usr/src/lib/libc/port/stdio/tmpfile.c

   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 }