Replace time_t with pg_time_t (same values, but always int64) in on-disk

data structures and backend internal APIs.  This solves problems we've seen
recently with inconsistent layout of pg_control between machines that have
32-bit time_t and those that have already migrated to 64-bit time_t.  Also,
we can get out from under the problem that Windows' Unix-API emulation is not
consistent about the width of time_t.

There are a few remaining places where local time_t variables are used to hold
the current or recent result of time(NULL).  I didn't bother changing these
since they do not affect any cross-module APIs and surely all platforms will
have 64-bit time_t before overflow becomes an actual risk.  time_t should
be avoided for anything visible to extension modules, however.

Author: tglsfdc

contrib/pgcrypto/internal.c

@@ -26,7 +26,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $PostgreSQL: pgsql/contrib/pgcrypto/internal.c,v 1.27 2007/11/15 21:14:31 momjian Exp $
+ * $PostgreSQL: pgsql/contrib/pgcrypto/internal.c,v 1.28 2008/02/17 02:09:26 tgl Exp $
  */
 
 #include "postgres.h"
@@ -649,7 +649,8 @@ system_reseed(void)
 		skip = 1;
 	else if ((t - seed_time) > SYSTEM_RESEED_MAX)
 		skip = 0;
-	else if (!check_time || (t - check_time) > SYSTEM_RESEED_CHECK_TIME)
+	else if (check_time == 0 ||
+			 (t - check_time) > SYSTEM_RESEED_CHECK_TIME)
 	{
 		check_time = t;
 

src/backend/access/transam/xlog.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.292 2008/01/21 11:17:46 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.293 2008/02/17 02:09:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -271,7 +271,7 @@ typedef struct XLogCtlWrite
 {
 	XLogwrtResult LogwrtResult; /* current value of LogwrtResult */
 	int			curridx;		/* cache index of next block to write */
-	time_t		lastSegSwitchTime;		/* time of last xlog segment switch */
+	pg_time_t	lastSegSwitchTime;		/* time of last xlog segment switch */
 } XLogCtlWrite;
 
 /*
@@ -1553,7 +1553,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible, bool xlog_switch)
 				if (XLogArchivingActive())
 					XLogArchiveNotifySeg(openLogId, openLogSeg);
 
-				Write->lastSegSwitchTime = time(NULL);
+				Write->lastSegSwitchTime = (pg_time_t) time(NULL);
 
 				/*
 				 * Signal bgwriter to start a checkpoint if we've consumed too
@@ -4217,7 +4217,7 @@ BootStrapXLOG(void)
 	checkPoint.nextOid = FirstBootstrapObjectId;
 	checkPoint.nextMulti = FirstMultiXactId;
 	checkPoint.nextMultiOffset = 0;
-	checkPoint.time = time(NULL);
+	checkPoint.time = (pg_time_t) time(NULL);
 
 	ShmemVariableCache->nextXid = checkPoint.nextXid;
 	ShmemVariableCache->nextOid = checkPoint.nextOid;
@@ -4972,7 +4972,7 @@ StartupXLOG(void)
 		ControlFile->checkPointCopy = checkPoint;
 		if (minRecoveryLoc.xlogid != 0 || minRecoveryLoc.xrecoff != 0)
 			ControlFile->minRecoveryPoint = minRecoveryLoc;
-		ControlFile->time = time(NULL);
+		ControlFile->time = (pg_time_t) time(NULL);
 		UpdateControlFile();
 
 		/*
@@ -5277,7 +5277,7 @@ StartupXLOG(void)
 	InRecovery = false;
 
 	ControlFile->state = DB_IN_PRODUCTION;
-	ControlFile->time = time(NULL);
+	ControlFile->time = (pg_time_t) time(NULL);
 	UpdateControlFile();
 
 	/* start the archive_timeout timer running */
@@ -5496,10 +5496,10 @@ GetInsertRecPtr(void)
 /*
  * Get the time of the last xlog segment switch
  */
-time_t
+pg_time_t
 GetLastSegSwitchTime(void)
 {
-	time_t		result;
+	pg_time_t	result;
 
 	/* Need WALWriteLock, but shared lock is sufficient */
 	LWLockAcquire(WALWriteLock, LW_SHARED);
@@ -5676,7 +5676,7 @@ CreateCheckPoint(int flags)
 	if (shutdown)
 	{
 		ControlFile->state = DB_SHUTDOWNING;
-		ControlFile->time = time(NULL);
+		ControlFile->time = (pg_time_t) time(NULL);
 		UpdateControlFile();
 	}
 
@@ -5690,7 +5690,7 @@ CreateCheckPoint(int flags)
 	/* Begin filling in the checkpoint WAL record */
 	MemSet(&checkPoint, 0, sizeof(checkPoint));
 	checkPoint.ThisTimeLineID = ThisTimeLineID;
-	checkPoint.time = time(NULL);
+	checkPoint.time = (pg_time_t) time(NULL);
 
 	/*
 	 * We must hold WALInsertLock while examining insert state to determine
@@ -5891,7 +5891,7 @@ CreateCheckPoint(int flags)
 	ControlFile->prevCheckPoint = ControlFile->checkPoint;
 	ControlFile->checkPoint = ProcLastRecPtr;
 	ControlFile->checkPointCopy = checkPoint;
-	ControlFile->time = time(NULL);
+	ControlFile->time = (pg_time_t) time(NULL);
 	UpdateControlFile();
 	LWLockRelease(ControlFileLock);
 
@@ -5992,7 +5992,7 @@ RecoveryRestartPoint(const CheckPoint *checkPoint)
 	 * Checking true elapsed time keeps us from doing restartpoints too often
 	 * while rapidly scanning large amounts of WAL.
 	 */
-	elapsed_secs = time(NULL) - ControlFile->time;
+	elapsed_secs = (pg_time_t) time(NULL) - ControlFile->time;
 	if (elapsed_secs < CheckPointTimeout / 2)
 		return;
 
@@ -6028,7 +6028,7 @@ RecoveryRestartPoint(const CheckPoint *checkPoint)
 	ControlFile->prevCheckPoint = ControlFile->checkPoint;
 	ControlFile->checkPoint = ReadRecPtr;
 	ControlFile->checkPointCopy = *checkPoint;
-	ControlFile->time = time(NULL);
+	ControlFile->time = (pg_time_t) time(NULL);
 	UpdateControlFile();
 
 	ereport((recoveryLogRestartpoints ? LOG : DEBUG2),

src/backend/postmaster/bgwriter.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.48 2008/01/01 19:45:51 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.49 2008/02/17 02:09:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -163,12 +163,12 @@ static bool am_bg_writer = false;
 static bool ckpt_active = false;
 
 /* these values are valid when ckpt_active is true: */
-static time_t ckpt_start_time;
+static pg_time_t ckpt_start_time;
 static XLogRecPtr ckpt_start_recptr;
 static double ckpt_cached_elapsed;
 
-static time_t last_checkpoint_time;
-static time_t last_xlog_switch_time;
+static pg_time_t last_checkpoint_time;
+static pg_time_t last_xlog_switch_time;
 
 /* Prototypes for private functions */
 
@@ -250,7 +250,7 @@ BackgroundWriterMain(void)
 	/*
 	 * Initialize so that first time-driven event happens at the correct time.
 	 */
-	last_checkpoint_time = last_xlog_switch_time = time(NULL);
+	last_checkpoint_time = last_xlog_switch_time = (pg_time_t) time(NULL);
 
 	/*
 	 * Create a resource owner to keep track of our resources (currently only
@@ -361,7 +361,7 @@ BackgroundWriterMain(void)
 	{
 		bool		do_checkpoint = false;
 		int			flags = 0;
-		time_t		now;
+		pg_time_t	now;
 		int			elapsed_secs;
 
 		/*
@@ -407,7 +407,7 @@ BackgroundWriterMain(void)
 		 * occurs without an external request, but we set the CAUSE_TIME flag
 		 * bit even if there is also an external request.
 		 */
-		now = time(NULL);
+		now = (pg_time_t) time(NULL);
 		elapsed_secs = now - last_checkpoint_time;
 		if (elapsed_secs >= CheckPointTimeout)
 		{
@@ -504,13 +504,13 @@ BackgroundWriterMain(void)
 static void
 CheckArchiveTimeout(void)
 {
-	time_t		now;
-	time_t		last_time;
+	pg_time_t	now;
+	pg_time_t	last_time;
 
 	if (XLogArchiveTimeout <= 0)
 		return;
 
-	now = time(NULL);
+	now = (pg_time_t) time(NULL);
 
 	/* First we do a quick check using possibly-stale local state. */
 	if ((int) (now - last_xlog_switch_time) < XLogArchiveTimeout)
@@ -730,7 +730,7 @@ IsCheckpointOnSchedule(double progress)
 	 * Check progress against time elapsed and checkpoint_timeout.
 	 */
 	gettimeofday(&now, NULL);
-	elapsed_time = ((double) (now.tv_sec - ckpt_start_time) +
+	elapsed_time = ((double) ((pg_time_t) now.tv_sec - ckpt_start_time) +
 					now.tv_usec / 1000000.0) / CheckPointTimeout;
 
 	if (progress < elapsed_time)

src/backend/postmaster/syslogger.c

@@ -18,7 +18,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/syslogger.c,v 1.44 2008/01/25 20:42:10 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/syslogger.c,v 1.45 2008/02/17 02:09:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -331,7 +331,7 @@ SysLoggerMain(int argc, char *argv[])
 		if (!rotation_requested && Log_RotationAge > 0)
 		{
 			/* Do a logfile rotation if it's time */
-			pg_time_t	now = time(NULL);
+			pg_time_t	now = (pg_time_t) time(NULL);
 
 			if (now >= next_rotation_time)
 				rotation_requested = time_based_rotation = true;

src/backend/utils/adt/date.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.138 2008/01/01 19:45:52 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.139 2008/02/17 02:09:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -945,8 +945,10 @@ tm2time(struct pg_tm * tm, fsec_t fsec, TimeADT *result)
 
 /* time2tm()
  * Convert time data type to POSIX time structure.
- * For dates within the system-supported time_t range, convert to the
- *	local time zone. If out of this range, leave as GMT. - tgl 97/05/27
+ *
+ * For dates within the range of pg_time_t, convert to the local time zone.
+ * If out of this range, leave as UTC (in practice that could only happen
+ * if pg_time_t is just 32 bits) - thomas 97/05/27
  */
 static int
 time2tm(TimeADT time, struct pg_tm * tm, fsec_t *fsec)
@@ -2466,10 +2468,9 @@ timetz_zone(PG_FUNCTION_ARGS)
 	if (tzp)
 	{
 		/* Get the offset-from-GMT that is valid today for the selected zone */
-		pg_time_t	now;
+		pg_time_t	now = (pg_time_t) time(NULL);
 		struct pg_tm *tm;
 
-		now = time(NULL);
 		tm = pg_localtime(&now, tzp);
 		tz = -tm->tm_gmtoff;
 	}

src/backend/utils/adt/datetime.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.184 2008/01/01 19:45:52 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.185 2008/02/17 02:09:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -650,9 +650,11 @@ ParseDateTime(const char *timestr, char *workbuf, size_t buflen,
  *				"20011225T040506.789-07"
  *
  * Use the system-provided functions to get the current time zone
- *	if not specified in the input string.
- * If the date is outside the time_t system-supported time range,
- *	then assume UTC time zone. - thomas 1997-05-27
+ * if not specified in the input string.
+ *
+ * If the date is outside the range of pg_time_t (in practice that could only
+ * happen if pg_time_t is just 32 bits), then assume UTC time zone - thomas
+ * 1997-05-27
  */
 int
 DecodeDateTime(char **field, int *ftype, int nf,

src/backend/utils/adt/nabstime.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/nabstime.c,v 1.152 2008/01/01 19:45:52 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/nabstime.c,v 1.153 2008/02/17 02:09:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -86,6 +86,8 @@ static void parsetinterval(char *i_string,
  * GetCurrentAbsoluteTime()
  *
  * Get the current system time (relative to Unix epoch).
+ *
+ * NB: this will overflow in 2038; it should be gone long before that.
  */
 AbsoluteTime
 GetCurrentAbsoluteTime(void)
@@ -1029,12 +1031,7 @@ tintervalrel(PG_FUNCTION_ARGS)
 Datum
 timenow(PG_FUNCTION_ARGS)
 {
-	time_t		sec;
-
-	if (time(&sec) < 0)
-		PG_RETURN_ABSOLUTETIME(INVALID_ABSTIME);
-
-	PG_RETURN_ABSOLUTETIME((AbsoluteTime) sec);
+	PG_RETURN_ABSOLUTETIME(GetCurrentAbsoluteTime());
 }
 
 /*

src/backend/utils/adt/timestamp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.184 2008/01/01 19:45:52 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.185 2008/02/17 02:09:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1264,9 +1264,14 @@ TimestampDifferenceExceeds(TimestampTz start_time,
  *
  * We do not use time_t internally in Postgres, but this is provided for use
  * by functions that need to interpret, say, a stat(2) result.
+ *
+ * To avoid having the function's ABI vary depending on the width of time_t,
+ * we declare the argument as pg_time_t, which is cast-compatible with
+ * time_t but always 64 bits wide (unless the platform has no 64-bit type).
+ * This detail should be invisible to callers, at least at source code level.
  */
 TimestampTz
-time_t_to_timestamptz(time_t tm)
+time_t_to_timestamptz(pg_time_t tm)
 {
 	TimestampTz result;
 
@@ -1284,17 +1289,22 @@ time_t_to_timestamptz(time_t tm)
  * Convert a TimestampTz to time_t.
  *
  * This too is just marginally useful, but some places need it.
+ *
+ * To avoid having the function's ABI vary depending on the width of time_t,
+ * we declare the result as pg_time_t, which is cast-compatible with
+ * time_t but always 64 bits wide (unless the platform has no 64-bit type).
+ * This detail should be invisible to callers, at least at source code level.
  */
-time_t
+pg_time_t
 timestamptz_to_time_t(TimestampTz t)
 {
-	time_t		result;
+	pg_time_t	result;
 
 #ifdef HAVE_INT64_TIMESTAMP
-	result = (time_t) (t / USECS_PER_SEC +
+	result = (pg_time_t) (t / USECS_PER_SEC +
 				 ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY));
 #else
-	result = (time_t) (t +
+	result = (pg_time_t) (t +
 				 ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY));
 #endif
 

src/backend/utils/init/globals.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/init/globals.c,v 1.104 2008/01/01 19:45:53 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/init/globals.c,v 1.105 2008/02/17 02:09:29 tgl Exp $
  *
  * NOTES
  *	  Globals used all over the place should be declared here and not
@@ -33,7 +33,7 @@ volatile uint32 InterruptHoldoffCount = 0;
 volatile uint32 CritSectionCount = 0;
 
 int			MyProcPid;
-time_t		MyStartTime;
+pg_time_t	MyStartTime;
 struct Port *MyProcPort;
 long		MyCancelKey;