Teach pg_ls_dir_files() to ignore ENOENT failures from stat().

tglsfdc · tglsfdc · commit 83f7761d84e6 · 2020-03-31T12:57:55.000-04:00
Buildfarm experience shows that this function can fail with ENOENT if some other process unlinks a file between when we read the directory entry and when we try to stat() it. The problem is old but we had not noticed it until 085b6b6 added regression test coverage. To fix, just ignore ENOENT failures. There is one other case that this might hide: a symlink that points to nowhere. That seems okay though, at least better than erroring. Back-patch to v10 where this function was added, since the regression test cases were too. Discussion: https://postgr.es/m/20200308173103.GC1357@telsasoft.com
diff --git a/src/backend/utils/adt/genfile.c b/src/backend/utils/adt/genfile.c
@@ -538,9 +538,14 @@ pg_ls_dir_files(FunctionCallInfo fcinfo, const char *dir)
 		/* Get the file info */
 		snprintf(path, sizeof(path), "%s/%s", dir, de->d_name);
 		if (stat(path, &attrib) < 0)
+		{
+			/* Ignore concurrently-deleted files, else complain */
+			if (errno == ENOENT)
+				continue;
 			ereport(ERROR,
 					(errcode_for_file_access(),
 					 errmsg("could not stat file \"%s\": %m", path)));
+		}
 
 		/* Ignore anything but regular files */
 		if (!S_ISREG(attrib.st_mode))
