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mktemp.c revision 1.8 
      1 /*	$NetBSD: mktemp.c,v 1.8 1997/07/07 17:47:00 phil 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 1.8 1997/07/07 17:47:00 phil 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 __warn_references(mktemp,
     70     "warning: mktemp() possibly used unsafely, consider using mkstemp()");
     71 
     72 char *
     73 mktemp(path)
     74 	char *path;
     75 {
     76 	return (_gettemp(path, (int *)NULL) ? path : (char *)NULL);
     77 }
     78 
     79 static int
     80 _gettemp(path, doopen)
     81 	char *path;
     82 	register int *doopen;
     83 {
     84 	extern int errno;
     85 	register char *start, *trv;
     86 	struct stat sbuf;
     87 	u_int pid;
     88 
     89 	/* To guarantee multiple calls generate unique names even if
     90 	   the file is not created. 676 different possibilities with 7
     91 	   or more X's, 26 with 6 or less. */
     92 	static char xtra[2] = "aa";
     93 	int xcnt = 0;
     94 
     95 	pid = getpid();
     96 
     97 	/* Move to end of path and count trailing X's. */
     98 	for (trv = path; *trv; ++trv)
     99 		if (*trv == 'X')
    100 			xcnt++;
    101 		else
    102 			xcnt = 0;
    103 
    104 	/* Use at least one from xtra.  Use 2 if more than 6 X's. */
    105 	if (*(trv-1) == 'X')
    106 		*--trv = xtra[0];
    107 	if (xcnt > 6 && *(trv-1) == 'X')
    108 		*--trv = xtra[1];
    109 
    110 	/* Set remaining X's to pid digits with 0's to the left. */
    111 	while (*--trv == 'X') {
    112 		*trv = (pid % 10) + '0';
    113 		pid /= 10;
    114 	}
    115 
    116 	/* update xtra for next call. */
    117 	if (xtra[0] != 'z')
    118 		xtra[0]++;
    119 	else {
    120 		xtra[0] = 'a';
    121 		if (xtra[1] != 'z')
    122 			xtra[1]++;
    123 		else
    124 			xtra[1] = 'a';
    125 	}
    126 
    127 	/*
    128 	 * check the target directory; if you have six X's and it
    129 	 * doesn't exist this runs for a *very* long time.
    130 	 */
    131 	for (start = trv + 1;; --trv) {
    132 		if (trv <= path)
    133 			break;
    134 		if (*trv == '/') {
    135 			*trv = '\0';
    136 			if (stat(path, &sbuf))
    137 				return (0);
    138 			if (!S_ISDIR(sbuf.st_mode)) {
    139 				errno = ENOTDIR;
    140 				return (0);
    141 			}
    142 			*trv = '/';
    143 			break;
    144 		}
    145 	}
    146 
    147 	for (;;) {
    148 		if (doopen) {
    149 			if ((*doopen =
    150 			    open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
    151 				return (1);
    152 			if (errno != EEXIST)
    153 				return (0);
    154 		}
    155 		else if (lstat(path, &sbuf))
    156 			return (errno == ENOENT ? 1 : 0);
    157 
    158 		/* tricky little algorithm for backward compatibility */
    159 		for (trv = start;;) {
    160 			if (!*trv)
    161 				return (0);
    162 			if (*trv == 'z')
    163 				*trv++ = 'a';
    164 			else {
    165 				if (isdigit(*trv))
    166 					*trv = 'a';
    167 				else
    168 					++*trv;
    169 				break;
    170 			}
    171 		}
    172 	}
    173 	/*NOTREACHED*/
    174 }
    175