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Add OpenTransientFile, with automatic cleanup at end-of-xact.

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Files opened with BasicOpenFile or PathNameOpenFile are not automatically
cleaned up on error. That puts unnecessary burden on callers that only want
to keep the file open for a short time. There is AllocateFile, but that
returns a buffered FILE * stream, which in many cases is not the nicest API
to work with. So add function called OpenTransientFile, which returns a
unbuffered fd that's cleaned up like the FILE* returned by AllocateFile().

This plugs a few rare fd leaks in error cases:

1. copy_file() - fixed by by using OpenTransientFile instead of BasicOpenFile
2. XLogFileInit() - fixed by adding close() calls to the error cases. Can't
   use OpenTransientFile here because the fd is supposed to persist over
   transaction boundaries.
3. lo_import/lo_export - fixed by using OpenTransientFile instead of
   PathNameOpenFile.

In addition to plugging those leaks, this replaces many BasicOpenFile() calls
with OpenTransientFile() that were not leaking, because the code meticulously
closed the file on error. That wasn't strictly necessary, but IMHO it's good
for robustness.

The same leaks exist in older versions, but given the rarity of the issues,
I'm not backpatching this. Not yet, anyway - it might be good to backpatch
later, after this mechanism has had some more testing in master branch.
This commit is contained in:
Heikki Linnakangas
2012-11-27 10:25:50 +02:00
parent 532994299e
commit 1f67078ea3
10 changed files with 209 additions and 112 deletions
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26
src/backend/storage/file/copydir.c
View File

@ -162,14 +162,14 @@ copy_file(char *fromfile, char *tofile)
/*
* Open the files
*/
srcfd = BasicOpenFile(fromfile, O_RDONLY | PG_BINARY, 0);
srcfd = OpenTransientFile(fromfile, O_RDONLY | PG_BINARY, 0);
if (srcfd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", fromfile)));
dstfd = BasicOpenFile(tofile, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
dstfd = OpenTransientFile(tofile, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
if (dstfd < 0)
ereport(ERROR,
(errcode_for_file_access(),
@ -209,12 +209,12 @@ copy_file(char *fromfile, char *tofile)
(void) pg_flush_data(dstfd, offset, nbytes);
}
if (close(dstfd))
if (CloseTransientFile(dstfd))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", tofile)));
close(srcfd);
CloseTransientFile(srcfd);
pfree(buffer);
}
@ -238,13 +238,13 @@ fsync_fname(char *fname, bool isdir)
* cases here
*/
if (!isdir)
fd = BasicOpenFile(fname,
O_RDWR | PG_BINARY,
S_IRUSR | S_IWUSR);
fd = OpenTransientFile(fname,
O_RDWR | PG_BINARY,
S_IRUSR | S_IWUSR);
else
fd = BasicOpenFile(fname,
O_RDONLY | PG_BINARY,
S_IRUSR | S_IWUSR);
fd = OpenTransientFile(fname,
O_RDONLY | PG_BINARY,
S_IRUSR | S_IWUSR);
/*
* Some OSs don't allow us to open directories at all (Windows returns
@ -263,7 +263,7 @@ fsync_fname(char *fname, bool isdir)
/* Some OSs don't allow us to fsync directories at all */
if (returncode != 0 && isdir && errno == EBADF)
{
close(fd);
CloseTransientFile(fd);
return;
}
@ -272,5 +272,5 @@ fsync_fname(char *fname, bool isdir)
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m", fname)));
close(fd);
CloseTransientFile(fd);
}