freebsd-nq/lib/libc/stdio/mktemp.c
Mark Johnston 076574744c Add mkostempsat(3).
This is a variant of mkostemps() which takes a directory descriptor and
returns a descriptor for a tempfile relative to that directory.  Unlike
the other mktemp functions, mkostempsat() can be used in capability
mode.

Reviewed by:	cem
Discussed with:	brooks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D21031
2019-07-29 19:02:16 +00:00

221 lines
5.3 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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.
* 3. 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(int, char *, int *, int, int, int);
static const unsigned char padchar[] =
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
int
mkostempsat(int dfd, char *path, int slen, int oflags)
{
int fd;
return (_gettemp(dfd, path, &fd, 0, slen, oflags) ? fd : -1);
}
int
mkostemps(char *path, int slen, int oflags)
{
int fd;
return (_gettemp(AT_FDCWD, path, &fd, 0, slen, oflags) ? fd : -1);
}
int
mkstemps(char *path, int slen)
{
int fd;
return (_gettemp(AT_FDCWD, path, &fd, 0, slen, 0) ? fd : -1);
}
int
mkostemp(char *path, int oflags)
{
int fd;
return (_gettemp(AT_FDCWD, path, &fd, 0, 0, oflags) ? fd : -1);
}
int
mkstemp(char *path)
{
int fd;
return (_gettemp(AT_FDCWD, path, &fd, 0, 0, 0) ? fd : -1);
}
char *
mkdtemp(char *path)
{
return (_gettemp(AT_FDCWD, path, (int *)NULL, 1, 0, 0) ? path : (char *)NULL);
}
char *
_mktemp(char *path)
{
return (_gettemp(AT_FDCWD, path, (int *)NULL, 0, 0, 0) ? path : (char *)NULL);
}
__warn_references(mktemp,
"warning: mktemp() possibly used unsafely; consider using mkstemp()");
char *
mktemp(char *path)
{
return (_mktemp(path));
}
static int
_gettemp(int dfd, char *path, int *doopen, int domkdir, int slen, int oflags)
{
char *start, *trv, *suffp, *carryp;
char *pad;
struct stat sbuf;
int rval;
uint32_t rand;
char carrybuf[MAXPATHLEN];
if ((doopen != NULL && domkdir) || slen < 0 ||
(oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK | O_EXLOCK | O_SYNC |
O_CLOEXEC)) != 0) {
errno = EINVAL;
return (0);
}
for (trv = path; *trv != '\0'; ++trv)
;
if (trv - path >= MAXPATHLEN) {
errno = ENAMETOOLONG;
return (0);
}
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 = fstatat(dfd, path, &sbuf, 0);
*trv = '/';
if (rval != 0)
return (0);
if (!S_ISDIR(sbuf.st_mode)) {
errno = ENOTDIR;
return (0);
}
break;
}
}
}
oflags |= O_CREAT | O_EXCL | O_RDWR;
for (;;) {
if (doopen) {
*doopen = _openat(dfd, path, oflags, 0600);
if (*doopen >= 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*/
}