Home | History | Annotate | Line # | Download | only in stdio
gettemp.c revision 1.21 
      1 /*	$NetBSD: gettemp.c,v 1.21 2017/01/10 17:45:12 christos 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 1.21 2017/01/10 17:45:12 christos 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 static const unsigned char padchar[] =
     51 "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
     52 
     53 int
     54 GETTEMP(char *path, int *doopen, int domkdir, int slen, int oflags)
     55 {
     56 	char *start, *trv, *suffp, *carryp;
     57 	char *pad;
     58 	struct stat sbuf;
     59 	int rval;
     60 	uint32_t r;
     61 	char carrybuf[MAXPATHLEN];
     62 
     63 	_DIAGASSERT(path != NULL);
     64 	/* doopen may be NULL */
     65 	if ((doopen != NULL && domkdir) || slen < 0 ||
     66 	    (oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK | O_EXLOCK | O_SYNC |
     67 	    O_CLOEXEC)) != 0) {
     68 		errno = EINVAL;
     69 		return 0;
     70 	}
     71 
     72 	for (trv = path; *trv != '\0'; ++trv)
     73 		continue;
     74 
     75 	if (trv - path >= MAXPATHLEN) {
     76 		errno = ENAMETOOLONG;
     77 		return 0;
     78 	}
     79 	trv -= slen;
     80 	suffp = trv;
     81 	--trv;
     82 	if (trv < path || NULL != strchr(suffp, '/')) {
     83 		errno = EINVAL;
     84 		return 0;
     85 	}
     86 
     87 	/* Fill space with random characters */
     88 	while (trv >= path && *trv == 'X') {
     89 		r = arc4random_uniform((unsigned int)(sizeof(padchar) - 1));
     90 		*trv-- = padchar[r];
     91 	}
     92 	start = trv + 1;
     93 
     94 	/* save first combination of random characters */
     95 	memcpy(carrybuf, start, (size_t)(suffp - start));
     96 
     97 	/*
     98 	 * check the target directory.
     99 	 */
    100 	if (doopen != NULL || domkdir) {
    101 		for (; trv > path; --trv) {
    102 			if (*trv == '/') {
    103 				*trv = '\0';
    104 				rval = stat(path, &sbuf);
    105 				*trv = '/';
    106 				if (rval != 0)
    107 					return 0;
    108 				if (!S_ISDIR(sbuf.st_mode)) {
    109 					errno = ENOTDIR;
    110 					return 0;
    111 				}
    112 				break;
    113 			}
    114 		}
    115 	}
    116 
    117 	for (;;) {
    118 		if (doopen) {
    119 			if ((*doopen = open(path, O_CREAT|O_EXCL|O_RDWR|oflags,
    120 			    0600)) != -1)
    121 				return 1;
    122 			if (errno != EEXIST)
    123 				return 0;
    124 		} else if (domkdir) {
    125 			if (mkdir(path, 0700) != -1)
    126 				return 1;
    127 			if (errno != EEXIST)
    128 				return 0;
    129 		} else if (lstat(path, &sbuf))
    130 			return errno == ENOENT;
    131 
    132 		/*
    133 		 * If we have a collision,
    134 		 * cycle through the space of filenames
    135 		 */
    136 		for (trv = start, carryp = carrybuf;;) {
    137 			/* have we tried all possible permutations? */
    138 			if (trv == suffp)
    139 				return 0; /* yes - exit with EEXIST */
    140 			pad = strchr((const char *)padchar, *trv);
    141 			if (pad == NULL) {
    142 				/* this should never happen */
    143 				errno = EIO;
    144 				return 0;
    145 			}
    146 			/* increment character */
    147 			*trv = (*++pad == '\0') ? padchar[0] : *pad;
    148 			/* carry to next position? */
    149 			if (*trv == *carryp) {
    150 				/* increment position and loop */
    151 				++trv;
    152 				++carryp;
    153 			} else {
    154 				/* try with new name */
    155 				break;
    156 			}
    157 		}
    158 	}
    159 	/*NOTREACHED*/
    160 }
    161 
    162 #endif /* !HAVE_NBTOOL_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP */
    163