Fix issue #194

- Remove use of SQLITE_EXTRA_INIT and SQLITE_EXTRA_SHUTDOWN
- Add SQLite patch to call sqlite3mc_initialize directly from within SQLite's guarded initialization context to avoid race condition (as described in issue #194)
- Add SQLite patch to call sqlite3mc_shutdown directly from sqlite3_shutdown

Author: utelle

scripts/patchsqlite3.sh

@@ -27,5 +27,7 @@ sed 's/sqlite3_file_control\(.*SQLITE_FCNTL_PRAGMA\)/sqlite3mcFileControlPragma\
     | sed '/^  if( sqlite3PCacheIsDirty(pPager->pPCache) ) return 0;/a \  if( sqlite3mcPagerHasCodec(pPager) != 0 ) return 0;' \
     | sed '/^  }else if( USEFETCH(pPager) ){/c \  }else if( USEFETCH(pPager) && sqlite3mcPagerHasCodec(pPager) == 0 ){' \
     | sed '/^  if( rc!=SQLITE_OK ) memset(&mem0, 0, sizeof(mem0));/a \\n  \/\* Initialize wrapper for memory management.\*\/\n  if( rc==SQLITE_OK ) {\n    sqlite3mcInitMemoryMethods();\n  }\n' \
+    | sed '/^      sqlite3GlobalConfig.isInit = 1;/i \ \n      int sqlite3mc_initialize(const char*);\n      rc = sqlite3mc_initialize(0);\n' \
+    | sed '/^    sqlite3_os_end();/i \ \n    void sqlite3mc_shutdown(void);\n    sqlite3mc_shutdown();\n' \
     | sed '/Lock the source database handle./i \  \/\* Check whether databases are compatible with backup \*\/\n  if (!sqlite3mcIsBackupSupported(pSrcDb, zSrcDb, pDestDb, zDestDb)){\n    sqlite3ErrorWithMsg(pDestDb, SQLITE_ERROR, \"backup is not supported with incompatible source and target databases\");\n    return NULL;\n  }\n' \
     | sed '/nRes = sqlite3BtreeGetRequestedReserve(pMain)/a \\n  \/\* A VACUUM cannot change the pagesize of an encrypted database. \*\/\n  if( db->nextPagesize ){\n    extern void sqlite3mcCodecGetKey(sqlite3*, int, void**, int*);\n    int nKey;\n    char *zKey;\n    sqlite3mcCodecGetKey(db, iDb, (void**)&zKey, &nKey);\n    if( nKey ) db->nextPagesize = 0;\n  }' \

src/sqlite3mc.c

@@ -37,19 +37,6 @@
 #endif
 #endif
 
-/*
-** Define function for extra initialization and extra shutdown
-**
-** The extra initialization function registers an extension function
-** which will be automatically executed for each new database connection.
-**
-** The extra shutdown function will be executed on the invocation of sqlite3_shutdown.
-** All created multiple ciphers VFSs will be unregistered and destroyed.
-*/
-
-#define SQLITE_EXTRA_INIT sqlite3mc_initialize
-#define SQLITE_EXTRA_SHUTDOWN sqlite3mc_shutdown
-
 /*
 ** Declare all internal functions as 'static' unless told otherwise
 */

src/sqlite3patched.c

@@ -181886,6 +181886,10 @@ SQLITE_API int sqlite3_initialize(void){
       sqlite3PCacheBufferSetup( sqlite3GlobalConfig.pPage,
           sqlite3GlobalConfig.szPage, sqlite3GlobalConfig.nPage);
       sqlite3MemoryBarrier();
+ 
+      int sqlite3mc_initialize(const char*);
+      rc = sqlite3mc_initialize(0);
+
       sqlite3GlobalConfig.isInit = 1;
 #ifdef SQLITE_EXTRA_INIT
       bRunExtraInit = 1;
@@ -181959,6 +181963,10 @@ SQLITE_API int sqlite3_shutdown(void){
     void SQLITE_EXTRA_SHUTDOWN(void);
     SQLITE_EXTRA_SHUTDOWN();
 #endif
+ 
+    void sqlite3mc_shutdown(void);
+    sqlite3mc_shutdown();
+
     sqlite3_os_end();
     sqlite3_reset_auto_extension();
     sqlite3GlobalConfig.isInit = 0;