C comment: mention why no setting lasterrno in dir_existsfile()

bmomjian · bmomjian · commit 3fdc1d269345 · 2023-10-31T11:59:14.000-04:00
Reported-by: Wei Sun Discussion: https://postgr.es/m/tencent_1276C08F98579CC19D8A4488C848A8411806@qq.com Backpatch-through: master
diff --git a/src/bin/pg_basebackup/walmethods.c b/src/bin/pg_basebackup/walmethods.c
@@ -594,6 +594,11 @@ dir_existsfile(WalWriteMethod *wwmethod, const char *pathname)
 
 	fd = open(tmppath, O_RDONLY | PG_BINARY, 0);
 	if (fd < 0)
+
+		/*
+		 * Skip setting dir_data->lasterrno here because we are only checking
+		 * for existence.
+		 */
 		return false;
 	close(fd);
 	return true;
