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Commit2a44383

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committed
Clean up memory leaks in LO operations by freeing LO's private
memory context at transaction commit or abort.
1 parent81ced1e commit2a44383

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3 files changed

+83
-28
lines changed

3 files changed

+83
-28
lines changed

‎src/backend/access/transam/xact.c

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.36 1999/05/25 16:07:50 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.37 1999/05/31 22:53:59 tgl Exp $
1111
*
1212
* NOTES
1313
*Transaction aborts can now occur two ways:
@@ -156,8 +156,6 @@
156156
#include<miscadmin.h>
157157
#include<commands/async.h>
158158
#include<commands/sequence.h>
159-
160-
/* included for _lo_commit [PA, 7/17/98] */
161159
#include<libpq/be-fsstubs.h>
162160

163161
staticvoidAbortTransaction(void);
@@ -938,7 +936,7 @@ CommitTransaction()
938936
*/
939937

940938
/* handle commit for large objects [ PA, 7/17/98 ] */
941-
_lo_commit();
939+
lo_commit(true);
942940

943941
/* NOTIFY commit must also come before lower-level cleanup */
944942
AtCommit_Notify();
@@ -1012,6 +1010,7 @@ AbortTransaction()
10121010
*do abort processing
10131011
* ----------------
10141012
*/
1013+
lo_commit(false);/* 'false' means it's abort */
10151014
UnlockBuffers();
10161015
AtAbort_Notify();
10171016
CloseSequences();

‎src/backend/libpq/be-fsstubs.c

Lines changed: 78 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -7,18 +7,25 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.33 1999/05/25 16:08:57momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.34 1999/05/31 22:53:57tgl Exp $
1111
*
1212
* NOTES
1313
* This should be moved to a more appropriate place. It is here
1414
* for lack of a better place.
1515
*
1616
* Builtin functions for open/close/read/write operations on large objects.
1717
*
18-
* These functions operate in the current portal variable context, which
19-
* means the large object descriptors hang around between transactions and
20-
* are not deallocated until explicitly closed, or until the portal is
21-
* closed.
18+
* These functions operate in a private GlobalMemoryContext, which means
19+
* that large object descriptors hang around until we destroy the context.
20+
* That happens in lo_commit(). It'd be possible to prolong the lifetime
21+
* of the context so that LO FDs are good across transactions (for example,
22+
* we could release the context only if we see that no FDs remain open).
23+
* But we'd need additional state in order to do the right thing at the
24+
* end of an aborted transaction. FDs opened during an aborted xact would
25+
* still need to be closed, since they might not be pointing at valid
26+
* relations at all. For now, we'll stick with the existing documented
27+
* semantics of LO FDs: they're only good within a transaction.
28+
*
2229
*-------------------------------------------------------------------------
2330
*/
2431

@@ -37,6 +44,7 @@
3744
#include<utils/memutils.h>
3845
#include<lib/fstack.h>
3946
#include<utils/mcxt.h>
47+
#include<catalog/pg_shadow.h>/* for superuser() */
4048
#include<storage/fd.h>/* for O_ */
4149
#include<storage/large_object.h>
4250
#include<libpq/be-fsstubs.h>
@@ -91,6 +99,11 @@ lo_open(Oid lobjId, int mode)
9199
/* switch context back to orig. */
92100
MemoryContextSwitchTo(currentContext);
93101

102+
#ifFSDB
103+
if (fd<0)/* newLOfd couldn't find a slot */
104+
elog(NOTICE,"Out of space for large object FDs");
105+
#endif
106+
94107
returnfd;
95108
}
96109

@@ -144,6 +157,8 @@ lo_read(int fd, char *buf, int len)
144157
elog(ERROR,"lo_read: invalid large obj descriptor (%d)",fd);
145158
return-3;
146159
}
160+
161+
Assert(fscxt!=NULL);
147162
currentContext=MemoryContextSwitchTo((MemoryContext)fscxt);
148163

149164
status=inv_read(cookies[fd],buf,len);
@@ -168,6 +183,8 @@ lo_write(int fd, char *buf, int len)
168183
elog(ERROR,"lo_write: invalid large obj descriptor (%d)",fd);
169184
return-3;
170185
}
186+
187+
Assert(fscxt!=NULL);
171188
currentContext=MemoryContextSwitchTo((MemoryContext)fscxt);
172189

173190
status=inv_write(cookies[fd],buf,len);
@@ -181,7 +198,7 @@ int
181198
lo_lseek(intfd,intoffset,intwhence)
182199
{
183200
MemoryContextcurrentContext;
184-
intret;
201+
intstatus;
185202

186203
if (fd<0||fd >=MAX_LOBJ_FDS)
187204
{
@@ -194,13 +211,14 @@ lo_lseek(int fd, int offset, int whence)
194211
return-3;
195212
}
196213

214+
Assert(fscxt!=NULL);
197215
currentContext=MemoryContextSwitchTo((MemoryContext)fscxt);
198216

199-
ret=inv_seek(cookies[fd],offset,whence);
217+
status=inv_seek(cookies[fd],offset,whence);
200218

201219
MemoryContextSwitchTo(currentContext);
202220

203-
returnret;
221+
returnstatus;
204222
}
205223

206224
Oid
@@ -246,12 +264,26 @@ lo_tell(int fd)
246264
elog(ERROR,"lo_tell: invalid large object descriptor (%d)",fd);
247265
return-3;
248266
}
267+
268+
/*
269+
* We assume we do not need to switch contexts for inv_tell.
270+
* That is true for now, but is probably more than this module
271+
* ought to assume...
272+
*/
249273
returninv_tell(cookies[fd]);
250274
}
251275

252276
int
253277
lo_unlink(OidlobjId)
254278
{
279+
/*
280+
* inv_destroy does not need a context switch, indeed it doesn't
281+
* touch any LO-specific data structures at all. (Again, that's
282+
* probably more than this module ought to be assuming.)
283+
*
284+
* XXX there ought to be some code to clean up any open LOs that
285+
* reference the specified relation... as is, they remain "open".
286+
*/
255287
returninv_destroy(lobjId);
256288
}
257289

@@ -297,24 +329,31 @@ lo_import(text *filename)
297329
Filefd;
298330
intnbytes,
299331
tmp;
300-
301332
charbuf[BUFSIZE];
302333
charfnamebuf[FNAME_BUFSIZE];
303334
LargeObjectDesc*lobj;
304335
OidlobjOid;
305336

337+
if (!superuser())
338+
elog(ERROR,"You must have Postgres superuser privilege to use "
339+
"server-side lo_import().\n\tAnyone can use the "
340+
"client-side lo_import() provided by libpq.");
341+
306342
/*
307343
* open the file to be read in
308344
*/
309-
StrNCpy(fnamebuf,VARDATA(filename),VARSIZE(filename)-VARHDRSZ+1);
345+
nbytes=VARSIZE(filename)-VARHDRSZ+1;
346+
if (nbytes>FNAME_BUFSIZE)
347+
nbytes=FNAME_BUFSIZE;
348+
StrNCpy(fnamebuf,VARDATA(filename),nbytes);
310349
#ifndef__CYGWIN32__
311350
fd=PathNameOpenFile(fnamebuf,O_RDONLY,0666);
312351
#else
313352
fd=PathNameOpenFile(fnamebuf,O_RDONLY |O_BINARY,0666);
314353
#endif
315354
if (fd<0)
316355
{/* error */
317-
elog(ERROR,"be_lo_import: can't open unix file \"%s\"\n",
356+
elog(ERROR,"lo_import: can't open unix file \"%s\": %m",
318357
fnamebuf);
319358
}
320359

@@ -341,10 +380,8 @@ lo_import(text *filename)
341380
{
342381
tmp=inv_write(lobj,buf,nbytes);
343382
if (tmp<nbytes)
344-
{
345383
elog(ERROR,"lo_import: error while reading \"%s\"",
346384
fnamebuf);
347-
}
348385
}
349386

350387
FileClose(fd);
@@ -363,12 +400,16 @@ lo_export(Oid lobjId, text *filename)
363400
Filefd;
364401
intnbytes,
365402
tmp;
366-
367403
charbuf[BUFSIZE];
368404
charfnamebuf[FNAME_BUFSIZE];
369405
LargeObjectDesc*lobj;
370406
mode_toumask;
371407

408+
if (!superuser())
409+
elog(ERROR,"You must have Postgres superuser privilege to use "
410+
"server-side lo_export().\n\tAnyone can use the "
411+
"client-side lo_export() provided by libpq.");
412+
372413
/*
373414
* open the inversion "object"
374415
*/
@@ -378,9 +419,16 @@ lo_export(Oid lobjId, text *filename)
378419

379420
/*
380421
* open the file to be written to
422+
*
423+
* Note: we reduce backend's normal 077 umask to the slightly
424+
* friendlier 022. This code used to drop it all the way to 0,
425+
* but creating world-writable export files doesn't seem wise.
381426
*/
382-
StrNCpy(fnamebuf,VARDATA(filename),VARSIZE(filename)-VARHDRSZ+1);
383-
oumask=umask((mode_t)0);
427+
nbytes=VARSIZE(filename)-VARHDRSZ+1;
428+
if (nbytes>FNAME_BUFSIZE)
429+
nbytes=FNAME_BUFSIZE;
430+
StrNCpy(fnamebuf,VARDATA(filename),nbytes);
431+
oumask=umask((mode_t)0022);
384432
#ifndef__CYGWIN32__
385433
fd=PathNameOpenFile(fnamebuf,O_CREAT |O_WRONLY |O_TRUNC,0666);
386434
#else
@@ -389,7 +437,7 @@ lo_export(Oid lobjId, text *filename)
389437
umask(oumask);
390438
if (fd<0)
391439
{/* error */
392-
elog(ERROR,"lo_export: can't open unix file \"%s\"",
440+
elog(ERROR,"lo_export: can't open unix file \"%s\": %m",
393441
fnamebuf);
394442
}
395443

@@ -400,10 +448,8 @@ lo_export(Oid lobjId, text *filename)
400448
{
401449
tmp=FileWrite(fd,buf,nbytes);
402450
if (tmp<nbytes)
403-
{
404451
elog(ERROR,"lo_export: error while writing \"%s\"",
405452
fnamebuf);
406-
}
407453
}
408454

409455
inv_close(lobj);
@@ -417,24 +463,34 @@ lo_export(Oid lobjId, text *filename)
417463
* prepares large objects for transaction commit [PA, 7/17/98]
418464
*/
419465
void
420-
_lo_commit(void)
466+
lo_commit(boolisCommit)
421467
{
422468
inti;
423469
MemoryContextcurrentContext;
424470

425471
if (fscxt==NULL)
426-
return;
472+
return;/* no LO operations in this xact */
427473

428474
currentContext=MemoryContextSwitchTo((MemoryContext)fscxt);
429475

476+
/* Clean out still-open index scans (not necessary if aborting)
477+
* and clear cookies array so that LO fds are no longer good.
478+
*/
430479
for (i=0;i<MAX_LOBJ_FDS;i++)
431480
{
432481
if (cookies[i]!=NULL)
433-
inv_cleanindex(cookies[i]);
482+
{
483+
if (isCommit)
484+
inv_cleanindex(cookies[i]);
485+
cookies[i]=NULL;
486+
}
434487
}
435488

436489
MemoryContextSwitchTo(currentContext);
437490

491+
/* Release the LO memory context to prevent permanent memory leaks. */
492+
GlobalMemoryDestroy(fscxt);
493+
fscxt=NULL;
438494
}
439495

440496

‎src/include/libpq/be-fsstubs.h

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: be-fsstubs.h,v 1.8 1999/02/13 23:21:34 momjian Exp $
9+
* $Id: be-fsstubs.h,v 1.9 1999/05/31 22:53:58 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -40,6 +40,6 @@ extern intlowrite(int fd, struct varlena * wbuf);
4040
/*
4141
* Added for buffer leak prevention [ Pascal André <andre@via.ecp.fr> ]
4242
*/
43-
externvoid_lo_commit(void);
43+
externvoidlo_commit(boolisCommit);
4444

4545
#endif/* BE_FSSTUBS_H */

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