freebsd-dev/lib/libc/stdio/mktemp.c
John Baldwin e68d07ff16 Fix a few bugs with the _gettemp() routine which implements mkstemp(),
mkstemps(), and mkdtemp().
- Add proper range checking for the 'slen' parameter passed to mkstemps().
- Try all possible permutations of a template if a collision is encountered.
  Previously, once a single template character reached 'z', it would not wrap
  around to '0' and keep going until it encountered the original starting
  letter.  In the edge case that the randomly generated starting name used
  all 'z' characters, only that single name would be tried before giving up.

PR:		standards/66531
Submitted by:	Jim Luther
Obtained from:	Apple
MFC after:	1 week
2008-07-28 21:18:59 +00:00

198 lines
4.7 KiB
C

/*
* Copyright (c) 1987, 1993
* The Regents of the University of California. All rights reserved.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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[] = "@(#)mktemp.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/param.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include "un-namespace.h"
char *_mktemp(char *);
static int _gettemp(char *, int *, int, int);
static const unsigned char padchar[] =
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
int
mkstemps(path, slen)
char *path;
int slen;
{
int fd;
return (_gettemp(path, &fd, 0, slen) ? fd : -1);
}
int
mkstemp(path)
char *path;
{
int fd;
return (_gettemp(path, &fd, 0, 0) ? fd : -1);
}
char *
mkdtemp(path)
char *path;
{
return (_gettemp(path, (int *)NULL, 1, 0) ? path : (char *)NULL);
}
char *
_mktemp(path)
char *path;
{
return (_gettemp(path, (int *)NULL, 0, 0) ? path : (char *)NULL);
}
__warn_references(mktemp,
"warning: mktemp() possibly used unsafely; consider using mkstemp()");
char *
mktemp(path)
char *path;
{
return (_mktemp(path));
}
static int
_gettemp(path, doopen, domkdir, slen)
char *path;
int *doopen;
int domkdir;
int slen;
{
char *start, *trv, *suffp, *carryp;
char *pad;
struct stat sbuf;
int rval;
uint32_t rand;
char carrybuf[MAXPATHLEN];
if ((doopen != NULL && domkdir) || slen < 0) {
errno = EINVAL;
return (0);
}
for (trv = path; *trv != '\0'; ++trv)
;
trv -= slen;
suffp = trv;
--trv;
if (trv < path || NULL != strchr(suffp, '/')) {
errno = EINVAL;
return (0);
}
/* Fill space with random characters */
while (trv >= path && *trv == 'X') {
rand = arc4random_uniform(sizeof(padchar) - 1);
*trv-- = padchar[rand];
}
start = trv + 1;
/* save first combination of random characters */
memcpy(carrybuf, start, suffp - start);
/*
* check the target directory.
*/
if (doopen != NULL || domkdir) {
for (; trv > path; --trv) {
if (*trv == '/') {
*trv = '\0';
rval = stat(path, &sbuf);
*trv = '/';
if (rval != 0)
return (0);
if (!S_ISDIR(sbuf.st_mode)) {
errno = ENOTDIR;
return (0);
}
break;
}
}
}
for (;;) {
if (doopen) {
if ((*doopen =
_open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
return (1);
if (errno != EEXIST)
return (0);
} else if (domkdir) {
if (mkdir(path, 0700) == 0)
return (1);
if (errno != EEXIST)
return (0);
} else if (lstat(path, &sbuf))
return (errno == ENOENT);
/* If we have a collision, cycle through the space of filenames */
for (trv = start, carryp = carrybuf;;) {
/* have we tried all possible permutations? */
if (trv == suffp)
return (0); /* yes - exit with EEXIST */
pad = strchr(padchar, *trv);
if (pad == NULL) {
/* this should never happen */
errno = EIO;
return (0);
}
/* increment character */
*trv = (*++pad == '\0') ? padchar[0] : *pad;
/* carry to next position? */
if (*trv == *carryp) {
/* increment position and loop */
++trv;
++carryp;
} else {
/* try with new name */
break;
}
}
}
/*NOTREACHED*/
}