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mktemp.c revision 1.12 
      1 /*	$NetBSD: mktemp.c,v 1.12 1998/06/01 20:17:50 kleink 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 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)mktemp.c	8.1 (Berkeley) 6/4/93";
     40 #else
     41 __RCSID("$NetBSD: mktemp.c,v 1.12 1998/06/01 20:17:50 kleink Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include <sys/types.h>
     46 #include <sys/stat.h>
     47 #include <fcntl.h>
     48 #include <errno.h>
     49 #include <stdio.h>
     50 #include <stdlib.h>
     51 #include <ctype.h>
     52 #include <unistd.h>
     53 #include <errno.h>
     54 #include "local.h"
     55 
     56 static int _gettemp __P((char *, int *));
     57 
     58 int
     59 mkstemp(path)
     60 	char *path;
     61 {
     62 	int fd;
     63 
     64 	return (_gettemp(path, &fd) ? fd : -1);
     65 }
     66 
     67 char *
     68 _mktemp(path)
     69 	char *path;
     70 {
     71 	return (_gettemp(path, (int *)NULL) ? path : (char *)NULL);
     72 }
     73 
     74 __warn_references(mktemp,
     75     "warning: mktemp() possibly used unsafely, consider using mkstemp()")
     76 
     77 char *
     78 mktemp(path)
     79 	char *path;
     80 {
     81 	return (_gettemp(path, (int *)NULL) ? path : (char *)NULL);
     82 }
     83 
     84 static int
     85 _gettemp(path, doopen)
     86 	char *path;
     87 	int *doopen;
     88 {
     89 	char *start, *trv;
     90 	struct stat sbuf;
     91 	u_int pid;
     92 
     93 	/* To guarantee multiple calls generate unique names even if
     94 	   the file is not created. 676 different possibilities with 7
     95 	   or more X's, 26 with 6 or less. */
     96 	static char xtra[2] = "aa";
     97 	int xcnt = 0;
     98 
     99 	pid = getpid();
    100 
    101 	/* Move to end of path and count trailing X's. */
    102 	for (trv = path; *trv; ++trv)
    103 		if (*trv == 'X')
    104 			xcnt++;
    105 		else
    106 			xcnt = 0;
    107 
    108 	/* Use at least one from xtra.  Use 2 if more than 6 X's. */
    109 	if (*(trv-1) == 'X')
    110 		*--trv = xtra[0];
    111 	if (xcnt > 6 && *(trv-1) == 'X')
    112 		*--trv = xtra[1];
    113 
    114 	/* Set remaining X's to pid digits with 0's to the left. */
    115 	while (*--trv == 'X') {
    116 		*trv = (pid % 10) + '0';
    117 		pid /= 10;
    118 	}
    119 
    120 	/* update xtra for next call. */
    121 	if (xtra[0] != 'z')
    122 		xtra[0]++;
    123 	else {
    124 		xtra[0] = 'a';
    125 		if (xtra[1] != 'z')
    126 			xtra[1]++;
    127 		else
    128 			xtra[1] = 'a';
    129 	}
    130 
    131 	/*
    132 	 * check the target directory; if you have six X's and it
    133 	 * doesn't exist this runs for a *very* long time.
    134 	 */
    135 	for (start = trv + 1;; --trv) {
    136 		if (trv <= path)
    137 			break;
    138 		if (*trv == '/') {
    139 			*trv = '\0';
    140 			if (stat(path, &sbuf))
    141 				return (0);
    142 			if (!S_ISDIR(sbuf.st_mode)) {
    143 				errno = ENOTDIR;
    144 				return (0);
    145 			}
    146 			*trv = '/';
    147 			break;
    148 		}
    149 	}
    150 
    151 	for (;;) {
    152 		if (doopen) {
    153 			if ((*doopen =
    154 			    open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
    155 				return (1);
    156 			if (errno != EEXIST)
    157 				return (0);
    158 		}
    159 		else if (lstat(path, &sbuf))
    160 			return (errno == ENOENT ? 1 : 0);
    161 
    162 		/* tricky little algorithm for backward compatibility */
    163 		for (trv = start;;) {
    164 			if (!*trv)
    165 				return (0);
    166 			if (*trv == 'z')
    167 				*trv++ = 'a';
    168 			else {
    169 				if (isdigit(*trv))
    170 					*trv = 'a';
    171 				else
    172 					++*trv;
    173 				break;
    174 			}
    175 		}
    176 	}
    177 	/*NOTREACHED*/
    178 }
    179