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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 
     22 /*
     23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 /*	Copyright (c) 1988 AT&T	*/
     28 /*	  All Rights Reserved  	*/
     29 
     30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     31 
     32 /*
     33  *	tmpfile - return a pointer to an update file that can be
     34  *		used for scratch. The file will automatically
     35  *		go away if the program using it terminates.
     36  */
     37 
     38 #include "lint.h"
     39 #include "mtlib.h"
     40 #include <sys/types.h>
     41 #include <unistd.h>
     42 #include <stdio.h>
     43 #include <string.h>
     44 #include <stdlib.h>
     45 #include <thread.h>
     46 #include <synch.h>
     47 #include <sys/stat.h>
     48 
     49 static char seed[] = { 'a', 'a', 'a', '\0' };
     50 static mutex_t seed_lk = DEFAULTMUTEX;
     51 
     52 #define	XS "\bXXXXXX"		/* a '\b' character is prepended to this */
     53 				/* string to avoid conflicts with names */
     54 				/* generated by tmpnam() */
     55 /*ARGSUSED*/
     56 static FILE *
     57 _common(boolean_t large_file)
     58 {
     59 	char	tfname[L_tmpnam];
     60 	FILE	*p;
     61 	char	*q;
     62 	int	mkret;
     63 	mode_t	current_umask;
     64 
     65 	(void) strcpy(tfname, P_tmpdir);
     66 	lmutex_lock(&seed_lk);
     67 	(void) strcat(tfname, seed);
     68 	(void) strcat(tfname, XS);
     69 
     70 	q = seed;
     71 	while (*q == 'z')
     72 		*q++ = 'a';
     73 	if (*q != '\0')
     74 		++*q;
     75 	lmutex_unlock(&seed_lk);
     76 
     77 #if !defined(_LP64)
     78 	if (large_file == B_TRUE) {
     79 		if ((mkret = mkstemp64(tfname)) == -1)
     80 			return (NULL);
     81 	} else
     82 #endif
     83 		if ((mkret = mkstemp(tfname)) == -1)
     84 			return (NULL);
     85 
     86 	(void) unlink(tfname);
     87 	current_umask = umask(0777);
     88 	(void) umask(current_umask);
     89 	(void) fchmod(mkret, 0666 & ~current_umask);
     90 	if ((p = fdopen(mkret, "w+")) == NULL) {
     91 		(void) close(mkret);
     92 		return (NULL);
     93 	}
     94 
     95 	return (p);
     96 }
     97 
     98 #if !defined(_LP64)
     99 FILE *
    100 tmpfile64(void)
    101 {
    102 	return (_common(B_TRUE));
    103 }
    104 #endif	/* _LP64 */
    105 
    106 /*
    107  * This is a bit confusing -- some explanation is in order.
    108  *
    109  * When we're compiled 64-bit, there's no point in distinguishing
    110  * a "large" file from a "small" file -- they're all "large".
    111  * The argument we pass to '_common' is ignored -- we always call
    112  * mkstemp which will just do the right thing for us.
    113  */
    114 FILE *
    115 tmpfile(void)
    116 {
    117 	return (_common(B_FALSE));
    118 }
    119