clib/mkstemp.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 #include "config.h"
  35
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 static const char sccsid[] = "@(#)mktemp.c      8.1 (Berkeley) 6/4/93";
  38 #endif /* LIBC_SCCS and not lint */
  39
  40 #include <sys/types.h>
  41 #include <sys/stat.h>
  42 #include <fcntl.h>
  43 #include <errno.h>
  44 #include <stdio.h>
  45 #include <ctype.h>
  46
  47 static int _gettemp();
  48
  49 /*
  50  * PUBLIC: #ifndef HAVE_MKSTEMP
  51  * PUBLIC: int mkstemp __P((char *));
  52  * PUBLIC: #endif
  53  */
  54 mkstemp(path)
  55         char *path;
  56 {
  57         int fd;
  58
  59         return (_gettemp(path, &fd) ? fd : -1);
  60 }
  61
  62 char *
  63 mktemp(path)
  64         char *path;
  65 {
  66         return(_gettemp(path, (int *)NULL) ? path : (char *)NULL);
  67 }
  68
  69 static
  70 _gettemp(path, doopen)
  71         char *path;
  72         register int *doopen;
  73 {
  74         extern int errno;
  75         register char *start, *trv;
  76         struct stat sbuf;
  77         u_int pid;
  78
  79         pid = getpid();
  80         for (trv = path; *trv; ++trv);          /* extra X's get set to 0's */
  81         while (*--trv == 'X') {
  82                 *trv = (pid % 10) + '0';
  83                 pid /= 10;
  84         }
  85
  86         /*
  87          * check the target directory; if you have six X's and it
  88          * doesn't exist this runs for a *very* long time.
  89          */
  90         for (start = trv + 1;; --trv) {
  91                 if (trv <= path)
  92                         break;
  93                 if (*trv == '/') {
  94                         *trv = '\0';
  95                         if (stat(path, &sbuf))
  96                                 return(0);
  97                         if (!S_ISDIR(sbuf.st_mode)) {
  98                                 errno = ENOTDIR;
  99                                 return(0);
 100                         }
 101                         *trv = '/';
 102                         break;
 103                 }
 104         }
 105
 106         for (;;) {
 107                 if (doopen) {
 108                         if ((*doopen =
 109                             open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
 110                                 return(1);
 111                         if (errno != EEXIST)
 112                                 return(0);
 113                 }
 114                 else if (stat(path, &sbuf))
 115                         return(errno == ENOENT ? 1 : 0);
 116
 117                 /* tricky little algorithm for backward compatibility */
 118                 for (trv = start;;) {
 119                         if (!*trv)
 120                                 return(0);
 121                         if (*trv == 'z')
 122                                 *trv++ = 'a';
 123                         else {
 124                                 if (isdigit(*trv))
 125                                         *trv = 'a';
 126                                 else
 127                                         ++*trv;
 128                                 break;
 129                         }
 130                 }
 131         }
 132         /*NOTREACHED*/
 133 }