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8654f9d7d6
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
111 lines
3.7 KiB
C
111 lines
3.7 KiB
C
/* Create /proc/self/fd-related names for subfiles of open directories.
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Copyright (C) 2006, 2009-2013 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Written by Paul Eggert. */
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#include <config.h>
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#include "openat-priv.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "intprops.h"
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/* The results of open() in this file are not used with fchdir,
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and we do not leak fds to any single-threaded code that could use stdio,
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therefore save some unnecessary work in fchdir.c.
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FIXME - if the kernel ever adds support for multi-thread safety for
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avoiding standard fds, then we should use open_safer. */
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#undef open
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#undef close
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#define PROC_SELF_FD_FORMAT "/proc/self/fd/%d/%s"
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#define PROC_SELF_FD_NAME_SIZE_BOUND(len) \
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(sizeof PROC_SELF_FD_FORMAT - sizeof "%d%s" \
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+ INT_STRLEN_BOUND (int) + (len) + 1)
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/* Set BUF to the expansion of PROC_SELF_FD_FORMAT, using FD and FILE
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respectively for %d and %s. If successful, return BUF if the
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result fits in BUF, dynamically allocated memory otherwise. But
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return NULL if /proc is not reliable, either because the operating
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system support is lacking or because memory is low. */
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char *
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openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file)
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{
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static int proc_status = 0;
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/* Make sure the caller gets ENOENT when appropriate. */
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if (!*file)
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{
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buf[0] = '\0';
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return buf;
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}
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if (! proc_status)
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{
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/* Set PROC_STATUS to a positive value if /proc/self/fd is
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reliable, and a negative value otherwise. Solaris 10
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/proc/self/fd mishandles "..", and any file name might expand
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to ".." after symbolic link expansion, so avoid /proc/self/fd
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if it mishandles "..". Solaris 10 has openat, but this
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problem is exhibited on code that built on Solaris 8 and
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running on Solaris 10. */
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int proc_self_fd = open ("/proc/self/fd",
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O_SEARCH | O_DIRECTORY | O_NOCTTY | O_NONBLOCK);
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if (proc_self_fd < 0)
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proc_status = -1;
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else
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{
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/* Detect whether /proc/self/fd/%i/../fd exists, where %i is the
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number of a file descriptor open on /proc/self/fd. On Linux,
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that name resolves to /proc/self/fd, which was opened above.
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However, on Solaris, it may resolve to /proc/self/fd/fd, which
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cannot exist, since all names in /proc/self/fd are numeric. */
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char dotdot_buf[PROC_SELF_FD_NAME_SIZE_BOUND (sizeof "../fd" - 1)];
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sprintf (dotdot_buf, PROC_SELF_FD_FORMAT, proc_self_fd, "../fd");
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proc_status = access (dotdot_buf, F_OK) ? -1 : 1;
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close (proc_self_fd);
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}
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}
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if (proc_status < 0)
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return NULL;
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else
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{
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size_t bufsize = PROC_SELF_FD_NAME_SIZE_BOUND (strlen (file));
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char *result = buf;
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if (OPENAT_BUFFER_SIZE < bufsize)
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{
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result = malloc (bufsize);
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if (! result)
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return NULL;
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}
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sprintf (result, PROC_SELF_FD_FORMAT, fd, file);
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return result;
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}
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}
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