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mktemp.c revision 1.5 
      1 /*	$NetBSD: mktemp.c,v 1.5 1995/02/02 02:10:09 jtc 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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #if defined(LIBC_SCCS) && !defined(lint)
     37 #if 0
     38 static char sccsid[] = "@(#)mktemp.c	8.1 (Berkeley) 6/4/93";
     39 #endif
     40 static char rcsid[] = "$NetBSD: mktemp.c,v 1.5 1995/02/02 02:10:09 jtc Exp $";
     41 #endif /* LIBC_SCCS and not lint */
     42 
     43 #include <sys/types.h>
     44 #include <sys/stat.h>
     45 #include <fcntl.h>
     46 #include <errno.h>
     47 #include <stdio.h>
     48 #include <ctype.h>
     49 #include <unistd.h>
     50 
     51 static int _gettemp();
     52 
     53 int
     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 int
     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 }
    134