1
0
mirror of https://git.savannah.gnu.org/git/emacs.git synced 2024-12-12 09:28:24 +00:00
emacs/m4/getgroups.m4

108 lines
3.6 KiB
Plaintext
Raw Normal View History

Use faccessat, not access, when checking file permissions. This fixes a bug that has been present in Emacs since its creation. It was reported by Chris Torek in 1983 even before GNU Emacs existed, which must set some sort of record. (Torek's bug report was against a predecessor of GNU Emacs, but GNU Emacs happened to have the same common flaw.) See Torek's Usenet posting "setuid/setgid programs & Emacs" Article-I.D.: sri-arpa.858 Posted: Fri Apr 8 14:18:56 1983. * .bzrignore: Add lib/fcntl.h. * configure.ac (euidaccess): Remove check; gnulib does this for us now. (gl_FCNTL_O_FLAGS): Define a dummy version. * lib/at-func.c, lib/euidaccess.c, lib/faccessat.c, lib/fcntl.in.h: * lib/getgroups.c, lib/group-member.c, lib/root-uid.h: * lib/xalloc-oversized.h, m4/euidaccess.m4, m4/faccessat.m4: * m4/fcntl_h.m4, m4/getgroups.m4, m4/group-member.m4: New files, from gnulib. * lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate. * admin/merge-gnulib (GNULIB_MODULES): Add faccessat. (GNULIB_TOOL_FLAGS): Avoid at-internal, fchdir, malloc-posix, openat-die, openat-h, save-cwd. Do not avoid fcntl-h. Omit gnulib's m4/fcntl-o.m4. * nt/inc/ms-w32.h (AT_FDCWD, AT_EACCESS): New symbols. (access): Remove. (faccessat): New macro. * src/Makefile.in (LIB_EACCESS): New macro. (LIBES): Use it. * src/callproc.c (init_callproc): * src/charset.c (init_charset): * src/fileio.c (check_existing, check_executable, check_writable) (Ffile_readable_p): * src/lread.c (openp, load_path_check): * src/process.c (allocate_pty): * src/xrdb.c (file_p): Use effective UID when checking permissions, not real UID. * src/callproc.c (init_callproc): * src/charset.c (init_charset): * src/lread.c (load_path_check, init_lread): Test whether directories are accessible, not merely whether they exist. * src/conf_post.h (GNULIB_SUPPORT_ONLY_AT_FDCWD): New macro. * src/fileio.c (check_existing, check_executable, check_writable) (Ffile_readable_p): Use symbolic names instead of integers for the flags, as they're portable now. (check_writable): New arg AMODE. All uses changed. Set errno on failure. (Ffile_readable_p): Use faccessat, not stat + open + close. (Ffile_writable_p): No need to call check_existing + check_writable. Just call check_writable and then look at errno. This saves a syscall. dir should never be nil; replace an unnecessary runtime check with an eassert. When checking the parent directory of a nonexistent file, check that the directory is searchable as well as writable, as we can't create files in unsearchable directories. (file_directory_p): New function, which uses 'stat' on most platforms but faccessat with D_OK (for efficiency) if WINDOWSNT. (Ffile_directory_p, Fset_file_times): Use it. (file_accessible_directory_p): New function, which uses a single syscall for efficiency. (Ffile_accessible_directory_p): Use it. * src/xrdb.c (file_p): Use file_directory_p. * src/lisp.h (file_directory_p, file_accessible_directory_p): New decls. * src/lread.c (openp): When opening a file, use fstat rather than stat, as that avoids a permissions race. When not opening a file, use file_directory_p rather than stat. (dir_warning): First arg is now a usage string, not a format. Use errno. All uses changed. * src/nsterm.m (ns_term_init): Remove unnecessary call to file-readable that merely introduced a race. * src/process.c, src/sysdep.c, src/term.c: All uses of '#ifdef O_NONBLOCK' changed to '#if O_NONBLOCK', to accommodate gnulib O_* style, and similarly for the other O_* flags. * src/w32.c (sys_faccessat): Rename from sys_access and switch to faccessat's API. All uses changed. * src/xrdb.c: Do not include <sys/stat.h>; no longer needed. (magic_db): Rename from magic_file_p. (magic_db, search_magic_path): Return an XrmDatabase rather than a char *, so that we don't have to test for file existence separately from opening the file for reading. This removes a race fixes a permission-checking problem, and simplifies the code. All uses changed. (file_p): Remove; no longer needed. Fixes: debbugs:12632
2012-11-14 04:55:41 +00:00
# serial 18
dnl From Jim Meyering.
dnl A wrapper around AC_FUNC_GETGROUPS.
# Copyright (C) 1996-1997, 1999-2004, 2008-2012 Free Software Foundation, Inc.
#
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.
m4_version_prereq([2.70], [] ,[
# This is taken from the following Autoconf patch:
# http://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9
AC_DEFUN([AC_FUNC_GETGROUPS],
[
AC_REQUIRE([AC_TYPE_GETGROUPS])dnl
AC_REQUIRE([AC_TYPE_SIZE_T])dnl
AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
AC_CHECK_FUNC([getgroups])
# If we don't yet have getgroups, see if it's in -lbsd.
# This is reported to be necessary on an ITOS 3000WS running SEIUX 3.1.
ac_save_LIBS=$LIBS
if test $ac_cv_func_getgroups = no; then
AC_CHECK_LIB(bsd, getgroups, [GETGROUPS_LIB=-lbsd])
fi
# Run the program to test the functionality of the system-supplied
# getgroups function only if there is such a function.
if test $ac_cv_func_getgroups = yes; then
AC_CACHE_CHECK([for working getgroups], [ac_cv_func_getgroups_works],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[AC_INCLUDES_DEFAULT],
[[/* On Ultrix 4.3, getgroups (0, 0) always fails. */
return getgroups (0, 0) == -1;]])
],
[ac_cv_func_getgroups_works=yes],
[ac_cv_func_getgroups_works=no],
[case "$host_os" in # ((
# Guess yes on glibc systems.
*-gnu*) ac_cv_func_getgroups_works="guessing yes" ;;
# If we don't know, assume the worst.
*) ac_cv_func_getgroups_works="guessing no" ;;
esac
])
])
else
ac_cv_func_getgroups_works=no
fi
case "$ac_cv_func_getgroups_works" in
*yes)
AC_DEFINE([HAVE_GETGROUPS], [1],
[Define to 1 if your system has a working `getgroups' function.])
;;
esac
LIBS=$ac_save_LIBS
])# AC_FUNC_GETGROUPS
])
AC_DEFUN([gl_FUNC_GETGROUPS],
[
AC_REQUIRE([AC_TYPE_GETGROUPS])
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_FUNC_GETGROUPS
if test $ac_cv_func_getgroups != yes; then
HAVE_GETGROUPS=0
else
if test "$ac_cv_type_getgroups" != gid_t \
|| { case "$ac_cv_func_getgroups_works" in
*yes) false;;
*) true;;
esac
}; then
REPLACE_GETGROUPS=1
AC_DEFINE([GETGROUPS_ZERO_BUG], [1], [Define this to 1 if
getgroups(0,NULL) does not return the number of groups.])
else
dnl Detect FreeBSD bug; POSIX requires getgroups(-1,ptr) to fail.
AC_CACHE_CHECK([whether getgroups handles negative values],
[gl_cv_func_getgroups_works],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
[[int size = getgroups (0, 0);
gid_t *list = malloc (size * sizeof *list);
return getgroups (-1, list) != -1;]])],
[gl_cv_func_getgroups_works=yes],
[gl_cv_func_getgroups_works=no],
[case "$host_os" in
# Guess yes on glibc systems.
*-gnu*) gl_cv_func_getgroups_works="guessing yes" ;;
# If we don't know, assume the worst.
*) gl_cv_func_getgroups_works="guessing no" ;;
esac
])])
case "$gl_cv_func_getgroups_works" in
*yes) ;;
*) REPLACE_GETGROUPS=1 ;;
esac
fi
fi
test -n "$GETGROUPS_LIB" && LIBS="$GETGROUPS_LIB $LIBS"
])