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gettemp.c revision 1.23 
      1 /*	$NetBSD: gettemp.c,v 1.23 2025/07/17 18:28:58 kre Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1987, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include "gettemp.h"
     33 
     34 #if !HAVE_NBTOOL_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)mktemp.c	8.1 (Berkeley) 6/4/93";
     40 #else
     41 __RCSID("$NetBSD: gettemp.c,v 1.23 2025/07/17 18:28:58 kre Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include <sys/param.h>
     46 #include <sys/stat.h>
     47 #include <fcntl.h>
     48 #include <string.h>
     49 
     50 #ifndef	O_CLOFORK			/*XXX temporary */
     51 #define	O_CLOFORK 0			/*XXX temporary */
     52 #endif					/*XXX temporary */
     53 
     54 static const unsigned char padchar[] =
     55 "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
     56 
     57 int
     58 GETTEMP(char *path, int *doopen, int domkdir, int slen, int oflags)
     59 {
     60 	char *start, *trv, *suffp, *carryp;
     61 	const char *pad;
     62 	struct stat sbuf;
     63 	int rval;
     64 	uint32_t r;
     65 	char carrybuf[MAXPATHLEN];
     66 
     67 	_DIAGASSERT(path != NULL);
     68 	/* doopen may be NULL */
     69 	if ((doopen != NULL && domkdir) || slen < 0 ||
     70 	    (oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK | O_EXLOCK | O_SYNC |
     71 	    O_CLOEXEC | O_CLOFORK)) != 0) {
     72 		errno = EINVAL;
     73 		return 0;
     74 	}
     75 
     76 	for (trv = path; *trv != '\0'; ++trv)
     77 		continue;
     78 
     79 	if (trv - path >= MAXPATHLEN) {
     80 		errno = ENAMETOOLONG;
     81 		return 0;
     82 	}
     83 	trv -= slen;
     84 	suffp = trv;
     85 	--trv;
     86 	if (trv < path || NULL != strchr(suffp, '/')) {
     87 		errno = EINVAL;
     88 		return 0;
     89 	}
     90 
     91 	/* Fill space with random characters */
     92 	while (trv >= path && *trv == 'X') {
     93 		r = arc4random_uniform((unsigned int)(sizeof(padchar) - 1));
     94 		*trv-- = padchar[r];
     95 	}
     96 	start = trv + 1;
     97 
     98 	/* save first combination of random characters */
     99 	memcpy(carrybuf, start, (size_t)(suffp - start));
    100 
    101 	/*
    102 	 * check the target directory.
    103 	 */
    104 	if (doopen != NULL || domkdir) {
    105 		for (; trv > path; --trv) {
    106 			if (*trv == '/') {
    107 				*trv = '\0';
    108 				rval = stat(path, &sbuf);
    109 				*trv = '/';
    110 				if (rval != 0)
    111 					return 0;
    112 				if (!S_ISDIR(sbuf.st_mode)) {
    113 					errno = ENOTDIR;
    114 					return 0;
    115 				}
    116 				break;
    117 			}
    118 		}
    119 	}
    120 
    121 	for (;;) {
    122 		if (doopen) {
    123 			if ((*doopen = open(path, O_CREAT|O_EXCL|O_RDWR|oflags,
    124 			    0600)) != -1)
    125 				return 1;
    126 			if (errno != EEXIST)
    127 				return 0;
    128 		} else if (domkdir) {
    129 			if (mkdir(path, 0700) != -1)
    130 				return 1;
    131 			if (errno != EEXIST)
    132 				return 0;
    133 		} else if (lstat(path, &sbuf))
    134 			return errno == ENOENT;
    135 
    136 		/*
    137 		 * If we have a collision,
    138 		 * cycle through the space of filenames
    139 		 */
    140 		for (trv = start, carryp = carrybuf;;) {
    141 			/* have we tried all possible permutations? */
    142 			if (trv == suffp)
    143 				return 0; /* yes - exit with EEXIST */
    144 			pad = strchr((const char *)padchar, *trv);
    145 			if (pad == NULL) {
    146 				/* this should never happen */
    147 				errno = EIO;
    148 				return 0;
    149 			}
    150 			/* increment character */
    151 			*trv = (*++pad == '\0') ? padchar[0] : *pad;
    152 			/* carry to next position? */
    153 			if (*trv == *carryp) {
    154 				/* increment position and loop */
    155 				++trv;
    156 				++carryp;
    157 			} else {
    158 				/* try with new name */
    159 				break;
    160 			}
    161 		}
    162 	}
    163 	/*NOTREACHED*/
    164 }
    165 
    166 #endif /* !HAVE_NBTOOL_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP */
    167