mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-26 12:41:05 +00:00
c6e0b0b5b0
It sync with gnulib version ae9fb3d66. The testcase for BZ#23741
(stdlib/test-bz22786.c) is adjusted to check also for ENOMEM.
The patch fixes multiple realpath issues:
- Portability fixes for errno clobbering on free (BZ#10635). The
function does not call free directly anymore, although it might be
done through scratch_buffer_free. The free errno clobbering is
being tracked by BZ#17924.
- Pointer arithmetic overflows in realpath (BZ#26592).
- Realpath cyclically call __alloca(path_max) to consume too much
stack space (BZ#26341).
- Realpath mishandles EOVERFLOW; stat not needed anyway (BZ#24970).
The check is done through faccessat now.
Checked on x86_64-linux-gnu and i686-linux-gnu.
468 lines
15 KiB
C
468 lines
15 KiB
C
/* Return the canonical absolute name of a given file.
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Copyright (C) 1996-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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, see
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<https://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 <libc-config.h>
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#endif
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/* Specification. */
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#include <stdlib.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <eloop-threshold.h>
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#include <filename.h>
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#include <idx.h>
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#include <intprops.h>
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#include <scratch_buffer.h>
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#ifdef _LIBC
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# include <shlib-compat.h>
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# define GCC_LINT 1
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# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
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#else
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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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# define __faccessat faccessat
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# if defined _WIN32 && !defined __CYGWIN__
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# define __getcwd _getcwd
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# elif 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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# if defined VMS && !defined getcwd
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/* We want the directory in Unix syntax, not in VMS syntax.
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The gnulib override of 'getcwd' takes 2 arguments; the original VMS
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'getcwd' takes 3 arguments. */
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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 __mempcpy mempcpy
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# define __pathconf pathconf
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# define __rawmemchr rawmemchr
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# define __readlink readlink
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# define __stat stat
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#endif
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/* Suppress bogus GCC -Wmaybe-uninitialized warnings. */
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#if defined GCC_LINT || defined lint
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# define IF_LINT(Code) Code
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#else
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# define IF_LINT(Code) /* empty */
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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 false
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#endif
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#if defined _LIBC || !FUNC_REALPATH_WORKS
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/* Return true if FILE's existence can be shown, false (setting errno)
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otherwise. Follow symbolic links. */
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static bool
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file_accessible (char const *file)
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{
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# if defined _LIBC || HAVE_FACCESSAT
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return __faccessat (AT_FDCWD, file, F_OK, AT_EACCESS) == 0;
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# else
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struct stat st;
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return __stat (file, &st) == 0 || errno == EOVERFLOW;
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# endif
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}
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/* True if concatenating END as a suffix to a file name means that the
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code needs to check that the file name is that of a searchable
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directory, since the canonicalize_filename_mode_stk code won't
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check this later anyway when it checks an ordinary file name
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component within END. END must either be empty, or start with a
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slash. */
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static bool _GL_ATTRIBUTE_PURE
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suffix_requires_dir_check (char const *end)
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{
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/* If END does not start with a slash, the suffix is OK. */
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while (ISSLASH (*end))
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{
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/* Two or more slashes act like a single slash. */
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do
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end++;
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while (ISSLASH (*end));
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switch (*end++)
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{
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default: return false; /* An ordinary file name component is OK. */
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case '\0': return true; /* Trailing "/" is trouble. */
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case '.': break; /* Possibly "." or "..". */
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}
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/* Trailing "/.", or "/.." even if not trailing, is trouble. */
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if (!*end || (*end == '.' && (!end[1] || ISSLASH (end[1]))))
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return true;
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}
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return false;
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}
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/* Append this to a file name to test whether it is a searchable directory.
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On POSIX platforms "/" suffices, but "/./" is sometimes needed on
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macOS 10.13 <https://bugs.gnu.org/30350>, and should also work on
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platforms like AIX 7.2 that need at least "/.". */
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#if defined _LIBC || defined LSTAT_FOLLOWS_SLASHED_SYMLINK
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static char const dir_suffix[] = "/";
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#else
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static char const dir_suffix[] = "/./";
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#endif
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/* Return true if DIR is a searchable dir, false (setting errno) otherwise.
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DIREND points to the NUL byte at the end of the DIR string.
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Store garbage into DIREND[0 .. strlen (dir_suffix)]. */
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static bool
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dir_check (char *dir, char *dirend)
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{
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strcpy (dirend, dir_suffix);
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return file_accessible (dir);
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}
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static idx_t
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get_path_max (void)
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{
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# ifdef PATH_MAX
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long int path_max = PATH_MAX;
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# else
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/* The caller invoked realpath with a null RESOLVED, even though
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PATH_MAX is not defined as a constant. The glibc manual says
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programs should not do this, and POSIX says the behavior is undefined.
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Historically, glibc here used the result of pathconf, or 1024 if that
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failed; stay consistent with this (dubious) historical practice. */
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int err = errno;
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long int path_max = __pathconf ("/", _PC_PATH_MAX);
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__set_errno (err);
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# endif
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return path_max < 0 ? 1024 : path_max <= IDX_MAX ? path_max : IDX_MAX;
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}
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/* Act like __realpath (see below), with an additional argument
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rname_buf that can be used as temporary storage.
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If GCC_LINT is defined, do not inline this function with GCC 10.1
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and later, to avoid creating a pointer to the stack that GCC
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-Wreturn-local-addr incorrectly complains about. See:
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93644
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Although the noinline attribute can hurt performance a bit, no better way
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to pacify GCC is known; even an explicit #pragma does not pacify GCC.
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When the GCC bug is fixed this workaround should be limited to the
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broken GCC versions. */
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#if __GNUC_PREREQ (10, 1)
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# if defined GCC_LINT || defined lint
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__attribute__ ((__noinline__))
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# elif __OPTIMIZE__ && !__NO_INLINE__
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# define GCC_BOGUS_WRETURN_LOCAL_ADDR
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# endif
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#endif
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static char *
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realpath_stk (const char *name, char *resolved,
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struct scratch_buffer *rname_buf)
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{
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char *dest;
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char const *start;
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char const *end;
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int num_links = 0;
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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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struct scratch_buffer extra_buffer, link_buffer;
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scratch_buffer_init (&extra_buffer);
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scratch_buffer_init (&link_buffer);
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scratch_buffer_init (rname_buf);
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char *rname_on_stack = rname_buf->data;
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char *rname = rname_on_stack;
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bool end_in_extra_buffer = false;
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bool failed = true;
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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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idx_t 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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while (!__getcwd (rname, rname_buf->length))
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{
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if (errno != ERANGE)
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{
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dest = rname;
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goto error;
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}
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if (!scratch_buffer_grow (rname_buf))
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goto error_nomem;
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rname = rname_buf->data;
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}
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dest = __rawmemchr (rname, '\0');
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start = name;
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prefix_len = FILE_SYSTEM_PREFIX_LEN (rname);
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}
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else
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{
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dest = __mempcpy (rname, name, prefix_len);
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*dest++ = '/';
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
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{
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if (prefix_len == 0 /* implies ISSLASH (name[0]) */
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&& ISSLASH (name[1]) && !ISSLASH (name[2]))
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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 ( ; *start; start = end)
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{
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/* Skip sequence of multiple file name separators. */
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while (ISSLASH (*start))
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++start;
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/* Find end of component. */
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for (end = start; *end && !ISSLASH (*end); ++end)
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/* Nothing. */;
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/* Length of this file name component; it can be zero if a file
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name ends in '/'. */
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idx_t startlen = end - start;
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if (startlen == 0)
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break;
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else if (startlen == 1 && start[0] == '.')
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/* nothing */;
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else if (startlen == 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 > rname + prefix_len + 1)
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for (--dest; dest > rname && !ISSLASH (dest[-1]); --dest)
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continue;
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT
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&& dest == rname + 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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if (!ISSLASH (dest[-1]))
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*dest++ = '/';
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while (rname + rname_buf->length - dest
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< startlen + sizeof dir_suffix)
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{
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idx_t dest_offset = dest - rname;
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if (!scratch_buffer_grow_preserve (rname_buf))
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goto error_nomem;
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rname = rname_buf->data;
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dest = rname + dest_offset;
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}
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dest = __mempcpy (dest, start, startlen);
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*dest = '\0';
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char *buf;
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ssize_t n;
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while (true)
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{
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buf = link_buffer.data;
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idx_t bufsize = link_buffer.length;
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n = __readlink (rname, buf, bufsize - 1);
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if (n < bufsize - 1)
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break;
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if (!scratch_buffer_grow (&link_buffer))
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goto error_nomem;
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}
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if (0 <= n)
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{
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if (++num_links > __eloop_threshold ())
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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[n] = '\0';
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char *extra_buf = extra_buffer.data;
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idx_t end_idx IF_LINT (= 0);
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if (end_in_extra_buffer)
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end_idx = end - extra_buf;
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size_t len = strlen (end);
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if (INT_ADD_OVERFLOW (len, n))
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{
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__set_errno (ENOMEM);
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goto error_nomem;
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}
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while (extra_buffer.length <= len + n)
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{
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if (!scratch_buffer_grow_preserve (&extra_buffer))
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goto error_nomem;
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extra_buf = extra_buffer.data;
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}
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if (end_in_extra_buffer)
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end = extra_buf + end_idx;
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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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end_in_extra_buffer = true;
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if (IS_ABSOLUTE_FILE_NAME (buf))
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{
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idx_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
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dest = __mempcpy (rname, buf, 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 > rname + prefix_len + 1)
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for (--dest; dest > rname && !ISSLASH (dest[-1]); --dest)
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continue;
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 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 (! (suffix_requires_dir_check (end)
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? dir_check (rname, dest)
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: errno == EINVAL))
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goto error;
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}
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}
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if (dest > rname + prefix_len + 1 && ISSLASH (dest[-1]))
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--dest;
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if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 1 && !prefix_len
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&& ISSLASH (*dest) && !ISSLASH (dest[1]))
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dest++;
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failed = false;
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error:
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*dest++ = '\0';
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if (resolved != NULL && dest - rname <= get_path_max ())
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rname = strcpy (resolved, rname);
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error_nomem:
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scratch_buffer_free (&extra_buffer);
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scratch_buffer_free (&link_buffer);
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if (failed || rname == resolved)
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{
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scratch_buffer_free (rname_buf);
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return failed ? NULL : resolved;
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}
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return scratch_buffer_dupfree (rname_buf, dest - rname);
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}
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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 file name
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separators ('/') or symlinks. All file name 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 name of the first component
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that cannot be resolved. If the name 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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#ifdef GCC_BOGUS_WRETURN_LOCAL_ADDR
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#warning "GCC might issue a bogus -Wreturn-local-addr warning here."
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#warning "See <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93644>."
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#endif
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struct scratch_buffer rname_buffer;
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return realpath_stk (name, resolved, &rname_buffer);
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}
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libc_hidden_def (__realpath)
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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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