platform_bionic/tests/sys_stat_test.cpp
Nick Kralevich 35778253a5 Fix "faccessat ignores flags"
The kernel system call faccessat() does not have any flags arguments,
so passing flags to the kernel is currently ignored.

Fix the kernel system call so that no flags argument is passed in.

Ensure that we don't support AT_SYMLINK_NOFOLLOW. This non-POSIX
(http://pubs.opengroup.org/onlinepubs/9699919799/functions/access.html)
flag is a glibc extension, and has non-intuitive, error prone behavior.

For example, consider the following code:

  symlink("foo.is.dangling", "foo");
  if (faccessat(AT_FDCWD, "foo", R_OK, AT_SYMLINK_NOFOLLOW) == 0) {
    int fd = openat(AT_FDCWD, "foo", O_RDONLY | O_NOFOLLOW);
  }

The faccessat() call in glibc will return true, but an attempt to
open the dangling symlink will end up failing. GLIBC documents this
as returning the access mode of the symlink itself, which will
always return true for any symlink on Linux.

Some further discussions of this are at:

  * http://lists.landley.net/pipermail/toybox-landley.net/2014-September/003617.html
  * http://permalink.gmane.org/gmane.linux.lib.musl.general/6952

AT_SYMLINK_NOFOLLOW seems broken by design. I suspect this is why this
function was never added to POSIX. (note that "access" is pretty much
broken by design too, since it introduces a race condition between
check and action). We shouldn't support this until it's clearly
documented by POSIX or we can have it produce intuitive results.

Don't support AT_EACCESS for now. Implementing it is complicated, and
pretty much useless on Android, since we don't have setuid binaries.
See http://git.musl-libc.org/cgit/musl/commit/?id=0a05eace163cee9b08571d2ff9d90f5e82d9c228
for how an implementation might look.

Bug: 18867827
Change-Id: I25b86c5020f3152ffa3ac3047f6c4152908d0e04
2015-02-24 13:40:43 -08:00

261 lines
7.1 KiB
C++

/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <gtest/gtest.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/stat.h>
#include "TemporaryFile.h"
TEST(sys_stat, futimens) {
FILE* fp = tmpfile();
ASSERT_TRUE(fp != NULL);
int fd = fileno(fp);
ASSERT_NE(fd, -1);
timespec times[2];
times[0].tv_sec = 123;
times[0].tv_nsec = 0;
times[1].tv_sec = 456;
times[1].tv_nsec = 0;
ASSERT_EQ(0, futimens(fd, times)) << strerror(errno);
struct stat sb;
ASSERT_EQ(0, fstat(fd, &sb));
ASSERT_EQ(times[0].tv_sec, static_cast<long>(sb.st_atime));
ASSERT_EQ(times[1].tv_sec, static_cast<long>(sb.st_mtime));
fclose(fp);
}
TEST(sys_stat, futimens_EBADF) {
timespec times[2];
times[0].tv_sec = 123;
times[0].tv_nsec = 0;
times[1].tv_sec = 456;
times[1].tv_nsec = 0;
ASSERT_EQ(-1, futimens(-1, times));
ASSERT_EQ(EBADF, errno);
}
TEST(sys_stat, mkfifo_failure) {
errno = 0;
ASSERT_EQ(-1, mkfifo("/", 0666));
ASSERT_EQ(EEXIST, errno);
}
TEST(sys_stat, mkfifoat_failure) {
errno = 0;
ASSERT_EQ(-1, mkfifoat(-2, "x", 0666));
ASSERT_EQ(EBADF, errno);
}
TEST(sys_stat, mkfifo) {
if (getuid() == 0) {
// Racy but probably sufficient way to get a suitable filename.
std::string path;
{
TemporaryFile tf;
path = tf.filename;
}
ASSERT_EQ(0, mkfifo(path.c_str(), 0666));
struct stat sb;
ASSERT_EQ(0, stat(path.c_str(), &sb));
ASSERT_TRUE(S_ISFIFO(sb.st_mode));
unlink(path.c_str());
} else {
// SELinux policy forbids us from creating FIFOs. http://b/17646702.
GTEST_LOG_(INFO) << "This test only performs a test when run as root.";
}
}
TEST(sys_stat, stat64_lstat64_fstat64) {
struct stat64 sb;
ASSERT_EQ(0, stat64("/proc/version", &sb));
ASSERT_EQ(0, lstat64("/proc/version", &sb));
int fd = open("/proc/version", O_RDONLY);
ASSERT_EQ(0, fstat64(fd, &sb));
close(fd);
}
TEST(sys_stat, fchmodat_EFAULT_file) {
ASSERT_EQ(-1, fchmodat(AT_FDCWD, (char *) 0x1, 0751, 0));
ASSERT_EQ(EFAULT, errno);
}
TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_EFAULT_file) {
ASSERT_EQ(-1, fchmodat(AT_FDCWD, (char *) 0x1, 0751, AT_SYMLINK_NOFOLLOW));
#if defined(__BIONIC__)
ASSERT_EQ(EFAULT, errno);
#else
// glibc 2.19 does not implement AT_SYMLINK_NOFOLLOW and always
// returns ENOTSUP
ASSERT_EQ(ENOTSUP, errno);
#endif
}
TEST(sys_stat, fchmodat_bad_flags) {
ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, ~AT_SYMLINK_NOFOLLOW));
ASSERT_EQ(EINVAL, errno);
}
TEST(sys_stat, fchmodat_bad_flags_ALL) {
ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, ~0));
ASSERT_EQ(EINVAL, errno);
}
TEST(sys_stat, fchmodat_nonexistant_file) {
ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, 0));
ASSERT_EQ(ENOENT, errno);
}
TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_nonexistant_file) {
ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, AT_SYMLINK_NOFOLLOW));
#if defined(__BIONIC__)
ASSERT_EQ(ENOENT, errno);
#else
// glibc 2.19 does not implement AT_SYMLINK_NOFOLLOW and always
// returns ENOTSUP
ASSERT_EQ(ENOTSUP, errno);
#endif
}
TEST(sys_stat, fchmodat_file) {
TemporaryFile tf;
struct stat sb;
ASSERT_EQ(0, fchmodat(AT_FDCWD, tf.filename, 0751, 0));
ASSERT_EQ(0, fstat(tf.fd, &sb));
ASSERT_TRUE(0751 == (sb.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO)));
}
TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_file) {
TemporaryFile tf;
errno = 0;
int result = fchmodat(AT_FDCWD, tf.filename, 0751, AT_SYMLINK_NOFOLLOW);
#if defined(__BIONIC__)
struct stat sb;
ASSERT_EQ(0, result);
ASSERT_EQ(0, errno);
ASSERT_EQ(0, fstat(tf.fd, &sb));
ASSERT_TRUE(0751 == (sb.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO)));
#else
// glibc 2.19 does not implement AT_SYMLINK_NOFOLLOW and always
// returns ENOTSUP
ASSERT_EQ(-1, result);
ASSERT_EQ(ENOTSUP, errno);
#endif
}
TEST(sys_stat, fchmodat_symlink) {
TemporaryFile tf;
char linkname[255];
struct stat sb;
snprintf(linkname, sizeof(linkname), "%s.link", tf.filename);
ASSERT_EQ(0, symlink(tf.filename, linkname));
ASSERT_EQ(0, fchmodat(AT_FDCWD, linkname, 0751, 0));
ASSERT_EQ(0, fstat(tf.fd, &sb));
ASSERT_TRUE(0751 == (sb.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO)));
unlink(linkname);
}
TEST(sys_stat, fchmodat_dangling_symlink) {
TemporaryFile tf;
char linkname[255];
char target[255];
snprintf(linkname, sizeof(linkname), "%s.link", tf.filename);
snprintf(target, sizeof(target), "%s.doesnotexist", tf.filename);
ASSERT_EQ(0, symlink(target, linkname));
ASSERT_EQ(-1, fchmodat(AT_FDCWD, linkname, 0751, 0));
ASSERT_EQ(ENOENT, errno);
unlink(linkname);
}
TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_with_symlink) {
TemporaryFile tf;
char linkname[255];
snprintf(linkname, sizeof(linkname), "%s.link", tf.filename);
ASSERT_EQ(0, symlink(tf.filename, linkname));
ASSERT_EQ(-1, fchmodat(AT_FDCWD, linkname, 0751, AT_SYMLINK_NOFOLLOW));
ASSERT_EQ(ENOTSUP, errno);
unlink(linkname);
}
TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_with_dangling_symlink) {
TemporaryFile tf;
char linkname[255];
char target[255];
snprintf(linkname, sizeof(linkname), "%s.link", tf.filename);
snprintf(target, sizeof(target), "%s.doesnotexist", tf.filename);
ASSERT_EQ(0, symlink(target, linkname));
ASSERT_EQ(-1, fchmodat(AT_FDCWD, linkname, 0751, AT_SYMLINK_NOFOLLOW));
ASSERT_EQ(ENOTSUP, errno);
unlink(linkname);
}
TEST(sys_stat, faccessat_EINVAL) {
ASSERT_EQ(-1, faccessat(AT_FDCWD, "/dev/null", F_OK, ~AT_SYMLINK_NOFOLLOW));
ASSERT_EQ(EINVAL, errno);
#if defined(__BIONIC__)
ASSERT_EQ(-1, faccessat(AT_FDCWD, "/dev/null", ~(R_OK | W_OK | X_OK), 0));
ASSERT_EQ(EINVAL, errno);
#else
ASSERT_EQ(0, faccessat(AT_FDCWD, "/dev/null", ~(R_OK | W_OK | X_OK), AT_SYMLINK_NOFOLLOW));
ASSERT_EQ(-1, faccessat(AT_FDCWD, "/dev/null", ~(R_OK | W_OK | X_OK), 0));
ASSERT_EQ(EINVAL, errno);
#endif
}
TEST(sys_stat, faccessat_AT_SYMLINK_NOFOLLOW_EINVAL) {
#if defined(__BIONIC__)
// Android doesn't support AT_SYMLINK_NOFOLLOW
ASSERT_EQ(-1, faccessat(AT_FDCWD, "/dev/null", F_OK, AT_SYMLINK_NOFOLLOW));
ASSERT_EQ(EINVAL, errno);
#else
ASSERT_EQ(0, faccessat(AT_FDCWD, "/dev/null", F_OK, AT_SYMLINK_NOFOLLOW));
#endif
}
TEST(sys_stat, faccessat_dev_null) {
ASSERT_EQ(0, faccessat(AT_FDCWD, "/dev/null", F_OK, 0));
ASSERT_EQ(0, faccessat(AT_FDCWD, "/dev/null", R_OK, 0));
ASSERT_EQ(0, faccessat(AT_FDCWD, "/dev/null", W_OK, 0));
ASSERT_EQ(0, faccessat(AT_FDCWD, "/dev/null", R_OK|W_OK, 0));
}
TEST(sys_stat, faccessat_nonexistant) {
ASSERT_EQ(-1, faccessat(AT_FDCWD, "/blah", F_OK, AT_SYMLINK_NOFOLLOW));
#if defined(__BIONIC__)
// Android doesn't support AT_SYMLINK_NOFOLLOW
ASSERT_EQ(EINVAL, errno);
#else
ASSERT_EQ(ENOENT, errno);
#endif
}