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Ensure that 'errno' is saved and restored by all signal handlers that

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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.
This commit is contained in:
Tom Lane
2000-12-18 17:33:42 +00:00
parent c431db9714
commit 5491233f52
6 changed files with 79 additions and 16 deletions
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57
src/backend/postmaster/postmaster.c
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@@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.198 2000/12/03 20:45:34 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.199 2000/12/18 17:33:40 tgl Exp $
*
* NOTES
*
@@ -217,7 +217,7 @@ static int initMasks(fd_set *rmask, fd_set *wmask);
static char *canAcceptConnections(void);
static long PostmasterRandom(void);
static void RandomSalt(char *salt);
static void SignalChildren(SIGNAL_ARGS);
static void SignalChildren(int signal);
static int CountChildren(void);
static bool CreateOptsFile(int argc, char *argv[]);
@@ -1303,10 +1303,13 @@ reset_shared(unsigned short port)
static void
SIGHUP_handler(SIGNAL_ARGS)
{
int save_errno = errno;
if (Shutdown > SmartShutdown)
return;
got_SIGHUP = true;
SignalChildren(SIGHUP);
errno = save_errno;
}
@@ -1317,6 +1320,8 @@ SIGHUP_handler(SIGNAL_ARGS)
static void
pmdie(SIGNAL_ARGS)
{
int save_errno = errno;
PG_SETMASK(&BlockSig);
if (DebugLvl >= 1)
@@ -1330,8 +1335,12 @@ pmdie(SIGNAL_ARGS)
* Send SIGUSR2 to all children (AsyncNotifyHandler)
*/
if (Shutdown > SmartShutdown)
{
errno = save_errno;
return;
}
SignalChildren(SIGUSR2);
errno = save_errno;
return;
case SIGTERM:
@@ -1342,24 +1351,34 @@ pmdie(SIGNAL_ARGS)
* let children to end their work and ShutdownDataBase.
*/
if (Shutdown >= SmartShutdown)
{
errno = save_errno;
return;
}
Shutdown = SmartShutdown;
tnow = time(NULL);
fprintf(stderr, "Smart Shutdown request at %s", ctime(&tnow));
fflush(stderr);
if (DLGetHead(BackendList)) /* let reaper() handle this */
{
errno = save_errno;
return;
}
/*
* No children left. Shutdown data base system.
*/
if (StartupPID > 0 || FatalError) /* let reaper() handle
* this */
{
errno = save_errno;
return;
}
if (ShutdownPID > 0)
abort();
ShutdownPID = ShutdownDataBase();
errno = save_errno;
return;
case SIGINT:
@@ -1371,7 +1390,10 @@ pmdie(SIGNAL_ARGS)
* and exit) and ShutdownDataBase.
*/
if (Shutdown >= FastShutdown)
{
errno = save_errno;
return;
}
tnow = time(NULL);
fprintf(stderr, "Fast Shutdown request at %s", ctime(&tnow));
fflush(stderr);
@@ -1384,11 +1406,13 @@ pmdie(SIGNAL_ARGS)
fflush(stderr);
SignalChildren(SIGTERM);
}
errno = save_errno;
return;
}
if (Shutdown > NoShutdown)
{
Shutdown = FastShutdown;
errno = save_errno;
return;
}
Shutdown = FastShutdown;
@@ -1398,11 +1422,15 @@ pmdie(SIGNAL_ARGS)
*/
if (StartupPID > 0 || FatalError) /* let reaper() handle
* this */
{
errno = save_errno;
return;
}
if (ShutdownPID > 0)
abort();
ShutdownPID = ShutdownDataBase();
errno = save_errno;
return;
case SIGQUIT:
@@ -1435,18 +1463,18 @@ pmdie(SIGNAL_ARGS)
static void
reaper(SIGNAL_ARGS)
{
/* GH: replace waitpid for !HAVE_WAITPID. Does this work ? */
int save_errno = errno;
#ifdef HAVE_WAITPID
int status; /* backend exit status */
#else
union wait status; /* backend exit status */
#endif
int exitstatus;
int pid; /* process id of dead backend */
PG_SETMASK(&BlockSig);
/* It's not really necessary to reset the handler each time is it? */
pqsignal(SIGCHLD, reaper);
if (DebugLvl)
fprintf(stderr, "%s: reaping dead processes...\n",
@@ -1499,12 +1527,11 @@ reaper(SIGNAL_ARGS)
CheckPointPID = 0;
checkpointed = time(NULL);
pqsignal(SIGCHLD, reaper);
errno = save_errno;
return;
}
CleanupProc(pid, exitstatus);
}
pqsignal(SIGCHLD, reaper);
if (FatalError)
{
@@ -1513,9 +1540,15 @@ reaper(SIGNAL_ARGS)
* Wait for all children exit, then reset shmem and StartupDataBase.
*/
if (DLGetHead(BackendList))
{
errno = save_errno;
return;
}
if (StartupPID > 0 || ShutdownPID > 0)
{
errno = save_errno;
return;
}
tnow = time(NULL);
fprintf(stderr, "Server processes were terminated at %s"
"Reinitializing shared memory and semaphores\n",
@@ -1526,18 +1559,26 @@ reaper(SIGNAL_ARGS)
reset_shared(PostPortNumber);
StartupPID = StartupDataBase();
errno = save_errno;
return;
}
if (Shutdown > NoShutdown)
{
if (DLGetHead(BackendList))
{
errno = save_errno;
return;
}
if (StartupPID > 0 || ShutdownPID > 0)
{
errno = save_errno;
return;
}
ShutdownPID = ShutdownDataBase();
}
errno = save_errno;
}
/*
@@ -2002,6 +2043,7 @@ ExitPostmaster(int status)
static void
dumpstatus(SIGNAL_ARGS)
{
int save_errno = errno;
Dlelem *curr;
PG_SETMASK(&BlockSig);
@@ -2015,6 +2057,7 @@ dumpstatus(SIGNAL_ARGS)
fprintf(stderr, "\tsock %d\n", port->sock);
curr = DLGetSucc(curr);
}
errno = save_errno;
}
/*