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. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)mktemp.c    8.1 (Berkeley) 6/4/93";
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 #include <sys/types.h>
  39 #include <sys/stat.h>
  40 #include <fcntl.h>
  41 #include <errno.h>
  42 #include <stdio.h>
  43 #include <ctype.h>
  44 #include <unistd.h>
  45 #include <stdlib.h>
  46
  47 static int _gettemp(char*,int*);
  48
  49 mkstemp(path)
  50         char *path;
  51 {
  52         int fd;
  53
  54         return (_gettemp(path, &fd) ? fd : -1);
  55 }
  56
  57 char *
  58 mktemp(path)
  59         char *path;
  60 {
  61         return(_gettemp(path, (int *)NULL) ? path : (char *)NULL);
  62 }
  63
  64 static
  65 _gettemp(path, doopen)
  66         char *path;
  67         register int *doopen;
  68 {
  69         extern int errno;
  70         register char *start, *trv;
  71         struct stat sbuf;
  72         u_int pid;
  73
  74         pid = getpid();
  75         for (trv = path; *trv; ++trv);          /* extra X's get set to 0's */
  76         while (*--trv == 'X') {
  77                 *trv = (pid % 10) + '0';
  78                 pid /= 10;
  79         }
  80
  81         /*
  82          * check the target directory; if you have six X's and it
  83          * doesn't exist this runs for a *very* long time.
  84          */
  85         for (start = trv + 1;; --trv) {
  86                 if (trv <= path)
  87                         break;
  88                 if (*trv == '/') {
  89                         *trv = '\0';
  90                         if (stat(path, &sbuf))
  91                                 return(0);
  92                         if (!S_ISDIR(sbuf.st_mode)) {
  93                                 errno = ENOTDIR;
  94                                 return(0);
  95                         }
  96                         *trv = '/';
  97                         break;
  98                 }
  99         }
 100
 101         for (;;) {
 102                 if (doopen) {
 103                         if ((*doopen =
 104                             open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
 105                                 return(1);
 106                         if (errno != EEXIST)
 107                                 return(0);
 108                 }
 109                 else if (stat(path, &sbuf))
 110                         return(errno == ENOENT ? 1 : 0);
 111
 112                 /* tricky little algorithm for backward compatibility */
 113                 for (trv = start;;) {
 114                         if (!*trv)
 115                                 return(0);
 116                         if (*trv == 'z')
 117                                 *trv++ = 'a';
 118                         else {
 119                                 if (isdigit(*trv))
 120                                         *trv = 'a';
 121                                 else
 122                                         ++*trv;
 123                                 break;
 124                         }
 125                 }
 126         }
 127         /*NOTREACHED*/
 128 }
 129
 130 /*
 131  * $PchId: mktemp.c,v 1.3 1995/11/20 19:10:39 philip Exp $
 132  */