412 lines
12 KiB
C
412 lines
12 KiB
C
/* Return the canonical absolute name of a given file.
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Copyright (C) 1996-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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#ifndef _LIBC
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/* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
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optimizes away the name == NULL test below. */
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# define _GL_ARG_NONNULL(params)
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# define _GL_USE_STDLIB_ALLOC 1
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# include <config.h>
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#endif
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#if !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || defined _LIBC
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/* Specification. */
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#include <stdlib.h>
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#include <alloca.h>
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#include <string.h>
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#include <unistd.h>
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#include <limits.h>
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#if HAVE_SYS_PARAM_H || defined _LIBC
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# include <sys/param.h>
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#endif
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#include <sys/stat.h>
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#include <errno.h>
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#include <stddef.h>
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#ifdef _LIBC
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# include <shlib-compat.h>
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#else
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# define SHLIB_COMPAT(lib, introduced, obsoleted) 0
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# define versioned_symbol(lib, local, symbol, version) extern int dummy
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# define compat_symbol(lib, local, symbol, version)
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# define weak_alias(local, symbol)
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# define __canonicalize_file_name canonicalize_file_name
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# define __realpath realpath
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# include "pathmax.h"
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# include "malloca.h"
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# include "dosname.h"
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# if HAVE_GETCWD
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# if IN_RELOCWRAPPER
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/* When building the relocatable program wrapper, use the system's getcwd
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function, not the gnulib override, otherwise we would get a link error.
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*/
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# undef getcwd
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# endif
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# ifdef VMS
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/* We want the directory in Unix syntax, not in VMS syntax. */
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# define __getcwd(buf, max) getcwd (buf, max, 0)
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# else
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# define __getcwd getcwd
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# endif
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# else
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# define __getcwd(buf, max) getwd (buf)
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# endif
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# define __readlink readlink
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# define __set_errno(e) errno = (e)
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# ifndef MAXSYMLINKS
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# ifdef SYMLOOP_MAX
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# define MAXSYMLINKS SYMLOOP_MAX
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# else
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# define MAXSYMLINKS 20
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# endif
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# endif
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#endif
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#ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
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# define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
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#endif
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#if !FUNC_REALPATH_WORKS || defined _LIBC
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/* Return the canonical absolute name of file NAME. A canonical name
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does not contain any ".", ".." components nor any repeated path
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separators ('/') or symlinks. All path components must exist. If
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RESOLVED is null, the result is malloc'd; otherwise, if the
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canonical name is PATH_MAX chars or more, returns null with 'errno'
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set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
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returns the name in RESOLVED. If the name cannot be resolved and
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RESOLVED is non-NULL, it contains the path of the first component
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that cannot be resolved. If the path can be resolved, RESOLVED
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holds the same value as the value returned. */
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char *
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__realpath (const char *name, char *resolved)
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{
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char *rpath, *dest, *extra_buf = NULL;
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const char *start, *end, *rpath_limit;
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long int path_max;
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int num_links = 0;
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size_t prefix_len;
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if (name == NULL)
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{
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/* As per Single Unix Specification V2 we must return an error if
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either parameter is a null pointer. We extend this to allow
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the RESOLVED parameter to be NULL in case the we are expected to
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allocate the room for the return value. */
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__set_errno (EINVAL);
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return NULL;
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}
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if (name[0] == '\0')
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{
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/* As per Single Unix Specification V2 we must return an error if
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the name argument points to an empty string. */
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__set_errno (ENOENT);
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return NULL;
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}
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#ifdef PATH_MAX
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path_max = PATH_MAX;
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#else
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path_max = pathconf (name, _PC_PATH_MAX);
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if (path_max <= 0)
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path_max = 8192;
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#endif
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if (resolved == NULL)
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{
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rpath = malloc (path_max);
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if (rpath == NULL)
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{
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/* It's easier to set errno to ENOMEM than to rely on the
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'malloc-posix' gnulib module. */
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errno = ENOMEM;
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return NULL;
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}
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}
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else
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rpath = resolved;
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rpath_limit = rpath + path_max;
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/* This is always zero for Posix hosts, but can be 2 for MS-Windows
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and MS-DOS X:/foo/bar file names. */
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prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
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if (!IS_ABSOLUTE_FILE_NAME (name))
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{
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if (!__getcwd (rpath, path_max))
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{
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rpath[0] = '\0';
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goto error;
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}
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dest = strchr (rpath, '\0');
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start = name;
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prefix_len = FILE_SYSTEM_PREFIX_LEN (rpath);
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}
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else
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{
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dest = rpath;
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if (prefix_len)
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{
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memcpy (rpath, name, prefix_len);
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dest += prefix_len;
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}
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*dest++ = '/';
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
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{
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if (ISSLASH (name[1]) && !ISSLASH (name[2]) && !prefix_len)
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*dest++ = '/';
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*dest = '\0';
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}
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start = name + prefix_len;
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}
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for (end = start; *start; start = end)
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{
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#ifdef _LIBC
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struct stat64 st;
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#else
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struct stat st;
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#endif
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int n;
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/* Skip sequence of multiple path-separators. */
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while (ISSLASH (*start))
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++start;
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/* Find end of path component. */
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for (end = start; *end && !ISSLASH (*end); ++end)
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/* Nothing. */;
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if (end - start == 0)
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break;
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else if (end - start == 1 && start[0] == '.')
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/* nothing */;
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else if (end - start == 2 && start[0] == '.' && start[1] == '.')
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{
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/* Back up to previous component, ignore if at root already. */
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if (dest > rpath + prefix_len + 1)
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for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
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continue;
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT
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&& dest == rpath + 1 && !prefix_len
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&& ISSLASH (*dest) && !ISSLASH (dest[1]))
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dest++;
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}
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else
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{
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size_t new_size;
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if (!ISSLASH (dest[-1]))
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*dest++ = '/';
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if (dest + (end - start) >= rpath_limit)
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{
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ptrdiff_t dest_offset = dest - rpath;
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char *new_rpath;
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if (resolved)
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{
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__set_errno (ENAMETOOLONG);
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if (dest > rpath + prefix_len + 1)
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dest--;
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*dest = '\0';
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goto error;
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}
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new_size = rpath_limit - rpath;
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if (end - start + 1 > path_max)
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new_size += end - start + 1;
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else
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new_size += path_max;
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new_rpath = (char *) realloc (rpath, new_size);
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if (new_rpath == NULL)
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{
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/* It's easier to set errno to ENOMEM than to rely on the
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'realloc-posix' gnulib module. */
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errno = ENOMEM;
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goto error;
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}
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rpath = new_rpath;
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rpath_limit = rpath + new_size;
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dest = rpath + dest_offset;
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}
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#ifdef _LIBC
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dest = __mempcpy (dest, start, end - start);
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#else
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memcpy (dest, start, end - start);
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dest += end - start;
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#endif
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*dest = '\0';
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#ifdef _LIBC
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if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
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#else
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if (lstat (rpath, &st) < 0)
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#endif
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goto error;
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if (S_ISLNK (st.st_mode))
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{
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char *buf;
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size_t len;
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if (++num_links > MAXSYMLINKS)
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{
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__set_errno (ELOOP);
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goto error;
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}
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buf = malloca (path_max);
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if (!buf)
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{
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errno = ENOMEM;
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goto error;
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}
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n = __readlink (rpath, buf, path_max - 1);
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if (n < 0)
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{
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int saved_errno = errno;
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freea (buf);
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errno = saved_errno;
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goto error;
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}
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buf[n] = '\0';
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if (!extra_buf)
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{
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extra_buf = malloca (path_max);
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if (!extra_buf)
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{
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freea (buf);
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errno = ENOMEM;
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goto error;
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}
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}
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len = strlen (end);
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if ((long int) (n + len) >= path_max)
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{
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freea (buf);
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__set_errno (ENAMETOOLONG);
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goto error;
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}
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/* Careful here, end may be a pointer into extra_buf... */
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memmove (&extra_buf[n], end, len + 1);
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name = end = memcpy (extra_buf, buf, n);
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if (IS_ABSOLUTE_FILE_NAME (buf))
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{
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size_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
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if (pfxlen)
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memcpy (rpath, buf, pfxlen);
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dest = rpath + pfxlen;
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*dest++ = '/'; /* It's an absolute symlink */
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
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{
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if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
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*dest++ = '/';
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*dest = '\0';
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}
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/* Install the new prefix to be in effect hereafter. */
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prefix_len = pfxlen;
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}
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else
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{
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/* Back up to previous component, ignore if at root
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already: */
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if (dest > rpath + prefix_len + 1)
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for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
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continue;
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
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&& ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
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dest++;
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}
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}
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else if (!S_ISDIR (st.st_mode) && *end != '\0')
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{
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__set_errno (ENOTDIR);
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goto error;
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}
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}
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}
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if (dest > rpath + prefix_len + 1 && ISSLASH (dest[-1]))
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--dest;
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && !prefix_len
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&& ISSLASH (*dest) && !ISSLASH (dest[1]))
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dest++;
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*dest = '\0';
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if (extra_buf)
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freea (extra_buf);
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return rpath;
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error:
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{
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int saved_errno = errno;
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if (extra_buf)
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freea (extra_buf);
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if (resolved == NULL)
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free (rpath);
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errno = saved_errno;
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}
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return NULL;
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}
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versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
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#endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
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#if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
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char *
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attribute_compat_text_section
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__old_realpath (const char *name, char *resolved)
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{
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if (resolved == 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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return __realpath (name, resolved);
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}
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compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
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#endif
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char *
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__canonicalize_file_name (const char *name)
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{
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return __realpath (name, NULL);
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}
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weak_alias (__canonicalize_file_name, canonicalize_file_name)
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#else
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/* This declaration is solely to ensure that after preprocessing
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this file is never empty. */
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typedef int dummy;
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#endif
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