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/* $OpenBSD: realpath.c,v 1.13 2005/08/08 08:05:37 espie Exp $ */
/*
* realpath:
* Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* strlcpy() / strlcat():
* Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <config.h>
#define FAKECHROOT_EXCEPTION 1
#include "ftpd.h"
#include "bsd-realpath.h"
#if !defined(HAVE_REALPATH) || defined(USE_BUILTIN_REALPATH)
# ifdef WITH_DMALLOC
# include <dmalloc.h>
# endif
# ifndef MAXSYMLINKS
# define MAXSYMLINKS 5
# endif
# if MAXSYMLINKS > UINT_MAX
# undef MAXSYMLINKS
# define MAXSYMLINKS UINT_MAX
# endif
#ifndef HAVE_STRLCPY
/*
* Copy src to string dst of size siz. At most siz-1 characters
* will be copied. Always NUL terminates (unless siz == 0).
* Returns strlen(src); if retval >= siz, truncation occurred.
*/
static size_t strlcpy(char *dst, const char * const src, const size_t siz)
{
char *d = dst;
const char *s = src;
size_t n = siz;
/* Copy as many bytes as will fit */
if (n != 0 && --n != 0) {
do {
if ((*d++ = *s++) == 0) {
break;
}
} while (--n != 0);
}
/* Not enough room in dst, add NUL and traverse rest of src */
if (n == 0) {
if (siz != 0) {
*d = '\0'; /* NUL-terminate dst */
}
while (*s++) {
}
}
return s - src - 1; /* count does not include NUL */
}
#endif
#ifndef HAVE_STRLCAT
/*
* Appends src to string dst of size siz (unlike strncat, siz is the
* full size of dst, not space left). At most siz-1 characters
* will be copied. Always NUL terminates (unless siz <= strlen(dst)).
* Returns strlen(src) + MIN(siz, strlen(initial dst)).
* If retval >= siz, truncation occurred.
*/
static size_t strlcat(char *dst, const char * const src, const size_t siz)
{
char *d = dst;
const char *s = src;
size_t n = siz;
size_t dlen;
/* Find the end of dst and adjust bytes left but don't go past end */
while (n-- != 0 && *d != '\0') {
d++;
}
dlen = d - dst;
n = siz - dlen;
if (n == 0) {
return dlen + strlen(s);
}
while (*s != '\0') {
if (n != 1) {
*d++ = *s;
n--;
}
s++;
}
*d = '\0';
return dlen + (s - src); /* count does not include NUL */
}
#endif
/*
* Find the real name of path, by removing all ".", ".." and symlink
* components. Returns resolved on success, or NULL on failure,
* in which case the path which caused trouble is left in (resolved).
*/
char *bsd_realpath(const char *path, char resolved[PATH_MAX])
{
struct stat sb;
char *p, *q, *s;
size_t left_len, resolved_len;
unsigned symlinks;
int serrno, slen;
char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
serrno = errno;
symlinks = 0;
if (path[0] == '/') {
resolved[0] = '/';
resolved[1] = '\0';
if (path[1] == '\0') {
return resolved;
}
resolved_len = 1;
left_len = strlcpy(left, path + 1, sizeof left);
} else {
if (getcwd(resolved, PATH_MAX) == NULL) {
strlcpy(resolved, ".", PATH_MAX);
return NULL;
}
resolved_len = strlen(resolved);
left_len = strlcpy(left, path, sizeof left);
}
if (left_len >= sizeof left || resolved_len >= PATH_MAX) {
errno = ENAMETOOLONG;
return NULL;
}
/*
* Iterate over path components in `left'.
*/
while (left_len != 0) {
/*
* Extract the next path component and adjust `left'
* and its length.
*/
p = strchr(left, '/');
s = p ? p : left + left_len;
if ((size_t) (s - left) >= sizeof next_token) {
errno = ENAMETOOLONG;
return NULL;
}
memcpy(next_token, left, s - left);
next_token[s - left] = '\0';
left_len -= s - left;
if (p != NULL) {
memmove(left, s + 1, left_len + 1);
}
if (resolved[resolved_len - 1] != '/') {
if (resolved_len + 1 >= PATH_MAX) {
errno = ENAMETOOLONG;
return NULL;
}
resolved[resolved_len++] = '/';
resolved[resolved_len] = '\0';
}
if (next_token[0] == '\0' || strcmp(next_token, ".") == 0) {
continue;
} else if (strcmp(next_token, "..") == 0) {
/*
* Strip the last path component except when we have
* single "/"
*/
if (resolved_len > 1) {
resolved[resolved_len - 1] = '\0';
q = strrchr(resolved, '/') + 1;
*q = '\0';
resolved_len = q - resolved;
}
continue;
}
/*
* Append the next path component and lstat() it.
*/
resolved_len = strlcat(resolved, next_token, PATH_MAX);
if (resolved_len >= PATH_MAX) {
errno = ENAMETOOLONG;
return NULL;
}
if (lstat(resolved, &sb) != 0) {
return NULL;
}
if (S_ISLNK(sb.st_mode)) {
if (symlinks++ > MAXSYMLINKS) {
errno = ELOOP;
return NULL;
}
slen = readlink(resolved, symlink, (sizeof symlink) - 1);
if (slen < 0) {
return NULL;
}
symlink[slen] = '\0';
if (symlink[0] == '/') {
resolved[1] = 0;
resolved_len = 1;
} else if (resolved_len > 1) {
/* Strip the last path component. */
resolved[resolved_len - 1] = '\0';
q = strrchr(resolved, '/') + 1;
*q = '\0';
resolved_len = q - resolved;
}
/*
* If there are any path components left, then
* append them to symlink. The result is placed
* in `left'.
*/
if (p != NULL) {
if (symlink[slen - 1] != '/') {
if ((size_t) slen >= (sizeof symlink) - 1U) {
errno = ENAMETOOLONG;
return NULL;
}
symlink[slen] = '/';
symlink[slen + 1] = 0;
}
left_len = strlcat(symlink, left, sizeof symlink);
if (left_len >= sizeof left) {
errno = ENAMETOOLONG;
return NULL;
}
}
left_len = strlcpy(left, symlink, sizeof left);
} else if (!S_ISDIR(sb.st_mode) && p != NULL) {
errno = ENOTDIR;
return NULL;
}
}
/*
* Remove trailing slash except when the resolved pathname
* is a single "/".
*/
if (resolved_len > 1 && resolved[resolved_len - 1] == '/') {
resolved[resolved_len - 1] = '\0';
}
return resolved;
}
#endif
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