posix: Allow glob to match dangling symlinks [BZ #866]

This patch makes glob match dangling symlinks.  Compared to other glob
implementation (*BSD, bash, musl, and other shells as well), GLIBC seems
the be the only one that does not match dangling symlinks.  As for
comment #5 in BZ #866, POSIX does not have any strict specification for
dangling symlinks match and it is reasonable that trying to glob everything
in a path should return all types of files (such as for a 'rm *').  Also,
comment #7 shows even more example where GLIBC current behavior is
unexepected.

I avoided adding another GNU specific flag to set this behavior and
instead make it the default.  Although this change the semanthic from
previous implementation, I think adding another compat symbol to be
really unecessary as from aforementioned reasons (current behavior not
defined in any standard, general idea of different implementation is
to list dangling symbols).

This also sync glob with gnulib commit fd1daf4 (glob: match dangling
symlinks).

Checked on x86_64-linux-gnu and on a build using build-many-glibcs.py
for all major architectures.

	[BZ #866]
	[BZ #1062]
	* posix/Makefile (tests): Remove bug-glob1 and tst-glob_symlinks.
	* posix/bug-glob1.c: Remove file.
	* posix/tst-glob_symlinks.c: New file.
	* posix/glob.c (__lstat64): New macro.
	(is_dir): New function.
	(glob, glob_in_dir): Match symlinks even if they are dangling.
	(link_stat, link_exists_p): Remove.  All uses removed.
This commit is contained in:
Adhemerval Zanella 2017-09-04 16:22:28 -03:00
parent 686f2ea183
commit 5554304f0d
5 changed files with 233 additions and 243 deletions

View File

@ -1,5 +1,15 @@
2017-09-08 Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #866]
[BZ #1062]
* posix/Makefile (tests): Remove bug-glob1 and tst-glob_symlinks.
* posix/bug-glob1.c: Remove file.
* posix/tst-glob_symlinks.c: New file.
* posix/glob.c (__lstat64): New macro.
(is_dir): New function.
(glob, glob_in_dir): Match symlinks even if they are dangling.
(link_stat, link_exists_p): Remove. All uses removed.
[BZ #1062]
[BZ #19971]
* posix/glob.c (struct readdir_result): Remove skip_entry member.

View File

@ -79,7 +79,7 @@ tests := test-errno tstgetopt testfnm runtests runptests \
tst-nice tst-nanosleep tst-regex2 \
transbug tst-rxspencer tst-pcre tst-boost \
bug-ga1 tst-vfork1 tst-vfork2 tst-vfork3 tst-waitid \
tst-getaddrinfo2 bug-glob1 bug-glob2 bug-glob3 tst-sysconf \
tst-getaddrinfo2 bug-glob2 bug-glob3 tst-sysconf \
tst-execvp1 tst-execvp2 tst-execlp1 tst-execlp2 \
tst-execv1 tst-execv2 tst-execl1 tst-execl2 \
tst-execve1 tst-execve2 tst-execle1 tst-execle2 \
@ -93,7 +93,7 @@ tests := test-errno tstgetopt testfnm runtests runptests \
tst-fnmatch3 bug-regex36 tst-getaddrinfo5 \
tst-posix_spawn-fd tst-posix_spawn-setsid \
tst-posix_fadvise tst-posix_fadvise64 \
tst-sysconf-empty-chroot
tst-sysconf-empty-chroot tst-glob_symlinks
tests-internal := bug-regex5 bug-regex20 bug-regex33 \
tst-rfc3484 tst-rfc3484-2 tst-rfc3484-3
xtests := bug-ga2

View File

@ -1,88 +0,0 @@
/* Test case for globbing dangling symlink. By Ulrich Drepper. */
#include <errno.h>
#include <error.h>
#include <glob.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static void prepare (int argc, char *argv[]);
#define PREPARE prepare
static int do_test (void);
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"
static char *fname;
static void
prepare (int argc, char *argv[])
{
if (argc < 2)
error (EXIT_FAILURE, 0, "missing argument");
size_t len = strlen (argv[1]);
static const char ext[] = "globXXXXXX";
fname = malloc (len + sizeof (ext));
if (fname == NULL)
error (EXIT_FAILURE, errno, "cannot create temp file");
again:
strcpy (stpcpy (fname, argv[1]), ext);
fname = mktemp (fname);
if (fname == NULL || *fname == '\0')
error (EXIT_FAILURE, errno, "cannot create temp file name");
if (symlink ("bug-glob1-does-not-exist", fname) != 0)
{
if (errno == EEXIST)
goto again;
error (EXIT_FAILURE, errno, "cannot create symlink");
}
add_temp_file (fname);
}
static int
do_test (void)
{
glob_t gl;
int retval = 0;
int e;
e = glob (fname, 0, NULL, &gl);
if (e == 0)
{
printf ("glob(\"%s\") succeeded\n", fname);
retval = 1;
}
globfree (&gl);
size_t fnamelen = strlen (fname);
char buf[fnamelen + 2];
strcpy (buf, fname);
buf[fnamelen - 1] = '?';
e = glob (buf, 0, NULL, &gl);
if (e == 0)
{
printf ("glob(\"%s\") succeeded\n", buf);
retval = 1;
}
globfree (&gl);
strcpy (buf, fname);
buf[fnamelen] = '*';
buf[fnamelen + 1] = '\0';
e = glob (buf, 0, NULL, &gl);
if (e == 0)
{
printf ("glob(\"%s\") succeeded\n", buf);
retval = 1;
}
globfree (&gl);
return retval;
}

View File

@ -57,6 +57,9 @@
# define readdir(str) __readdir64 (str)
# define getpwnam_r(name, bufp, buf, len, res) \
__getpwnam_r (name, bufp, buf, len, res)
# ifndef __lstat64
# define __lstat64(fname, buf) __lxstat64 (_STAT_VER, fname, buf)
# endif
# ifndef __stat64
# define __stat64(fname, buf) __xstat64 (_STAT_VER, fname, buf)
# endif
@ -64,6 +67,7 @@
# define FLEXIBLE_ARRAY_MEMBER
#else /* !_LIBC */
# define __getlogin_r(buf, len) getlogin_r (buf, len)
# define __lstat64(fname, buf) lstat (fname, buf)
# define __stat64(fname, buf) stat (fname, buf)
# define __fxstatat64(_, d, f, st, flag) fstatat (d, f, st, flag)
# define struct_stat64 struct stat
@ -226,6 +230,18 @@ static int prefix_array (const char *prefix, char **array, size_t n) __THROWNL;
static int collated_compare (const void *, const void *) __THROWNL;
/* Return true if FILENAME is a directory or a symbolic link to a directory.
Use FLAGS and PGLOB to resolve the filename. */
static bool
is_dir (char const *filename, int flags, glob_t const *pglob)
{
struct stat st;
struct_stat64 st64;
return (__glibc_unlikely (flags & GLOB_ALTDIRFUNC)
? pglob->gl_stat (filename, &st) == 0 && S_ISDIR (st.st_mode)
: __stat64 (filename, &st64) == 0 && S_ISDIR (st64.st_mode));
}
/* Find the end of the sub-pattern in a brace expression. */
static const char *
next_brace_sub (const char *cp, int flags)
@ -975,68 +991,53 @@ glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
can give the answer now. */
if (filename == NULL)
{
struct stat st;
struct_stat64 st64;
size_t newcount = pglob->gl_pathc + pglob->gl_offs;
char **new_gl_pathv;
/* Return the directory if we don't check for error or if it exists. */
if ((flags & GLOB_NOCHECK)
|| (((__builtin_expect (flags & GLOB_ALTDIRFUNC, 0))
? ((*pglob->gl_stat) (dirname, &st) == 0
&& S_ISDIR (st.st_mode))
: (__stat64 (dirname, &st64) == 0 && S_ISDIR (st64.st_mode)))))
{
size_t newcount = pglob->gl_pathc + pglob->gl_offs;
char **new_gl_pathv;
if (newcount > SIZE_MAX / sizeof (char *) - 2)
{
nospace:
free (pglob->gl_pathv);
pglob->gl_pathv = NULL;
pglob->gl_pathc = 0;
retval = GLOB_NOSPACE;
goto out;
}
if (newcount > SIZE_MAX / sizeof (char *) - 2)
{
nospace:
free (pglob->gl_pathv);
pglob->gl_pathv = NULL;
pglob->gl_pathc = 0;
retval = GLOB_NOSPACE;
goto out;
}
new_gl_pathv = realloc (pglob->gl_pathv,
(newcount + 2) * sizeof (char *));
if (new_gl_pathv == NULL)
goto nospace;
pglob->gl_pathv = new_gl_pathv;
new_gl_pathv = realloc (pglob->gl_pathv,
(newcount + 2) * sizeof (char *));
if (new_gl_pathv == NULL)
goto nospace;
pglob->gl_pathv = new_gl_pathv;
if (flags & GLOB_MARK && is_dir (dirname, flags, pglob))
{
char *p;
pglob->gl_pathv[newcount] = malloc (dirlen + 2);
if (pglob->gl_pathv[newcount] == NULL)
goto nospace;
p = mempcpy (pglob->gl_pathv[newcount], dirname, dirlen);
p[0] = '/';
p[1] = '\0';
if (__glibc_unlikely (malloc_dirname))
free (dirname);
}
else
{
if (__glibc_unlikely (malloc_dirname))
pglob->gl_pathv[newcount] = dirname;
else
{
pglob->gl_pathv[newcount] = strdup (dirname);
if (pglob->gl_pathv[newcount] == NULL)
goto nospace;
}
}
pglob->gl_pathv[++newcount] = NULL;
++pglob->gl_pathc;
pglob->gl_flags = flags;
if (flags & GLOB_MARK)
{
char *p;
pglob->gl_pathv[newcount] = malloc (dirlen + 2);
if (pglob->gl_pathv[newcount] == NULL)
goto nospace;
p = mempcpy (pglob->gl_pathv[newcount], dirname, dirlen);
p[0] = '/';
p[1] = '\0';
if (__glibc_unlikely (malloc_dirname))
free (dirname);
}
else
{
if (__glibc_unlikely (malloc_dirname))
pglob->gl_pathv[newcount] = dirname;
else
{
pglob->gl_pathv[newcount] = strdup (dirname);
if (pglob->gl_pathv[newcount] == NULL)
goto nospace;
}
}
pglob->gl_pathv[++newcount] = NULL;
++pglob->gl_pathc;
pglob->gl_flags = flags;
return 0;
}
/* Not found. */
retval = GLOB_NOMATCH;
goto out;
return 0;
}
meta = __glob_pattern_type (dirname, !(flags & GLOB_NOESCAPE));
@ -1244,15 +1245,9 @@ glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
{
/* Append slashes to directory names. */
size_t i;
struct stat st;
struct_stat64 st64;
for (i = oldcount; i < pglob->gl_pathc + pglob->gl_offs; ++i)
if ((__builtin_expect (flags & GLOB_ALTDIRFUNC, 0)
? ((*pglob->gl_stat) (pglob->gl_pathv[i], &st) == 0
&& S_ISDIR (st.st_mode))
: (__stat64 (pglob->gl_pathv[i], &st64) == 0
&& S_ISDIR (st64.st_mode))))
if (is_dir (pglob->gl_pathv[i], flags, pglob))
{
size_t len = strlen (pglob->gl_pathv[i]) + 2;
char *new = realloc (pglob->gl_pathv[i], len);
@ -1358,56 +1353,6 @@ prefix_array (const char *dirname, char **array, size_t n)
return 0;
}
/* We put this in a separate function mainly to allow the memory
allocated with alloca to be recycled. */
static int
__attribute_noinline__
link_stat (const char *dir, size_t dirlen, const char *fname,
glob_t *pglob
# if !defined _LIBC && !HAVE_FSTATAT
, int flags
# endif
)
{
size_t fnamelen = strlen (fname);
char *fullname = __alloca (dirlen + 1 + fnamelen + 1);
struct stat st;
mempcpy (mempcpy (mempcpy (fullname, dir, dirlen), "/", 1),
fname, fnamelen + 1);
# if !defined _LIBC && !HAVE_FSTATAT
if (__builtin_expect ((flags & GLOB_ALTDIRFUNC) == 0, 1))
{
struct_stat64 st64;
return __stat64 (fullname, &st64);
}
# endif
return (*pglob->gl_stat) (fullname, &st);
}
/* Return true if DIR/FNAME exists. */
static int
link_exists_p (int dfd, const char *dir, size_t dirlen, const char *fname,
glob_t *pglob, int flags)
{
int status;
# if defined _LIBC || HAVE_FSTATAT
if (__builtin_expect (flags & GLOB_ALTDIRFUNC, 0))
status = link_stat (dir, dirlen, fname, pglob);
else
{
/* dfd cannot be -1 here, because dirfd never returns -1 on
glibc, or on hosts that have fstatat. */
struct_stat64 st64;
status = __fxstatat64 (_STAT_VER, dfd, fname, &st64, 0);
}
# else
status = link_stat (dir, dirlen, fname, pglob, flags);
# endif
return status == 0 || errno == EOVERFLOW;
}
/* Like 'glob', but PATTERN is a final pathname component,
and matches are searched for in DIRECTORY.
The GLOB_NOSORT bit in FLAGS is ignored. No sorting is ever done.
@ -1449,8 +1394,6 @@ glob_in_dir (const char *pattern, const char *directory, int flags,
}
else if (meta == 0)
{
/* Since we use the normal file functions we can also use stat()
to verify the file is there. */
union
{
struct stat st;
@ -1475,8 +1418,8 @@ glob_in_dir (const char *pattern, const char *directory, int flags,
"/", 1),
pattern, patlen + 1);
if (((__builtin_expect (flags & GLOB_ALTDIRFUNC, 0)
? (*pglob->gl_stat) (fullname, &ust.st)
: __stat64 (fullname, &ust.st64))
? (*pglob->gl_lstat) (fullname, &ust.st)
: __lstat64 (fullname, &ust.st64))
== 0)
|| errno == EOVERFLOW)
/* We found this file to be existing. Now tell the rest
@ -1500,8 +1443,6 @@ glob_in_dir (const char *pattern, const char *directory, int flags,
}
else
{
int dfd = (__builtin_expect (flags & GLOB_ALTDIRFUNC, 0)
? -1 : dirfd ((DIR *) stream));
int fnm_flags = ((!(flags & GLOB_PERIOD) ? FNM_PERIOD : 0)
| ((flags & GLOB_NOESCAPE) ? FNM_NOESCAPE : 0));
flags |= GLOB_MAGCHAR;
@ -1535,42 +1476,34 @@ glob_in_dir (const char *pattern, const char *directory, int flags,
if (fnmatch (pattern, d.name, fnm_flags) == 0)
{
/* If the file we found is a symlink we have to
make sure the target file exists. */
dirent_type type = readdir_result_type (d);
if (! (type == DT_LNK || type == DT_UNKNOWN)
|| link_exists_p (dfd, directory, dirlen, d.name,
pglob, flags))
if (cur == names->count)
{
if (cur == names->count)
{
struct globnames *newnames;
size_t count = names->count * 2;
size_t nameoff = offsetof (struct globnames, name);
size_t size = FLEXSIZEOF (struct globnames, name,
count * sizeof (char *));
if ((SIZE_MAX - nameoff) / 2 / sizeof (char *)
< names->count)
goto memory_error;
if (glob_use_alloca (alloca_used, size))
newnames = names_alloca
= alloca_account (size, alloca_used);
else if ((newnames = malloc (size))
== NULL)
goto memory_error;
newnames->count = count;
newnames->next = names;
names = newnames;
cur = 0;
}
names->name[cur] = strdup (d.name);
if (names->name[cur] == NULL)
struct globnames *newnames;
size_t count = names->count * 2;
size_t nameoff = offsetof (struct globnames, name);
size_t size = FLEXSIZEOF (struct globnames, name,
count * sizeof (char *));
if ((SIZE_MAX - nameoff) / 2 / sizeof (char *)
< names->count)
goto memory_error;
++cur;
++nfound;
if (SIZE_MAX - pglob->gl_offs <= nfound)
if (glob_use_alloca (alloca_used, size))
newnames = names_alloca
= alloca_account (size, alloca_used);
else if ((newnames = malloc (size))
== NULL)
goto memory_error;
newnames->count = count;
newnames->next = names;
names = newnames;
cur = 0;
}
names->name[cur] = strdup (d.name);
if (names->name[cur] == NULL)
goto memory_error;
++cur;
++nfound;
if (SIZE_MAX - pglob->gl_offs <= nfound)
goto memory_error;
}
}
}

135
posix/tst-glob_symlinks.c Normal file
View File

@ -0,0 +1,135 @@
/* Test glob danglin symlink match (BZ #866).
Copyright (C) 2017 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/>. */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h>
#include <stddef.h>
#include <glob.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <support/check.h>
#include <support/temp_file.h>
static void do_prepare (int argc, char *argv[]);
#define PREPARE do_prepare
static int do_test (void);
#include <support/test-driver.c>
/* Maximum number of symlink calls for create_link function. */
#define MAX_CREATE_LINK_TRIES 10
static void
create_link (const char *base, const char *fname, char *linkname,
size_t linknamesize)
{
int ntries = 0;
while (1)
{
snprintf (linkname, linknamesize, "%s/%s%02d", test_dir, base,
ntries);
if (symlink (fname, linkname) == 0)
break;
if (errno != EEXIST)
FAIL_EXIT1 ("symlink failed: %m");
if (ntries++ == MAX_CREATE_LINK_TRIES)
FAIL_EXIT1 ("symlink failed with EEXIST too many times");
}
add_temp_file (linkname);
}
static char valid_link[PATH_MAX];
static char dangling_link[PATH_MAX];
static char dangling_dir[PATH_MAX];
static void
do_prepare (int argc, char *argv[])
{
char *fname;
create_temp_file ("tst-glob_symlinks.", &fname);
/* Create an existing symlink. */
create_link ("valid-symlink-tst-glob_symlinks", fname, valid_link,
sizeof valid_link);
/* Create a dangling symlink to a file. */
int fd = create_temp_file ("dangling-tst-glob_file", &fname);
TEST_VERIFY_EXIT (close (fd) == 0);
/* It throws a warning at process end due 'add_temp_file' trying to
unlink it again. */
TEST_VERIFY_EXIT (unlink (fname) == 0);
create_link ("dangling-symlink-file-tst-glob", fname, dangling_link,
sizeof dangling_link);
/* Create a dangling symlink to a directory. */
char tmpdir[PATH_MAX];
snprintf (tmpdir, sizeof tmpdir, "%s/dangling-tst-glob_folder.XXXXXX",
test_dir);
TEST_VERIFY_EXIT (mkdtemp (tmpdir) != NULL);
create_link ("dangling-symlink-dir-tst-glob", tmpdir, dangling_dir,
sizeof dangling_dir);
TEST_VERIFY_EXIT (rmdir (tmpdir) == 0);
}
static int
do_test (void)
{
char buf[PATH_MAX];
glob_t gl;
TEST_VERIFY_EXIT (glob (valid_link, 0, NULL, &gl) == 0);
TEST_VERIFY_EXIT (gl.gl_pathc == 1);
TEST_VERIFY_EXIT (strcmp (gl.gl_pathv[0], valid_link) == 0);
globfree (&gl);
TEST_VERIFY_EXIT (glob (dangling_link, 0, NULL, &gl) == 0);
TEST_VERIFY_EXIT (gl.gl_pathc == 1);
TEST_VERIFY_EXIT (strcmp (gl.gl_pathv[0], dangling_link) == 0);
globfree (&gl);
TEST_VERIFY_EXIT (glob (dangling_dir, 0, NULL, &gl) == 0);
TEST_VERIFY_EXIT (gl.gl_pathc == 1);
TEST_VERIFY_EXIT (strcmp (gl.gl_pathv[0], dangling_dir) == 0);
globfree (&gl);
snprintf (buf, sizeof buf, "%s", dangling_link);
buf[strlen(buf) - 1] = '?';
TEST_VERIFY_EXIT (glob (buf, 0, NULL, &gl) == 0);
TEST_VERIFY_EXIT (gl.gl_pathc == 1);
TEST_VERIFY_EXIT (strcmp (gl.gl_pathv[0], dangling_link) == 0);
globfree (&gl);
/* glob should handle dangling symbol as normal file, so <file>? should
return an empty string. */
snprintf (buf, sizeof buf, "%s?", dangling_link);
TEST_VERIFY_EXIT (glob (buf, 0, NULL, &gl) != 0);
globfree (&gl);
snprintf (buf, sizeof buf, "%s*", dangling_link);
TEST_VERIFY_EXIT (glob (buf, 0, NULL, &gl) == 0);
TEST_VERIFY_EXIT (gl.gl_pathc == 1);
TEST_VERIFY_EXIT (strcmp (gl.gl_pathv[0], dangling_link) == 0);
globfree (&gl);
return 0;
}