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Clean up memory leaks in LO operations by freeing LO's private

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memory context at transaction commit or abort.
REL6_5_PATCHES
Tom Lane 27 years ago
parent 81ced1e037
commit 2a44383a2d
3 changed files with 83 additions and 28 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 7
      src/backend/access/transam/xact.c
  2. 100
      src/backend/libpq/be-fsstubs.c
  3. 4
      src/include/libpq/be-fsstubs.h

7
src/backend/access/transam/xact.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.36 1999/05/25 16:07:50 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.37 1999/05/31 22:53:59 tgl Exp $
*
* NOTES
* Transaction aborts can now occur two ways:
@ -156,8 +156,6 @@
#include <miscadmin.h>
#include <commands/async.h>
#include <commands/sequence.h>
/* included for _lo_commit [PA, 7/17/98] */
#include <libpq/be-fsstubs.h>
static void AbortTransaction(void);
@ -938,7 +936,7 @@ CommitTransaction()
*/
/* handle commit for large objects [ PA, 7/17/98 ] */
_lo_commit();
lo_commit(true);
/* NOTIFY commit must also come before lower-level cleanup */
AtCommit_Notify();
@ -1012,6 +1010,7 @@ AbortTransaction()
* do abort processing
* ----------------
*/
lo_commit(false); /* 'false' means it's abort */
UnlockBuffers();
AtAbort_Notify();
CloseSequences();

100
src/backend/libpq/be-fsstubs.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.33 1999/05/25 16:08:57 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.34 1999/05/31 22:53:57 tgl Exp $
*
* NOTES
* This should be moved to a more appropriate place. It is here
@ -15,10 +15,17 @@
*
* Builtin functions for open/close/read/write operations on large objects.
*
* These functions operate in the current portal variable context, which
* means the large object descriptors hang around between transactions and
* are not deallocated until explicitly closed, or until the portal is
* closed.
* These functions operate in a private GlobalMemoryContext, which means
* that large object descriptors hang around until we destroy the context.
* That happens in lo_commit(). It'd be possible to prolong the lifetime
* of the context so that LO FDs are good across transactions (for example,
* we could release the context only if we see that no FDs remain open).
* But we'd need additional state in order to do the right thing at the
* end of an aborted transaction. FDs opened during an aborted xact would
* still need to be closed, since they might not be pointing at valid
* relations at all. For now, we'll stick with the existing documented
* semantics of LO FDs: they're only good within a transaction.
*
*-------------------------------------------------------------------------
*/
@ -37,6 +44,7 @@
#include <utils/memutils.h>
#include <lib/fstack.h>
#include <utils/mcxt.h>
#include <catalog/pg_shadow.h> /* for superuser() */
#include <storage/fd.h> /* for O_ */
#include <storage/large_object.h>
#include <libpq/be-fsstubs.h>
@ -91,6 +99,11 @@ lo_open(Oid lobjId, int mode)
/* switch context back to orig. */
MemoryContextSwitchTo(currentContext);
#if FSDB
if (fd < 0) /* newLOfd couldn't find a slot */
elog(NOTICE, "Out of space for large object FDs");
#endif
return fd;
}
@ -144,6 +157,8 @@ lo_read(int fd, char *buf, int len)
elog(ERROR, "lo_read: invalid large obj descriptor (%d)", fd);
return -3;
}
Assert(fscxt != NULL);
currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
status = inv_read(cookies[fd], buf, len);
@ -168,6 +183,8 @@ lo_write(int fd, char *buf, int len)
elog(ERROR, "lo_write: invalid large obj descriptor (%d)", fd);
return -3;
}
Assert(fscxt != NULL);
currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
status = inv_write(cookies[fd], buf, len);
@ -181,7 +198,7 @@ int
lo_lseek(int fd, int offset, int whence)
{
MemoryContext currentContext;
int ret;
int status;
if (fd < 0 || fd >= MAX_LOBJ_FDS)
{
@ -194,13 +211,14 @@ lo_lseek(int fd, int offset, int whence)
return -3;
}
Assert(fscxt != NULL);
currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
ret = inv_seek(cookies[fd], offset, whence);
status = inv_seek(cookies[fd], offset, whence);
MemoryContextSwitchTo(currentContext);
return ret;
return status;
}
Oid
@ -246,12 +264,26 @@ lo_tell(int fd)
elog(ERROR, "lo_tell: invalid large object descriptor (%d)", fd);
return -3;
}
/*
* We assume we do not need to switch contexts for inv_tell.
* That is true for now, but is probably more than this module
* ought to assume...
*/
return inv_tell(cookies[fd]);
}
int
lo_unlink(Oid lobjId)
{
/*
* inv_destroy does not need a context switch, indeed it doesn't
* touch any LO-specific data structures at all. (Again, that's
* probably more than this module ought to be assuming.)
*
* XXX there ought to be some code to clean up any open LOs that
* reference the specified relation... as is, they remain "open".
*/
return inv_destroy(lobjId);
}
@ -297,16 +329,23 @@ lo_import(text *filename)
File fd;
int nbytes,
tmp;
char buf[BUFSIZE];
char fnamebuf[FNAME_BUFSIZE];
LargeObjectDesc *lobj;
Oid lobjOid;
if (!superuser())
elog(ERROR, "You must have Postgres superuser privilege to use "
"server-side lo_import().\n\tAnyone can use the "
"client-side lo_import() provided by libpq.");
/*
* open the file to be read in
*/
StrNCpy(fnamebuf, VARDATA(filename), VARSIZE(filename) - VARHDRSZ + 1);
nbytes = VARSIZE(filename) - VARHDRSZ + 1;
if (nbytes > FNAME_BUFSIZE)
nbytes = FNAME_BUFSIZE;
StrNCpy(fnamebuf, VARDATA(filename), nbytes);
#ifndef __CYGWIN32__
fd = PathNameOpenFile(fnamebuf, O_RDONLY, 0666);
#else
@ -314,7 +353,7 @@ lo_import(text *filename)
#endif
if (fd < 0)
{ /* error */
elog(ERROR, "be_lo_import: can't open unix file \"%s\"\n",
elog(ERROR, "lo_import: can't open unix file \"%s\": %m",
fnamebuf);
}
@ -341,10 +380,8 @@ lo_import(text *filename)
{
tmp = inv_write(lobj, buf, nbytes);
if (tmp < nbytes)
{
elog(ERROR, "lo_import: error while reading \"%s\"",
fnamebuf);
}
}
FileClose(fd);
@ -363,12 +400,16 @@ lo_export(Oid lobjId, text *filename)
File fd;
int nbytes,
tmp;
char buf[BUFSIZE];
char fnamebuf[FNAME_BUFSIZE];
LargeObjectDesc *lobj;
mode_t oumask;
if (!superuser())
elog(ERROR, "You must have Postgres superuser privilege to use "
"server-side lo_export().\n\tAnyone can use the "
"client-side lo_export() provided by libpq.");
/*
* open the inversion "object"
*/
@ -378,9 +419,16 @@ lo_export(Oid lobjId, text *filename)
/*
* open the file to be written to
*
* Note: we reduce backend's normal 077 umask to the slightly
* friendlier 022. This code used to drop it all the way to 0,
* but creating world-writable export files doesn't seem wise.
*/
StrNCpy(fnamebuf, VARDATA(filename), VARSIZE(filename) - VARHDRSZ + 1);
oumask = umask((mode_t) 0);
nbytes = VARSIZE(filename) - VARHDRSZ + 1;
if (nbytes > FNAME_BUFSIZE)
nbytes = FNAME_BUFSIZE;
StrNCpy(fnamebuf, VARDATA(filename), nbytes);
oumask = umask((mode_t) 0022);
#ifndef __CYGWIN32__
fd = PathNameOpenFile(fnamebuf, O_CREAT | O_WRONLY | O_TRUNC, 0666);
#else
@ -389,7 +437,7 @@ lo_export(Oid lobjId, text *filename)
umask(oumask);
if (fd < 0)
{ /* error */
elog(ERROR, "lo_export: can't open unix file \"%s\"",
elog(ERROR, "lo_export: can't open unix file \"%s\": %m",
fnamebuf);
}
@ -400,10 +448,8 @@ lo_export(Oid lobjId, text *filename)
{
tmp = FileWrite(fd, buf, nbytes);
if (tmp < nbytes)
{
elog(ERROR, "lo_export: error while writing \"%s\"",
fnamebuf);
}
}
inv_close(lobj);
@ -417,24 +463,34 @@ lo_export(Oid lobjId, text *filename)
* prepares large objects for transaction commit [PA, 7/17/98]
*/
void
_lo_commit(void)
lo_commit(bool isCommit)
{
int i;
MemoryContext currentContext;
if (fscxt == NULL)
return;
return; /* no LO operations in this xact */
currentContext = MemoryContextSwitchTo((MemoryContext) fscxt);
/* Clean out still-open index scans (not necessary if aborting)
* and clear cookies array so that LO fds are no longer good.
*/
for (i = 0; i < MAX_LOBJ_FDS; i++)
{
if (cookies[i] != NULL)
inv_cleanindex(cookies[i]);
{
if (isCommit)
inv_cleanindex(cookies[i]);
cookies[i] = NULL;
}
}
MemoryContextSwitchTo(currentContext);
/* Release the LO memory context to prevent permanent memory leaks. */
GlobalMemoryDestroy(fscxt);
fscxt = NULL;
}

4
src/include/libpq/be-fsstubs.h
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@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: be-fsstubs.h,v 1.8 1999/02/13 23:21:34 momjian Exp $
* $Id: be-fsstubs.h,v 1.9 1999/05/31 22:53:58 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -40,6 +40,6 @@ extern int lowrite(int fd, struct varlena * wbuf);
/*
* Added for buffer leak prevention [ Pascal André <andre@via.ecp.fr> ]
*/
extern void _lo_commit(void);
extern void lo_commit(bool isCommit);
#endif /* BE_FSSTUBS_H */

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