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Avoid calling sqlite3_randomness and taking the PRNG mutex when writing a journal header in "journal_mode=memory" mode.

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FossilOrigin-Name: c84e4483cb44f827416d8caafa22f076b2f31b2024fe8c5b5bcb0c9955149d11
This commit is contained in:
dan
2023-10-09 17:54:34 +00:00
parent 01a5a19919
commit 6c96bf2c3f
3 changed files with 32 additions and 9 deletions
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25
src/pager.c
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@@ -1492,9 +1492,32 @@ static int writeJournalHdr(Pager *pPager){
memset(zHeader, 0, sizeof(aJournalMagic)+4);
}
/* The random check-hash initializer */
sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
if( pPager->journalMode!=PAGER_JOURNALMODE_MEMORY ){
sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
}
#ifdef SQLITE_DEBUG
else{
/* The Pager.cksumInit variable is usually randomized above to protect
** against there being existing records in the journal file. This is
** dangerous, as following a crash they may be mistaken for records
** written by the current transaction and rolled back into the database
** file, causing corruption. The following assert statements verify
** that this is not required in "journal_mode=memory" mode, as in that
** case the journal file is always 0 bytes in size at this point.
** It is advantageous to avoid the sqlite3_randomness() call if possible
** as it takes the global PRNG mutex. */
i64 sz = 0;
sqlite3OsFileSize(pPager->jfd, &sz);
assert( sz==0 );
assert( pPager->journalOff==journalHdrOffset(pPager) );
assert( sqlite3JournalIsInMemory(pPager->jfd) );
}
#endif
put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
/* The initial database size */
put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbOrigSize);
/* The assumed sector size for this process */