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Ensure that 'errno' is saved and restored by all signal handlers that
might change it. Experimentation shows that the signal handler call mechanism does not save/restore errno for you, at least not on Linux or HPUX, so this is definitely a real risk.
1 parent c431db9 commit 5491233

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6 files changed

+79
-16
lines changed

6 files changed

+79
-16
lines changed

‎src/backend/commands/async.c

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.73 2000/11/28 23:27:54 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.74 2000/12/18 17:33:40 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -589,6 +589,7 @@ AtAbort_Notify()
589589
void
590590
Async_NotifyHandler(SIGNAL_ARGS)
591591
{
592+
int save_errno = errno;
592593

593594
/*
594595
* Note: this is a SIGNAL HANDLER. You must be very wary what you do
@@ -637,6 +638,8 @@ Async_NotifyHandler(SIGNAL_ARGS)
637638
*/
638639
notifyInterruptOccurred = 1;
639640
}
641+
642+
errno = save_errno;
640643
}
641644

642645
/*

‎src/backend/postmaster/postmaster.c

Lines changed: 50 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
*
1212
*
1313
* IDENTIFICATION
14-
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.198 2000/12/03 20:45:34 tgl Exp $
14+
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.199 2000/12/18 17:33:40 tgl Exp $
1515
*
1616
* NOTES
1717
*
@@ -217,7 +217,7 @@ static int initMasks(fd_set *rmask, fd_set *wmask);
217217
static char *canAcceptConnections(void);
218218
static long PostmasterRandom(void);
219219
static void RandomSalt(char *salt);
220-
static void SignalChildren(SIGNAL_ARGS);
220+
static void SignalChildren(int signal);
221221
static int CountChildren(void);
222222
static bool CreateOptsFile(int argc, char *argv[]);
223223

@@ -1303,10 +1303,13 @@ reset_shared(unsigned short port)
13031303
static void
13041304
SIGHUP_handler(SIGNAL_ARGS)
13051305
{
1306+
int save_errno = errno;
1307+
13061308
if (Shutdown > SmartShutdown)
13071309
return;
13081310
got_SIGHUP = true;
13091311
SignalChildren(SIGHUP);
1312+
errno = save_errno;
13101313
}
13111314

13121315

@@ -1317,6 +1320,8 @@ SIGHUP_handler(SIGNAL_ARGS)
13171320
static void
13181321
pmdie(SIGNAL_ARGS)
13191322
{
1323+
int save_errno = errno;
1324+
13201325
PG_SETMASK(&BlockSig);
13211326

13221327
if (DebugLvl >= 1)
@@ -1330,8 +1335,12 @@ pmdie(SIGNAL_ARGS)
13301335
* Send SIGUSR2 to all children (AsyncNotifyHandler)
13311336
*/
13321337
if (Shutdown > SmartShutdown)
1338+
{
1339+
errno = save_errno;
13331340
return;
1341+
}
13341342
SignalChildren(SIGUSR2);
1343+
errno = save_errno;
13351344
return;
13361345

13371346
case SIGTERM:
@@ -1342,24 +1351,34 @@ pmdie(SIGNAL_ARGS)
13421351
* let children to end their work and ShutdownDataBase.
13431352
*/
13441353
if (Shutdown >= SmartShutdown)
1354+
{
1355+
errno = save_errno;
13451356
return;
1357+
}
13461358
Shutdown = SmartShutdown;
13471359
tnow = time(NULL);
13481360
fprintf(stderr, "Smart Shutdown request at %s", ctime(&tnow));
13491361
fflush(stderr);
13501362
if (DLGetHead(BackendList)) /* let reaper() handle this */
1363+
{
1364+
errno = save_errno;
13511365
return;
1366+
}
13521367

13531368
/*
13541369
* No children left. Shutdown data base system.
13551370
*/
13561371
if (StartupPID > 0 || FatalError) /* let reaper() handle
13571372
* this */
1373+
{
1374+
errno = save_errno;
13581375
return;
1376+
}
13591377
if (ShutdownPID > 0)
13601378
abort();
13611379

13621380
ShutdownPID = ShutdownDataBase();
1381+
errno = save_errno;
13631382
return;
13641383

13651384
case SIGINT:
@@ -1371,7 +1390,10 @@ pmdie(SIGNAL_ARGS)
13711390
* and exit) and ShutdownDataBase.
13721391
*/
13731392
if (Shutdown >= FastShutdown)
1393+
{
1394+
errno = save_errno;
13741395
return;
1396+
}
13751397
tnow = time(NULL);
13761398
fprintf(stderr, "Fast Shutdown request at %s", ctime(&tnow));
13771399
fflush(stderr);
@@ -1384,11 +1406,13 @@ pmdie(SIGNAL_ARGS)
13841406
fflush(stderr);
13851407
SignalChildren(SIGTERM);
13861408
}
1409+
errno = save_errno;
13871410
return;
13881411
}
13891412
if (Shutdown > NoShutdown)
13901413
{
13911414
Shutdown = FastShutdown;
1415+
errno = save_errno;
13921416
return;
13931417
}
13941418
Shutdown = FastShutdown;
@@ -1398,11 +1422,15 @@ pmdie(SIGNAL_ARGS)
13981422
*/
13991423
if (StartupPID > 0 || FatalError) /* let reaper() handle
14001424
* this */
1425+
{
1426+
errno = save_errno;
14011427
return;
1428+
}
14021429
if (ShutdownPID > 0)
14031430
abort();
14041431

14051432
ShutdownPID = ShutdownDataBase();
1433+
errno = save_errno;
14061434
return;
14071435

14081436
case SIGQUIT:
@@ -1435,18 +1463,18 @@ pmdie(SIGNAL_ARGS)
14351463
static void
14361464
reaper(SIGNAL_ARGS)
14371465
{
1438-
/* GH: replace waitpid for !HAVE_WAITPID. Does this work ? */
1466+
int save_errno = errno;
14391467
#ifdef HAVE_WAITPID
14401468
int status; /* backend exit status */
1441-
14421469
#else
14431470
union wait status; /* backend exit status */
1444-
14451471
#endif
14461472
int exitstatus;
14471473
int pid; /* process id of dead backend */
14481474

14491475
PG_SETMASK(&BlockSig);
1476+
/* It's not really necessary to reset the handler each time is it? */
1477+
pqsignal(SIGCHLD, reaper);
14501478

14511479
if (DebugLvl)
14521480
fprintf(stderr, "%s: reaping dead processes...\n",
@@ -1499,12 +1527,11 @@ reaper(SIGNAL_ARGS)
14991527
CheckPointPID = 0;
15001528
checkpointed = time(NULL);
15011529

1502-
pqsignal(SIGCHLD, reaper);
1530+
errno = save_errno;
15031531
return;
15041532
}
15051533
CleanupProc(pid, exitstatus);
15061534
}
1507-
pqsignal(SIGCHLD, reaper);
15081535

15091536
if (FatalError)
15101537
{
@@ -1513,9 +1540,15 @@ reaper(SIGNAL_ARGS)
15131540
* Wait for all children exit, then reset shmem and StartupDataBase.
15141541
*/
15151542
if (DLGetHead(BackendList))
1543+
{
1544+
errno = save_errno;
15161545
return;
1546+
}
15171547
if (StartupPID > 0 || ShutdownPID > 0)
1548+
{
1549+
errno = save_errno;
15181550
return;
1551+
}
15191552
tnow = time(NULL);
15201553
fprintf(stderr, "Server processes were terminated at %s"
15211554
"Reinitializing shared memory and semaphores\n",
@@ -1526,18 +1559,26 @@ reaper(SIGNAL_ARGS)
15261559
reset_shared(PostPortNumber);
15271560

15281561
StartupPID = StartupDataBase();
1562+
errno = save_errno;
15291563
return;
15301564
}
15311565

15321566
if (Shutdown > NoShutdown)
15331567
{
15341568
if (DLGetHead(BackendList))
1569+
{
1570+
errno = save_errno;
15351571
return;
1572+
}
15361573
if (StartupPID > 0 || ShutdownPID > 0)
1574+
{
1575+
errno = save_errno;
15371576
return;
1577+
}
15381578
ShutdownPID = ShutdownDataBase();
15391579
}
15401580

1581+
errno = save_errno;
15411582
}
15421583

15431584
/*
@@ -2002,6 +2043,7 @@ ExitPostmaster(int status)
20022043
static void
20032044
dumpstatus(SIGNAL_ARGS)
20042045
{
2046+
int save_errno = errno;
20052047
Dlelem *curr;
20062048

20072049
PG_SETMASK(&BlockSig);
@@ -2015,6 +2057,7 @@ dumpstatus(SIGNAL_ARGS)
20152057
fprintf(stderr, "\tsock %d\n", port->sock);
20162058
curr = DLGetSucc(curr);
20172059
}
2060+
errno = save_errno;
20182061
}
20192062

20202063
/*

‎src/backend/storage/lmgr/proc.c

Lines changed: 10 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/storage/lmgr/proc.c,v 1.87 2000/12/18 00:44:47 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.88 2000/12/18 17:33:41 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -48,10 +48,11 @@
4848
* This is so that we can support more backends. (system-wide semaphore
4949
* sets run out pretty fast.) -ay 4/95
5050
*
51-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.87 2000/12/18 00:44:47 tgl Exp $
51+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.88 2000/12/18 17:33:41 tgl Exp $
5252
*/
5353
#include "postgres.h"
5454

55+
#include <errno.h>
5556
#include <sys/time.h>
5657
#include <unistd.h>
5758
#include <signal.h>
@@ -298,7 +299,7 @@ InitProcess(void)
298299
}
299300

300301
/* -----------------------
301-
* get off the wait queue
302+
* get process off any wait queue it might be on
302303
* -----------------------
303304
*/
304305
static bool
@@ -623,10 +624,11 @@ ins:;
623624
waitQueue->size++;
624625

625626
lock->waitMask |= myMask;
626-
SpinRelease(spinlock);
627627

628628
MyProc->errType = NO_ERROR; /* initialize result for success */
629629

630+
SpinRelease(spinlock);
631+
630632
/* --------------
631633
* Set timer so we can wake up after awhile and check for a deadlock.
632634
* If a deadlock is detected, the handler releases the process's
@@ -826,6 +828,7 @@ ProcAddLock(SHM_QUEUE *elem)
826828
void
827829
HandleDeadLock(SIGNAL_ARGS)
828830
{
831+
int save_errno = errno;
829832
LOCK *mywaitlock;
830833

831834
LockLockTable();
@@ -846,6 +849,7 @@ HandleDeadLock(SIGNAL_ARGS)
846849
MyProc->links.next == INVALID_OFFSET)
847850
{
848851
UnlockLockTable();
852+
errno = save_errno;
849853
return;
850854
}
851855

@@ -858,6 +862,7 @@ HandleDeadLock(SIGNAL_ARGS)
858862
{
859863
/* No deadlock, so keep waiting */
860864
UnlockLockTable();
865+
errno = save_errno;
861866
return;
862867
}
863868

@@ -891,6 +896,7 @@ HandleDeadLock(SIGNAL_ARGS)
891896
* conditions. i don't claim to understand this...
892897
*/
893898
UnlockLockTable();
899+
errno = save_errno;
894900
}
895901

896902
void

‎src/backend/tcop/postgres.c

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.195 2000/12/18 00:44:47 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.196 2000/12/18 17:33:41 tgl Exp $
1212
*
1313
* NOTES
1414
* this is the "main" module of the postgres backend and
@@ -984,8 +984,11 @@ FloatExceptionHandler(SIGNAL_ARGS)
984984
static void
985985
QueryCancelHandler(SIGNAL_ARGS)
986986
{
987+
int save_errno = errno;
988+
987989
QueryCancel = true;
988990
LockWaitCancel();
991+
errno = save_errno;
989992
}
990993

991994
void
@@ -1646,7 +1649,7 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
16461649
if (!IsUnderPostmaster)
16471650
{
16481651
puts("\nPOSTGRES backend interactive interface ");
1649-
puts("$Revision: 1.195 $ $Date: 2000/12/18 00:44:47 $\n");
1652+
puts("$Revision: 1.196 $ $Date: 2000/12/18 17:33:41 $\n");
16501653
}
16511654

16521655
/*

‎src/bin/psql/common.c

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
*
44
* Copyright 2000 by PostgreSQL Global Development Group
55
*
6-
* $Header: /cvsroot/pgsql/src/bin/psql/common.c,v 1.28 2000/12/15 17:54:43 petere Exp $
6+
* $Header: /cvsroot/pgsql/src/bin/psql/common.c,v 1.29 2000/12/18 17:33:42 tgl Exp $
77
*/
88
#include "postgres.h"
99
#include "common.h"
@@ -258,6 +258,8 @@ volatile bool cancel_pressed;
258258
void
259259
handle_sigint(SIGNAL_ARGS)
260260
{
261+
int save_errno = errno;
262+
261263
/* Don't muck around if copying in or prompting for a password. */
262264
if ((copy_in_state && pset.cur_cmd_interactive) || prompt_state)
263265
return;
@@ -274,6 +276,7 @@ handle_sigint(SIGNAL_ARGS)
274276
write_stderr("Could not send cancel request: ");
275277
write_stderr(PQerrorMessage(cancelConn));
276278
}
279+
errno = save_errno; /* just in case the write changed it */
277280
}
278281

279282
#endif /* not WIN32 */

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