Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit14bc951

Browse files
committed
Fix low-probability bug in relcache startup: write_irels wrote the
pg_internal.init file in-place, which meant that if another backendstarted at about the same time, it might read the incomplete file.init_irels tries to guard against that, but I have now seen a crashdue to reading bad data from a partly-written file. (This may indicatea kernel bug on my platform? Not sure.) Anyway, clearly the safestcourse is to write the new pg_internal.init file under a unique temporaryfilename, and rename it into place only after it's all written.
1 parentdbc9346 commit14bc951

File tree

1 file changed

+23
-4
lines changed

1 file changed

+23
-4
lines changed

‎src/backend/utils/cache/relcache.c

Lines changed: 23 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.93 2000/03/17 02:36:27 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.94 2000/03/31 19:39:22 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -33,6 +33,7 @@
3333
#include<errno.h>
3434
#include<sys/file.h>
3535
#include<fcntl.h>
36+
#include<unistd.h>
3637

3738
#include"postgres.h"
3839

@@ -2266,14 +2267,26 @@ write_irels(void)
22662267
inti;
22672268
intrelno;
22682269
RelationBuildDescInfobi;
2270+
chartempfilename[MAXPGPATH];
2271+
charfinalfilename[MAXPGPATH];
2272+
2273+
/*
2274+
* We must write a temporary file and rename it into place. Otherwise,
2275+
* another backend starting at about the same time might crash trying to
2276+
* read the partially-complete file.
2277+
*/
2278+
snprintf(tempfilename,sizeof(tempfilename),"%s%c%s.%d",
2279+
DatabasePath,SEP_CHAR,RELCACHE_INIT_FILENAME,MyProcPid);
2280+
snprintf(finalfilename,sizeof(finalfilename),"%s%c%s",
2281+
DatabasePath,SEP_CHAR,RELCACHE_INIT_FILENAME);
22692282

22702283
#ifndef__CYGWIN32__
2271-
fd=FileNameOpenFile(RELCACHE_INIT_FILENAME,O_WRONLY |O_CREAT |O_TRUNC,0600);
2284+
fd=PathNameOpenFile(tempfilename,O_WRONLY |O_CREAT |O_TRUNC,0600);
22722285
#else
2273-
fd=FileNameOpenFile(RELCACHE_INIT_FILENAME,O_WRONLY |O_CREAT |O_TRUNC |O_BINARY,0600);
2286+
fd=PathNameOpenFile(tempfilename,O_WRONLY |O_CREAT |O_TRUNC |O_BINARY,0600);
22742287
#endif
22752288
if (fd<0)
2276-
elog(FATAL,"cannot create init file %s",RELCACHE_INIT_FILENAME);
2289+
elog(FATAL,"cannot create init file %s",tempfilename);
22772290

22782291
FileSeek(fd,0L,SEEK_SET);
22792292

@@ -2397,4 +2410,10 @@ write_irels(void)
23972410
}
23982411

23992412
FileClose(fd);
2413+
2414+
/*
2415+
* And rename the temp file to its final name, deleting any previously-
2416+
* existing init file.
2417+
*/
2418+
rename(tempfilename,finalfilename);
24002419
}

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp