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Commit28e4632

Browse files
Centralize logic for restoring errno in signal handlers.
Presently, we rely on each individual signal handler to save theinitial value of errno and then restore it before returning ifneeded. This is easily forgotten and, if missed, often goesundetected for a long time.In commit3b00fdb, we introduced a wrapper signal handlerfunction that checks whether MyProcPid matches getpid(). Thiscommit moves the aforementioned errno restoration code from theindividual signal handlers to the new wrapper handler so that we nolonger need to worry about missing it.Reviewed-by: Andres Freund, Noah MischDiscussion:https://postgr.es/m/20231121212008.GA3742740%40nathanxps13
1 parent3b00fdb commit28e4632

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15 files changed

+6
-87
lines changed

15 files changed

+6
-87
lines changed

‎doc/src/sgml/sources.sgml

Lines changed: 0 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -1007,18 +1007,10 @@ MemoryContextSwitchTo(MemoryContext context)
10071007
static void
10081008
handle_sighup(SIGNAL_ARGS)
10091009
{
1010-
int save_errno = errno;
1011-
10121010
got_SIGHUP = true;
10131011
SetLatch(MyLatch);
1014-
1015-
errno = save_errno;
10161012
}
10171013
</programlisting>
1018-
<varname>errno</varname> is saved and restored because
1019-
<function>SetLatch()</function> might change it. If that were not done
1020-
interrupted code that's currently inspecting <varname>errno</varname> might see the wrong
1021-
value.
10221014
</para>
10231015
</simplesect>
10241016

‎src/backend/postmaster/autovacuum.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1410,12 +1410,8 @@ AutoVacWorkerFailed(void)
14101410
staticvoid
14111411
avl_sigusr2_handler(SIGNAL_ARGS)
14121412
{
1413-
intsave_errno=errno;
1414-
14151413
got_SIGUSR2= true;
14161414
SetLatch(MyLatch);
1417-
1418-
errno=save_errno;
14191415
}
14201416

14211417

‎src/backend/postmaster/checkpointer.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -852,15 +852,11 @@ IsCheckpointOnSchedule(double progress)
852852
staticvoid
853853
ReqCheckpointHandler(SIGNAL_ARGS)
854854
{
855-
intsave_errno=errno;
856-
857855
/*
858856
* The signaling process should have set ckpt_flags nonzero, so all we
859857
* need do is ensure that our main loop gets kicked out of any wait.
860858
*/
861859
SetLatch(MyLatch);
862-
863-
errno=save_errno;
864860
}
865861

866862

‎src/backend/postmaster/interrupt.c

Lines changed: 0 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -60,12 +60,8 @@ HandleMainLoopInterrupts(void)
6060
void
6161
SignalHandlerForConfigReload(SIGNAL_ARGS)
6262
{
63-
intsave_errno=errno;
64-
6563
ConfigReloadPending= true;
6664
SetLatch(MyLatch);
67-
68-
errno=save_errno;
6965
}
7066

7167
/*
@@ -108,10 +104,6 @@ SignalHandlerForCrashExit(SIGNAL_ARGS)
108104
void
109105
SignalHandlerForShutdownRequest(SIGNAL_ARGS)
110106
{
111-
intsave_errno=errno;
112-
113107
ShutdownRequestPending= true;
114108
SetLatch(MyLatch);
115-
116-
errno=save_errno;
117109
}

‎src/backend/postmaster/pgarch.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -283,13 +283,9 @@ PgArchWakeup(void)
283283
staticvoid
284284
pgarch_waken_stop(SIGNAL_ARGS)
285285
{
286-
intsave_errno=errno;
287-
288286
/* set flag to do a final cycle and shut down afterwards */
289287
ready_to_stop= true;
290288
SetLatch(MyLatch);
291-
292-
errno=save_errno;
293289
}
294290

295291
/*

‎src/backend/postmaster/postmaster.c

Lines changed: 0 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -2612,12 +2612,8 @@ InitProcessGlobals(void)
26122612
staticvoid
26132613
handle_pm_pmsignal_signal(SIGNAL_ARGS)
26142614
{
2615-
intsave_errno=errno;
2616-
26172615
pending_pm_pmsignal= true;
26182616
SetLatch(MyLatch);
2619-
2620-
errno=save_errno;
26212617
}
26222618

26232619
/*
@@ -2626,12 +2622,8 @@ handle_pm_pmsignal_signal(SIGNAL_ARGS)
26262622
staticvoid
26272623
handle_pm_reload_request_signal(SIGNAL_ARGS)
26282624
{
2629-
intsave_errno=errno;
2630-
26312625
pending_pm_reload_request= true;
26322626
SetLatch(MyLatch);
2633-
2634-
errno=save_errno;
26352627
}
26362628

26372629
/*
@@ -2711,8 +2703,6 @@ process_pm_reload_request(void)
27112703
staticvoid
27122704
handle_pm_shutdown_request_signal(SIGNAL_ARGS)
27132705
{
2714-
intsave_errno=errno;
2715-
27162706
switch (postgres_signal_arg)
27172707
{
27182708
caseSIGTERM:
@@ -2729,8 +2719,6 @@ handle_pm_shutdown_request_signal(SIGNAL_ARGS)
27292719
break;
27302720
}
27312721
SetLatch(MyLatch);
2732-
2733-
errno=save_errno;
27342722
}
27352723

27362724
/*
@@ -2890,12 +2878,8 @@ process_pm_shutdown_request(void)
28902878
staticvoid
28912879
handle_pm_child_exit_signal(SIGNAL_ARGS)
28922880
{
2893-
intsave_errno=errno;
2894-
28952881
pending_pm_child_exit= true;
28962882
SetLatch(MyLatch);
2897-
2898-
errno=save_errno;
28992883
}
29002884

29012885
/*

‎src/backend/postmaster/startup.c

Lines changed: 0 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -95,32 +95,22 @@ static void StartupProcExit(int code, Datum arg);
9595
staticvoid
9696
StartupProcTriggerHandler(SIGNAL_ARGS)
9797
{
98-
intsave_errno=errno;
99-
10098
promote_signaled= true;
10199
WakeupRecovery();
102-
103-
errno=save_errno;
104100
}
105101

106102
/* SIGHUP: set flag to re-read config file at next convenient time */
107103
staticvoid
108104
StartupProcSigHupHandler(SIGNAL_ARGS)
109105
{
110-
intsave_errno=errno;
111-
112106
got_SIGHUP= true;
113107
WakeupRecovery();
114-
115-
errno=save_errno;
116108
}
117109

118110
/* SIGTERM: set flag to abort redo and exit */
119111
staticvoid
120112
StartupProcShutdownHandler(SIGNAL_ARGS)
121113
{
122-
intsave_errno=errno;
123-
124114
if (in_restore_command)
125115
{
126116
/*
@@ -139,8 +129,6 @@ StartupProcShutdownHandler(SIGNAL_ARGS)
139129
else
140130
shutdown_requested= true;
141131
WakeupRecovery();
142-
143-
errno=save_errno;
144132
}
145133

146134
/*

‎src/backend/postmaster/syslogger.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1642,10 +1642,6 @@ RemoveLogrotateSignalFiles(void)
16421642
staticvoid
16431643
sigUsr1Handler(SIGNAL_ARGS)
16441644
{
1645-
intsave_errno=errno;
1646-
16471645
rotation_requested= true;
16481646
SetLatch(MyLatch);
1649-
1650-
errno=save_errno;
16511647
}

‎src/backend/replication/walsender.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -3476,12 +3476,8 @@ HandleWalSndInitStopping(void)
34763476
staticvoid
34773477
WalSndLastCycleHandler(SIGNAL_ARGS)
34783478
{
3479-
intsave_errno=errno;
3480-
34813479
got_SIGUSR2= true;
34823480
SetLatch(MyLatch);
3483-
3484-
errno=save_errno;
34853481
}
34863482

34873483
/* Set up signal handlers */

‎src/backend/storage/ipc/latch.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -2243,12 +2243,8 @@ GetNumRegisteredWaitEvents(WaitEventSet *set)
22432243
staticvoid
22442244
latch_sigurg_handler(SIGNAL_ARGS)
22452245
{
2246-
intsave_errno=errno;
2247-
22482246
if (waiting)
22492247
sendSelfPipeByte();
2250-
2251-
errno=save_errno;
22522248
}
22532249

22542250
/* Send one byte to the self-pipe, to wake up WaitLatch */

‎src/backend/storage/ipc/procsignal.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -638,8 +638,6 @@ CheckProcSignal(ProcSignalReason reason)
638638
void
639639
procsignal_sigusr1_handler(SIGNAL_ARGS)
640640
{
641-
intsave_errno=errno;
642-
643641
if (CheckProcSignal(PROCSIG_CATCHUP_INTERRUPT))
644642
HandleCatchupInterrupt();
645643

@@ -683,6 +681,4 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
683681
HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
684682

685683
SetLatch(MyLatch);
686-
687-
errno=save_errno;
688684
}

‎src/backend/tcop/postgres.c

Lines changed: 0 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -2970,8 +2970,6 @@ quickdie(SIGNAL_ARGS)
29702970
void
29712971
die(SIGNAL_ARGS)
29722972
{
2973-
intsave_errno=errno;
2974-
29752973
/* Don't joggle the elbow of proc_exit */
29762974
if (!proc_exit_inprogress)
29772975
{
@@ -2993,8 +2991,6 @@ die(SIGNAL_ARGS)
29932991
*/
29942992
if (DoingCommandRead&&whereToSendOutput!=DestRemote)
29952993
ProcessInterrupts();
2996-
2997-
errno=save_errno;
29982994
}
29992995

30002996
/*
@@ -3004,8 +3000,6 @@ die(SIGNAL_ARGS)
30043000
void
30053001
StatementCancelHandler(SIGNAL_ARGS)
30063002
{
3007-
intsave_errno=errno;
3008-
30093003
/*
30103004
* Don't joggle the elbow of proc_exit
30113005
*/
@@ -3017,8 +3011,6 @@ StatementCancelHandler(SIGNAL_ARGS)
30173011

30183012
/* If we're still here, waken anything waiting on the process latch */
30193013
SetLatch(MyLatch);
3020-
3021-
errno=save_errno;
30223014
}
30233015

30243016
/* signal handler for floating point exception */

‎src/backend/utils/misc/timeout.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -363,8 +363,6 @@ schedule_alarm(TimestampTz now)
363363
staticvoid
364364
handle_sig_alarm(SIGNAL_ARGS)
365365
{
366-
intsave_errno=errno;
367-
368366
/*
369367
* Bump the holdoff counter, to make sure nothing we call will process
370368
* interrupts directly. No timeout handler should do that, but these
@@ -452,8 +450,6 @@ handle_sig_alarm(SIGNAL_ARGS)
452450
}
453451

454452
RESUME_INTERRUPTS();
455-
456-
errno=save_errno;
457453
}
458454

459455

‎src/fe_utils/cancel.c

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -152,7 +152,6 @@ ResetCancelConn(void)
152152
staticvoid
153153
handle_sigint(SIGNAL_ARGS)
154154
{
155-
intsave_errno=errno;
156155
charerrbuf[256];
157156

158157
CancelRequested= true;
@@ -173,8 +172,6 @@ handle_sigint(SIGNAL_ARGS)
173172
write_stderr(errbuf);
174173
}
175174
}
176-
177-
errno=save_errno;/* just in case the write changed it */
178175
}
179176

180177
/*

‎src/port/pqsignal.c

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -80,10 +80,14 @@ static volatile pqsigfunc pqsignal_handlers[PG_NSIG];
8080
* processes do not modify shared memory, which is often detrimental. If the
8181
* check succeeds, the function originally provided to pqsignal() is called.
8282
* Otherwise, the default signal handler is installed and then called.
83+
*
84+
* This wrapper also handles restoring the value of errno.
8385
*/
8486
staticvoid
8587
wrapper_handler(SIGNAL_ARGS)
8688
{
89+
intsave_errno=errno;
90+
8791
#ifndefFRONTEND
8892

8993
/*
@@ -102,6 +106,8 @@ wrapper_handler(SIGNAL_ARGS)
102106
#endif
103107

104108
(*pqsignal_handlers[postgres_signal_arg]) (postgres_signal_arg);
109+
110+
errno=save_errno;
105111
}
106112

107113
/*

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