+2020-02-07 Paul Eggert <eggert@cs.ucla.edu>
+
+ fchmodat: AT_SYMLINK_NOFOLLOW fix for non-symlinks
+ Fix lchmod, and fchmodat with AT_SYMLINK_NOFOLLOW, so that
+ they act like chmod on non-symlinks.
+ * NEWS:
+ * doc/glibc-functions/lchmod.texi (lchmod):
+ * doc/posix-functions/fchmodat.texi (fchmodat):
+ Mention this.
+ * lib/fchmodat.c: Define __need_system_sys_stat_h before including
+ config.h, and undef it after including sys/stat.h the first time.
+ Include fcntl.h, stdio.h, unistd.h, intprops.h, and include
+ sys/stat.h a second time after defining orig_fchmodat.
+ (orig_fchmodat) [HAVE_FCHMODAT]: New function.
+ (fchmodat) [HAVE_FCHMODAT]: Work around the AT_SYMLINK_NOFOLLOW bug.
+ * lib/lchmod.c: New file.
+ * lib/sys_stat.in.h (fchmodat, lchmod):
+ Support replacing these functions.
+ * m4/fchmodat.m4 (gl_FUNC_FCHMODAT): If fchmodat exists,
+ test that AT_SYMLINK_NOFOLLOW works on non-symlinks.
+ * m4/lchmod.m4 (gl_FUNC_LCHMOD): Check for lstat.
+ Test that lchmod works on non-symlinks.
+ * m4/sys_stat_h.m4 (gl_SYS_STAT_H_DEFAULTS):
+ Default REPLACE_FCHMODAT and REPLACE_LCHMOD to 0.
+ * modules/fchmodat (Depends-on): Add fstatat, intprops, lchmod, unistd.
+ (Depends-on, configure.ac): Check REPLACE_FCHMODAT too.
+ * modules/lchmod (Files): Add lib/lchmod.c.
+ (Depends-on): Add errno, fcntl-h, fchmodat, intprops, lstat, unistd.
+ (configure.ac): Compile lchmod.c if needed.
+ (lib_SOURCES): Add lchmod.c.
+ * modules/sys_stat (sys/stat.h): Substitute REPLACE_FCHMODAT
+ and REPLACE_LCHMOD.
+ * tests/test-fchmodat.c: Include fcntl.h, sys/stat.h.
+ (main): Test fchmodat with AT_SYMLINK_NOFOLLOW on non-symlinks.
+
2020-02-05 Marc Dionne <marc.dionne@auristor.com> (tiny change)
mountlist: Consider AFS filesystems as remote
Date Modules Changes
+2020-02-07 fchmodat When applied to non-symlinks, these now act like
+ lchmod chmod (the BSD behavior, which POSIX requires for
+ fchmodat + AT_SYMLINK_NOFOLLOW), instead of failing
+ (the GNU/Linux behavior through glibc 2.31).
+ Future versions of GNU/Linux are planned to act as
+ per POSIX and BSD.
+
2020-01-15 gc-pbkdf2-sha1 This module is deprecated. Use gc-pbkdf2 instead.
2019-12-12 dfa Its API now uses ptrdiff_t instead of size_t.
@item
This function is missing on some platforms:
OpenBSD 3.8, Minix 3.1.8, AIX 5.1, IRIX 6.5, Solaris 11.4, Cygwin, mingw, MSVC 14, Android 9.0.
+@item
+This function always fails with @code{errno} set to @code{ENOSYS},
+even when the file is not a symbolic link:
+GNU/Linux with glibc 2.31.
@end itemize
Portability problems not fixed by Gnulib:
Portability problems fixed by Gnulib:
@itemize
@item
+When given the @code{AT_SYMLINK_NOFOLLOW} flag,
+this function fails with @code{errno} set to @code{ENOTSUP},
+even when the file is not a symbolic link:
+GNU/Linux and Cygwin with glibc 2.31.
+@item
This function is missing on some platforms:
glibc 2.3.6, Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8,
AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 10, Cygwin 1.5.x, mingw, MSVC 14.
@itemize
@item
Some platforms do not allow changing the access bits on symbolic
-links. POSIX states that @code{fchmodat(@dots{},AT_SYMLINK_NOFOLLOW)}
-may fail with @code{EOPNOTSUPP} when called on a symlink, but some
-platforms, as well as the gnulib replacement, fail for any use of
-AT_SYMLINK_NOFOLLOW even if the target was not a symlink:
-glibc, Cygwin.
+links.
@end itemize
/* written by Jim Meyering */
+/* If the user's config.h happens to include <sys/stat.h>, let it include only
+ the system's <sys/stat.h> here, so that orig_fchmodat doesn't recurse to
+ rpl_fchmodat. */
+#define __need_system_sys_stat_h
#include <config.h>
/* Specification. */
#include <sys/stat.h>
+#undef __need_system_sys_stat_h
#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
#include <stdlib.h>
+#include <unistd.h>
-#ifndef HAVE_LCHMOD
-/* Use a different name, to avoid conflicting with any
- system-supplied declaration. */
-# undef lchmod
-# define lchmod lchmod_rpl
+#if HAVE_FCHMODAT
static int
-lchmod (char const *f _GL_UNUSED, mode_t m _GL_UNUSED)
+orig_fchmodat (int dir, char const *file, mode_t mode, int flags)
{
- errno = ENOSYS;
- return -1;
+ return fchmodat (dir, file, mode, flags);
}
#endif
-/* Solaris 10 has no function like this.
- Invoke chmod or lchmod on file, FILE, using mode MODE, in the directory
+#ifdef __osf__
+/* Write "sys/stat.h" here, not <sys/stat.h>, otherwise OSF/1 5.1 DTK cc
+ eliminates this include because of the preliminary #include <sys/stat.h>
+ above. */
+# include "sys/stat.h"
+#else
+# include <sys/stat.h>
+#endif
+
+#include <intprops.h>
+
+/* Invoke chmod or lchmod on FILE, using mode MODE, in the directory
open on descriptor FD. If possible, do it without changing the
working directory. Otherwise, resort to using save_cwd/fchdir,
then (chmod|lchmod)/restore_cwd. If either the save_cwd or the
Note that an attempt to use a FLAG value of AT_SYMLINK_NOFOLLOW
on a system without lchmod support causes this function to fail. */
-#define AT_FUNC_NAME fchmodat
-#define AT_FUNC_F1 lchmod
-#define AT_FUNC_F2 chmod
-#define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
-#define AT_FUNC_POST_FILE_PARAM_DECLS , mode_t mode, int flag
-#define AT_FUNC_POST_FILE_ARGS , mode
-#include "at-func.c"
+#if HAVE_FCHMODAT
+int
+fchmodat (int dir, char const *file, mode_t mode, int flags)
+{
+ if (flags & AT_SYMLINK_NOFOLLOW)
+ {
+# ifdef O_PATH
+ int fd = openat (dir, file, O_PATH | O_NOFOLLOW | O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+ static char const fmt[] = "/proc/self/fd/%d";
+ char buf[sizeof fmt - sizeof "%d" + INT_BUFSIZE_BOUND (int)];
+ sprintf (buf, fmt, fd);
+ int chmod_result = chmod (buf, mode);
+ int chmod_errno = errno;
+ close (fd);
+ if (chmod_result == 0)
+ return chmod_result;
+ if (chmod_errno != ENOENT)
+ {
+ errno = chmod_errno;
+ return chmod_result;
+ }
+ /* /proc is not mounted; fall back on racy implementation. */
+# endif
+
+ struct stat st;
+ int fstatat_result = fstatat (dir, file, &st, AT_SYMLINK_NOFOLLOW);
+ if (fstatat_result != 0)
+ return fstatat_result;
+ if (S_ISLNK (st.st_mode))
+ {
+ errno = EOPNOTSUPP;
+ return -1;
+ }
+ flags &= ~AT_SYMLINK_NOFOLLOW;
+ }
+
+ return orig_fchmodat (dir, file, mode, flags);
+}
+#else
+# define AT_FUNC_NAME fchmodat
+# define AT_FUNC_F1 lchmod
+# define AT_FUNC_F2 chmod
+# define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
+# define AT_FUNC_POST_FILE_PARAM_DECLS , mode_t mode, int flag
+# define AT_FUNC_POST_FILE_ARGS , mode
+# include "at-func.c"
+#endif
--- /dev/null
+/* Implement lchmod on platforms where it does not work correctly.
+
+ Copyright 2020 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ 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.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* written by Paul Eggert */
+
+#include <config.h>
+
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <intprops.h>
+
+/* Work like lchmod, except when FILE is a symbolic link.
+ In that case, set errno to EOPNOTSUPP and return -1. */
+
+int
+lchmod (char const *file, mode_t mode)
+{
+#if HAVE_FCHMODAT
+ return fchmodat (AT_FDCWD, file, mode, AT_SYMLINK_NOFOLLOW);
+#elif defined O_PATH && defined AT_FDCWD
+ int fd = openat (AT_FDCWD, file, O_PATH | O_NOFOLLOW | O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+ static char const fmt[] = "/proc/self/fd/%d";
+ char buf[sizeof fmt - sizeof "%d" + INT_BUFSIZE_BOUND (int)];
+ sprintf (buf, fmt, fd);
+ int chmod_result = chmod (buf, mode);
+ int chmod_errno = errno;
+ close (fd);
+ if (chmod_result == 0)
+ return chmod_result;
+ if (chmod_errno != ENOENT)
+ {
+ errno = chmod_errno;
+ return chmod_result;
+ }
+ /* /proc is not mounted; fall back on racy implementation. */
+#endif
+
+#if HAVE_LSTAT
+ struct stat st;
+ int lstat_result = lstat (file, &st);
+ if (lstat_result != 0)
+ return lstat_result;
+ if (S_ISLNK (st.st_mode))
+ {
+ errno = EOPNOTSUPP;
+ return -1;
+ }
+#endif
+
+ return chmod (file, mode);
+}
#if @GNULIB_FCHMODAT@
-# if !@HAVE_FCHMODAT@
+# if @REPLACE_FCHMODAT@
+# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+# undef fchmodat
+# define fchmodat rpl_fchmodat
+# endif
+_GL_FUNCDECL_RPL (fchmodat, int,
+ (int fd, char const *file, mode_t mode, int flag)
+ _GL_ARG_NONNULL ((2)));
+_GL_CXXALIAS_RPL (fchmodat, int,
+ (int fd, char const *file, mode_t mode, int flag));
+# else
+# if !@HAVE_FCHMODAT@
_GL_FUNCDECL_SYS (fchmodat, int,
(int fd, char const *file, mode_t mode, int flag)
_GL_ARG_NONNULL ((2)));
-# endif
+# endif
_GL_CXXALIAS_SYS (fchmodat, int,
(int fd, char const *file, mode_t mode, int flag));
+# endif
_GL_CXXALIASWARN (fchmodat);
#elif defined GNULIB_POSIXCHECK
# undef fchmodat
#if @GNULIB_LCHMOD@
/* Change the mode of FILENAME to MODE, without dereferencing it if FILENAME
denotes a symbolic link. */
-# if !@HAVE_LCHMOD@
-/* The lchmod replacement follows symbolic links. Callers should take
- this into account; lchmod should be applied only to arguments that
- are known to not be symbolic links. On hosts that lack lchmod,
- this can lead to race conditions between the check and the
- invocation of lchmod, but we know of no workarounds that are
- reliable in general. You might try requesting support for lchmod
- from your operating system supplier. */
+# if @REPLACE_LCHMOD@
# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
-# define lchmod chmod
+# undef lchmod
+# define lchmod rpl_lchmod
# endif
-/* Need to cast, because on mingw, the second parameter of chmod is
- int mode. */
-_GL_CXXALIAS_RPL_CAST_1 (lchmod, chmod, int,
- (const char *filename, mode_t mode));
+_GL_FUNCDECL_RPL (lchmod, int,
+ (char const *filename, mode_t mode)
+ _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (lchmod, int,
+ (char const *filename, mode_t mode));
# else
-# if 0 /* assume already declared */
+# if !@HAVE_LCHMOD@
_GL_FUNCDECL_SYS (lchmod, int, (const char *filename, mode_t mode)
_GL_ARG_NONNULL ((1)));
# endif
_GL_CXXALIAS_SYS (lchmod, int, (const char *filename, mode_t mode));
# endif
-# if @HAVE_LCHMOD@
_GL_CXXALIASWARN (lchmod);
-# endif
#elif defined GNULIB_POSIXCHECK
# undef lchmod
# if HAVE_RAW_DECL_LCHMOD
-# fchmodat.m4 serial 1
+# fchmodat.m4 serial 2
dnl Copyright (C) 2004-2020 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
AC_CHECK_FUNCS_ONCE([fchmodat lchmod])
if test $ac_cv_func_fchmodat != yes; then
HAVE_FCHMODAT=0
+ else
+ AC_CACHE_CHECK(
+ [whether fchmodat+AT_SYMLINK_NOFOLLOW works on non-symlinks],
+ [gl_cv_func_fchmodat_works],
+ [AC_RUN_IFELSE(
+ [AC_LANG_PROGRAM(
+ [
+ AC_INCLUDES_DEFAULT[
+ #include <fcntl.h>
+ #ifndef S_IRUSR
+ #define S_IRUSR 0400
+ #endif
+ #ifndef S_IWUSR
+ #define S_IWUSR 0200
+ #endif
+ #ifndef S_IRWXU
+ #define S_IRWXU 0700
+ #endif
+ #ifndef S_IRWXG
+ #define S_IRWXG 0070
+ #endif
+ #ifndef S_IRWXO
+ #define S_IRWXO 0007
+ #endif
+ ]],
+ [[
+ int permissive = S_IRWXU | S_IRWXG | S_IRWXO;
+ int desired = S_IRUSR | S_IWUSR;
+ static char const f[] = "conftest.fchmodat";
+ struct stat st;
+ if (creat (f, permissive) < 0)
+ return 1;
+ if (fchmodat (AT_FDCWD, f, desired, AT_SYMLINK_NOFOLLOW) != 0)
+ return 1;
+ if (stat (f, &st) != 0)
+ return 1;
+ return ! ((st.st_mode & permissive) == desired);
+ ]])],
+ [gl_cv_func_fchmodat_works=yes],
+ [gl_cv_func_fchmodat_works=no],
+ [gl_cv_func_fchmodat_works=$gl_cross_guess_normal])
+ rm -f conftest.fchmodat])
+ case $gl_cv_func_fchmodat_works in
+ *yes) ;;
+ *) REPLACE_FCHMODAT=1;;
+ esac
fi
])
-#serial 3
+#serial 4
dnl Copyright (C) 2005-2006, 2008-2020 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl with or without modifications, as long as this notice is preserved.
dnl From Paul Eggert.
-dnl Provide a replacement for lchmod on hosts that lack it.
+dnl Provide a replacement for lchmod on hosts that lack a working version.
AC_DEFUN([gl_FUNC_LCHMOD],
[
dnl Persuade glibc <sys/stat.h> to declare lchmod().
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
- AC_CHECK_FUNCS_ONCE([lchmod])
- if test $ac_cv_func_lchmod = no; then
+ AC_CHECK_FUNCS_ONCE([fchmodat lchmod lstat])
+ if test "$ac_cv_func_lchmod" = no; then
HAVE_LCHMOD=0
+ else
+ AC_CACHE_CHECK([whether lchmod works on non-symlinks],
+ [gl_cv_func_lchmod_works],
+ [AC_RUN_IFELSE(
+ [AC_LANG_PROGRAM(
+ [
+ AC_INCLUDES_DEFAULT[
+ #ifndef S_IRUSR
+ #define S_IRUSR 0400
+ #endif
+ #ifndef S_IWUSR
+ #define S_IWUSR 0200
+ #endif
+ #ifndef S_IRWXU
+ #define S_IRWXU 0700
+ #endif
+ #ifndef S_IRWXG
+ #define S_IRWXG 0070
+ #endif
+ #ifndef S_IRWXO
+ #define S_IRWXO 0007
+ #endif
+ ]],
+ [[
+ int permissive = S_IRWXU | S_IRWXG | S_IRWXO;
+ int desired = S_IRUSR | S_IWUSR;
+ static char const f[] = "conftest.lchmod";
+ struct stat st;
+ if (creat (f, permissive) < 0)
+ return 1;
+ if (lchmod (f, desired) != 0)
+ return 1;
+ if (stat (f, &st) != 0)
+ return 1;
+ return ! ((st.st_mode & permissive) == desired);
+ ]])],
+ [gl_cv_func_lchmod_works=yes],
+ [gl_cv_func_lchmod_works=no],
+ [gl_cv_func_lchmod_works=$gl_cross_guess_normal])
+ rm -f conftest.lchmod])
+ case $gl_cv_func_lchmod_works in
+ *yes) ;;
+ *) REPLACE_LCHMOD=1;;
+ esac
fi
])
-# sys_stat_h.m4 serial 31 -*- Autoconf -*-
+# sys_stat_h.m4 serial 32 -*- Autoconf -*-
dnl Copyright (C) 2006-2020 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
HAVE_MKNOD=1; AC_SUBST([HAVE_MKNOD])
HAVE_MKNODAT=1; AC_SUBST([HAVE_MKNODAT])
HAVE_UTIMENSAT=1; AC_SUBST([HAVE_UTIMENSAT])
+ REPLACE_FCHMODAT=0; AC_SUBST([REPLACE_FCHMODAT])
REPLACE_FSTAT=0; AC_SUBST([REPLACE_FSTAT])
REPLACE_FSTATAT=0; AC_SUBST([REPLACE_FSTATAT])
REPLACE_FUTIMENS=0; AC_SUBST([REPLACE_FUTIMENS])
+ REPLACE_LCHMOD=0; AC_SUBST([REPLACE_LCHMOD])
REPLACE_LSTAT=0; AC_SUBST([REPLACE_LSTAT])
REPLACE_MKDIR=0; AC_SUBST([REPLACE_MKDIR])
REPLACE_MKFIFO=0; AC_SUBST([REPLACE_MKFIFO])
extensions
at-internal [test $HAVE_FCHMODAT = 0]
dosname [test $HAVE_FCHMODAT = 0]
-errno [test $HAVE_FCHMODAT = 0]
+errno [test $HAVE_FCHMODAT = 0 || test $REPLACE_FCHMODAT = 1]
extern-inline [test $HAVE_FCHMODAT = 0]
fchdir [test $HAVE_FCHMODAT = 0]
-fcntl-h [test $HAVE_FCHMODAT = 0]
+fcntl-h [test $HAVE_FCHMODAT = 0 || test $REPLACE_FCHMODAT = 1]
+fstatat [test $REPLACE_FCHMODAT = 1]
+intprops [test $HAVE_FCHMODAT = 0 || test $REPLACE_FCHMODAT = 1]
+lchmod [test $HAVE_FCHMODAT = 0]
openat-die [test $HAVE_FCHMODAT = 0]
openat-h [test $HAVE_FCHMODAT = 0]
save-cwd [test $HAVE_FCHMODAT = 0]
+unistd [test $HAVE_FCHMODAT = 0 || test $REPLACE_FCHMODAT = 1]
configure.ac:
gl_FUNC_FCHMODAT
-if test $HAVE_FCHMODAT = 0; then
+if test $HAVE_FCHMODAT = 0 || test $REPLACE_FCHMODAT = 1; then
AC_LIBOBJ([fchmodat])
fi
gl_MODULE_INDICATOR([fchmodat]) dnl for lib/openat.h
lchmod that is actually chmod (!) on hosts lacking lchmod
Files:
+lib/lchmod.c
m4/lchmod.m4
Depends-on:
-sys_stat
+errno [test $HAVE_LCHMOD = 0 || test $REPLACE_LCHMOD = 1]
extensions
+fcntl-h [test $HAVE_LCHMOD = 0 || test $REPLACE_LCHMOD = 1]
+fchmodat [test $HAVE_LCHMOD = 0 || test $REPLACE_LCHMOD = 1]
+intprops [test $HAVE_LCHMOD = 0 || test $REPLACE_LCHMOD = 1]
+lstat [test $HAVE_LCHMOD = 0 || test $REPLACE_LCHMOD = 1]
+sys_stat
+unistd [test $HAVE_LCHMOD = 0 || test $REPLACE_LCHMOD = 1]
configure.ac:
gl_FUNC_LCHMOD
+if test $HAVE_LCHMOD = 0 || test $REPLACE_LCHMOD = 1; then
+ AC_LIBOBJ([lchmod])
+fi
gl_SYS_STAT_MODULE_INDICATOR([lchmod])
Makefile.am:
+lib_SOURCES += lchmod.c
Include:
<sys/stat.h>
-e 's|@''HAVE_MKNOD''@|$(HAVE_MKNOD)|g' \
-e 's|@''HAVE_MKNODAT''@|$(HAVE_MKNODAT)|g' \
-e 's|@''HAVE_UTIMENSAT''@|$(HAVE_UTIMENSAT)|g' \
+ -e 's|@''REPLACE_FCHMODAT''@|$(REPLACE_FCHMODAT)|g' \
-e 's|@''REPLACE_FSTAT''@|$(REPLACE_FSTAT)|g' \
-e 's|@''REPLACE_FSTATAT''@|$(REPLACE_FSTATAT)|g' \
-e 's|@''REPLACE_FUTIMENS''@|$(REPLACE_FUTIMENS)|g' \
+ -e 's|@''REPLACE_LCHMOD''@|$(REPLACE_LCHMOD)|g' \
-e 's|@''REPLACE_LSTAT''@|$(REPLACE_LSTAT)|g' \
-e 's|@''REPLACE_MKDIR''@|$(REPLACE_MKDIR)|g' \
-e 's|@''REPLACE_MKFIFO''@|$(REPLACE_MKFIFO)|g' \
SIGNATURE_CHECK (fchmodat, int, (int, const char *, mode_t, int));
#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
#include <unistd.h>
#include "macros.h"
ASSERT (errno == EBADF);
}
+ /* Test that fchmodat works on non-symlinks, when given
+ the AT_SYMLINK_NOFOLLOW flag. */
+ {
+ ASSERT (close (creat ("file", 0600)) == 0);
+ ASSERT (fchmodat (AT_FDCWD, "file", 0700, AT_SYMLINK_NOFOLLOW) == 0);
+ ASSERT (unlink ("file") == 0);
+ }
+
return 0;
}