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emacs/m4/fstatat.m4
Paul Eggert 8654f9d7d6 Use fdopendir, fstatat and readlinkat, for efficiency.
On my host, this speeds up directory-files-and-attributes by a
factor of 3, when applied to Emacs's src directory.
These functions are standardized by POSIX and are common these
days; fall back on a (slower) gnulib implementation if the host
is too old to supply them.
* .bzrignore: Add lib/dirent.h.
* lib/Makefile.am (libgnu_a_SOURCES): Add openat-die.c, save-cwd.c.
* lib/careadlinkat.c, lib/careadlinkat.h: Merge from gnulib,
incorporating: 2013-01-29 careadlinkat: do not provide careadlinkatcwd.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib/dirent.in.h, lib/fdopendir.c, lib/fstatat.c, lib/openat-priv.h:
* lib/openat-proc.c, lib/openat.h, m4/dirent_h.m4, m4/fdopendir.m4:
* m4/fstatat.m4: New files, from gnulib.
* lib/openat-die.c, lib/save-cwd.c, lib/save-cwd.h: New files.
These last three are specific to Emacs and are not copied from gnulib.
They are simpler than the gnulib versions and are tuned for Emacs.
* admin/merge-gnulib (GNULIB_MODULES): Add fdopendir, fstatat, readlinkat.
(GNULIB_TOOL_FLAGS): Do not avoid at-internal, openat-h.
Avoid dup, open, opendir.
* nt/inc/sys/stat.h (fstatat):
* nt/inc/unistd.h (readlinkat): New decls.
* src/conf_post.h (GNULIB_SUPPORT_ONLY_AT_FDCWD): Remove.
* src/dired.c: Include <fcntl.h>.
(open_directory): New function, which uses open and fdopendir
rather than opendir.  DOS_NT platforms still use opendir, though.
(directory_files_internal, file_name_completion): Use it.
(file_attributes): New function, with most of the old Ffile_attributes.
(directory_files_internal, Ffile_attributes): Use it.
(file_attributes, file_name_completion_stat): First arg is now fd,
not dir name.  All uses changed.  Use fstatat rather than lstat +
stat.
(file_attributes): Use emacs_readlinkat rather than Ffile_symlink_p.
* src/fileio.c: Include <allocator.h>, <careadlinkat.h>.
(emacs_readlinkat): New function, with much of the old
Ffile_symlink_p, but with an fd argument for speed.
It uses readlinkat rather than careadlinkatcwd, so that it
need not assume the working directory.
(Ffile_symlink_p): Use it.
* src/filelock.c (current_lock_owner): Use emacs_readlinkat
rather than emacs_readlink.
* src/lisp.h (emacs_readlinkat): New decl.
(READLINK_BUFSIZE, emacs_readlink): Remove.
* src/sysdep.c: Do not include <allocator.h>, <careadlinkat.h>.
(emacs_norealloc_allocator, emacs_readlink): Remove.
This stuff is moved to fileio.c.
* src/w32.c (fstatat, readlinkat): New functions.
(careadlinkat): Don't check that fd == AT_FDCWD.
(careadlinkatcwd): Remove; no longer needed.

Fixes: debbugs:13539
2013-01-31 22:30:51 -08:00

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# fstatat.m4 serial 3
dnl Copyright (C) 2004-2013 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
# Written by Jim Meyering.
# If we have the fstatat function, and it has the bug (in AIX 7.1)
# that it does not fill in st_size correctly, use the replacement function.
AC_DEFUN([gl_FUNC_FSTATAT],
[
AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CHECK_FUNCS_ONCE([fstatat])
if test $ac_cv_func_fstatat = no; then
HAVE_FSTATAT=0
else
dnl Test for an AIX 7.1 bug; see
dnl <http://lists.gnu.org/archive/html/bug-tar/2011-09/msg00015.html>.
AC_CACHE_CHECK([whether fstatat (..., 0) works],
[gl_cv_func_fstatat_zero_flag],
[AC_RUN_IFELSE(
[AC_LANG_SOURCE(
[[
#include <fcntl.h>
#include <sys/stat.h>
int
main (void)
{
struct stat a;
return fstatat (AT_FDCWD, ".", &a, 0) != 0;
}
]])],
[gl_cv_func_fstatat_zero_flag=yes],
[gl_cv_func_fstatat_zero_flag=no],
[case "$host_os" in
aix*) gl_cv_func_fstatat_zero_flag="guessing no";;
*) gl_cv_func_fstatat_zero_flag="guessing yes";;
esac
])
])
case $gl_cv_func_fstatat_zero_flag+$gl_cv_func_lstat_dereferences_slashed_symlink in
*yes+*yes) ;;
*) REPLACE_FSTATAT=1
case $gl_cv_func_fstatat_zero_flag in
*yes)
AC_DEFINE([HAVE_WORKING_FSTATAT_ZERO_FLAG], [1],
[Define to 1 if fstatat (..., 0) works.
For example, it does not work in AIX 7.1.])
;;
esac
;;
esac
fi
])