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mktemp.c revision 1.4 
      1 /*
      2  * Copyright (c) 1987 Regents of the University of California.
      3  * 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 = "from: @(#)mktemp.c	5.10 (Berkeley) 2/24/91";*/
     36 static char *rcsid = "$Id: mktemp.c,v 1.4 1993/11/11 19:04:43 jtc Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/types.h>
     40 #include <sys/stat.h>
     41 #include <fcntl.h>
     42 #include <errno.h>
     43 #include <stdio.h>
     44 #include <ctype.h>
     45 #include <unistd.h>
     46 
     47 static int _gettemp();
     48 
     49 int
     50 mkstemp(path)
     51 	char *path;
     52 {
     53 	int fd;
     54 
     55 	return (_gettemp(path, &fd) ? fd : -1);
     56 }
     57 
     58 char *
     59 mktemp(path)
     60 	char *path;
     61 {
     62 	return(_gettemp(path, (int *)NULL) ? path : (char *)NULL);
     63 }
     64 
     65 static int
     66 _gettemp(path, doopen)
     67 	char *path;
     68 	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 }
    130