lib/libc/stdio/gettemp.c

   1 /*      $NetBSD: gettemp.c,v 1.20 2015/02/05 16:05:20 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 1.20 2015/02/05 16:05:20 christos Exp $");
  42 #endif
  43 #endif /* LIBC_SCCS and not lint */
  44
  45 #include <sys/param.h>
  46 #include <fcntl.h>
  47 #include <string.h>
  48
  49 static const unsigned char padchar[] =
  50 "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
  51
  52 int
  53 GETTEMP(char *path, int *doopen, int domkdir, int slen, int oflags)
  54 {
  55         char *start, *trv, *suffp, *carryp;
  56         char *pad;
  57         struct stat sbuf;
  58         int rval;
  59         uint32_t r;
  60         char carrybuf[MAXPATHLEN];
  61
  62         _DIAGASSERT(path != NULL);
  63         /* doopen may be NULL */
  64         if ((doopen != NULL && domkdir) || slen < 0 ||
  65             (oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK | O_EXLOCK | O_SYNC |
  66             O_CLOEXEC)) != 0) {
  67                 errno = EINVAL;
  68                 return 0;
  69         }
  70
  71         for (trv = path; *trv != '\0'; ++trv)
  72                 continue;
  73
  74         if (trv - path >= MAXPATHLEN) {
  75                 errno = ENAMETOOLONG;
  76                 return 0;
  77         }
  78         trv -= slen;
  79         suffp = trv;
  80         --trv;
  81         if (trv < path || NULL != strchr(suffp, '/')) {
  82                 errno = EINVAL;
  83                 return 0;
  84         }
  85
  86         /* Fill space with random characters */
  87         while (trv >= path && *trv == 'X') {
  88                 r = arc4random_uniform((unsigned int)(sizeof(padchar) - 1));
  89                 *trv-- = padchar[r];
  90         }
  91         start = trv + 1;
  92
  93         /* save first combination of random characters */
  94         memcpy(carrybuf, start, (size_t)(suffp - start));
  95
  96         /*
  97          * check the target directory.
  98          */
  99         if (doopen != NULL || domkdir) {
 100                 for (; trv > path; --trv) {
 101                         if (*trv == '/') {
 102                                 *trv = '\0';
 103                                 rval = stat(path, &sbuf);
 104                                 *trv = '/';
 105                                 if (rval != 0)
 106                                         return 0;
 107                                 if (!S_ISDIR(sbuf.st_mode)) {
 108                                         errno = ENOTDIR;
 109                                         return 0;
 110                                 }
 111                                 break;
 112                         }
 113                 }
 114         }
 115
 116         for (;;) {
 117                 if (doopen) {
 118                         if ((*doopen = open(path, O_CREAT|O_EXCL|O_RDWR|oflags,
 119                             0600)) != -1)
 120                                 return 1;
 121                         if (errno != EEXIST)
 122                                 return 0;
 123                 } else if (domkdir) {
 124                         if (mkdir(path, 0700) != -1)
 125                                 return 1;
 126                         if (errno != EEXIST)
 127                                 return 0;
 128                 } else if (lstat(path, &sbuf))
 129                         return errno == ENOENT;
 130
 131                 /*
 132                  * If we have a collision,
 133                  * cycle through the space of filenames
 134                  */
 135                 for (trv = start, carryp = carrybuf;;) {
 136                         /* have we tried all possible permutations? */
 137                         if (trv == suffp)
 138                                 return 0; /* yes - exit with EEXIST */
 139                         pad = strchr((const char *)padchar, *trv);
 140                         if (pad == NULL) {
 141                                 /* this should never happen */
 142                                 errno = EIO;
 143                                 return 0;
 144                         }
 145                         /* increment character */
 146                         *trv = (*++pad == '\0') ? padchar[0] : *pad;
 147                         /* carry to next position? */
 148                         if (*trv == *carryp) {
 149                                 /* increment position and loop */
 150                                 ++trv;
 151                                 ++carryp;
 152                         } else {
 153                                 /* try with new name */
 154                                 break;
 155                         }
 156                 }
 157         }
 158         /*NOTREACHED*/
 159 }
 160
 161 #endif /* !HAVE_NBTOOL_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP */