Add test case for O_TMPFILE handling in open, openat

Also put xasprintf into test-skeleton.c (written in such a way that
including <stdarg.h> is not needed).

ChangeLog

@@ -1,3 +1,9 @@
+2016-09-21  Florian Weimer  <fweimer@redhat.com>
+
+	* test-skeleton.c (xasprintf): Add function.
+	* io/tst-open-tmpfile.c: New test.
+	* io/Makefile (tests): Add it.
+
 2016-09-21  Florian Weimer  <fweimer@redhat.com>
 
 	Avoid running $(CXX) during build to obtain header file paths.

io/Makefile

@@ -71,7 +71,8 @@ tests		:= test-utime test-stat test-stat2 test-lfs tst-getcwd \
 		   tst-renameat tst-fchownat tst-fchmodat tst-faccessat \
 		   tst-symlinkat tst-linkat tst-readlinkat tst-mkdirat \
 		   tst-mknodat tst-mkfifoat tst-ttyname_r bug-ftw5 \
-		   tst-posix_fallocate tst-fts tst-fts-lfs
+		   tst-posix_fallocate tst-fts tst-fts-lfs \
+		   tst-open-tmpfile
 
 ifeq ($(run-built-tests),yes)
 tests-special += $(objpfx)ftwtest.out

io/tst-open-tmpfile.c

@@ -0,0 +1,216 @@
+/* Test open and openat with O_TMPFILE.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This test verifies that open and openat work as expected, i.e. they
+   create a deleted file with the requested file mode.  */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+static int do_test (void);
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
+
+#ifdef O_TMPFILE
+typedef int (*wrapper_func) (const char *, int, mode_t);
+
+/* Error-checking wrapper for the open function, compatible with the
+   wrapper_func type.  */
+static int
+wrap_open (const char *path, int flags, mode_t mode)
+{
+  int ret = open (path, flags, mode);
+  if (ret < 0)
+    {
+      printf ("error: open (\"%s\", 0x%x, 0%03o): %m\n", path, flags, mode);
+      exit (1);
+    }
+  return ret;
+}
+
+/* Error-checking wrapper for the openat function, compatible with the
+   wrapper_func type.  */
+static int
+wrap_openat (const char *path, int flags, mode_t mode)
+{
+  int ret = openat (AT_FDCWD, path, flags, mode);
+  if (ret < 0)
+    {
+      printf ("error: openat (\"%s\", 0x%x, 0%03o): %m\n", path, flags, mode);
+      exit (1);
+    }
+  return ret;
+}
+
+/* Return true if FD is flagged as deleted in /proc/self/fd, false if
+   not.  */
+static bool
+is_file_deteted (int fd)
+{
+  char *proc_fd_path = xasprintf ("/proc/self/fd/%d", fd);
+  char file_path[4096];
+  ssize_t file_path_length
+    = readlink (proc_fd_path, file_path, sizeof (file_path));
+  if (file_path_length < 0)
+    {
+      printf ("error: readlink (\"%s\"): %m", proc_fd_path);
+      free (proc_fd_path);
+      exit (1);
+    }
+  free (proc_fd_path);
+  if (file_path_length == sizeof (file_path))
+    {
+      printf ("error: path in /proc resolves to overlong file name: %.*s\n",
+              (int) file_path_length, file_path);
+      exit (1);
+    }
+  const char *deleted = " (deleted)";
+  if (file_path_length < strlen (deleted))
+    {
+      printf ("error: path in /proc is too short: %.*s\n",
+              (int) file_path_length, file_path);
+      exit (1);
+    }
+  return memcmp (file_path + file_path_length - strlen (deleted),
+              deleted, strlen (deleted)) == 0;
+}
+
+/* Check open/openat (as specified by OP and WRAPPER) with a specific
+   PATH/FLAGS/MODE combination.  */
+static void
+check_wrapper_flags_mode (const char *op, wrapper_func wrapper,
+                          const char *path, int flags, mode_t mode)
+{
+  int fd = wrapper (path, flags | O_TMPFILE, mode);
+  struct stat64 st;
+  if (fstat64 (fd, &st) != 0)
+    {
+      printf ("error: fstat64: %m\n");
+      exit (1);
+    }
+
+  /* Verify that the mode was correctly processed.  */
+  int actual_mode = st.st_mode & 0777;
+  if (actual_mode != mode)
+    {
+      printf ("error: unexpected mode; expected 0%03o, actual 0%03o\n",
+              mode, actual_mode);
+      exit (1);
+    }
+
+  /* Check that the file is marked as deleted in /proc.  */
+  if (!is_file_deteted (fd))
+    {
+      printf ("error: path in /proc is not marked as deleted\n");
+      exit (1);
+    }
+
+  close (fd);
+}
+
+/* Check OP/WRAPPER with various flags at a specific PATH and
+   MODE.  */
+static void
+check_wrapper_mode (const char *op, wrapper_func wrapper,
+                    const char *path, mode_t mode)
+{
+  check_wrapper_flags_mode (op, wrapper, path, O_WRONLY, mode);
+  check_wrapper_flags_mode (op, wrapper, path, O_WRONLY | O_EXCL, mode);
+  check_wrapper_flags_mode (op, wrapper, path, O_RDWR, mode);
+  check_wrapper_flags_mode (op, wrapper, path, O_RDWR | O_EXCL, mode);
+}
+
+/* Check open/openat with varying permissions.  */
+static void
+check_wrapper (const char *op, wrapper_func wrapper,
+                    const char *path)
+{
+  printf ("info: testing %s at: %s\n", op, path);
+  check_wrapper_mode (op, wrapper, path, 0);
+  check_wrapper_mode (op, wrapper, path, 0640);
+  check_wrapper_mode (op, wrapper, path, 0600);
+  check_wrapper_mode (op, wrapper, path, 0755);
+  check_wrapper_mode (op, wrapper, path, 0750);
+}
+
+/* Verify that the directory at PATH supports O_TMPFILE.  Exit with
+   status 77 (unsupported) if the kernel does not support O_TMPFILE.
+   Even with kernel support, not all file systems O_TMPFILE, so return
+   true if the directory supports O_TMPFILE, false if not.  */
+static bool
+probe_path (const char *path)
+{
+  int fd = openat (AT_FDCWD, path, O_TMPFILE | O_RDWR, 0);
+  if (fd < 0)
+    {
+      if (errno == EISDIR)
+        /* The system does not support O_TMPFILE.  */
+        {
+          printf ("info: kernel does not support O_TMPFILE\n");
+          exit (77);
+        }
+      if (errno == EOPNOTSUPP)
+        {
+          printf ("info: path does not support O_TMPFILE: %s\n", path);
+          return false;
+        }
+      printf ("error: openat (\"%s\", O_TMPFILE | O_RDWR): %m\n", path);
+      exit (1);
+    }
+  close (fd);
+  return true;
+}
+
+static int
+do_test (void)
+{
+  umask (0);
+  const char *paths[] = { ".", "/dev/shm", "/tmp",
+                          getenv ("TEST_TMPFILE_PATH"),
+                          NULL };
+  bool supported = false;
+  for (int i = 0; paths[i] != NULL; ++i)
+    if (probe_path (paths[i]))
+      {
+        supported = true;
+        check_wrapper ("open", wrap_open, paths[i]);
+        check_wrapper ("openat", wrap_openat, paths[i]);
+      }
+
+  if (!supported)
+    return 77;
+
+  return 0;
+}
+
+#else  /* !O_TMPFILE */
+
+static int
+do_test (void)
+{
+  return 77;
+}
+
+#endif  /* O_TMPFILE */

test-skeleton.c

@@ -33,6 +33,7 @@
 #include <sys/wait.h>
 #include <sys/param.h>
 #include <time.h>
+#include <stdarg.h>
 
 /* The test function is normally called `do_test' and it is called
    with argc and argv as the arguments.  We nevertheless provide the
@@ -115,6 +116,20 @@ xrealloc (void *p, size_t n)
   return result;
 }
 
+/* Call asprintf with error checking.  */
+__attribute__ ((always_inline, format (printf, 1, 2)))
+static __inline__ char *
+xasprintf (const char *format, ...)
+{
+  char *result;
+  if (asprintf (&result, format, __builtin_va_arg_pack ()) < 0)
+    {
+      printf ("error: asprintf: %m\n");
+      exit (1);
+    }
+  return result;
+}
+
 /* Write a message to standard output.  Can be used in signal
    handlers.  */
 static void