Minor enhancement to the pager so that it remembers if the underlying database

files is immutable.

FossilOrigin-Name: 64db614eddd664e074021ce2fab123efc49eb250f70e55fed96f7d5ea2a32747

manifest

@@ -1,5 +1,5 @@
-C Disallow\sthe\suse\sof\swindow\sfunctions\sin\sthe\srecursive\spart\sof\sa\srecursive\sCTE.
-D 2018-09-27T12:14:15.056
+C Minor\senhancement\sto\sthe\spager\sso\sthat\sit\sremembers\sif\sthe\sunderlying\sdatabase\nfiles\sis\simmutable.
+D 2018-09-27T14:24:22.733
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 01e95208a78b57d056131382c493c963518f36da4c42b12a97eb324401b3a334
@@ -489,8 +489,8 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
 F src/os_unix.c 7cfd67db0e2f926243f646db7ec1caa33ca9bee45799b0160ddfcd6ccfc175d2
 F src/os_win.c 070cdbb400097c6cda54aa005356095afdc2f3ee691d17192c54724ef146a971
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
-F src/pager.c a0d8f686ef64549ad5b356fd30429bd9ee7a06dd42b4d6faa096352ff26b1c5b
-F src/pager.h ecc554a55bc55d1c4ba5e17137b72e238e00bd81e72ff2662d8b9c8c10ae3963
+F src/pager.c 09621e99f96e34529b5ed61b4c1ba87743917cf3f06b00ff4bedb67124e51228
+F src/pager.h d141d2f2f7024d3988b6e03068d25cb8100846c9ab8a0338a3f3c07c43a00da8
 F src/parse.y 6840fe7c0b5eb4dd25ee5d075213bc8255ed4c0678d71bfb6744d0520d91c179
 F src/pcache.c 4196eb6ed3bbf00b80596c8e0b4f50e57eb7d890c19fb27a7354306abb7f983d
 F src/pcache.h 072f94d29281cffd99e46c1539849f248c4b56ae7684c1f36626797fee375170
@@ -1769,7 +1769,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P bd250533a06e4a11c1f548c3de66b8562fc627383848570d7d030cf132fd336f
-R f859da5dfe791e15b8e90067f7a4610e
-U dan
-Z 08a7f25691627dd6eb8a24e372187fa8
+P 7fc2994434c7d9ed29c96a69c07e8eb4e97be776473c170c63f9a1bbaa09fa68
+R e6d82739c190925225a822d1b7e6dedb
+T *branch * immutable-pager
+T *sym-immutable-pager *
+T -sym-trunk *
+U drh
+Z f57501b34f168481651a726b32cc4ecd

manifest.uuid

@@ -1 +1 @@
-7fc2994434c7d9ed29c96a69c07e8eb4e97be776473c170c63f9a1bbaa09fa68
+64db614eddd664e074021ce2fab123efc49eb250f70e55fed96f7d5ea2a32747

src/pager.c

@@ -4729,7 +4729,7 @@ int sqlite3PagerOpen(
 #else
 # define memJM 0
 #endif
-  int readOnly = 0;        /* True if this is a read-only file */
+  int readOnly = PAGER_READWRITE;   /* True if this is a read-only file */
   int journalFileSize;     /* Bytes to allocate for each journal fd */
   char *zPathname = 0;     /* Full path to database file */
   int nPathname = 0;       /* Number of bytes in zPathname */
@@ -4860,6 +4860,7 @@ int sqlite3PagerOpen(
     memJM = (fout&SQLITE_OPEN_MEMORY)!=0;
 #endif
     readOnly = (fout&SQLITE_OPEN_READONLY)!=0;
+    assert( readOnly==PAGER_READWRITE || readOnly==PAGER_READONLY );
 
     /* If the file was successfully opened for read/write access,
     ** choose a default page size in case we have to create the
@@ -4899,6 +4900,7 @@ int sqlite3PagerOpen(
       if( (iDc & SQLITE_IOCAP_IMMUTABLE)!=0
        || sqlite3_uri_boolean(zFilename, "immutable", 0) ){
           vfsFlags |= SQLITE_OPEN_READONLY;
+          readOnly = PAGER_IMMUTABLE;
           goto act_like_temp_file;
       }
     }
@@ -4918,7 +4920,9 @@ act_like_temp_file:
     pPager->eState = PAGER_READER;     /* Pretend we already have a lock */
     pPager->eLock = EXCLUSIVE_LOCK;    /* Pretend we are in EXCLUSIVE mode */
     pPager->noLock = 1;                /* Do no locking */
-    readOnly = (vfsFlags&SQLITE_OPEN_READONLY);
+    if( (vfsFlags & SQLITE_OPEN_READONLY)!=0 && readOnly==PAGER_READWRITE ){
+      readOnly = PAGER_READONLY;
+    }
   }
 
   /* The following call to PagerSetPagesize() serves to set the value of 
@@ -6696,6 +6700,12 @@ int sqlite3PagerRollback(Pager *pPager){
 /*
 ** Return TRUE if the database file is opened read-only.  Return FALSE
 ** if the database is (in theory) writable.
+**
+** Actually, the return value is one of:
+**
+**     PAGER_READWRITE  (value 0 - false)
+**     PAGER_READONLY   (value 1 - true)
+**     PAGER_IMMUTABLE  (value 2 - also true)
 */
 u8 sqlite3PagerIsreadonly(Pager *pPager){
   return pPager->readOnly;

src/pager.h

@@ -199,6 +199,10 @@ int sqlite3PagerSharedLock(Pager *pPager);
 
 /* Functions used to query pager state and configuration. */
 u8 sqlite3PagerIsreadonly(Pager*);
+/* Return values from sqlite3PagerIsreadonly() */
+#define PAGER_READWRITE  0   /* Read/write database */
+#define PAGER_READONLY   1   /* Read only but might change by outside forces */
+#define PAGER_IMMUTABLE  2   /* Guaranteed to never change */
 u32 sqlite3PagerDataVersion(Pager*);
 #ifdef SQLITE_DEBUG
   int sqlite3PagerRefcount(Pager*);