Add testing of O_TMPFILE umask

There were kernels that didn't apply the current umask to inode modes
created with O_TMPFILE without acls.  Let's have a test running to make
sure that we're not surprised if we come across one.

Signed-off-by: Zach Brown <zab@versity.com>

tests/.gitignore

@@ -8,3 +8,4 @@ src/bulk_create_paths
 src/find_xattrs
 src/stage_tmpfile
 src/create_xattr_loop
+src/o_tmpfile_umask

tests/Makefile

@@ -11,7 +11,8 @@ BIN := src/createmany			\
 	src/stage_tmpfile		\
 	src/find_xattrs			\
 	src/create_xattr_loop		\
-	src/fragmented_data_extents
+	src/fragmented_data_extents	\
+	src/o_tmpfile_umask
 
 DEPS := $(wildcard src/*.d)
 

tests/golden/o_tmpfile

@@ -1,3 +1,10 @@
+== non-acl O_TMPFILE creation honors umask
+umask 022
+fstat after open(0777): 0100755
+stat after linkat: 0100755
+umask 077
+fstat after open(0777): 0100700
+stat after linkat: 0100700
 == stage from tmpfile
 total file size 33669120
 00000000  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|

tests/src/o_tmpfile_umask.c

@@ -0,0 +1,97 @@
+/*
+ * Show the modes of files as we create them with O_TMPFILE and link
+ * them into the namespace.
+ *
+ * Copyright (C) 2022 Versity Software, Inc.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <assert.h>
+#include <limits.h>
+
+static void linkat_tmpfile_modes(char *dir, char *lpath, mode_t mode)
+{
+	char proc_self[PATH_MAX];
+	struct stat st;
+	int ret;
+	int fd;
+
+	umask(mode);
+	printf("umask 0%o\n", mode);
+
+	fd = open(dir, O_RDWR | O_TMPFILE, 0777);
+	if (fd < 0) {
+		perror("open(O_TMPFILE)");
+		exit(1);
+	}
+
+	ret = fstat(fd, &st);
+	if (ret < 0) {
+		perror("fstat");
+		exit(1);
+	}
+
+	printf("fstat after open(0777): 0%o\n", st.st_mode);
+
+	snprintf(proc_self, sizeof(proc_self), "/proc/self/fd/%d", fd);
+
+	ret = linkat(AT_FDCWD, proc_self, AT_FDCWD, lpath, AT_SYMLINK_FOLLOW);
+	if (ret < 0) {
+		perror("linkat");
+		exit(1);
+	}
+
+	close(fd);
+
+	ret = stat(lpath, &st);
+	if (ret < 0) {
+		perror("fstat");
+		exit(1);
+	}
+
+	printf("stat after linkat: 0%o\n", st.st_mode);
+
+	ret = unlink(lpath);
+	if (ret < 0) {
+		perror("unlink");
+		exit(1);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	char *lpath;
+	char *dir;
+
+	if (argc < 3) {
+		printf("%s <open_dir> <linkat_path>\n", argv[0]);
+		return 1;
+	}
+
+	dir = argv[1];
+	lpath = argv[2];
+
+	linkat_tmpfile_modes(dir, lpath, 022);
+	linkat_tmpfile_modes(dir, lpath, 077);
+
+	return 0;
+}

tests/tests/o_tmpfile.sh

@@ -4,6 +4,9 @@
 
 t_require_commands stage_tmpfile hexdump
 
+echo "== non-acl O_TMPFILE creation honors umask"
+o_tmpfile_umask "$T_D0" "$T_D0/umask-file" 
+
 echo "== stage from tmpfile"
 DEST_FILE="$T_D0/dest_file"
 stage_tmpfile $T_D0 $DEST_FILE