qiurui
/
glibc
mirror of git://sourceware.org/git/glibc.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Remove eloop-threshold.h 

On both Linux and Hurd the __eloop_threshold() is always a constant
(40 and 32 respectively), so there is no need to always call
__sysconf (_SC_SYMLOOP_MAX) for Linux case (!SYMLOOP_MAX).  To avoid
a name clash with gnulib, rename the new file min-eloop-threshold.h.

Checked on x86_64-linux-gnu and with a build for x86_64-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
This commit is contained in:
Adhemerval Zanella 2025-03-04 15:13:41 -03:00
parent 855561a1fb
commit 1894e219dc
8 changed files with 60 additions and 93 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
elf/chroot_canon.c
View File

@ -23,8 +23,7 @@
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <eloop-threshold.h>
#include <min-eloop-threshold.h>
#include <ldconfig.h>
#ifndef PATH_MAX
@ -126,7 +125,7 @@ chroot_canon (const char *chroot, const char *name)
char *buf = alloca (PATH_MAX);
size_t len;
if (++num_links > __eloop_threshold ())
if (++num_links > MIN_ELOOP_THRESHOLD)
{
__set_errno (ELOOP);
goto error;

6
hurd/lookup-retry.c
View File

@ -24,7 +24,7 @@
#include <fcntl.h>
#include <string.h>
#include <_itoa.h>
#include <eloop-threshold.h>
#include <min-eloop-threshold.h>
#include <unistd.h>
/* Translate the error from dir_lookup into the error the user sees. */
@ -113,7 +113,7 @@ __hurd_file_name_lookup_retry (error_t (*use_init_port)
/* Fall through. */
case FS_RETRY_NORMAL:
if (nloops++ >= __eloop_threshold ())
if (nloops++ >= MIN_ELOOP_THRESHOLD)
{
__mach_port_deallocate (__mach_task_self (), *result);
err = ELOOP;
@ -207,7 +207,7 @@ __hurd_file_name_lookup_retry (error_t (*use_init_port)
dirport = INIT_PORT_CRDIR;
if (*result != MACH_PORT_NULL)
__mach_port_deallocate (__mach_task_self (), *result);
if (nloops++ >= __eloop_threshold ())
if (nloops++ >= MIN_ELOOP_THRESHOLD)
{
err = ELOOP;
goto out;

6
stdlib/canonicalize.c
View File

@ -36,17 +36,19 @@
#include <sys/stat.h>
#include <unistd.h>
#include <eloop-threshold.h>
#include <filename.h>
#include <idx.h>
#include <intprops.h>
#include <scratch_buffer.h>
#ifdef _LIBC
# include <min-eloop-threshold.h>
# include <shlib-compat.h>
# define GCC_LINT 1
# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
#else
# include <eloop-threshold.h>
# define MIN_ELOOP_THRESHOLD __eloop_threshold ()
# define __canonicalize_file_name canonicalize_file_name
# define __realpath realpath
# define __strdup strdup
@ -310,7 +312,7 @@ realpath_stk (const char *name, char *resolved, struct realpath_bufs *bufs)
}
if (0 <= n)
{
if (++num_links > __eloop_threshold ())
if (++num_links > MIN_ELOOP_THRESHOLD)
{
__set_errno (ELOOP);
goto error;

4
stdlib/tst-canon-bz26341.c
View File

@ -23,7 +23,7 @@
#include <unistd.h>
#define __sysconf sysconf
#include <eloop-threshold.h>
#include <min-eloop-threshold.h>
#include <support/check.h>
#include <support/support.h>
#include <support/temp_file.h>
@ -54,7 +54,7 @@ create_link (void)
/* Create MAXLINKS symbolic links to the temporary filename.
On exit, linkname has the last link created. */
char *prevlink = filename;
int maxlinks = __eloop_threshold ();
int maxlinks = MIN_ELOOP_THRESHOLD;
for (int i = 0; i < maxlinks; i++)
{
linkname = xasprintf ("%s%d", filename, i);

72
sysdeps/generic/eloop-threshold.h
View File

@ -1,72 +0,0 @@
/* Threshold at which to diagnose ELOOP. Generic version.
Copyright (C) 2012-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _ELOOP_THRESHOLD_H
#define _ELOOP_THRESHOLD_H 1
#include <limits.h>
#include <sys/param.h>
/* POSIX specifies SYMLOOP_MAX as the "Maximum number of symbolic
links that can be reliably traversed in the resolution of a
pathname in the absence of a loop." This makes it a minimum that
we should certainly accept. But it leaves open the possibility
that more might sometimes work--just not "reliably".
For example, Linux implements a complex policy whereby there is a
small limit on the number of direct symlink traversals (a symlink
to a symlink to a symlink), but larger limit on the total number of
symlink traversals overall. Hence the SYMLOOP_MAX number should be
the small one, but the limit library functions enforce on users
should be the larger one.
So, we use the larger of the reported SYMLOOP_MAX (if any) and our
own constant MIN_ELOOP_THRESHOLD, below. This constant should be
large enough that it never rules out a file name and directory tree
that the underlying system (i.e. calls to 'open' et al) would
resolve successfully. It should be small enough that actual loops
are detected without a huge number of iterations. */
#ifndef MIN_ELOOP_THRESHOLD
# define MIN_ELOOP_THRESHOLD 40
#endif
/* Return the maximum number of symlink traversals to permit
before diagnosing ELOOP. */
static inline unsigned int __attribute__ ((const))
__eloop_threshold (void)
{
#ifdef SYMLOOP_MAX
const int symloop_max = SYMLOOP_MAX;
#else
/* The function is marked 'const' even though we use memory and
call a function, because sysconf is required to return the
same value in every call and so it must always be safe to
call __eloop_threshold exactly once and reuse the value. */
static long int sysconf_symloop_max;
if (sysconf_symloop_max == 0)
sysconf_symloop_max = __sysconf (_SC_SYMLOOP_MAX);
const unsigned int symloop_max = (sysconf_symloop_max <= 0
? _POSIX_SYMLOOP_MAX
: sysconf_symloop_max);
#endif
return MAX (symloop_max, MIN_ELOOP_THRESHOLD);
}
#endif /* eloop-threshold.h */

42
sysdeps/generic/min-eloop-threshold.h Normal file
View File

@ -0,0 +1,42 @@
/* Minimum threshold at which to diagnose ELOOP. Generic version.
Copyright (C) 2012-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _MIN_ELOOP_THRESHOLD_H
#define _MIN_ELOOP_THRESHOLD_H 1
/* POSIX specifies SYMLOOP_MAX as the "Maximum number of symbolic
links that can be reliably traversed in the resolution of a
pathname in the absence of a loop." This makes it a minimum that
we should certainly accept. But it leaves open the possibility
that more might sometimes work--just not "reliably".
For example, Linux implements a complex policy whereby there is a
small limit on the number of direct symlink traversals (a symlink
to a symlink to a symlink), but larger limit on the total number of
symlink traversals overall. Hence the SYMLOOP_MAX number should be
the small one, but the limit library functions enforce on users
should be the larger one.
This constant should be large enough that it never rules out a file
name and directory tree that the underlying system (i.e. calls to 'open'
et al) would resolve successfully. It should be small enough that
actual loops are detected without a huge number of iterations. */
#define MIN_ELOOP_THRESHOLD 40
#endif

14
sysdeps/mach/hurd/eloop-threshold.h → sysdeps/mach/hurd/min-eloop-threshold.h
View File

@ -1,4 +1,4 @@
/* Threshold at which to diagnose ELOOP. Hurd version.
/* Minimum threshold at which to diagnose ELOOP. Hurd version.
Copyright (C) 2012-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
@ -16,8 +16,8 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _ELOOP_THRESHOLD_H
#define _ELOOP_THRESHOLD_H 1
#ifndef _MIN_ELOOP_THRESHOLD_H
#define _MIN_ELOOP_THRESHOLD_H 1
/* Return the maximum number of symlink traversals to permit
before diagnosing ELOOP.
@ -28,10 +28,6 @@
but instead use sysconf and the number can be changed here to
affect sysconf's result. */
static inline unsigned int __attribute__ ((const))
__eloop_threshold (void)
{
return 32;
}
#define MIN_ELOOP_THRESHOLD 32
#endif /* eloop-threshold.h */
#endif

4
sysdeps/mach/hurd/sysconf.c
View File

@ -19,8 +19,8 @@
#include <limits.h>
#include <unistd.h>
#include <eloop-threshold.h>
#include <min-eloop-threshold.h>
#define SYMLOOP_MAX (__eloop_threshold ())
#define SYMLOOP_MAX MIN_ELOOP_THRESHOLD
#include <sysdeps/posix/sysconf.c>