lib/libc/stdio/gettemp.c

   1 /*      $NetBSD: gettemp.c,v 1.16 2013/04/22 20:57:36 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 #if HAVE_NBTOOL_CONFIG_H
  33 #include "nbtool_config.h"
  34 #endif
  35
  36 #if !HAVE_NBTOOL_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP
  37
  38 #include <sys/cdefs.h>
  39 #if defined(LIBC_SCCS) && !defined(lint)
  40 #if 0
  41 static char sccsid[] = "@(#)mktemp.c    8.1 (Berkeley) 6/4/93";
  42 #else
  43 __RCSID("$NetBSD: gettemp.c,v 1.16 2013/04/22 20:57:36 christos Exp $");
  44 #endif
  45 #endif /* LIBC_SCCS and not lint */
  46
  47 #include <sys/types.h>
  48 #include <sys/stat.h>
  49
  50 #include <assert.h>
  51 #include <ctype.h>
  52 #include <errno.h>
  53 #include <fcntl.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <unistd.h>
  57
  58 #if HAVE_NBTOOL_CONFIG_H
  59 #define GETTEMP         __nbcompat_gettemp
  60 #else
  61 #include "reentrant.h"
  62 #include "local.h"
  63 #define GETTEMP         __gettemp
  64 #endif
  65
  66 int
  67 GETTEMP(char *path, int *doopen, int domkdir)
  68 {
  69         char *start, *trv;
  70         struct stat sbuf;
  71         u_int pid;
  72
  73         /* To guarantee multiple calls generate unique names even if
  74            the file is not created. 676 different possibilities with 7
  75            or more X's, 26 with 6 or less. */
  76         static char xtra[2] = "aa";
  77         int xcnt = 0;
  78
  79         _DIAGASSERT(path != NULL);
  80         /* doopen may be NULL */
  81
  82         pid = getpid();
  83
  84         /* Move to end of path and count trailing X's. */
  85         for (trv = path; *trv; ++trv)
  86                 if (*trv == 'X')
  87                         xcnt++;
  88                 else
  89                         xcnt = 0;
  90
  91         /* Use at least one from xtra.  Use 2 if more than 6 X's. */
  92         if (*(trv - 1) == 'X')
  93                 *--trv = xtra[0];
  94         if (xcnt > 6 && *(trv - 1) == 'X')
  95                 *--trv = xtra[1];
  96
  97         /* Set remaining X's to pid digits with 0's to the left. */
  98         while (*--trv == 'X') {
  99                 *trv = (pid % 10) + '0';
 100                 pid /= 10;
 101         }
 102
 103         /* update xtra for next call. */
 104         if (xtra[0] != 'z')
 105                 xtra[0]++;
 106         else {
 107                 xtra[0] = 'a';
 108                 if (xtra[1] != 'z')
 109                         xtra[1]++;
 110                 else
 111                         xtra[1] = 'a';
 112         }
 113
 114         /*
 115          * check the target directory; if you have six X's and it
 116          * doesn't exist this runs for a *very* long time.
 117          */
 118         for (start = trv + 1;; --trv) {
 119                 if (trv <= path)
 120                         break;
 121                 if (*trv == '/') {
 122                         int e;
 123                         *trv = '\0';
 124                         e = stat(path, &sbuf);
 125                         *trv = '/';
 126                         if (e == -1)
 127                                 return doopen == NULL && !domkdir;
 128                         if (!S_ISDIR(sbuf.st_mode)) {
 129                                 errno = ENOTDIR;
 130                                 return doopen == NULL && !domkdir;
 131                         }
 132                         break;
 133                 }
 134         }
 135
 136         for (;;) {
 137                 if (doopen) {
 138                         if ((*doopen =
 139                             open(path, O_CREAT | O_EXCL | O_RDWR, 0600)) >= 0)
 140                                 return 1;
 141                         if (errno != EEXIST)
 142                                 return 0;
 143                 } else if (domkdir) {
 144                         if (mkdir(path, 0700) >= 0)
 145                                 return 1;
 146                         if (errno != EEXIST)
 147                                 return 0;
 148                 } else if (lstat(path, &sbuf))
 149                         return errno == ENOENT ? 1 : 0;
 150
 151                 /* tricky little algorithm for backward compatibility */
 152                 for (trv = start;;) {
 153                         if (!*trv)
 154                                 return 0;
 155                         if (*trv == 'z')
 156                                 *trv++ = 'a';
 157                         else {
 158                                 if (isdigit((unsigned char)*trv))
 159                                         *trv = 'a';
 160                                 else
 161                                         ++*trv;
 162                                 break;
 163                         }
 164                 }
 165         }
 166         /*NOTREACHED*/
 167 }
 168
 169 #endif /* !HAVE_NBTOOL_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP */