lib/libc/stdio/mktemp.c

   1 /*
   2  * Copyright (c) 1987, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)mktemp.c 8.1 (Berkeley) 6/4/93
  30  * $FreeBSD: src/lib/libc/stdio/mktemp.c,v 1.31 2008/07/28 21:18:59 jhb Exp $
  31  * $DragonFly: src/lib/libc/stdio/mktemp.c,v 1.7 2005/11/20 11:07:30 swildner Exp $
  32  */
  33
  34 #include "namespace.h"
  35 #include <sys/param.h>
  36 #include <sys/stat.h>
  37 #include <fcntl.h>
  38 #include <errno.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42 #include <ctype.h>
  43 #include <unistd.h>
  44 #include "un-namespace.h"
  45
  46 char *_mktemp(char *);
  47
  48 static int _gettemp(char *, int *, int, int);
  49
  50 static const unsigned char padchar[] =
  51 "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
  52
  53 int
  54 mkstemps(char *path, int slen)
  55 {
  56         int fd;
  57
  58         return (_gettemp(path, &fd, 0, slen) ? fd : -1);
  59 }
  60
  61 int
  62 mkstemp(char *path)
  63 {
  64         int fd;
  65
  66         return (_gettemp(path, &fd, 0, 0) ? fd : -1);
  67 }
  68
  69 char *
  70 mkdtemp(char *path)
  71 {
  72         return (_gettemp(path, NULL, 1, 0) ? path : NULL);
  73 }
  74
  75 char *
  76 _mktemp(char *path)
  77 {
  78         return (_gettemp(path, NULL, 0, 0) ? path : NULL);
  79 }
  80
  81 __warn_references(mktemp,
  82     "warning: mktemp() possibly used unsafely; consider using mkstemp()");
  83
  84 char *
  85 mktemp(char *path)
  86 {
  87         return (_mktemp(path));
  88 }
  89
  90 static int
  91 _gettemp(char *path, int *doopen, int domkdir, int slen)
  92 {
  93         char *start, *trv, *suffp, *carryp;
  94         char *pad;
  95         struct stat sbuf;
  96         int rval;
  97         uint32_t rand;
  98         char carrybuf[MAXPATHLEN];
  99
 100         if ((doopen != NULL && domkdir) || slen < 0) {
 101                 errno = EINVAL;
 102                 return (0);
 103         }
 104
 105         for (trv = path; *trv != '\0'; ++trv)
 106                 ;
 107         trv -= slen;
 108         suffp = trv;
 109         --trv;
 110         if (trv < path || NULL != strchr(suffp, '/')) {
 111                 errno = EINVAL;
 112                 return (0);
 113         }
 114
 115         /* Fill space with random characters */
 116         while (trv >= path && *trv == 'X') {
 117                 rand = arc4random_uniform(sizeof(padchar) - 1);
 118                 *trv-- = padchar[rand];
 119         }
 120         start = trv + 1;
 121
 122         /* save first combination of random characters */
 123         memcpy(carrybuf, start, suffp - start);
 124
 125         /*
 126          * check the target directory.
 127          */
 128         if (doopen != NULL || domkdir) {
 129                 for (; trv > path; --trv) {
 130                         if (*trv == '/') {
 131                                 *trv = '\0';
 132                                 rval = stat(path, &sbuf);
 133                                 *trv = '/';
 134                                 if (rval != 0)
 135                                         return (0);
 136                                 if (!S_ISDIR(sbuf.st_mode)) {
 137                                         errno = ENOTDIR;
 138                                         return (0);
 139                                 }
 140                                 break;
 141                         }
 142                 }
 143         }
 144
 145         for (;;) {
 146                 if (doopen) {
 147                         if ((*doopen =
 148                             _open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
 149                                 return (1);
 150                         if (errno != EEXIST)
 151                                 return (0);
 152                 } else if (domkdir) {
 153                         if (mkdir(path, 0700) == 0)
 154                                 return (1);
 155                         if (errno != EEXIST)
 156                                 return (0);
 157                 } else if (lstat(path, &sbuf))
 158                         return (errno == ENOENT);
 159
 160                 /* If we have a collision, cycle through the space of filenames */
 161                 for (trv = start, carryp = carrybuf;;) {
 162                         /* have we tried all possible permutations? */
 163                         if (trv == suffp)
 164                                 return (0); /* yes - exit with EEXIST */
 165                         pad = strchr(padchar, *trv);
 166                         if (pad == NULL) {
 167                                 /* this should never happen */
 168                                 errno = EIO;
 169                                 return (0);
 170                         }
 171                         /* increment character */
 172                         *trv = (*++pad == '\0') ? padchar[0] : *pad;
 173                         /* carry to next position? */
 174                         if (*trv == *carryp) {
 175                                 /* increment position and loop */
 176                                 ++trv;
 177                                 ++carryp;
 178                         } else {
 179                                 /* try with new name */
 180                                 break;
 181                         }
 182                 }
 183         }
 184         /*NOTREACHED*/
 185 }