[v2] linux: make getcwd(3) fail if it cannot obtain an absolute path [BZ #22679]
Commit Message
As the underlying getcwd syscall, starting with linux commit
v2.6.36-rc1~96^2~2, may succeed without returning an absolute path,
check for the path returned by syscall and fall back to generic_getcwd
if the path is not absolute.
[BZ #22679]
* sysdeps/unix/sysv/linux/getcwd.c (__getcwd): Fall back to
generic_getcwd if the path returned by getcwd syscall is not absolute.
* sysdeps/unix/sysv/linux/tst-getcwd-abspath.c: New test.
* sysdeps/unix/sysv/linux/Makefile (tests): Add tst-getcwd-abspath.
---
ChangeLog | 8 ++++
sysdeps/unix/sysv/linux/Makefile | 2 +-
sysdeps/unix/sysv/linux/getcwd.c | 8 ++--
sysdeps/unix/sysv/linux/tst-getcwd-abspath.c | 58 ++++++++++++++++++++++++++++
4 files changed, 71 insertions(+), 5 deletions(-)
create mode 100644 sysdeps/unix/sysv/linux/tst-getcwd-abspath.c
Comments
* Dmitry V. Levin:
> + TEST_VERIFY_EXIT (cwd == NULL && errno == ENOENT);
Using
TEST_COMPARE (errno, ENOENT);
for the second check would make it easier to diagnose test failures
without recompiling the test.
@@ -51,7 +51,7 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
tst-quota tst-sync_file_range tst-sysconf-iov_max tst-ttyname \
- test-errno-linux
+ test-errno-linux tst-getcwd-abspath
# Generate the list of SYS_* macros for the system calls (__NR_* macros).
@@ -76,7 +76,7 @@ __getcwd (char *buf, size_t size)
int retval;
retval = INLINE_SYSCALL (getcwd, 2, path, alloc_size);
- if (retval >= 0)
+ if (retval > 0 && path[0] == '/')
{
#ifndef NO_ALLOCATION
if (buf == NULL && size == 0)
@@ -92,10 +92,10 @@ __getcwd (char *buf, size_t size)
return buf;
}
- /* The system call cannot handle paths longer than a page.
- Neither can the magic symlink in /proc/self. Just use the
+ /* The system call either cannot handle paths longer than a page
+ or can succeed without returning an absolute path. Just use the
generic implementation right away. */
- if (errno == ENAMETOOLONG)
+ if (retval >= 0 || errno == ENAMETOOLONG)
{
#ifndef NO_ALLOCATION
if (buf == NULL && size == 0)
new file mode 100644
@@ -0,0 +1,58 @@
+/* BZ #22679 getcwd(3) does not succeed without returning an absolute path.
+
+ Copyright (C) 2018 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/namespace.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/test-driver.h>
+#include <support/xunistd.h>
+#include <unistd.h>
+
+static char *chroot_dir;
+
+/* The actual test. Run it in a subprocess, so that the test harness
+ can remove the temporary directory in --direct mode. */
+static void
+getcwd_callback (void *closure)
+{
+ xchroot (chroot_dir);
+ errno = 0;
+ char *cwd = getcwd (NULL, 0);
+ TEST_VERIFY_EXIT (cwd == NULL && errno == ENOENT);
+ _exit (0);
+}
+
+static int
+do_test (void)
+{
+ support_become_root ();
+ if (!support_can_chroot ())
+ return EXIT_UNSUPPORTED;
+
+ chroot_dir = support_create_temp_directory ("tst-getcwd-abspath-");
+ support_isolate_in_subprocess (getcwd_callback, NULL);
+
+ return 0;
+}
+
+#include <support/test-driver.c>