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      1 /*	$OpenBSD: mktemp.c,v 1.19 2005/08/08 08:05:36 espie Exp $ */
      2 /*
      3  * Copyright (c) 1987, 1993
      4  *	The Regents of the University of California.  All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. Neither the name of the University nor the names of its contributors
     15  *    may be used to endorse or promote products derived from this software
     16  *    without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     28  * SUCH DAMAGE.
     29  */
     30 
     31 #include <sys/types.h>
     32 #include <sys/stat.h>
     33 #include <fcntl.h>
     34 #include <errno.h>
     35 #include <stdio.h>
     36 #include <stdlib.h>
     37 #include <ctype.h>
     38 #include <unistd.h>
     39 
     40 static int _gettemp(char *, int *, int, int);
     41 
     42 extern uint32_t  arc4random();
     43 
     44 int
     45 mkstemps(char *path, int slen)
     46 {
     47 	int fd;
     48 
     49 	return (_gettemp(path, &fd, 0, slen) ? fd : -1);
     50 }
     51 
     52 int
     53 mkstemp(char *path)
     54 {
     55 	int fd;
     56 
     57 	return (_gettemp(path, &fd, 0, 0) ? fd : -1);
     58 }
     59 
     60 char *
     61 mkdtemp(char *path)
     62 {
     63 	return(_gettemp(path, (int *)NULL, 1, 0) ? path : (char *)NULL);
     64 }
     65 
     66 char *_mktemp(char *);
     67 
     68 __LIBC_HIDDEN__ char *
     69 _mktemp(char *path)
     70 {
     71 	return(_gettemp(path, (int *)NULL, 0, 0) ? path : (char *)NULL);
     72 }
     73 
     74 __warn_references(mktemp,
     75     "warning: mktemp() possibly used unsafely; consider using mkstemp()");
     76 
     77 char *
     78 mktemp(char *path)
     79 {
     80 	return(_mktemp(path));
     81 }
     82 
     83 
     84 static int
     85 _gettemp(char *path, int *doopen, int domkdir, int slen)
     86 {
     87 	char *start, *trv, *suffp;
     88 	struct stat sbuf;
     89 	int rval;
     90 	pid_t pid;
     91 
     92 	if (doopen && domkdir) {
     93 		errno = EINVAL;
     94 		return(0);
     95 	}
     96 
     97 	for (trv = path; *trv; ++trv)
     98 		;
     99 	trv -= slen;
    100 	suffp = trv;
    101 	--trv;
    102 	if (trv < path) {
    103 		errno = EINVAL;
    104 		return (0);
    105 	}
    106 	pid = getpid();
    107 	while (trv >= path && *trv == 'X' && pid != 0) {
    108 		*trv-- = (pid % 10) + '0';
    109 		pid /= 10;
    110 	}
    111 	while (trv >= path && *trv == 'X') {
    112 		char c;
    113 
    114 		pid = (arc4random() & 0xffff) % (26+26);
    115 		if (pid < 26)
    116 			c = pid + 'A';
    117 		else
    118 			c = (pid - 26) + 'a';
    119 		*trv-- = c;
    120 	}
    121 	start = trv + 1;
    122 
    123 	/*
    124 	 * check the target directory; if you have six X's and it
    125 	 * doesn't exist this runs for a *very* long time.
    126 	 */
    127 	if (doopen || domkdir) {
    128 		for (;; --trv) {
    129 			if (trv <= path)
    130 				break;
    131 			if (*trv == '/') {
    132 				*trv = '\0';
    133 				rval = stat(path, &sbuf);
    134 				*trv = '/';
    135 				if (rval != 0)
    136 					return(0);
    137 				if (!S_ISDIR(sbuf.st_mode)) {
    138 					errno = ENOTDIR;
    139 					return(0);
    140 				}
    141 				break;
    142 			}
    143 		}
    144 	}
    145 
    146 	for (;;) {
    147 		if (doopen) {
    148 			if ((*doopen =
    149 			    open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
    150 				return(1);
    151 			if (errno != EEXIST)
    152 				return(0);
    153 		} else if (domkdir) {
    154 			if (mkdir(path, 0700) == 0)
    155 				return(1);
    156 			if (errno != EEXIST)
    157 				return(0);
    158 		} else if (lstat(path, &sbuf))
    159 			return(errno == ENOENT ? 1 : 0);
    160 
    161 		/* tricky little algorithm for backward compatibility */
    162 		for (trv = start;;) {
    163 			if (!*trv)
    164 				return (0);
    165 			if (*trv == 'Z') {
    166 				if (trv == suffp)
    167 					return (0);
    168 				*trv++ = 'a';
    169 			} else {
    170 				if (isdigit(*trv))
    171 					*trv = 'a';
    172 				else if (*trv == 'z')	/* inc from z to A */
    173 					*trv = 'A';
    174 				else {
    175 					if (trv == suffp)
    176 						return (0);
    177 					++*trv;
    178 				}
    179 				break;
    180 			}
    181 		}
    182 	}
    183 	/*NOTREACHED*/
    184 }
    185