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  * 3. 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, 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, 0) ? fd : -1);
  59 }
  60
  61 int
  62 mkostemps(char *path, int slen, int oflags)
  63 {
  64         int fd;
  65
  66         return (_gettemp(path, &fd, 0, slen, oflags) ? fd : -1);
  67 }
  68
  69 int
  70 mkstemp(char *path)
  71 {
  72         int fd;
  73
  74         return (_gettemp(path, &fd, 0, 0, 0) ? fd : -1);
  75 }
  76
  77 int
  78 mkostemp(char *path, int oflags)
  79 {
  80         int fd;
  81
  82         return (_gettemp(path, &fd, 0, 0, oflags) ? fd : -1);
  83 }
  84
  85 char *
  86 mkdtemp(char *path)
  87 {
  88         return (_gettemp(path, NULL, 1, 0, 0) ? path : NULL);
  89 }
  90
  91 char *
  92 _mktemp(char *path)
  93 {
  94         return (_gettemp(path, NULL, 0, 0, 0) ? path : NULL);
  95 }
  96
  97 __warn_references(mktemp,
  98     "warning: mktemp() possibly used unsafely; consider using mkstemp()");
  99
 100 char *
 101 mktemp(char *path)
 102 {
 103         return (_mktemp(path));
 104 }
 105
 106 static int
 107 _gettemp(char *path, int *doopen, int domkdir, int slen, int oflags)
 108 {
 109         char *start, *trv, *suffp, *carryp;
 110         char *pad;
 111         struct stat sbuf;
 112         int rval;
 113         uint32_t rand;
 114         char carrybuf[MAXPATHLEN];
 115
 116         if ((oflags & ~(O_APPEND | O_DIRECT | O_SHLOCK |
 117                         O_EXLOCK | O_SYNC | O_CLOEXEC)) != 0) {
 118                 errno = EINVAL;
 119                 return (0);
 120         }
 121         if ((doopen != NULL && domkdir) || slen < 0) {
 122                 errno = EINVAL;
 123                 return (0);
 124         }
 125
 126         for (trv = path; *trv != '\0'; ++trv)
 127                 ;
 128         trv -= slen;
 129         suffp = trv;
 130         --trv;
 131         if (trv < path || NULL != strchr(suffp, '/')) {
 132                 errno = EINVAL;
 133                 return (0);
 134         }
 135
 136         /* Fill space with random characters */
 137         while (trv >= path && *trv == 'X') {
 138                 rand = arc4random_uniform(sizeof(padchar) - 1);
 139                 *trv-- = padchar[rand];
 140         }
 141         start = trv + 1;
 142
 143         /* save first combination of random characters */
 144         memcpy(carrybuf, start, suffp - start);
 145
 146         /*
 147          * check the target directory.
 148          */
 149         if (doopen != NULL || domkdir) {
 150                 for (; trv > path; --trv) {
 151                         if (*trv == '/') {
 152                                 *trv = '\0';
 153                                 rval = stat(path, &sbuf);
 154                                 *trv = '/';
 155                                 if (rval != 0)
 156                                         return (0);
 157                                 if (!S_ISDIR(sbuf.st_mode)) {
 158                                         errno = ENOTDIR;
 159                                         return (0);
 160                                 }
 161                                 break;
 162                         }
 163                 }
 164         }
 165
 166         for (;;) {
 167                 if (doopen) {
 168                         if ((*doopen =
 169                             _open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
 170                                 return (1);
 171                         if (errno != EEXIST)
 172                                 return (0);
 173                 } else if (domkdir) {
 174                         if (mkdir(path, 0700) == 0)
 175                                 return (1);
 176                         if (errno != EEXIST)
 177                                 return (0);
 178                 } else if (lstat(path, &sbuf))
 179                         return (errno == ENOENT);
 180
 181                 /* If we have a collision, cycle through the space of filenames */
 182                 for (trv = start, carryp = carrybuf;;) {
 183                         /* have we tried all possible permutations? */
 184                         if (trv == suffp)
 185                                 return (0); /* yes - exit with EEXIST */
 186                         pad = strchr(padchar, *trv);
 187                         if (pad == NULL) {
 188                                 /* this should never happen */
 189                                 errno = EIO;
 190                                 return (0);
 191                         }
 192                         /* increment character */
 193                         *trv = (*++pad == '\0') ? padchar[0] : *pad;
 194                         /* carry to next position? */
 195                         if (*trv == *carryp) {
 196                                 /* increment position and loop */
 197                                 ++trv;
 198                                 ++carryp;
 199                         } else {
 200                                 /* try with new name */
 201                                 break;
 202                         }
 203                 }
 204         }
 205         /*NOTREACHED*/
 206 }