| Index: src/btree.c |
| =================================================================== |
| --- src/btree.c 2009-09-09 06:45:19.000000000 -0700 |
| +++ src/btree.c 2009-09-14 18:17:53.000000000 -0700 |
| @@ -24,6 +24,12 @@ |
| static const char zMagicHeader[] = SQLITE_FILE_HEADER; |
| |
| /* |
| +** The header string that appears at the beginning of a SQLite |
| +** database which has been poisoned. |
| +*/ |
| +static const char zPoisonHeader[] = "SQLite poison 3"; |
| + |
| +/* |
| ** Set this global variable to 1 to enable tracing using the TRACE |
| ** macro. |
| */ |
| @@ -2337,6 +2343,7 @@ |
| if( rc ) return rc; |
| memcpy(data, zMagicHeader, sizeof(zMagicHeader)); |
| assert( sizeof(zMagicHeader)==16 ); |
| + assert( sizeof(zMagicHeader)==sizeof(zPoisonHeader) ); |
| put2byte(&data[16], pBt->pageSize); |
| data[18] = 1; |
| data[19] = 1; |
| @@ -7804,4 +7811,72 @@ |
| assert(!pCur->aOverflow); |
| pCur->isIncrblobHandle = 1; |
| } |
| + |
| +/* Poison the db so that other clients error out as quickly as |
| +** possible. |
| +*/ |
| +int sqlite3Poison(sqlite3 *db){ |
| + int rc; |
| + Btree *p; |
| + BtShared *pBt; |
| + unsigned char *pP1; |
| + |
| + if( db == NULL) return SQLITE_OK; |
| + |
| + /* Database 0 corrosponds to the main database. */ |
| + if( db->nDb<1 ) return SQLITE_OK; |
| + p = db->aDb[0].pBt; |
| + pBt = p->pBt; |
| + |
| + /* If in a transaction, roll it back. Committing any changes to a |
| + ** corrupt database may mess up evidence, we definitely don't want |
| + ** to allow poisoning to be rolled back, and the database is anyhow |
| + ** going bye-bye RSN. |
| + */ |
| + /* TODO(shess): Figure out if this might release the lock and let |
| + ** someone else get in there, which might deny us the lock a couple |
| + ** lines down. |
| + */ |
| + if( sqlite3BtreeIsInTrans(p) ) sqlite3BtreeRollback(p); |
| + |
| + /* Start an exclusive transaction. This will check the headers, so |
| + ** if someone else poisoned the database we should get an error. |
| + */ |
| + rc = sqlite3BtreeBeginTrans(p, 2); |
| + /* TODO(shess): Handle SQLITE_BUSY? */ |
| + if( rc!=SQLITE_OK ) return rc; |
| + |
| + /* Copied from sqlite3BtreeUpdateMeta(). Writing the old version of |
| + ** the page to the journal may be overkill, but it probably won't |
| + ** hurt. |
| + */ |
| + assert( pBt->inTrans==TRANS_WRITE ); |
| + assert( pBt->pPage1!=0 ); |
| + rc = sqlite3PagerWrite(pBt->pPage1->pDbPage); |
| + if( rc ) goto err; |
| + |
| + /* "SQLite format 3" changes to |
| + ** "SQLite poison 3". Be extra paranoid about making this change. |
| + */ |
| + if( sizeof(zMagicHeader)!=16 || |
| + sizeof(zPoisonHeader)!=sizeof(zMagicHeader) ){ |
| + rc = SQLITE_ERROR; |
| + goto err; |
| + } |
| + pP1 = pBt->pPage1->aData; |
| + if( memcmp(pP1, zMagicHeader, 16)!=0 ){ |
| + rc = SQLITE_CORRUPT; |
| + goto err; |
| + } |
| + memcpy(pP1, zPoisonHeader, 16); |
| + |
| + /* Push it to the database file. */ |
| + return sqlite3BtreeCommit(p); |
| + |
| + err: |
| + /* TODO(shess): What about errors, here? */ |
| + sqlite3BtreeRollback(p); |
| + return rc; |
| +} |
| + |
| #endif |