Do not invoke usleep() for more than 999999 microseconds.

FossilOrigin-Name: 1f0055d0a2b36f9bd27d9d47a45a01be2644fc3be53d7c598fa8e112dd13e12b

manifest

@@ -1,5 +1,5 @@
-C Fix\sa\stsan\serror\sthat\scould\soccur\swhen\susing\sshared-cache\smode.
-D 2020-09-16T16:45:35.491
+C Do\snot\sinvoke\susleep()\sfor\smore\sthan\s999999\smicroseconds.
+D 2020-09-16T16:48:13.112
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -519,7 +519,7 @@ F src/os.c 80e4cf3e5da06be03ca641661e331ce60eeeeabf0d7354dbb1c0e166d0eedbbe
 F src/os.h 48388821692e87da174ea198bf96b1b2d9d83be5dfc908f673ee21fafbe0d432
 F src/os_common.h b2f4707a603e36811d9b1a13278bffd757857b85
 F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
-F src/os_unix.c 7a306a01c32928171526ca6d5e2d2fc5e39af2f12acbae43365d9521c761be2d
+F src/os_unix.c 89f19aec76a049b4deb5f1fc16afd4786bd1d151d20467abc6570c822abbfb35
 F src/os_win.c a2149ff0a85c1c3f9cc102a46c673ce87e992396ba3411bfb53db66813b32f1d
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c 3700a1c55427a3d4168ad1f1b8a8b0cb9ace1d107e4506e30a8f1e66d8a1195e
@@ -536,7 +536,7 @@ F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
 F src/resolve.c 97b91fb25d86881ff20c9ad2ad98412c6c1bb5f7d6c9bb044db250cbc9cfcd4b
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
 F src/select.c 233e884d7da6601486c7b93aedb97fd29302ae5c03742d0e0eccb4790638bb77
-F src/shell.c.in b9b819feede7b85585ab0826490a352e04e2ee46e8132c92597d29972b2be1d7
+F src/shell.c.in 651e844efde4bb1b6a0d43502b6ee7ef0e5e229b52b4f1e47ef11e08d1442fc9
 F src/sqlite.h.in d2c03414a8ee5d4a6855c04dd7cd5998e45139b0fe66b65bae86d4223edd091f
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 2d1af80082edffd71c6f96f70ad1ce6a4fb46615ad10291fc77fe0dea9ff0197
@@ -1880,8 +1880,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 553e20c3d7dcd35077d758987c411806c4574b0f8b8a1fbd63d3321dd076a0b0
-Q +de80bc87300257cc49d98e2d22e914211f213dce912f320c8b37b3883c73923c
-R 286669a37fca71d0e175626276bb973d
+P 61981b97475a747dc04e6fb80e01e35e41e5d7d30a1207f82b2ef7be3866d30a
+Q +1f5ed852f25515bbc0a7aaf236fdef40fa7e31805eee1249277fde4e68f95130
+R 095902dfcb3c2a4da5e5a0b4967cfc40
 U dan
-Z 60bbc2c4ca2feb1b2bbc49267c238176
+Z c14daca6c0f63cba8ca3beff44ac028f

manifest.uuid

@@ -1 +1 @@
-61981b97475a747dc04e6fb80e01e35e41e5d7d30a1207f82b2ef7be3866d30a
+1f0055d0a2b36f9bd27d9d47a45a01be2644fc3be53d7c598fa8e112dd13e12b

src/os_unix.c

@@ -1544,6 +1544,9 @@ static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){
   return rc;
 }
 
+/* Forward declaration*/
+static int unixSleep(sqlite3_vfs*,int);
+
 /*
 ** Set a posix-advisory-lock.
 **
@@ -1573,7 +1576,7 @@ static int osSetPosixAdvisoryLock(
     ** generic posix, however, there is no such API.  So we simply try the
     ** lock once every millisecond until either the timeout expires, or until
     ** the lock is obtained. */
-    usleep(1000);
+    unixSleep(0,1000);
     rc = osFcntl(h,F_SETLK,pLock);
     tm--;
   }
@@ -6544,7 +6547,8 @@ static int unixSleep(sqlite3_vfs *NotUsed, int microseconds){
   UNUSED_PARAMETER(NotUsed);
   return microseconds;
 #elif defined(HAVE_USLEEP) && HAVE_USLEEP
-  usleep(microseconds);
+  if( microseconds>=1000000 ) sleep(microseconds/1000000);
+  if( microseconds%1000000 ) usleep(microseconds%1000000);
   UNUSED_PARAMETER(NotUsed);
   return microseconds;
 #else
@@ -7117,7 +7121,7 @@ static int proxyConchLock(unixFile *pFile, uuid_t myHostID, int lockType){
       
       if( nTries==1 ){
         conchModTime = buf.st_mtimespec;
-        usleep(500000); /* wait 0.5 sec and try the lock again*/
+        unixSleep(0,500000); /* wait 0.5 sec and try the lock again*/
         continue;  
       }
 
@@ -7143,7 +7147,7 @@ static int proxyConchLock(unixFile *pFile, uuid_t myHostID, int lockType){
           /* don't break the lock on short read or a version mismatch */
           return SQLITE_BUSY;
         }
-        usleep(10000000); /* wait 10 sec and try the lock again */
+        unixSleep(0,10000000); /* wait 10 sec and try the lock again */
         continue; 
       }
       

src/shell.c.in

@@ -4426,6 +4426,19 @@ static void shellIdQuote(
   }
 }
 
+/*
+** Scalar function "usleep(X)" invokes sqlite3_sleep(X) and returns X.
+*/
+static void shellUSleepFunc(
+  sqlite3_context *context, 
+  int argc, 
+  sqlite3_value **argv
+){
+  int sleep = sqlite3_value_int(argv[0]);
+  sqlite3_sleep(sleep/1000);
+  sqlite3_result_int(context, sleep);
+}
+
 /*
 ** Scalar function "shell_escape_crnl" used by the .recover command.
 ** The argument passed to this function is the output of built-in
@@ -4609,6 +4622,8 @@ static void open_db(ShellState *p, int openFlags){
                             shellInt32, 0, 0);
     sqlite3_create_function(p->db, "shell_idquote", 1, SQLITE_UTF8, 0,
                             shellIdQuote, 0, 0);
+    sqlite3_create_function(p->db, "usleep",1,SQLITE_UTF8,0,
+                            shellUSleepFunc, 0, 0);
 #ifndef SQLITE_NOHAVE_SYSTEM
     sqlite3_create_function(p->db, "edit", 1, SQLITE_UTF8, 0,
                             editFunc, 0, 0);