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