pg_waldump: Fix error message for WAL files smaller than XLOG_BLCKSZ.

anarazel · anarazel · commit 5407241a8ec1 · 2022-02-25T10:34:38.000-08:00
When opening a WAL file smaller than XLOG_BLCKSZ (e.g. 0 bytes long) while determining the wal_segment_size, pg_waldump checked errno, despite errno not being set by the short read. Resulting in a bogus error message. Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://postgr.es/m/20220214.181847.775024684568733277.horikyota.ntt@gmail.com Backpatch: 11-, the bug was introducedin fc49e24
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
@@ -207,15 +207,12 @@ search_directory(const char *directory, const char *fname)
 									 WalSegSz),
 							fname, WalSegSz);
 		}
+		else if (r < 0)
+			fatal_error("could not read file \"%s\": %s",
+						fname, strerror(errno));
 		else
-		{
-			if (errno != 0)
-				fatal_error("could not read file \"%s\": %s",
-							fname, strerror(errno));
-			else
-				fatal_error("could not read file \"%s\": read %d of %zu",
-							fname, r, (Size) XLOG_BLCKSZ);
-		}
+			fatal_error("could not read file \"%s\": read %d of %zu",
+						fname, r, (Size) XLOG_BLCKSZ);
 		close(fd);
 		return true;
 	}
