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Overview
| Comment: | On the first connection to a WAL-mode database that was not cleanly shut down and contains a left-over -shm file, truncate the -shm file to 3 bytes instead of to 0 bytes. Avoiding a truncation to 0 means that system monitoring tools can better detect if a process illegitimately tries to truncate a -shm file. Such a rogue process might think it is being helpful by cleaning up old files, but there is a race condition that can cause damage to the database. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
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| SHA3-256: |
90cf32cde072a305f30c75a71665d1f9 |
| User & Date: | drh 2018-10-11 13:51:48 |
Context
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2018-10-11
| ||
| 16:38 | Always reset the pager before changing the codec. (check-in: 0bf0fd24 user: drh tags: trunk) | |
| 13:57 | Merge enhancements from trunk. (check-in: 9e10d88b user: drh tags: apple-osx) | |
| 13:51 | On the first connection to a WAL-mode database that was not cleanly shut down and contains a left-over -shm file, truncate the -shm file to 3 bytes instead of to 0 bytes. Avoiding a truncation to 0 means that system monitoring tools can better detect if a process illegitimately tries to truncate a -shm file. Such a rogue process might think it is being helpful by cleaning up old files, but there is a race condition that can cause damage to the database. (check-in: 90cf32cd user: drh tags: trunk) | |
| 10:37 | In the CLI, fix a file descriptor leak following OOM and a missing va_end() call. (check-in: ec36d15a user: drh tags: trunk) | |
Changes
Changes to src/os_unix.c.
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rc = SQLITE_IOERR_LOCK;
}else if( lock.l_type==F_UNLCK ){
if( pShmNode->isReadonly ){
pShmNode->isUnlocked = 1;
rc = SQLITE_READONLY_CANTINIT;
}else{
rc = unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1);
if( rc==SQLITE_OK && robust_ftruncate(pShmNode->hShm, 0) ){
rc = unixLogError(SQLITE_IOERR_SHMOPEN,"ftruncate",pShmNode->zFilename);
}
}
}else if( lock.l_type==F_WRLCK ){
rc = SQLITE_BUSY;
}
|
> > > > > | |
4431 4432 4433 4434 4435 4436 4437 4438 4439 4440 4441 4442 4443 4444 4445 4446 4447 4448 4449 4450 |
rc = SQLITE_IOERR_LOCK;
}else if( lock.l_type==F_UNLCK ){
if( pShmNode->isReadonly ){
pShmNode->isUnlocked = 1;
rc = SQLITE_READONLY_CANTINIT;
}else{
rc = unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1);
/* The first connection to attach must truncate the -shm file. We
** truncate to 3 bytes (an arbitrary small number, less than the
** -shm header size) rather than 0 as a system debugging aid, to
** help detect if a -shm file truncation is legitimate or is the work
** or a rogue process. */
if( rc==SQLITE_OK && robust_ftruncate(pShmNode->hShm, 3) ){
rc = unixLogError(SQLITE_IOERR_SHMOPEN,"ftruncate",pShmNode->zFilename);
}
}
}else if( lock.l_type==F_WRLCK ){
rc = SQLITE_BUSY;
}
|