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Avoid most stat calls when completing file names

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* admin/merge-gnulib (GNULIB_MODULES): Add d-type.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* m4/d-type.m4: New file, copied from gnulib.
* src/dired.c (DT_UNKNOWN, DT_DIR, DT_LINK)
[!HAVE_STRUCT_DIRENT_D_TYPE]: New constants.
(dirent_type): New function.
(file_name_completion): Use it, to avoid unnecessary calls to
stat-like functions on GNU/Linux and other platforms with d_type.
(file_name_completion_stat): Just follow the link; there is no
need to try first with AT_SYMLINK_NOFOLLOW since the directory
entry was already checked to exist.
This commit is contained in:
Paul Eggert 2017-07-31 12:31:02 -07:00
parent 192342a3a9
commit 3a8d0cc825
5 changed files with 79 additions and 32 deletions
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3
admin/merge-gnulib
View file

@ -30,7 +30,8 @@ GNULIB_MODULES='
careadlinkat close-stream
count-leading-zeros count-one-bits count-trailing-zeros
crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512
diffseq dtoastr dtotimespec dup2 environ execinfo explicit_bzero faccessat
d-type diffseq dtoastr dtotimespec dup2
environ execinfo explicit_bzero faccessat
fcntl fcntl-h fdatasync fdopendir
filemode filevercmp flexmember fstatat fsync
getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog

2
lib/gnulib.mk.in
View file

@ -21,7 +21,7 @@
# the same distribution terms as the rest of that program.
#
# Generated by gnulib-tool.
# Reproduce by: gnulib-tool --import --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=setenv --avoid=sigprocmask --avoid=stat --avoid=stdarg --avoid=stdbool --avoid=threadlib --avoid=tzset --avoid=unsetenv --avoid=utime --avoid=utime-h --gnu-make --makefile-name=gnulib.mk.in --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt binary-io byteswap c-ctype c-strcase careadlinkat close-stream count-leading-zeros count-one-bits count-trailing-zeros crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 diffseq dtoastr dtotimespec dup2 environ execinfo explicit_bzero faccessat fcntl fcntl-h fdatasync fdopendir filemode filevercmp flexmember fstatat fsync getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog ignore-value intprops largefile lstat manywarnings memrchr minmax mkostemp mktime nstrftime pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat sig2str socklen stat-time std-gnu11 stdalign stddef stdio stpcpy strtoimax symlink sys_stat sys_time time time_r time_rz timegm timer-time timespec-add timespec-sub unlocked-io update-copyright utimens vla warnings
# Reproduce by: gnulib-tool --import --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=setenv --avoid=sigprocmask --avoid=stat --avoid=stdarg --avoid=stdbool --avoid=threadlib --avoid=tzset --avoid=unsetenv --avoid=utime --avoid=utime-h --gnu-make --makefile-name=gnulib.mk.in --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt binary-io byteswap c-ctype c-strcase careadlinkat close-stream count-leading-zeros count-one-bits count-trailing-zeros crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 d-type diffseq dtoastr dtotimespec dup2 environ execinfo explicit_bzero faccessat fcntl fcntl-h fdatasync fdopendir filemode filevercmp flexmember fstatat fsync getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog ignore-value intprops largefile lstat manywarnings memrchr minmax mkostemp mktime nstrftime pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat sig2str socklen stat-time std-gnu11 stdalign stddef stdio stpcpy strtoimax symlink sys_stat sys_time time time_r time_rz timegm timer-time timespec-add timespec-sub unlocked-io update-copyright utimens vla warnings
MOSTLYCLEANFILES += core *.stackdump

32
m4/d-type.m4 Normal file
View file

@ -0,0 +1,32 @@
# serial 12
dnl From Jim Meyering.
dnl
dnl Check whether struct dirent has a member named d_type.
dnl
# Copyright (C) 1997, 1999-2004, 2006, 2009-2017 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.
AC_DEFUN([gl_CHECK_TYPE_STRUCT_DIRENT_D_TYPE],
[AC_CACHE_CHECK([for d_type member in directory struct],
[gl_cv_struct_dirent_d_type],
[AC_LINK_IFELSE([AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <dirent.h>
]],
[[struct dirent dp; dp.d_type = 0;]])],
[gl_cv_struct_dirent_d_type=yes],
[gl_cv_struct_dirent_d_type=no])
]
)
if test $gl_cv_struct_dirent_d_type = yes; then
AC_DEFINE([HAVE_STRUCT_DIRENT_D_TYPE], [1],
[Define if there is a member named d_type in the struct describing
directory headers.])
fi
]
)

3
m4/gnulib-comp.m4
View file

@ -61,6 +61,7 @@ AC_DEFUN([gl_EARLY],
# Code from module crypto/sha1:
# Code from module crypto/sha256:
# Code from module crypto/sha512:
# Code from module d-type:
# Code from module diffseq:
# Code from module dirent:
# Code from module dirfd:
@ -199,6 +200,7 @@ AC_DEFUN([gl_INIT],
gl_SHA1
gl_SHA256
gl_SHA512
gl_CHECK_TYPE_STRUCT_DIRENT_D_TYPE
gl_DIRENT_H
AC_REQUIRE([gl_C99_STRTOLD])
gl_FUNC_DUP2
@ -968,6 +970,7 @@ AC_DEFUN([gl_FILE_LIST], [
m4/count-leading-zeros.m4
m4/count-one-bits.m4
m4/count-trailing-zeros.m4
m4/d-type.m4
m4/dirent_h.m4
m4/dirfd.m4
m4/dup2.m4

71
src/dired.c
View file

@ -64,6 +64,21 @@ dirent_namelen (struct dirent *dp)
#endif
}
#ifndef HAVE_STRUCT_DIRENT_D_TYPE
enum { DT_UNKNOWN, DT_DIR, DT_LNK };
#endif
/* Return the file type of DP. */
static int
dirent_type (struct dirent *dp)
{
#ifdef HAVE_STRUCT_DIRENT_D_TYPE
return dp->d_type;
#else
return DT_UNKNOWN;
#endif
}
static DIR *
open_directory (Lisp_Object dirname, int *fdp)
{
@ -434,7 +449,7 @@ is matched against file and directory names relative to DIRECTORY. */)
return file_name_completion (file, directory, 1, Qnil);
}
static int file_name_completion_stat (int, struct dirent *, struct stat *);
static bool file_name_completion_dirp (int, struct dirent *, ptrdiff_t);
static Lisp_Object
file_name_completion (Lisp_Object file, Lisp_Object dirname, bool all_flag,
@ -448,7 +463,6 @@ file_name_completion (Lisp_Object file, Lisp_Object dirname, bool all_flag,
Lisp_Object bestmatch, tem, elt, name;
Lisp_Object encoded_file;
Lisp_Object encoded_dir;
struct stat st;
bool directoryp;
/* If not INCLUDEALL, exclude files in completion-ignored-extensions as
well as "." and "..". Until shown otherwise, assume we can't exclude
@ -512,10 +526,21 @@ file_name_completion (Lisp_Object file, Lisp_Object dirname, bool all_flag,
>= 0))
continue;
if (file_name_completion_stat (fd, dp, &st) < 0)
continue;
switch (dirent_type (dp))
{
case DT_DIR:
directoryp = true;
break;
case DT_LNK: case DT_UNKNOWN:
directoryp = file_name_completion_dirp (fd, dp, len);
break;
default:
directoryp = false;
break;
}
directoryp = S_ISDIR (st.st_mode) != 0;
tem = Qnil;
/* If all_flag is set, always include all.
It would not actually be helpful to the user to ignore any possible
@ -781,32 +806,18 @@ scmp (const char *s1, const char *s2, ptrdiff_t len)
return len - l;
}
static int
file_name_completion_stat (int fd, struct dirent *dp, struct stat *st_addr)
/* Return true if in the directory FD the directory entry DP, whose
string length is LEN, is that of a subdirectory that can be searched. */
static bool
file_name_completion_dirp (int fd, struct dirent *dp, ptrdiff_t len)
{
int value;
#ifdef MSDOS
/* Some fields of struct stat are *very* expensive to compute on MS-DOS,
but aren't required here. Avoid computing the following fields:
st_inode, st_size and st_nlink for directories, and the execute bits
in st_mode for non-directory files with non-standard extensions. */
unsigned short save_djstat_flags = _djstat_flags;
_djstat_flags = _STAT_INODE | _STAT_EXEC_MAGIC | _STAT_DIRSIZE;
#endif /* MSDOS */
/* We want to return success if a link points to a nonexistent file,
but we want to return the status for what the link points to,
in case it is a directory. */
value = fstatat (fd, dp->d_name, st_addr, AT_SYMLINK_NOFOLLOW);
if (value == 0 && S_ISLNK (st_addr->st_mode))
fstatat (fd, dp->d_name, st_addr, 0);
#ifdef MSDOS
_djstat_flags = save_djstat_flags;
#endif /* MSDOS */
return value;
USE_SAFE_ALLOCA;
char *subdir_name = SAFE_ALLOCA (len + 2);
memcpy (subdir_name, dp->d_name, len);
strcpy (subdir_name + len, "/");
bool dirp = faccessat (fd, subdir_name, F_OK, AT_EACCESS) == 0;
SAFE_FREE ();
return dirp;
}
static char *