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/* $OpenBSD: __mktemp4.c,v 1.1 2024/01/19 19:45:02 millert Exp $ */
/*
* Copyright (c) 1996-1998, 2008 Theo de Raadt
* Copyright (c) 1997, 2008-2009, 2024 Todd C. Miller
*
* 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 <errno.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#define TEMPCHARS "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
#define NUM_CHARS (sizeof(TEMPCHARS) - 1)
#define MIN_X 6
#ifndef nitems
#define nitems(_a) (sizeof((_a)) / sizeof((_a)[0]))
#endif
/*
* Internal driver for the mktemp(3) family of functions.
* The supplied callback does the actual work of testing or
* creating the file/directory.
*/
int
__mktemp4(char *path, int slen, int flags, int (*cb)(const char *, int))
{
char *start, *cp, *ep;
const char tempchars[] = TEMPCHARS;
unsigned int tries;
size_t len;
int ret;
len = strlen(path);
if (len < MIN_X || slen < 0 || (size_t)slen > len - MIN_X) {
errno = EINVAL;
return -1;
}
ep = path + len - slen;
for (start = ep; start > path && start[-1] == 'X'; start--)
;
if (ep - start < MIN_X) {
errno = EINVAL;
return -1;
}
tries = INT_MAX;
do {
cp = start;
do {
unsigned short rbuf[16];
unsigned int i;
/*
* Avoid lots of arc4random() calls by using
* a buffer sized for up to 16 Xs at a time.
*/
arc4random_buf(rbuf, sizeof(rbuf));
for (i = 0; i < nitems(rbuf) && cp != ep; i++)
*cp++ = tempchars[rbuf[i] % NUM_CHARS];
} while (cp != ep);
ret = cb(path, flags);
if (ret != -1 || errno != EEXIST)
return ret;
} while (--tries);
errno = EEXIST;
return -1;
}
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