Suppress -Warray-bounds warning in 9.2's xlog.c.

tglsfdc · tglsfdc · commit 985c8de212fa · 2021-12-13T11:57:11.000-05:00
Late-model gcc delivers a confusing warning "'memcpy' offset [0, 63] is out of the bounds [0, 0]" here, which turns out to be because it thinks the "record" pointer might be NULL, which again is because it doesn't know ereport(PANIC) won't return. The least invasive way to fix that is to insert a couple of abort() calls. It's surprising/fortunate that we don't have this issue in more places ... but this is the last remaining build warning with gcc 11.2.1, so I'll settle for a narrow fix. Discussion: https://postgr.es/m/d0316012-ece7-7b7e-2d36-9c38cb77cb3b@enterprisedb.com
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
@@ -6601,6 +6601,7 @@ StartupXLOG(void)
 			 */
 			ereport(PANIC,
 					(errmsg("could not locate a valid checkpoint record")));
+			abort();			/* NOTREACHED */
 		}
 		else
 		{
@@ -6614,8 +6615,11 @@ StartupXLOG(void)
 				InRecovery = true;		/* force recovery even if SHUTDOWNED */
 			}
 			else
+			{
 				ereport(PANIC,
 					 (errmsg("could not locate a valid checkpoint record")));
+				abort();		/* NOTREACHED */
+			}
 		}
 		memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint));
 		wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN);

Original file line number	Diff line number	Diff line change
`@@ -6601,6 +6601,7 @@ StartupXLOG(void)`
`6601`	`6601`	`*/`
`6602`	`6602`	`ereport(PANIC,`
`6603`	`6603`	`(errmsg("could not locate a valid checkpoint record")));`
	`6604`	`+ abort(); /* NOTREACHED */`
`6604`	`6605`	`}`
`6605`	`6606`	`else`
`6606`	`6607`	`{`
`@@ -6614,8 +6615,11 @@ StartupXLOG(void)`
`6614`	`6615`	`InRecovery = true; /* force recovery even if SHUTDOWNED */`
`6615`	`6616`	`}`
`6616`	`6617`	`else`
	`6618`	`+ {`
`6617`	`6619`	`ereport(PANIC,`
`6618`	`6620`	`(errmsg("could not locate a valid checkpoint record")));`
	`6621`	`+ abort(); /* NOTREACHED */`
	`6622`	`+ }`
`6619`	`6623`	`}`
`6620`	`6624`	`memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint));`
`6621`	`6625`	`wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN);`