Fix Y2038 issues with MyStartTime.

Several places treat MyStartTime as a "long", which is only 32 bits
wide on some platforms.  In reality, MyStartTime is a pg_time_t,
i.e., a signed 64-bit integer.  This will lead to interesting bugs
on the aforementioned systems in 2038 when signed 32-bit integers
are no longer sufficient to store Unix time (e.g., "pg_ctl start"
hanging).  To fix, ensure that MyStartTime is handled as a 64-bit
value everywhere.  (Of course, users will need to ensure that
time_t is 64 bits wide on their system, too.)

Co-authored-by: Max Johnson
Discussion: https://postgr.es/m/CO1PR07MB905262E8AC270FAAACED66008D682%40CO1PR07MB9052.namprd07.prod.outlook.com
Backpatch-through: 12

Author: nathan-bossart

contrib/postgres_fdw/option.c

@@ -522,7 +522,7 @@ process_pgfdw_appname(const char *appname)
 				appendStringInfoString(&buf, application_name);
 				break;
 			case 'c':
-				appendStringInfo(&buf, "%lx.%x", (long) (MyStartTime), MyProcPid);
+				appendStringInfo(&buf, "%" INT64_MODIFIER "x.%x", MyStartTime, MyProcPid);
 				break;
 			case 'C':
 				appendStringInfoString(&buf, cluster_name);

src/backend/utils/error/csvlog.c

@@ -120,7 +120,7 @@ write_csvlog(ErrorData *edata)
 	appendStringInfoChar(&buf, ',');
 
 	/* session id */
-	appendStringInfo(&buf, "%lx.%x", (long) MyStartTime, MyProcPid);
+	appendStringInfo(&buf, "%" INT64_MODIFIER "x.%x", MyStartTime, MyProcPid);
 	appendStringInfoChar(&buf, ',');
 
 	/* Line number */

src/backend/utils/error/elog.c

@@ -2944,12 +2944,12 @@ log_status_format(StringInfo buf, const char *format, ErrorData *edata)
 				{
 					char		strfbuf[128];
 
-					snprintf(strfbuf, sizeof(strfbuf) - 1, "%lx.%x",
-							 (long) (MyStartTime), MyProcPid);
+					snprintf(strfbuf, sizeof(strfbuf) - 1, "%" INT64_MODIFIER "x.%x",
+							 MyStartTime, MyProcPid);
 					appendStringInfo(buf, "%*s", padding, strfbuf);
 				}
 				else
-					appendStringInfo(buf, "%lx.%x", (long) (MyStartTime), MyProcPid);
+					appendStringInfo(buf, "%" INT64_MODIFIER "x.%x", MyStartTime, MyProcPid);
 				break;
 			case 'p':
 				if (padding != 0)

src/backend/utils/error/jsonlog.c

@@ -168,8 +168,8 @@ write_jsonlog(ErrorData *edata)
 	}
 
 	/* Session id */
-	appendJSONKeyValueFmt(&buf, "session_id", true, "%lx.%x",
-						  (long) MyStartTime, MyProcPid);
+	appendJSONKeyValueFmt(&buf, "session_id", true, "%" INT64_MODIFIER "x.%x",
+						  MyStartTime, MyProcPid);
 
 	/* Line number */
 	appendJSONKeyValueFmt(&buf, "line_num", false, "%ld", log_line_number);

src/backend/utils/init/miscinit.c

@@ -1372,10 +1372,10 @@ CreateLockFile(const char *filename, bool amPostmaster,
 	 * both datadir and socket lockfiles; although more stuff may get added to
 	 * the datadir lockfile later.
 	 */
-	snprintf(buffer, sizeof(buffer), "%d\n%s\n%ld\n%d\n%s\n",
+	snprintf(buffer, sizeof(buffer), "%d\n%s\n" INT64_FORMAT "\n%d\n%s\n",
 			 amPostmaster ? (int) my_pid : -((int) my_pid),
 			 DataDir,
-			 (long) MyStartTime,
+			 MyStartTime,
 			 PostPortNumber,
 			 socketDir);
 

src/bin/pg_ctl/pg_ctl.c

@@ -618,7 +618,7 @@ wait_for_postmaster_start(pid_t pm_pid, bool do_checkpoint)
 			 * Allow 2 seconds slop for possible cross-process clock skew.
 			 */
 			pmpid = atol(optlines[LOCK_FILE_LINE_PID - 1]);
-			pmstart = atol(optlines[LOCK_FILE_LINE_START_TIME - 1]);
+			pmstart = atoll(optlines[LOCK_FILE_LINE_START_TIME - 1]);
 			if (pmstart >= start_time - 2 &&
 #ifndef WIN32
 				pmpid == pm_pid