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6c7a57538a
2006-04-02 Ulrich Drepper <drepper@redhat.com> [BZ #2418] * sysdeps/unix/sysv/linux/bits/socket.h: Use larger of PATH_MAX and page size when allocating buffer.
223 lines
5.6 KiB
C
223 lines
5.6 KiB
C
/* Determine current working directory. Linux version.
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Copyright (C) 1997,1998,1999,2000,2002,2003,2006
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Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <assert.h>
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#include <errno.h>
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#include <limits.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sysdep.h>
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#include <sys/syscall.h>
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#include <bp-checks.h>
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#include <kernel-features.h>
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/* If we compile the file for use in ld.so we don't need the feature
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that getcwd() allocates the buffers itself. */
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#ifdef IS_IN_rtld
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# define NO_ALLOCATION 1
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#endif
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#if __ASSUME_GETCWD_SYSCALL > 0
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/* Kernel 2.1.92 introduced a third way to get the current working
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directory: a syscall. We've got to be careful that even when
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compiling under 2.1.92+ the libc still runs under older kernels. */
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# define no_syscall_getcwd 0
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# define have_new_dcache 1
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/* This is a trick since we don't define generic_getcwd. */
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# define generic_getcwd getcwd
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#else
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/* The "proc" filesystem provides an easy method to retrieve the value.
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For each process, the corresponding directory contains a symbolic link
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named `cwd'. Reading the content of this link immediate gives us the
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information. But we have to take care for systems which do not have
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the proc filesystem mounted. Use the POSIX implementation in this case. */
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static char *generic_getcwd (char *buf, size_t size) internal_function;
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# if __NR_getcwd
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/* Kernel 2.1.92 introduced a third way to get the current working
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directory: a syscall. We've got to be careful that even when
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compiling under 2.1.92+ the libc still runs under older kernels. */
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static int no_syscall_getcwd;
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static int have_new_dcache;
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# else
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# define no_syscall_getcwd 1
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static int have_new_dcache = 1;
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# endif
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#endif
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char *
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__getcwd (char *buf, size_t size)
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{
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char *path;
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int n;
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char *result;
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if (no_syscall_getcwd && !have_new_dcache)
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return generic_getcwd (buf, size);
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#ifndef NO_ALLOCATION
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size_t alloc_size = size;
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if (size == 0)
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{
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if (buf != NULL)
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{
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__set_errno (EINVAL);
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return NULL;
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}
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alloc_size = MAX (PATH_MAX, __getpagesize ());
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}
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if (buf == NULL)
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{
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path = malloc (alloc_size);
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if (path == NULL)
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return NULL;
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}
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else
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#else
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# define alloc_size size
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#endif
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path = buf;
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#if defined __NR_getcwd || __LINUX_GETCWD_SYSCALL > 0
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if (!no_syscall_getcwd)
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{
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int retval;
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retval = INLINE_SYSCALL (getcwd, 2, CHECK_STRING (path), alloc_size);
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if (retval >= 0)
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{
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# ifndef NO_ALLOCATION
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if (buf == NULL && size == 0)
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/* Ensure that the buffer is only as large as necessary. */
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buf = realloc (path, (size_t) retval);
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if (buf == NULL)
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/* Either buf was NULL all along, or `realloc' failed but
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we still have the original string. */
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buf = path;
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# endif
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return buf;
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}
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# if __ASSUME_GETCWD_SYSCALL
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/* It should never happen that the `getcwd' syscall failed because
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the buffer is too small if we allocated the buffer ourselves
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large enough. */
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assert (errno != ERANGE || buf != NULL || size != 0);
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# ifndef NO_ALLOCATION
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if (buf == NULL)
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free (path);
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# endif
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return NULL;
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# else
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if (errno == ENOSYS)
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{
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no_syscall_getcwd = 1;
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have_new_dcache = 1; /* Now we will try the /proc method. */
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}
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else if (errno != ERANGE || buf != NULL)
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{
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# ifndef NO_ALLOCATION
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if (buf == NULL)
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free (path);
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# endif
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return NULL;
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}
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# endif
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}
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#endif
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n = __readlink ("/proc/self/cwd", path, alloc_size - 1);
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if (n != -1)
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{
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if (path[0] == '/')
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{
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if ((size_t) n >= alloc_size - 1)
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{
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#ifndef NO_ALLOCATION
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if (buf == NULL)
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free (path);
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#endif
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return NULL;
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}
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path[n] = '\0';
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#ifndef NO_ALLOCATION
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if (buf == NULL && size == 0)
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/* Ensure that the buffer is only as large as necessary. */
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buf = realloc (path, (size_t) n + 1);
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if (buf == NULL)
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/* Either buf was NULL all along, or `realloc' failed but
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we still have the original string. */
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buf = path;
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#endif
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return buf;
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}
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#ifndef have_new_dcache
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else
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have_new_dcache = 0;
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#endif
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}
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#if __ASSUME_GETCWD_SYSCALL == 0
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/* Set to have_new_dcache only if error indicates that proc doesn't
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exist. */
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if (errno != EACCES && errno != ENAMETOOLONG)
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have_new_dcache = 0;
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#endif
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#ifndef NO_ALLOCATION
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/* Don't put restrictions on the length of the path unless the user does. */
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if (size == 0)
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{
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free (path);
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path = NULL;
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}
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#endif
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result = generic_getcwd (path, size);
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#ifndef NO_ALLOCATION
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if (result == NULL && buf == NULL && size != 0)
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free (path);
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#endif
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return result;
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}
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weak_alias (__getcwd, getcwd)
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#if __ASSUME_GETCWD_SYSCALL == 0
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/* Get the code for the generic version. */
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# define GETCWD_RETURN_TYPE static char * internal_function
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# define __getcwd generic_getcwd
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# include <sysdeps/posix/getcwd.c>
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#endif
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