Fix issue with changing page size via VACUUM

Trying to change the page size for an encrypted database by issuing PRAGMA PAGE_SIZE followed by VACUUM results in a corrupted database. This has been fixed by adjusting the VACUUM procedure to ignore a page size change request for encrypted databases.

Author: utelle

scripts/patchsqlite3.sh

@@ -27,4 +27,5 @@ 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 '/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 '/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/sqlite3patched.c

@@ -156216,6 +156216,15 @@ SQLITE_PRIVATE SQLITE_NOINLINE int sqlite3RunVacuum(
   }
   nRes = sqlite3BtreeGetRequestedReserve(pMain);
 
+  /* A VACUUM cannot change the pagesize of an encrypted database. */
+  if( db->nextPagesize ){
+    extern void sqlite3mcCodecGetKey(sqlite3*, int, void**, int*);
+    int nKey;
+    char *zKey;
+    sqlite3mcCodecGetKey(db, iDb, (void**)&zKey, &nKey);
+    if( nKey ) db->nextPagesize = 0;
+  }
+
   sqlite3BtreeSetCacheSize(pTemp, db->aDb[iDb].pSchema->cache_size);
   sqlite3BtreeSetSpillSize(pTemp, sqlite3BtreeSetSpillSize(pMain,0));
   sqlite3BtreeSetPagerFlags(pTemp, pgflags|PAGER_CACHESPILL);