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/* Return the canonical absolute name of a given file.
Copyright (C) 1996-2001, 2002 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include "headers.h"
#include "sbutil.h"
#include "libsandbox.h"
#ifndef __set_errno
# define __set_errno(val) errno = (val)
#endif
/* Return the canonical absolute name of file NAME. A canonical name
does not contain any `.', `..' components nor any repeated path
separators ('/') or symlinks. All path components must exist. If
RESOLVED is null, the result is malloc'd; otherwise, if the
canonical name is SB_PATH_MAX chars or more, returns null with `errno'
set to ENAMETOOLONG; if the name fits in fewer than SB_PATH_MAX chars,
returns the name in RESOLVED. If the name cannot be resolved and
RESOLVED is non-NULL, it contains the path of the first component
that cannot be resolved. If the path can be resolved, RESOLVED
holds the same value as the value returned. */
/* Modified: 19 Aug 2002; Martin Schlemmer <azarah@gentoo.org>
*
* Cleaned up unneeded stuff, and change so that it will not
* resolve symlinks. Also prepended a 'e' to functions that
* I did not rip out.
*
*/
char *
erealpath(const char *name, char *resolved)
{
char *rpath, *dest, *recover;
const char *start, *end, *rpath_limit;
if (name == NULL) {
/* As per Single Unix Specification V2 we must return an error if
either parameter is a null pointer. We extend this to allow
the RESOLVED parameter to be NULL in case the we are expected to
allocate the room for the return value. */
__set_errno(EINVAL);
return NULL;
}
if (name[0] == '\0') {
/* As per Single Unix Specification V2 we must return an error if
the name argument points to an empty string. */
__set_errno(ENOENT);
return NULL;
}
if (resolved == NULL) {
rpath = xmalloc(SB_PATH_MAX);
} else {
/* We can't handle resolving a buffer inline, so demand
* separate read and write strings.
*/
sb_assert(name != resolved);
rpath = resolved;
}
rpath_limit = rpath + SB_PATH_MAX;
recover = NULL;
if (name[0] != '/') {
if (!egetcwd(rpath, SB_PATH_MAX)) {
rpath[0] = '\0';
goto error;
}
/* This stat business uses relative paths atm. */
if (trace_pid)
goto no_recover;
/* Can we actually access the working dir (sane perms) ?
* If not, try a little harder to consume this path in
* case it has symlinks out into a better world ...
*/
struct stat64 st;
if (lstat64(rpath, &st) == -1 && errno == EACCES) {
char *p = rpath;
strcpy(rpath, name);
do {
p = strchr(p, '/');
if (p) *p = '\0';
if (lstat64(rpath, &st))
break;
if (S_ISLNK(st.st_mode)) {
char buffer[SB_PATH_MAX];
ssize_t cnt = readlink(rpath, buffer, SB_PATH_MAX - 1);
if (cnt == -1)
break;
buffer[cnt] = '\0';
strcpy(rpath, buffer);
if (p) {
size_t bytes_left = strlen(p);
if (bytes_left >= SB_PATH_MAX)
break;
strncat(rpath, name + (p - rpath + 1),
SB_PATH_MAX - bytes_left - 1);
}
/* Ok, we have a chance at something better. If
* this fails, we give up. Otherwise we set things
* to match the new paths that we've found and hook
* back into the normal process.
*/
recover = erealpath(rpath, NULL);
if (recover) {
if (recover[0] != '/') {
strcpy(rpath, recover);
break;
} else {
name = recover;
goto recover_full;
}
} else
goto error;
}
if (p) *p++ = '/';
} while (p);
}
no_recover:
dest = strchr(rpath, '\0');
} else {
recover_full:
rpath[0] = '/';
dest = rpath + 1;
}
for (start = end = name; *start; start = end) {
/* Skip sequence of multiple path-separators. */
while (*start == '/')
++start;
/* Find end of path component. */
for (end = start; *end && *end != '/'; ++end)
/* Nothing. */ ;
if (end - start == 0)
break;
else if (end - start == 1 && start[0] == '.')
/* nothing */ ;
else if (end - start == 2 && start[0] == '.' && start[1] == '.') {
/* Back up to previous component, ignore if at root already. */
if (dest > rpath + 1)
while (dest > rpath && (--dest)[-1] != '/')
continue;
} else {
size_t new_size;
if (dest[-1] != '/')
*dest++ = '/';
if (dest + (end - start) >= rpath_limit) {
ptrdiff_t dest_offset = dest - rpath;
char *new_rpath;
if (resolved) {
__set_errno(ENAMETOOLONG);
if (dest > rpath + 1)
dest--;
*dest = '\0';
goto error;
}
new_size = rpath_limit - rpath;
if (end - start + 1 > SB_PATH_MAX)
new_size += end - start + 1;
else
new_size += SB_PATH_MAX;
new_rpath = (char *) xrealloc(rpath, new_size);
rpath = new_rpath;
rpath_limit = rpath + new_size;
dest = rpath + dest_offset;
}
memcpy(dest, start, end - start);
dest += end - start;
*dest = '\0';
}
}
#if 1
if (dest > rpath + 1 && dest[-1] == '/')
--dest;
#endif
*dest = '\0';
return rpath;
error:
if (resolved)
snprintf(resolved, SB_PATH_MAX, "%s", rpath);
else
free(rpath);
free(recover);
return NULL;
}
// vim:noexpandtab noai:cindent ai
|
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