freebsd-nq/lib/libc/stdlib/realpath.c
Andrey A. Chernov 5f5a50728c 1) Although unpublished version of standard
http://austingroupbugs.net/view.php?id=385#c713
(Resolved state) recommend this way for the current standard (called
"earlier" in the text)

"However, earlier versions of this standard did not require this, and the
same example had to be written as:

    // buf was obtained by malloc(buflen)
    ret = write(fd, buf, buflen);
    if (ret < 0) {
        int save = errno;
        free(buf);
        errno = save;
        return ret;
    }
"

from feedback I have for previous commit it seems that many people prefer
to avoid mass code change needed for current standard compliance
and prefer to track unpublished standard instead, which requires now
that free() itself must save errno, not its usage code.

So, I back out "save errno across free()" part of previous commit,
and will fill PR for changing free() isntead.

2) Remove now unused serrno.

MFC after:      1 week
2012-06-05 16:16:33 +00:00

252 lines
6.4 KiB
C

/*
* 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"
/*
* 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 *
realpath(const char * __restrict path, char * __restrict resolved)
{
struct stat sb;
char *p, *q, *s;
size_t left_len, resolved_len;
unsigned symlinks;
int m, slen;
char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
if (path == NULL) {
errno = EINVAL;
return (NULL);
}
if (path[0] == '\0') {
errno = ENOENT;
return (NULL);
}
if (resolved == NULL) {
resolved = malloc(PATH_MAX);
if (resolved == NULL)
return (NULL);
m = 1;
} else
m = 0;
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) {
if (m)
free(resolved);
else {
resolved[0] = '.';
resolved[1] = '\0';
}
return (NULL);
}
resolved_len = strlen(resolved);
left_len = strlcpy(left, path, sizeof(left));
}
if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
if (m)
free(resolved);
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 (s - left >= sizeof(next_token)) {
if (m)
free(resolved);
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) {
if (m)
free(resolved);
errno = ENAMETOOLONG;
return (NULL);
}
resolved[resolved_len++] = '/';
resolved[resolved_len] = '\0';
}
if (next_token[0] == '\0') {
/*
* Handle consequential slashes. The path
* before slash shall point to a directory.
*
* Only the trailing slashes are not covered
* by other checks in the loop, but we verify
* the prefix for any (rare) "//" or "/\0"
* occurence to not implement lookahead.
*/
if (lstat(resolved, &sb) != 0) {
if (m)
free(resolved);
return (NULL);
}
if (!S_ISDIR(sb.st_mode)) {
if (m)
free(resolved);
errno = ENOTDIR;
return (NULL);
}
continue;
}
else if (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) {
if (m)
free(resolved);
errno = ENAMETOOLONG;
return (NULL);
}
if (lstat(resolved, &sb) != 0) {
if (errno != ENOENT || p != NULL)
errno = ENOTDIR;
if (m)
free(resolved);
return (NULL);
}
if (S_ISLNK(sb.st_mode)) {
if (symlinks++ > MAXSYMLINKS) {
if (m)
free(resolved);
errno = ELOOP;
return (NULL);
}
slen = readlink(resolved, symlink, sizeof(symlink) - 1);
if (slen < 0) {
if (m)
free(resolved);
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 (slen + 1 >= sizeof(symlink)) {
if (m)
free(resolved);
errno = ENAMETOOLONG;
return (NULL);
}
symlink[slen] = '/';
symlink[slen + 1] = 0;
}
left_len = strlcat(symlink, left,
sizeof(symlink));
if (left_len >= sizeof(left)) {
if (m)
free(resolved);
errno = ENAMETOOLONG;
return (NULL);
}
}
left_len = strlcpy(left, symlink, sizeof(left));
}
}
/*
* 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);
}