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gettemp.c revision 1.10 
      1 /*	$NetBSD: gettemp.c,v 1.10 2003/08/07 16:43:27 agc 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #if HAVE_CONFIG_H
     33 #include "config.h"
     34 #endif
     35 
     36 #if !HAVE_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP
     37 
     38 #include <sys/cdefs.h>
     39 #if defined(LIBC_SCCS) && !defined(lint)
     40 #if 0
     41 static char sccsid[] = "@(#)mktemp.c	8.1 (Berkeley) 6/4/93";
     42 #else
     43 __RCSID("$NetBSD: gettemp.c,v 1.10 2003/08/07 16:43:27 agc Exp $");
     44 #endif
     45 #endif /* LIBC_SCCS and not lint */
     46 
     47 #include <sys/types.h>
     48 #include <sys/stat.h>
     49 
     50 #include <assert.h>
     51 #include <ctype.h>
     52 #include <errno.h>
     53 #include <fcntl.h>
     54 #include <stdio.h>
     55 #include <stdlib.h>
     56 #include <unistd.h>
     57 
     58 #include "reentrant.h"
     59 
     60 #if HAVE_CONFIG_H
     61 #define	GETTEMP		gettemp
     62 #else
     63 #include "local.h"
     64 #define	GETTEMP		__gettemp
     65 #endif
     66 
     67 int
     68 GETTEMP(path, doopen, domkdir)
     69 	char *path;
     70 	int *doopen;
     71 	int domkdir;
     72 {
     73 	char *start, *trv;
     74 	struct stat sbuf;
     75 	u_int pid;
     76 
     77 	/* To guarantee multiple calls generate unique names even if
     78 	   the file is not created. 676 different possibilities with 7
     79 	   or more X's, 26 with 6 or less. */
     80 	static char xtra[2] = "aa";
     81 	int xcnt = 0;
     82 
     83 	_DIAGASSERT(path != NULL);
     84 	/* doopen may be NULL */
     85 
     86 	pid = getpid();
     87 
     88 	/* Move to end of path and count trailing X's. */
     89 	for (trv = path; *trv; ++trv)
     90 		if (*trv == 'X')
     91 			xcnt++;
     92 		else
     93 			xcnt = 0;
     94 
     95 	/* Use at least one from xtra.  Use 2 if more than 6 X's. */
     96 	if (*(trv-1) == 'X')
     97 		*--trv = xtra[0];
     98 	if (xcnt > 6 && *(trv-1) == 'X')
     99 		*--trv = xtra[1];
    100 
    101 	/* Set remaining X's to pid digits with 0's to the left. */
    102 	while (*--trv == 'X') {
    103 		*trv = (pid % 10) + '0';
    104 		pid /= 10;
    105 	}
    106 
    107 	/* update xtra for next call. */
    108 	if (xtra[0] != 'z')
    109 		xtra[0]++;
    110 	else {
    111 		xtra[0] = 'a';
    112 		if (xtra[1] != 'z')
    113 			xtra[1]++;
    114 		else
    115 			xtra[1] = 'a';
    116 	}
    117 
    118 	/*
    119 	 * check the target directory; if you have six X's and it
    120 	 * doesn't exist this runs for a *very* long time.
    121 	 */
    122 	for (start = trv + 1;; --trv) {
    123 		if (trv <= path)
    124 			break;
    125 		if (*trv == '/') {
    126 			*trv = '\0';
    127 			if (stat(path, &sbuf))
    128 				return (0);
    129 			if (!S_ISDIR(sbuf.st_mode)) {
    130 				errno = ENOTDIR;
    131 				return (0);
    132 			}
    133 			*trv = '/';
    134 			break;
    135 		}
    136 	}
    137 
    138 	for (;;) {
    139 		if (doopen) {
    140 			if ((*doopen =
    141 			    open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
    142 				return (1);
    143 			if (errno != EEXIST)
    144 				return (0);
    145 		} else if (domkdir) {
    146 			if (mkdir(path, 0700) >= 0)
    147 				return (1);
    148 			if (errno != EEXIST)
    149 				return (0);
    150 		} else if (lstat(path, &sbuf))
    151 			return (errno == ENOENT ? 1 : 0);
    152 
    153 		/* tricky little algorithm for backward compatibility */
    154 		for (trv = start;;) {
    155 			if (!*trv)
    156 				return (0);
    157 			if (*trv == 'z')
    158 				*trv++ = 'a';
    159 			else {
    160 				if (isdigit((unsigned char)*trv))
    161 					*trv = 'a';
    162 				else
    163 					++*trv;
    164 				break;
    165 			}
    166 		}
    167 	}
    168 	/*NOTREACHED*/
    169 }
    170 
    171 #endif /* !HAVE_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP */
    172