sqlite3_step(), pSub will hold a NULL.  It is
-      ** initialized to a BLOB by the P4_SUBPROGRAM processing logic below */
-      nSub = pSub->n/sizeof(Vdbe*);
-      apSub = (SubProgram **)pSub->z;
-    }
-    for(i=0; i<nSub; i++){
-      nRow += apSub[i]->nOp;
-    }
+  }else{
+    pSub = 0;
  }

-  while(1){  /* Loop exits via break */
-    i = p->pc++;
-    if( i>=nRow ){
-      p->rc = SQLITE_OK;
-      rc = SQLITE_DONE;
-      break;
-    }
-    if( i<p->nOp ){
-      /* The output line number is small enough that we are still in the
-      ** main program. */
-      pOp = &p->aOp[i];
-    }else{
-      /* We are currently listing subprograms.  Figure out which one and
-      ** pick up the appropriate opcode. */
-      int j;
-      i -= p->nOp;
-      assert( apSub!=0 );
-      assert( nSub>0 );
-      for(j=0; i>=apSub[j]->nOp; j++){
-        i -= apSub[j]->nOp;
-        assert( i<apSub[j]->nOp || j+1<nSub );
-      }
-      pOp = &apSub[j]->aOp[i];
-    }
-
-    /* When an OP_Program opcode is encounter (the only opcode that has
-    ** a P4_SUBPROGRAM argument), expand the size of the array of subprograms
-    ** kept in p->aMem[9].z to hold the new program - assuming this subprogram
-    ** has not already been seen.
-    */
-    if( bListSubprogs && pOp->p4type==P4_SUBPROGRAM ){
-      int nByte = (nSub+1)*sizeof(SubProgram*);
-      int j;
-      for(j=0; j<nSub; j++){
-        if( apSub[j]==pOp->p4.pProgram ) break;
-      }
-      if( j==nSub ){
-        p->rc = sqlite3VdbeMemGrow(pSub, nByte, nSub!=0);
-        if( p->rc!=SQLITE_OK ){
-          rc = SQLITE_ERROR;
-          break;
-        }
-        apSub = (SubProgram **)pSub->z;
-        apSub[nSub++] = pOp->p4.pProgram;
-        pSub->flags |= MEM_Blob;
-        pSub->n = nSub*sizeof(SubProgram*);
-        nRow += pOp->p4.pProgram->nOp;
-      }
-    }
-    if( p->explain<2 ) break;
-    if( pOp->opcode==OP_Explain ) break;
-    if( pOp->opcode==OP_Init && p->pc>1 ) break;
-  }
+  /* Figure out which opcode is next to display */
+  rc = sqlite3VdbeNextOpcode(p, pSub, p->explain==2, &p->pc, &i, &aOp);

  if( rc==SQLITE_OK ){
+    pOp = aOp + i;
    if( AtomicLoad(&db->u1.isInterrupted) ){
      p->rc = SQLITE_INTERRUPT;
      rc = SQLITE_ERROR;
      sqlite3VdbeError(p, sqlite3ErrStr(p->rc));
    }else{
-      char *zP4;
-      if( p->explain==1 ){
-        pMem->flags = MEM_Int;
-        pMem->u.i = i;                                /* Program counter */
-        pMem++;
-    
-        pMem->flags = MEM_Static|MEM_Str|MEM_Term;
-        pMem->z = (char*)sqlite3OpcodeName(pOp->opcode); /* Opcode */
-        assert( pMem->z!=0 );
-        pMem->n = sqlite3Strlen30(pMem->z);
-        pMem->enc = SQLITE_UTF8;
-        pMem++;
-      }
-
-      pMem->flags = MEM_Int;
-      pMem->u.i = pOp->p1;                          /* P1 */
-      pMem++;
-
-      pMem->flags = MEM_Int;
-      pMem->u.i = pOp->p2;                          /* P2 */
-      pMem++;
-
-      pMem->flags = MEM_Int;
-      pMem->u.i = pOp->p3;                          /* P3 */
-      pMem++;
-
-      if( sqlite3VdbeMemClearAndResize(pMem, 100) ){ /* P4 */
-        assert( p->db->mallocFailed );
-        return SQLITE_ERROR;
-      }
-      pMem->flags = MEM_Str|MEM_Term;
-      zP4 = displayP4(pOp, pMem->z, pMem->szMalloc);
-      if( zP4!=pMem->z ){
-        pMem->n = 0;
-        sqlite3VdbeMemSetStr(pMem, zP4, -1, SQLITE_UTF8, 0);
+      char *zP4 = sqlite3VdbeDisplayP4(db, pOp);
+      if( p->explain==2 ){
+        sqlite3VdbeMemSetInt64(pMem, pOp->p1);
+        sqlite3VdbeMemSetInt64(pMem+1, pOp->p2);
+        sqlite3VdbeMemSetInt64(pMem+2, pOp->p3);
+        sqlite3VdbeMemSetStr(pMem+3, zP4, -1, SQLITE_UTF8, sqlite3_free);     
+        p->nResColumn = 4;
      }else{
-        assert( pMem->z!=0 );
-        pMem->n = sqlite3Strlen30(pMem->z);
-        pMem->enc = SQLITE_UTF8;
-      }
-      pMem++;
-
-      if( p->explain==1 ){
-        if( sqlite3VdbeMemClearAndResize(pMem, 4) ){
-          assert( p->db->mallocFailed );
-          return SQLITE_ERROR;
-        }
-        pMem->flags = MEM_Str|MEM_Term;
-        pMem->n = 2;
-        sqlite3_snprintf(3, pMem->z, "%.2x", pOp->p5);   /* P5 */
-        pMem->enc = SQLITE_UTF8;
-        pMem++;
-    
+        sqlite3VdbeMemSetInt64(pMem+0, i);
+        sqlite3VdbeMemSetStr(pMem+1, (char*)sqlite3OpcodeName(pOp->opcode),
+                             -1, SQLITE_UTF8, SQLITE_STATIC);
+        sqlite3VdbeMemSetInt64(pMem+2, pOp->p1);
+        sqlite3VdbeMemSetInt64(pMem+3, pOp->p2);
+        sqlite3VdbeMemSetInt64(pMem+4, pOp->p3);
+        /* pMem+5 for p4 is done last */
+        sqlite3VdbeMemSetInt64(pMem+6, pOp->p5);
 #ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
-        if( sqlite3VdbeMemClearAndResize(pMem, 500) ){
-          assert( p->db->mallocFailed );
-          return SQLITE_ERROR;
+        {
+          char *zCom = sqlite3VdbeDisplayComment(db, pOp, zP4);
+          sqlite3VdbeMemSetStr(pMem+7, zCom, -1, SQLITE_UTF8, sqlite3_free);
        }
-        pMem->flags = MEM_Str|MEM_Term;
-        pMem->n = displayComment(pOp, zP4, pMem->z, 500);
-        pMem->enc = SQLITE_UTF8;
 #else
-        pMem->flags = MEM_Null;                       /* Comment */
+        sqlite3VdbeMemSetNull(pMem+7);
 #endif
+        sqlite3VdbeMemSetStr(pMem+5, zP4, -1, SQLITE_UTF8, sqlite3_free);
+        p->nResColumn = 8;
+      }
+      p->pResultSet = pMem;
+      if( db->mallocFailed ){
+        p->rc = SQLITE_NOMEM;
+        rc = SQLITE_ERROR;
+      }else{
+        p->rc = SQLITE_OK;
+        rc = SQLITE_ROW;
      }
-
-      p->nResColumn = 8 - 4*(p->explain-1);
-      p->pResultSet = &p->aMem[1];
-      p->rc = SQLITE_OK;
-      rc = SQLITE_ROW;
    }
  }
  return rc;
@@ -2737,8 +2751,9 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){

    /* Select a master journal file name */
    nMainFile = sqlite3Strlen30(zMainFile);
-    zMaster = sqlite3MPrintf(db, "%s-mjXXXXXX9XXz%c%c", zMainFile, 0, 0);
+    zMaster = sqlite3MPrintf(db, "%.4c%s%.16c", 0,zMainFile,0);
    if( zMaster==0 ) return SQLITE_NOMEM_BKPT;
+    zMaster += 4;
    do {
      u32 iRandom;
      if( retryCount ){
@@ -2768,7 +2783,7 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
      );
    }
    if( rc!=SQLITE_OK ){
-      sqlite3DbFree(db, zMaster);
+      sqlite3DbFree(db, zMaster-4);
      return rc;
    }
 
@@ -2791,7 +2806,7 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
        if( rc!=SQLITE_OK ){
          sqlite3OsCloseFree(pMaster);
          sqlite3OsDelete(pVfs, zMaster, 0);
-          sqlite3DbFree(db, zMaster);
+          sqlite3DbFree(db, zMaster-4);
          return rc;
        }
      }
@@ -2805,7 +2820,7 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
    ){
      sqlite3OsCloseFree(pMaster);
      sqlite3OsDelete(pVfs, zMaster, 0);
-      sqlite3DbFree(db, zMaster);
+      sqlite3DbFree(db, zMaster-4);
      return rc;
    }

@@ -2828,7 +2843,7 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
    sqlite3OsCloseFree(pMaster);
    assert( rc!=SQLITE_BUSY );
    if( rc!=SQLITE_OK ){
-      sqlite3DbFree(db, zMaster);
+      sqlite3DbFree(db, zMaster-4);
      return rc;
    }

@@ -2837,7 +2852,7 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
    ** transaction files are deleted.
    */
    rc = sqlite3OsDelete(pVfs, zMaster, 1);
-    sqlite3DbFree(db, zMaster);
+    sqlite3DbFree(db, zMaster-4);
    zMaster = 0;
    if( rc ){
      return rc;
@@ -0,0 +1,422 @@
+/*
+** 2020-03-23
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file implements virtual-tables for examining the bytecode content
+** of a prepared statement.
+*/
+#ifdef SQLITE_ENABLE_BYTECODE_VTAB
+#include "sqliteInt.h"
+#include "vdbeInt.h"
+
+/* An instance of the bytecode() table-valued function.
+*/
+typedef struct bytecodevtab bytecodevtab;
+struct bytecodevtab {
+  sqlite3_vtab base;     /* Base class - must be first */
+  sqlite3 *db;           /* Database connection */
+  int bTablesUsed;       /* 2 for tables_used().  0 for bytecode(). */
+};
+
+/* A cursor for scanning through the bytecode
+*/
+typedef struct bytecodevtab_cursor bytecodevtab_cursor;
+struct bytecodevtab_cursor {
+  sqlite3_vtab_cursor base;  /* Base class - must be first */
+  sqlite3_stmt *pStmt;       /* The statement whose bytecode is displayed */
+  int iRowid;                /* The rowid of the output table */
+  int iAddr;                 /* Address */
+  int needFinalize;          /* Cursors owns pStmt and must finalize it */
+  int showSubprograms;       /* Provide a listing of subprograms */
+  Op *aOp;                   /* Operand array */
+  char *zP4;                 /* Rendered P4 value */
+  const char *zType;         /* tables_used.type */
+  const char *zSchema;       /* tables_used.schema */
+  const char *zName;         /* tables_used.name */
+  Mem sub;                   /* Subprograms */
+};
+
+/*
+** Create a new bytecode() table-valued function.
+*/
+static int bytecodevtabConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  bytecodevtab *pNew;
+  int rc;
+  int isTabUsed = pAux!=0;
+  const char *azSchema[2] = {
+    /* bytecode() schema */
+    "CREATE TABLE x("
+      "addr INT,"
+      "opcode TEXT,"
+      "p1 INT,"
+      "p2 INT,"
+      "p3 INT,"
+      "p4 TEXT,"
+      "p5 INT,"
+      "comment TEXT,"
+      "subprog TEXT," 
+      "stmt HIDDEN"
+    ");",
+
+    /* Tables_used() schema */
+    "CREATE TABLE x("
+      "type TEXT,"
+      "schema TEXT,"
+      "name TEXT,"
+      "wr INT,"
+      "subprog TEXT," 
+      "stmt HIDDEN"
+   ");"
+  };
+
+  rc = sqlite3_declare_vtab(db, azSchema[isTabUsed]);
+  if( rc==SQLITE_OK ){
+    pNew = sqlite3_malloc( sizeof(*pNew) );
+    *ppVtab = (sqlite3_vtab*)pNew;
+    if( pNew==0 ) return SQLITE_NOMEM;
+    memset(pNew, 0, sizeof(*pNew));
+    pNew->db = db;
+    pNew->bTablesUsed = isTabUsed*2;
+  }
+  return rc;
+}
+
+/*
+** This method is the destructor for bytecodevtab objects.
+*/
+static int bytecodevtabDisconnect(sqlite3_vtab *pVtab){
+  bytecodevtab *p = (bytecodevtab*)pVtab;
+  sqlite3_free(p);
+  return SQLITE_OK;
+}
+
+/*
+** Constructor for a new bytecodevtab_cursor object.
+*/
+static int bytecodevtabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
+  bytecodevtab *pVTab = (bytecodevtab*)p;
+  bytecodevtab_cursor *pCur;
+  pCur = sqlite3_malloc( sizeof(*pCur) );
+  if( pCur==0 ) return SQLITE_NOMEM;
+  memset(pCur, 0, sizeof(*pCur));
+  sqlite3VdbeMemInit(&pCur->sub, pVTab->db, 1);
+  *ppCursor = &pCur->base;
+  return SQLITE_OK;
+}
+
+/*
+** Clear all internal content from a bytecodevtab cursor.
+*/
+static void bytecodevtabCursorClear(bytecodevtab_cursor *pCur){
+  sqlite3_free(pCur->zP4);
+  pCur->zP4 = 0;
+  sqlite3VdbeMemRelease(&pCur->sub);
+  sqlite3VdbeMemSetNull(&pCur->sub);
+  if( pCur->needFinalize ){
+    sqlite3_finalize(pCur->pStmt);
+  }
+  pCur->pStmt = 0;
+  pCur->needFinalize = 0;
+  pCur->zType = 0;
+  pCur->zSchema = 0;
+  pCur->zName = 0;
+}
+
+/*
+** Destructor for a bytecodevtab_cursor.
+*/
+static int bytecodevtabClose(sqlite3_vtab_cursor *cur){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+  bytecodevtabCursorClear(pCur);
+  sqlite3_free(pCur);
+  return SQLITE_OK;
+}
+
+
+/*
+** Advance a bytecodevtab_cursor to its next row of output.
+*/
+static int bytecodevtabNext(sqlite3_vtab_cursor *cur){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+  bytecodevtab *pTab = (bytecodevtab*)cur->pVtab;
+  int rc;
+  if( pCur->zP4 ){
+    sqlite3_free(pCur->zP4);
+    pCur->zP4 = 0;
+  }
+  if( pCur->zName ){
+    pCur->zName = 0;
+    pCur->zType = 0;
+    pCur->zSchema = 0;
+  }
+  rc = sqlite3VdbeNextOpcode(
+           (Vdbe*)pCur->pStmt, 
+           pCur->showSubprograms ? &pCur->sub : 0,
+           pTab->bTablesUsed,
+           &pCur->iRowid,
+           &pCur->iAddr,
+           &pCur->aOp);
+  if( rc!=SQLITE_OK ){
+    sqlite3VdbeMemSetNull(&pCur->sub);
+    pCur->aOp = 0;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Return TRUE if the cursor has been moved off of the last
+** row of output.
+*/
+static int bytecodevtabEof(sqlite3_vtab_cursor *cur){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+  return pCur->aOp==0;
+}
+
+/*
+** Return values of columns for the row at which the bytecodevtab_cursor
+** is currently pointing.
+*/
+static int bytecodevtabColumn(
+  sqlite3_vtab_cursor *cur,   /* The cursor */
+  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
+  int i                       /* Which column to return */
+){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+  bytecodevtab *pVTab = (bytecodevtab*)cur->pVtab;
+  Op *pOp = pCur->aOp + pCur->iAddr;
+  if( pVTab->bTablesUsed ){
+    if( i==4 ){
+      i = 8;
+    }else{
+      if( i<=2 && pCur->zType==0 ){
+        Schema *pSchema;
+        HashElem *k;
+        int iDb = pOp->p3;
+        int iRoot = pOp->p2;
+        sqlite3 *db = pVTab->db;
+        pSchema = db->aDb[iDb].pSchema;
+        pCur->zSchema = db->aDb[iDb].zDbSName;
+        for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
+          Table *pTab = (Table*)sqliteHashData(k);
+          if( !IsVirtual(pTab) && pTab->tnum==iRoot ){
+            pCur->zName = pTab->zName;
+            pCur->zType = "table";
+            break;
+          }
+        }
+        if( pCur->zName==0 ){
+          for(k=sqliteHashFirst(&pSchema->idxHash); k; k=sqliteHashNext(k)){
+            Index *pIdx = (Index*)sqliteHashData(k);
+            if( pIdx->tnum==iRoot ){
+              pCur->zName = pIdx->zName;
+              pCur->zType = "index";
+            }
+          }
+        }
+      }
+      i += 10;
+    }
+  }
+  switch( i ){
+    case 0:   /* addr */
+      sqlite3_result_int(ctx, pCur->iAddr);
+      break;
+    case 1:   /* opcode */
+      sqlite3_result_text(ctx, (char*)sqlite3OpcodeName(pOp->opcode),
+                          -1, SQLITE_STATIC);
+      break;
+    case 2:   /* p1 */
+      sqlite3_result_int(ctx, pOp->p1);
+      break;
+    case 3:   /* p2 */
+      sqlite3_result_int(ctx, pOp->p2);
+      break;
+    case 4:   /* p3 */
+      sqlite3_result_int(ctx, pOp->p3);
+      break;
+    case 5:   /* p4 */
+    case 7:   /* comment */
+      if( pCur->zP4==0 ){
+        pCur->zP4 = sqlite3VdbeDisplayP4(pVTab->db, pOp);
+      }
+      if( i==5 ){
+        sqlite3_result_text(ctx, pCur->zP4, -1, SQLITE_STATIC);
+      }else{
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+        char *zCom = sqlite3VdbeDisplayComment(pVTab->db, pOp, pCur->zP4);
+        sqlite3_result_text(ctx, zCom, -1, sqlite3_free);
+#endif
+      }
+      break;
+    case 6:     /* p5 */
+      sqlite3_result_int(ctx, pOp->p5);
+      break;
+    case 8: {   /* subprog */
+      Op *aOp = pCur->aOp;
+      assert( aOp[0].opcode==OP_Init );
+      assert( aOp[0].p4.z==0 || strncmp(aOp[0].p4.z,"-" "- ",3)==0 );
+      if( pCur->iRowid==pCur->iAddr+1 ){
+        break;  /* Result is NULL for the main program */
+      }else if( aOp[0].p4.z!=0 ){
+         sqlite3_result_text(ctx, aOp[0].p4.z+3, -1, SQLITE_STATIC);
+      }else{
+         sqlite3_result_text(ctx, "(FK)", 4, SQLITE_STATIC);
+      }
+      break;
+    }
+    case 10:  /* tables_used.type */
+      sqlite3_result_text(ctx, pCur->zType, -1, SQLITE_STATIC);
+      break;
+    case 11:  /* tables_used.schema */
+      sqlite3_result_text(ctx, pCur->zSchema, -1, SQLITE_STATIC);
+      break;
+    case 12:  /* tables_used.name */
+      sqlite3_result_text(ctx, pCur->zName, -1, SQLITE_STATIC);
+      break;
+    case 13:  /* tables_used.wr */
+      sqlite3_result_int(ctx, pOp->opcode==OP_OpenWrite);
+      break;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Return the rowid for the current row.  In this implementation, the
+** rowid is the same as the output value.
+*/
+static int bytecodevtabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+  *pRowid = pCur->iRowid;
+  return SQLITE_OK;
+}
+
+/*
+** Initialize a cursor.
+**
+**    idxNum==0     means show all subprograms
+**    idxNum==1     means show only the main bytecode and omit subprograms.
+*/
+static int bytecodevtabFilter(
+  sqlite3_vtab_cursor *pVtabCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor *)pVtabCursor;
+  bytecodevtab *pVTab = (bytecodevtab *)pVtabCursor->pVtab;
+  int rc = SQLITE_OK;
+
+  bytecodevtabCursorClear(pCur);
+  pCur->iRowid = 0;
+  pCur->iAddr = 0;
+  pCur->showSubprograms = idxNum==0;
+  assert( argc==1 );
+  if( sqlite3_value_type(argv[0])==SQLITE_TEXT ){
+    const char *zSql = (const char*)sqlite3_value_text(argv[0]);
+    if( zSql==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare_v2(pVTab->db, zSql, -1, &pCur->pStmt, 0);
+      pCur->needFinalize = 1;
+    }
+  }else{
+    pCur->pStmt = (sqlite3_stmt*)sqlite3_value_pointer(argv[0],"stmt-pointer");
+  }
+  if( pCur->pStmt==0 ){
+    pVTab->base.zErrMsg = sqlite3_mprintf(
+       "argument to %s() is not a valid SQL statement",
+       pVTab->bTablesUsed ? "tables_used" : "bytecode"
+    );
+    rc = SQLITE_ERROR;
+  }else{
+    bytecodevtabNext(pVtabCursor);
+  }
+  return rc;
+}
+
+/*
+** We must have a single stmt=? constraint that will be passed through
+** into the xFilter method.  If there is no valid stmt=? constraint,
+** then return an SQLITE_CONSTRAINT error.
+*/
+static int bytecodevtabBestIndex(
+  sqlite3_vtab *tab,
+  sqlite3_index_info *pIdxInfo
+){
+  int i;
+  int rc = SQLITE_CONSTRAINT;
+  struct sqlite3_index_constraint *p;
+  bytecodevtab *pVTab = (bytecodevtab*)tab;
+  int iBaseCol = pVTab->bTablesUsed ? 4 : 8;
+  pIdxInfo->estimatedCost = (double)100;
+  pIdxInfo->estimatedRows = 100;
+  pIdxInfo->idxNum = 0;
+  for(i=0, p=pIdxInfo->aConstraint; i<pIdxInfo->nConstraint; i++, p++){
+    if( p->usable==0 ) continue;
+    if( p->op==SQLITE_INDEX_CONSTRAINT_EQ && p->iColumn==iBaseCol+1 ){
+      rc = SQLITE_OK;
+      pIdxInfo->aConstraintUsage[i].omit = 1;
+      pIdxInfo->aConstraintUsage[i].argvIndex = 1;
+    }
+    if( p->op==SQLITE_INDEX_CONSTRAINT_ISNULL && p->iColumn==iBaseCol ){
+      pIdxInfo->aConstraintUsage[i].omit = 1;
+      pIdxInfo->idxNum = 1;
+    }
+  }
+  return rc;
+}
+
+/*
+** This following structure defines all the methods for the 
+** virtual table.
+*/
+static sqlite3_module bytecodevtabModule = {
+  /* iVersion    */ 0,
+  /* xCreate     */ 0,
+  /* xConnect    */ bytecodevtabConnect,
+  /* xBestIndex  */ bytecodevtabBestIndex,
+  /* xDisconnect */ bytecodevtabDisconnect,
+  /* xDestroy    */ 0,
+  /* xOpen       */ bytecodevtabOpen,
+  /* xClose      */ bytecodevtabClose,
+  /* xFilter     */ bytecodevtabFilter,
+  /* xNext       */ bytecodevtabNext,
+  /* xEof        */ bytecodevtabEof,
+  /* xColumn     */ bytecodevtabColumn,
+  /* xRowid      */ bytecodevtabRowid,
+  /* xUpdate     */ 0,
+  /* xBegin      */ 0,
+  /* xSync       */ 0,
+  /* xCommit     */ 0,
+  /* xRollback   */ 0,
+  /* xFindMethod */ 0,
+  /* xRename     */ 0,
+  /* xSavepoint  */ 0,
+  /* xRelease    */ 0,
+  /* xRollbackTo */ 0,
+  /* xShadowName */ 0
+};
+
+
+int sqlite3VdbeBytecodeVtabInit(sqlite3 *db){
+  int rc;
+  rc = sqlite3_create_module(db, "bytecode", &bytecodevtabModule, 0);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_create_module(db, "tables_used", &bytecodevtabModule, &db);
+  }
+  return rc;
+}
+#endif /* SQLITE_ENABLE_BYTECODE_VTAB */
@@ -467,6 +467,9 @@ struct Wal {
 #ifdef SQLITE_ENABLE_SNAPSHOT
  WalIndexHdr *pSnapshot;    /* Start transaction here if not NULL */
 #endif
+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+  sqlite3 *db;
+#endif
 };

 /*
@@ -840,7 +843,7 @@ static int walLockShared(Wal *pWal, int lockIdx){
                        SQLITE_SHM_LOCK | SQLITE_SHM_SHARED);
  WALTRACE(("WAL%p: acquire SHARED-%s %s\n", pWal,
            walLockName(lockIdx), rc ? "failed" : "ok"));
-  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
+  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && (rc&0xFF)!=SQLITE_BUSY); )
  return rc;
 }
 static void walUnlockShared(Wal *pWal, int lockIdx){
@@ -856,7 +859,7 @@ static int walLockExclusive(Wal *pWal, int lockIdx, int n){
                        SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE);
  WALTRACE(("WAL%p: acquire EXCLUSIVE-%s cnt=%d %s\n", pWal,
            walLockName(lockIdx), n, rc ? "failed" : "ok"));
-  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
+  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && (rc&0xFF)!=SQLITE_BUSY); )
  return rc;
 }
 static void walUnlockExclusive(Wal *pWal, int lockIdx, int n){
@@ -1128,11 +1131,6 @@ static int walIndexRecover(Wal *pWal){
  u32 aFrameCksum[2] = {0, 0};
  int iLock;                      /* Lock offset to lock for checkpoint */

-#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
-  int tmout = 0;
-  sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout);
-#endif
-
  /* Obtain an exclusive lock on all byte in the locking range not already
  ** locked by the caller. The caller is guaranteed to have locked the
  ** WAL_WRITE_LOCK byte, and may have also locked the WAL_CKPT_LOCK byte.
@@ -1681,6 +1679,89 @@ static int walIteratorInit(Wal *pWal, u32 nBackfill, WalIterator **pp){
  return rc;
 }

+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+/*
+** Attempt to enable blocking locks. Blocking locks are enabled only if (a)
+** they are supported by the VFS, and (b) the database handle is configured 
+** with a busy-timeout. Return 1 if blocking locks are successfully enabled, 
+** or 0 otherwise.
+*/
+static int walEnableBlocking(Wal *pWal){
+  int res = 0;
+  if( pWal->db ){
+    int tmout = pWal->db->busyTimeout;
+    if( tmout ){
+      int rc;
+      rc = sqlite3OsFileControl(
+          pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout
+      );
+      res = (rc==SQLITE_OK);
+    }
+  }
+  return res;
+}
+
+/*
+** Disable blocking locks.
+*/
+static void walDisableBlocking(Wal *pWal){
+  int tmout = 0;
+  sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout);
+}
+
+/*
+** If parameter bLock is true, attempt to enable blocking locks, take
+** the WRITER lock, and then disable blocking locks. If blocking locks
+** cannot be enabled, no attempt to obtain the WRITER lock is made. Return 
+** an SQLite error code if an error occurs, or SQLITE_OK otherwise. It is not
+** an error if blocking locks can not be enabled.
+**
+** If the bLock parameter is false and the WRITER lock is held, release it.
+*/
+int sqlite3WalWriteLock(Wal *pWal, int bLock){
+  int rc = SQLITE_OK;
+  assert( pWal->readLock<0 || bLock==0 );
+  if( bLock ){
+    assert( pWal->db );
+    if( walEnableBlocking(pWal) ){
+      rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
+      if( rc==SQLITE_OK ){
+        pWal->writeLock = 1;
+      }
+      walDisableBlocking(pWal);
+    }
+  }else if( pWal->writeLock ){
+    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
+    pWal->writeLock = 0;
+  }
+  return rc;
+}
+
+/*
+** Set the database handle used to determine if blocking locks are required.
+*/
+void sqlite3WalDb(Wal *pWal, sqlite3 *db){
+  pWal->db = db;
+}
+
+/*
+** Take an exclusive WRITE lock. Blocking if so configured.
+*/
+static int walLockWriter(Wal *pWal){
+  int rc;
+  walEnableBlocking(pWal);
+  rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
+  walDisableBlocking(pWal);
+  return rc;
+}
+#else
+# define walEnableBlocking(x) 0
+# define walDisableBlocking(x)
+# define walLockWriter(pWal) walLockExclusive((pWal), WAL_WRITE_LOCK, 1)
+# define sqlite3WalDb(pWal, db)
+#endif   /* ifdef SQLITE_ENABLE_SETLK_TIMEOUT */
+
+
 /*
 ** Attempt to obtain the exclusive WAL lock defined by parameters lockIdx and
 ** n. If the attempt fails and parameter xBusy is not NULL, then it is a
@@ -1698,6 +1779,12 @@ static int walBusyLock(
  do {
    rc = walLockExclusive(pWal, lockIdx, n);
  }while( xBusy && rc==SQLITE_BUSY && xBusy(pBusyArg) );
+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+  if( rc==SQLITE_BUSY_TIMEOUT ){
+    walDisableBlocking(pWal);
+    rc = SQLITE_BUSY;
+  }
+#endif
  return rc;
 }

@@ -1868,6 +1955,7 @@ static int walCheckpoint(
      if( rc==SQLITE_OK ){
        i64 nReq = ((i64)mxPage * szPage);
        i64 nSize;                    /* Current size of database file */
+        sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_CKPT_START, 0);
        rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);
        if( rc==SQLITE_OK && nSize<nReq ){
          sqlite3OsFileControlHint(pWal->pDbFd, SQLITE_FCNTL_SIZE_HINT, &nReq);
@@ -1895,6 +1983,7 @@ static int walCheckpoint(
        rc = sqlite3OsWrite(pWal->pDbFd, zBuf, szPage, iOffset);
        if( rc!=SQLITE_OK ) break;
      }
+      sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_CKPT_DONE, 0);

      /* If work was actually accomplished... */
      if( rc==SQLITE_OK ){
@@ -1906,10 +1995,6 @@ static int walCheckpoint(
            rc = sqlite3OsSync(pWal->pDbFd, CKPT_SYNC_FLAGS(sync_flags));
          }
        }
-        if( rc==SQLITE_OK ){
-          rc = sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_CKPT_DONE, 0);
-          if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
-        }
        if( rc==SQLITE_OK ){
          pInfo->nBackfill = mxSafeFrame;
        }
@@ -2179,28 +2264,32 @@ static int walIndexReadHdr(Wal *pWal, int *pChanged){
  /* If the first attempt failed, it might have been due to a race
  ** with a writer.  So get a WRITE lock and try again.
  */
-  assert( badHdr==0 || pWal->writeLock==0 );
  if( badHdr ){
    if( pWal->bShmUnreliable==0 && (pWal->readOnly & WAL_SHM_RDONLY) ){
      if( SQLITE_OK==(rc = walLockShared(pWal, WAL_WRITE_LOCK)) ){
        walUnlockShared(pWal, WAL_WRITE_LOCK);
        rc = SQLITE_READONLY_RECOVERY;
      }
-    }else if( SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1)) ){
-      pWal->writeLock = 1;
-      if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
-        badHdr = walIndexTryHdr(pWal, pChanged);
-        if( badHdr ){
-          /* If the wal-index header is still malformed even while holding
-          ** a WRITE lock, it can only mean that the header is corrupted and
-          ** needs to be reconstructed.  So run recovery to do exactly that.
-          */
-          rc = walIndexRecover(pWal);
-          *pChanged = 1;
+    }else{
+      int bWriteLock = pWal->writeLock;
+      if( bWriteLock || SQLITE_OK==(rc = walLockWriter(pWal)) ){
+        pWal->writeLock = 1;
+        if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
+          badHdr = walIndexTryHdr(pWal, pChanged);
+          if( badHdr ){
+            /* If the wal-index header is still malformed even while holding
+            ** a WRITE lock, it can only mean that the header is corrupted and
+            ** needs to be reconstructed.  So run recovery to do exactly that.
+            */
+            rc = walIndexRecover(pWal);
+            *pChanged = 1;
+          }
+        }
+        if( bWriteLock==0 ){
+          pWal->writeLock = 0;
+          walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
        }
      }
-      pWal->writeLock = 0;
-      walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
    }
  }

@@ -2752,22 +2841,34 @@ int sqlite3WalSnapshotRecover(Wal *pWal){
 int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
  int rc;                         /* Return code */
  int cnt = 0;                    /* Number of TryBeginRead attempts */
-#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
-  int tmout = 0;
-#endif
+
+  assert( pWal->ckptLock==0 );

 #ifdef SQLITE_ENABLE_SNAPSHOT
  int bChanged = 0;
  WalIndexHdr *pSnapshot = pWal->pSnapshot;
-  if( pSnapshot && memcmp(pSnapshot, &pWal->hdr, sizeof(WalIndexHdr))!=0 ){
-    bChanged = 1;
-  }
-#endif
+  if( pSnapshot ){
+    if( memcmp(pSnapshot, &pWal->hdr, sizeof(WalIndexHdr))!=0 ){
+      bChanged = 1;
+    }

-#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
-  /* Disable blocking locks. They are not useful when trying to open a
-  ** read-transaction, and blocking may cause deadlock anyway. */
-  sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout);
+    /* It is possible that there is a checkpointer thread running 
+    ** concurrent with this code. If this is the case, it may be that the
+    ** checkpointer has already determined that it will checkpoint 
+    ** snapshot X, where X is later in the wal file than pSnapshot, but 
+    ** has not yet set the pInfo->nBackfillAttempted variable to indicate 
+    ** its intent. To avoid the race condition this leads to, ensure that
+    ** there is no checkpointer process by taking a shared CKPT lock 
+    ** before checking pInfo->nBackfillAttempted.  */
+    (void)walEnableBlocking(pWal);
+    rc = walLockShared(pWal, WAL_CKPT_LOCK);
+    walDisableBlocking(pWal);
+
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    pWal->ckptLock = 1;
+  }
 #endif

  do{
@@ -2778,16 +2879,6 @@ int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
  testcase( rc==SQLITE_PROTOCOL );
  testcase( rc==SQLITE_OK );

-#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
-  /* If they were disabled earlier and the read-transaction has been
-  ** successfully opened, re-enable blocking locks. This is because the
-  ** connection may attempt to upgrade to a write-transaction, which does
-  ** benefit from using blocking locks.  */
-  if( rc==SQLITE_OK ){
-    sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout);
-  }
-#endif
-
 #ifdef SQLITE_ENABLE_SNAPSHOT
  if( rc==SQLITE_OK ){
    if( pSnapshot && memcmp(pSnapshot, &pWal->hdr, sizeof(WalIndexHdr))!=0 ){
@@ -2809,48 +2900,42 @@ int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
      assert( pWal->readLock>0 || pWal->hdr.mxFrame==0 );
      assert( pInfo->aReadMark[pWal->readLock]<=pSnapshot->mxFrame );

-      /* It is possible that there is a checkpointer thread running 
-      ** concurrent with this code. If this is the case, it may be that the
-      ** checkpointer has already determined that it will checkpoint 
-      ** snapshot X, where X is later in the wal file than pSnapshot, but 
-      ** has not yet set the pInfo->nBackfillAttempted variable to indicate 
-      ** its intent. To avoid the race condition this leads to, ensure that
-      ** there is no checkpointer process by taking a shared CKPT lock 
-      ** before checking pInfo->nBackfillAttempted.  
-      **
-      ** TODO: Does the aReadMark[] lock prevent a checkpointer from doing
-      **       this already?
-      */
-      rc = walLockShared(pWal, WAL_CKPT_LOCK);
-
-      if( rc==SQLITE_OK ){
-        /* Check that the wal file has not been wrapped. Assuming that it has
-        ** not, also check that no checkpointer has attempted to checkpoint any
-        ** frames beyond pSnapshot->mxFrame. If either of these conditions are
-        ** true, return SQLITE_ERROR_SNAPSHOT. Otherwise, overwrite pWal->hdr
-        ** with *pSnapshot and set *pChanged as appropriate for opening the
-        ** snapshot.  */
-        if( !memcmp(pSnapshot->aSalt, pWal->hdr.aSalt, sizeof(pWal->hdr.aSalt))
-         && pSnapshot->mxFrame>=pInfo->nBackfillAttempted
-        ){
-          assert( pWal->readLock>0 );
-          memcpy(&pWal->hdr, pSnapshot, sizeof(WalIndexHdr));
-          *pChanged = bChanged;
-        }else{
-          rc = SQLITE_ERROR_SNAPSHOT;
-        }
-
-        /* Release the shared CKPT lock obtained above. */
-        walUnlockShared(pWal, WAL_CKPT_LOCK);
-        pWal->minFrame = 1;
+      /* Check that the wal file has not been wrapped. Assuming that it has
+      ** not, also check that no checkpointer has attempted to checkpoint any
+      ** frames beyond pSnapshot->mxFrame. If either of these conditions are
+      ** true, return SQLITE_ERROR_SNAPSHOT. Otherwise, overwrite pWal->hdr
+      ** with *pSnapshot and set *pChanged as appropriate for opening the
+      ** snapshot.  */
+      if( !memcmp(pSnapshot->aSalt, pWal->hdr.aSalt, sizeof(pWal->hdr.aSalt))
+       && pSnapshot->mxFrame>=pInfo->nBackfillAttempted
+      ){
+        assert( pWal->readLock>0 );
+        memcpy(&pWal->hdr, pSnapshot, sizeof(WalIndexHdr));
+        *pChanged = bChanged;
+      }else{
+        rc = SQLITE_ERROR_SNAPSHOT;
      }

+      /* A client using a non-current snapshot may not ignore any frames
+      ** from the start of the wal file. This is because, for a system
+      ** where (minFrame < iSnapshot < maxFrame), a checkpointer may
+      ** have omitted to checkpoint a frame earlier than minFrame in 
+      ** the file because there exists a frame after iSnapshot that
+      ** is the same database page.  */
+      pWal->minFrame = 1;

      if( rc!=SQLITE_OK ){
        sqlite3WalEndReadTransaction(pWal);
      }
    }
  }
+
+  /* Release the shared CKPT lock obtained above. */
+  if( pWal->ckptLock ){
+    assert( pSnapshot );
+    walUnlockShared(pWal, WAL_CKPT_LOCK);
+    pWal->ckptLock = 0;
+  }
 #endif
  return rc;
 }
@@ -3021,6 +3106,16 @@ Pgno sqlite3WalDbsize(Wal *pWal){
 int sqlite3WalBeginWriteTransaction(Wal *pWal){
  int rc;

+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+  /* If the write-lock is already held, then it was obtained before the
+  ** read-transaction was even opened, making this call a no-op.
+  ** Return early. */
+  if( pWal->writeLock ){
+    assert( !memcmp(&pWal->hdr,(void *)walIndexHdr(pWal),sizeof(WalIndexHdr)) );
+    return SQLITE_OK;
+  }
+#endif
+
  /* Cannot start a write transaction without first holding a read
  ** transaction. */
  assert( pWal->readLock>=0 );
@@ -3597,45 +3692,52 @@ int sqlite3WalCheckpoint(
  if( pWal->readOnly ) return SQLITE_READONLY;
  WALTRACE(("WAL%p: checkpoint begins\n", pWal));

-  /* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive 
-  ** "checkpoint" lock on the database file. */
-  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
-  if( rc ){
-    /* EVIDENCE-OF: R-10421-19736 If any other process is running a
-    ** checkpoint operation at the same time, the lock cannot be obtained and
-    ** SQLITE_BUSY is returned.
-    ** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
-    ** it will not be invoked in this case.
-    */
-    testcase( rc==SQLITE_BUSY );
-    testcase( xBusy!=0 );
-    return rc;
-  }
-  pWal->ckptLock = 1;
+  /* Enable blocking locks, if possible. If blocking locks are successfully
+  ** enabled, set xBusy2=0 so that the busy-handler is never invoked. */
+  sqlite3WalDb(pWal, db);
+  (void)walEnableBlocking(pWal);

-  /* IMPLEMENTATION-OF: R-59782-36818 The SQLITE_CHECKPOINT_FULL, RESTART and
-  ** TRUNCATE modes also obtain the exclusive "writer" lock on the database
-  ** file.
-  **
-  ** EVIDENCE-OF: R-60642-04082 If the writer lock cannot be obtained
-  ** immediately, and a busy-handler is configured, it is invoked and the
-  ** writer lock retried until either the busy-handler returns 0 or the
-  ** lock is successfully obtained.
+  /* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive 
+  ** "checkpoint" lock on the database file.
+  ** EVIDENCE-OF: R-10421-19736 If any other process is running a
+  ** checkpoint operation at the same time, the lock cannot be obtained and
+  ** SQLITE_BUSY is returned.
+  ** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
+  ** it will not be invoked in this case.
  */
-  if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
-    rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_WRITE_LOCK, 1);
-    if( rc==SQLITE_OK ){
-      pWal->writeLock = 1;
-    }else if( rc==SQLITE_BUSY ){
-      eMode2 = SQLITE_CHECKPOINT_PASSIVE;
-      xBusy2 = 0;
-      rc = SQLITE_OK;
+  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
+  testcase( rc==SQLITE_BUSY );
+  testcase( rc!=SQLITE_OK && xBusy2!=0 );
+  if( rc==SQLITE_OK ){
+    pWal->ckptLock = 1;
+
+    /* IMPLEMENTATION-OF: R-59782-36818 The SQLITE_CHECKPOINT_FULL, RESTART and
+    ** TRUNCATE modes also obtain the exclusive "writer" lock on the database
+    ** file.
+    **
+    ** EVIDENCE-OF: R-60642-04082 If the writer lock cannot be obtained
+    ** immediately, and a busy-handler is configured, it is invoked and the
+    ** writer lock retried until either the busy-handler returns 0 or the
+    ** lock is successfully obtained.
+    */
+    if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
+      rc = walBusyLock(pWal, xBusy2, pBusyArg, WAL_WRITE_LOCK, 1);
+      if( rc==SQLITE_OK ){
+        pWal->writeLock = 1;
+      }else if( rc==SQLITE_BUSY ){
+        eMode2 = SQLITE_CHECKPOINT_PASSIVE;
+        xBusy2 = 0;
+        rc = SQLITE_OK;
+      }
    }
  }

+
  /* Read the wal-index header. */
  if( rc==SQLITE_OK ){
+    walDisableBlocking(pWal);
    rc = walIndexReadHdr(pWal, &isChanged);
+    (void)walEnableBlocking(pWal);
    if( isChanged && pWal->pDbFd->pMethods->iVersion>=3 ){
      sqlite3OsUnfetch(pWal->pDbFd, 0, 0);
    }
@@ -3667,11 +3769,19 @@ int sqlite3WalCheckpoint(
    memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
  }

+  walDisableBlocking(pWal);
+  sqlite3WalDb(pWal, 0);
+
  /* Release the locks. */
  sqlite3WalEndWriteTransaction(pWal);
-  walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1);
-  pWal->ckptLock = 0;
+  if( pWal->ckptLock ){
+    walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1);
+    pWal->ckptLock = 0;
+  }
  WALTRACE(("WAL%p: checkpoint %s\n", pWal, rc ? "failed" : "ok"));
+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+  if( rc==SQLITE_BUSY_TIMEOUT ) rc = SQLITE_BUSY;
+#endif
  return (rc==SQLITE_OK && eMode!=eMode2 ? SQLITE_BUSY : rc);
 }

@@ -3788,7 +3898,10 @@ int sqlite3WalSnapshotGet(Wal *pWal, sqlite3_snapshot **ppSnapshot){

 /* Try to open on pSnapshot when the next read-transaction starts
 */
-void sqlite3WalSnapshotOpen(Wal *pWal, sqlite3_snapshot *pSnapshot){
+void sqlite3WalSnapshotOpen(
+  Wal *pWal, 
+  sqlite3_snapshot *pSnapshot
+){
  pWal->pSnapshot = (WalIndexHdr*)pSnapshot;
 }

@@ -146,5 +146,10 @@ int sqlite3WalFramesize(Wal *pWal);
 /* Return the sqlite3_file object for the WAL file */
 sqlite3_file *sqlite3WalFile(Wal *pWal);

+#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
+int sqlite3WalWriteLock(Wal *pWal, int bLock);
+void sqlite3WalDb(Wal *pWal, sqlite3 *db);
+#endif
+
 #endif /* ifndef SQLITE_OMIT_WAL */
 #endif /* SQLITE_WAL_H */
@@ -51,8 +51,8 @@ proc do_temptables_test {tn sql temptables} {
    set ret ""
    db eval "EXPLAIN [set sql]" {
      if {$opcode == "OpenEphemeral" || $opcode == "SorterOpen"} { 
-        if {$p5 != "08" && $p5!="00"} { error "p5 = $p5" }
-        if {$p5 == "08"} {
+        if {$p5!=8 && $p5!=0} { error "p5 = $p5" }
+        if {$p5==8} {
          lappend ret hash
        } else {
          lappend ret btree
@@ -43,6 +43,7 @@ proc sqlite3_wal {args} {
  [lindex $args 0] eval { PRAGMA journal_mode = wal }
  [lindex $args 0] eval { PRAGMA synchronous = normal }
  [lindex $args 0] function blob blob
+  db timeout 1000
 }

 proc log_deleted {logfile} {
@@ -0,0 +1,198 @@
+# 2020 May 06
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+set testprefix walsetlk
+
+ifcapable !wal {finish_test ; return }
+db timeout 1000
+
+#-------------------------------------------------------------------------
+# 1.*: Test that nothing goes wrong if recovery is forced while opening
+#      a write transaction or performing a checkpoint with blocking locks.
+#
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x, y);
+  PRAGMA journal_mode = wal;
+  INSERT INTO t1 VALUES(1, 2);
+  INSERT INTO t1 VALUES(3, 4);
+  INSERT INTO t1 VALUES(5, 6);
+  INSERT INTO t1 VALUES(7, 8);
+} {wal}
+
+sqlite3 db2 test.db
+db2 timeout 1000
+
+do_execsql_test -db db2 1.1 {
+  SELECT * FROM t1
+} {1 2 3 4 5 6 7 8}
+
+set fd [open test.db-shm r+]
+puts $fd "blahblahblahblah"
+flush $fd
+
+do_execsql_test 1.2 {
+  BEGIN;
+    INSERT INTO t1 VALUES(9, 10);
+}
+
+do_execsql_test -db db2 1.3 {
+  SELECT * FROM t1
+} {1 2 3 4 5 6 7 8}
+
+do_test 1.4 {
+  list [catch {db2 eval { BEGIN EXCLUSIVE }} msg] $msg
+} {1 {database is locked}}
+
+do_execsql_test 1.5 { COMMIT }
+do_execsql_test -db db2 1.6 {
+  SELECT * FROM t1
+} {1 2 3 4 5 6 7 8 9 10}
+
+puts $fd "blahblahblahblah"
+flush $fd
+
+do_execsql_test -db db2 1.7 {
+  PRAGMA wal_checkpoint = TRUNCATE
+} {0 0 0}
+
+do_test 1.8 {
+  file size test.db-wal
+} 0
+
+close $fd
+db close
+db2 close
+#-------------------------------------------------------------------------
+
+do_multiclient_test tn {
+  do_test 2.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(s, v);
+      INSERT INTO t1 VALUES(1, 2);
+      INSERT INTO t1 VALUES(3, 4);
+      INSERT INTO t1 VALUES(5, 6);
+    }
+    code1 { db timeout 2000 }
+  } {}
+
+  do_test 2.$tn.2 {
+    sql2 {
+      BEGIN;
+        INSERT INTO t1 VALUES(7, 8);
+    }
+  } {}
+
+  do_test 2.$tn.3 {
+    set us [lindex [time { catch {db eval "BEGIN EXCLUSIVE"} }] 0]
+    expr $us>1000000 && $us<4000000
+  } {1}
+
+  do_test 2.$tn.4 {
+    sql2 { COMMIT }
+    sql1 { SELECT * FROM t1 }
+  } {1 2 3 4 5 6 7 8}
+
+  do_test 2.$tn.5 {
+    sql2 {
+      BEGIN;
+        INSERT INTO t1 VALUES(9, 10);
+    }
+  } {}
+
+  do_test 2.$tn.6 {
+    set us [lindex [time { catch {db eval "PRAGMA wal_checkpoint=RESTART"} }] 0]
+    expr $us>1000000 && $us<4000000
+  } {1}
+
+  do_test 2.$tn.7 {
+    sql2 {
+      COMMIT;
+      BEGIN;
+        SELECT * FROM t1;
+    }
+  } {1 2 3 4 5 6 7 8 9 10}
+
+  do_test 2.$tn.8 {
+    set us [lindex [time { catch {db eval "PRAGMA wal_checkpoint=RESTART"} }] 0]
+    expr $us>1000000 && $us<4000000
+  } {1}
+
+  do_test 2.$tn.9 {
+    sql3 {
+      INSERT INTO t1 VALUES(11, 12);
+    }
+    sql2 {
+      COMMIT;
+      BEGIN;
+        SELECT * FROM t1;
+    }
+    sql3 {
+      INSERT INTO t1 VALUES(13, 14);
+    }
+  } {}
+
+  do_test 2.$tn.10 {
+    set us [lindex [time { catch {db eval "PRAGMA wal_checkpoint=RESTART"} }] 0]
+    expr $us>1000000 && $us<4000000
+  } {1}
+
+  do_test 2.$tn.11 {
+    sql3 {
+      BEGIN;
+        SELECT * FROM t1;
+    }
+    sql1 { INSERT INTO t1 VALUES(15, 16); }
+  } {}
+
+  do_test 2.$tn.12 {
+    set us [lindex [time { catch {db eval "PRAGMA wal_checkpoint=RESTART"} }] 0]
+    expr $us>1000000 && $us<4000000
+  } {1}
+
+  do_test 2.$tn.13 {
+    sql2 {
+      COMMIT;
+      BEGIN;
+        SELECT * FROM t1;
+    }
+    sql1 { INSERT INTO t1 VALUES(17, 18); }
+  } {}
+
+  do_test 2.$tn.14 {
+    set us [lindex [time { catch {db eval "PRAGMA wal_checkpoint=RESTART"} }] 0]
+    expr $us>1000000 && $us<4000000
+  } {1}
+  
+}
+
+#-------------------------------------------------------------------------
+reset_db
+sqlite3 db2 test.db
+db2 timeout 1000
+do_execsql_test 3.0 {
+  PRAGMA journal_mode = wal;
+  CREATE TABLE x1(x, y);
+  BEGIN;
+    INSERT INTO x1 VALUES(1, 2);
+} {wal}
+
+do_test 3.1 {
+  list [catch { db2 eval {BEGIN EXCLUSIVE} } msg] $msg
+} {1 {database is locked}}
+
+finish_test
+
@@ -341,6 +341,7 @@ foreach file {
   vdbe.c
   vdbeblob.c
   vdbesort.c
+   vdbevtab.c
   memjournal.c

   walker.c
Author	SHA1	Message	Date
dan	11a8182e5c	Fix an error that could occur if the first transaction executed by a connection configured to use blocking locks is a write-transaction for which the WRITER lock cannot be obtained. FossilOrigin-Name: 49e4dc72f7a4b28e4b49d7b91030bc986aea3ff44dac38cb6e68305800cd1de5	2020-05-07 14:26:40 +00:00
dan	4cbe5d3588	Merge trunk changes into this branch. FossilOrigin-Name: ac4ee69664278a828e0a64c5be3b96fdb6eb6acc95646a9425c667aea328791c	2020-05-07 14:05:08 +00:00
drh	e937df81f0	Fix the handling of reserve-bytes so that the maximum value of 255 can be used. FossilOrigin-Name: 99749d4fd4930ccf15227f67c732266af9e09dd3cabdc0834fb450ef98196441	2020-05-07 01:56:57 +00:00
dan	a8aae52391	Avoid leaking a file-handle in test file walsetlk.test. FossilOrigin-Name: 3cfc675e2e917b69108feb3a75728b573abe8e44f0890a7d20d307b0b6784c0e	2020-05-06 21:25:39 +00:00
dan	bc9fc18e45	Fix an assert() failure that could follow an IO error. FossilOrigin-Name: e89c864299024cdce395a15c19b000b976142b9eed267901a288adaa695f9e65	2020-05-06 21:24:29 +00:00
drh	783e159e48	Fix harmless compiler warnings. FossilOrigin-Name: 92dc59132f8547635d73c61c21ea29b380c401ddc84a6d01412808e00386b9e8	2020-05-06 20:55:38 +00:00
dan	7a623e1d25	Fix a problem preventing building without SQLITE_ENABLE_SETLK_TIMEOUT defined. FossilOrigin-Name: 98eb54c6d83992886f17a00b6fc8998df230e3b5f45bafc6fae0d15a9ee5a4c6	2020-05-06 20:45:11 +00:00
dan	7bb8b8a4f7	Add error code SQLITE_BUSY_TIMEOUT, used internally by the OS layer to indicate that a call to xShmLock() has failed due to timeout of a blocking lock. FossilOrigin-Name: f3ef9c7c2b4ba3de1057ad569f068b241d5f23e6629d8e0dacf85e57fd13b8aa	2020-05-06 20:27:18 +00:00
dan	fc87ab8c4a	Fix compiler warnings in non-SQLITE_ENABLE_SETLK_TIMEOUT builds. FossilOrigin-Name: 22de99ef410ba2a540871f3e61157d8dc4b969416f14808aeca73971b17fcd51	2020-05-06 19:22:59 +00:00
dan	861fb1e9dc	Block on the WRITER lock when attempting to run recovery. FossilOrigin-Name: 105d6c9bbcadc64faa2b24e315cb13227b17cfc6bf1b3512713f80ce56976a3d	2020-05-06 19:14:41 +00:00
drh	e0a8b712c1	Provide the SQLITE_DEFAULT_LEGACY_ALTER_TABLE compile-time option. FossilOrigin-Name: 63e659d9a793227604aa95685a8d83cd08305f1d01e135407a3ffc6d54482ab8	2020-05-06 18:43:57 +00:00
dan	d0e6d13301	Add tests for running recovery when opening a write transaction or performing a checkpoint with blocking locks enabled. Fix some failing assert() statements. FossilOrigin-Name: d096ea3fe20f8af90f9e3f798fd0a69527b32ac8e208ade58b9d0af0e831f41b	2020-05-06 17:18:57 +00:00
dan	293e9f5d6c	Merge latest trunk changes into this branch. FossilOrigin-Name: a3727dba10b476f414f0a049b35f2a5c169a408eccefa6833821560684e07f8b	2020-05-06 15:07:25 +00:00
dan	58021b237a	Unless upgrading an existing read transaction, have ENABLE_SETLK_TIMEOUT builds attempt to use a blocking lock when opening a write transaction on a wal mode database. FossilOrigin-Name: d6f819a9e6b35f3fd558bd93255a6a24ad690a0fa15a82b009ca9c641db983c6	2020-05-05 20:30:07 +00:00
drh	fde2592503	The only known path to a corruption detection branch was cut off by the previous commit implementing earlier index corruption. So make the branch NEVER. Maybe a fuzzer will find a new path. FossilOrigin-Name: 9a84d8eb44b12ddea921baa73ac3bffa8c8d23a852605dc1dbde37907360bd79	2020-05-05 19:54:02 +00:00
drh	85bd353ac2	Earlier detection of index corruption caused by missing index entries. FossilOrigin-Name: f339f31f9e9a856b576f99c5230fdf6d60fdc2873e48cb5aa0a4ab1d04e3c930	2020-05-05 18:42:49 +00:00
drh	eb8305bbc7	Fix a compiler warning in cksumvfs.c. FossilOrigin-Name: 68033bcade87e6046f4c0a49936d63ce531c680c1def98fae02afa0c79db2c7f	2020-05-05 13:41:40 +00:00
drh	3d42fb788a	Fix harmless compiler warnings. FossilOrigin-Name: 8eee591d3cb9fadfd5cac5543bd66ef9cb371a72d3ad3241fb3bfd67fb216eda	2020-05-04 19:52:00 +00:00
dan	8714de97c0	Changes to avoid deadlock in SQLITE_ENABLE_SETLK_TIMEOUT builds. FossilOrigin-Name: 553423c23142cf0ec219192315d57ce8a0e10c3d8678d28bc110a1a9a7c17cee	2020-05-04 19:42:35 +00:00
drh	44a5c86c6c	Minor change to the sqlite_stmt virtual table, for test coverage. FossilOrigin-Name: 838987b2097c4b7acaa65aea99cfdaf199f04d76bcf6ef12743c60b338a965f7	2020-05-04 19:04:23 +00:00
drh	20e34f9110	Simplify the initialization of built-in extensions. FossilOrigin-Name: 729f2397358d0382e255ba0058bf70bc9ed410b7621a67466da13de437d3ba5c	2020-05-04 17:15:21 +00:00
drh	995e1af9fa	Ensure that the master-journal name is in a form suitable to be passed into sqlite3_uri_parameter(). FossilOrigin-Name: d1ba026d882f070b351280028e2fa88a3cca59b46d4683302e24c6677e0951b9	2020-05-04 11:47:38 +00:00
drh	278b0517d8	Add the SQLITE_FCNTL_CKPT_START file-control and use it to optimize the cksumvfs extension. FossilOrigin-Name: efdecb13091316aeac2722f58577cb0314e008e857f2816a2a222bac0a83e9e1	2020-05-02 04:08:23 +00:00
drh	477a357278	Add support for PRAGMA analyze_limit and approximate analysis. FossilOrigin-Name: 812547525d35df975f40cbbeb604cc9cd2dec809c1ca083cbb139fe59ffa1d73	2020-05-02 03:46:32 +00:00
drh	c75921ac4e	Merge the bytecode and tables_used table-valued functions. Requires -DSQLITE_ENABLE_BYTECODE_VTAB at compile-time. FossilOrigin-Name: d09bcce37f1eaf084e3b07eb4a23653ea1f370cdd290ce3875408186adf87022	2020-05-02 00:31:00 +00:00
drh	7e088a6c0a	Corner-case changes to the bytecode virtual table for testability and correctness. FossilOrigin-Name: baa720e4a88f268ed95337daab5f434fd3263b00f09101cddc6424765bf3b722	2020-05-02 00:01:39 +00:00
drh	51f1c6f3ec	Merge recent enhancements from trunk. FossilOrigin-Name: 96dfc71ea599702ef38b60952d03e95dce5a8c534cd943e076e9c76b00e61e65	2020-05-01 18:58:21 +00:00
drh	fcf31b28ff	Add the SQLITE_FCNTL_CKPT_START file-control. Use it to optimize the cksumvfs extension. FossilOrigin-Name: b40f5aa344ae10cf4da83b3aa9e4866d6f6ffb06ba7e34ec1ce80c92468cf3bf	2020-05-01 18:37:34 +00:00
drh	75b5f22c01	Merge recent trunk enhancements into the bytecode-function branch. FossilOrigin-Name: 7e6576ec00fde277c5c7abac264f7ec7e531de00c4e112bf733a07fe703fadcc	2020-04-09 15:07:22 +00:00
drh	eb110d9687	Merge updates from trunk. FossilOrigin-Name: 348c40136c8ec20f36ccdd4c8a6d4ec2d8274328b86b25b385813e3aae31ea8b	2020-04-03 15:48:05 +00:00
drh	49d01abaac	Fix a minor problem with EXPLAIN QUERY PLAN for triggers. FossilOrigin-Name: 6e11c03f84efa93b218b07e39b6b56b1d872639f39c18498ee54d8cd8364d4f5	2020-04-02 19:58:31 +00:00
drh	e1cd73f671	Minor changes for better test coverage. FossilOrigin-Name: ae3ac297d2deee2a687ae2e9cf98aaf3e1b41196363238101a19d38092aebec6	2020-04-02 17:21:51 +00:00
drh	c004bd54e3	Fix another harmless compiler warning. FossilOrigin-Name: 949eec2530bbe7f48daddfb3022d60ea5d7a43f0f5d120e71c682054feb721db	2020-04-02 13:08:54 +00:00
drh	e0ef4e2b47	Add a missing #ifdef to avoid a harmless compiler warning. FossilOrigin-Name: cc54de354317ebc080d4d1ee25427b31a49c4a75e01cb5d9966f1aaeb2ad098d	2020-04-02 12:53:17 +00:00
drh	e065a18a4b	Merge enhancements from trunk. FossilOrigin-Name: d1731385c077f298b0cf654d6183ed40f7e5c07e4e2ab7f69109cf951ce99d9e	2020-04-02 12:24:08 +00:00
drh	8f78a528d5	Add the tables_used() table-valued function as a variation on bytecode(). FossilOrigin-Name: 6283c677d57220e54375a6463f453c6d068e042263558df16cff1055d1b0d3f5	2020-03-26 16:48:18 +00:00
drh	c5eeacd58b	Merge updates from trunk. FossilOrigin-Name: d7db09101878102e192ee7a81437e8f6f2e317ddf110852673a2e81d1f80ae0e	2020-03-26 15:28:46 +00:00
drh	7797207554	Optimize the "subprog IS NULL" constraint. FossilOrigin-Name: ca8c5f028b9f6f32639c8bc9df5dc02537e21385fcbe7e1ae600c640977ea0d5	2020-03-24 18:41:58 +00:00
drh	cf08f08d2c	Fix a memory leak. FossilOrigin-Name: c9f3405eeac8aff171b5d76bae954f3b51b353d16286a3d2af43ef942c212abc	2020-03-24 17:52:31 +00:00
drh	0518d06117	Provide content for the bytecode.subprog column. FossilOrigin-Name: df893364b7cea07ff2b15b80cb294dccaffe701d51452264599b55304a36fa7c	2020-03-24 13:27:53 +00:00
drh	eeb55d8694	Fix the build so that it works even without SQLITE_ENABLE_EXPLAIN_COMMENTS. FossilOrigin-Name: 5896cbf4d0c7854c29c96d2ea2cea4adaedaa027a0fe4a3f0ac4dfbeaabb8dec	2020-03-23 23:17:38 +00:00
drh	8c5163a697	The bytecode() function now runs and sometimes works, but it untested and there are known problems. FossilOrigin-Name: 6819b86eb2de516c445655a83f9b2ba5ae0bff660cffaf84f1345d9be79b051e	2020-03-23 20:58:55 +00:00
drh	cb49f5468e	Further simplification and modularization of the EXPLAIN logic. FossilOrigin-Name: aee1c12f4227cea9e8c6295cee3ec11797422c31b48c9468f176eb52f8261fe8	2020-03-23 19:14:11 +00:00
drh	356cd76aa8	Begin breaking appear the sqlite3VdbeList() routine into subroutines that can be reused by the bytecode() table. FossilOrigin-Name: 2c4dd79fbd4b9f72634a732abb9ed833cd8c9b05fe1e10af8f23e6d6ec023c7c	2020-03-23 17:24:46 +00:00
drh	691b5c54b8	Infrastructure for the bytecode() table-valued function. The function itself is not yet implemented. FossilOrigin-Name: 2795f0d633577e0de66b389d9e8e44c55e85975bdc62f1a0b8f93959d19b22bf	2020-03-23 15:49:22 +00:00