| 1 | /* tempname.c - generate the name of a temporary file.
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| 2 |
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| 3 | Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
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| 4 | 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
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| 5 |
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| 6 | This program is free software; you can redistribute it and/or modify
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| 7 | it under the terms of the GNU General Public License as published by
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| 8 | the Free Software Foundation; either version 2, or (at your option)
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| 9 | any later version.
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| 10 |
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| 11 | This program is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | GNU General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU General Public License along
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| 17 | with this program; if not, write to the Free Software Foundation,
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| 18 | Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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| 19 |
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| 20 | #if HAVE_CONFIG_H
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| 21 | # include <config.h>
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| 22 | #endif
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| 23 |
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| 24 | #include <sys/types.h>
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| 25 | #include <assert.h>
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| 26 |
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| 27 | #include <errno.h>
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| 28 | #ifndef __set_errno
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| 29 | # define __set_errno(Val) errno = (Val)
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| 30 | #endif
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| 31 |
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| 32 | #include <stdio.h>
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| 33 | #ifndef P_tmpdir
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| 34 | # define P_tmpdir "/tmp"
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| 35 | #endif
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| 36 | #ifndef TMP_MAX
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| 37 | # define TMP_MAX 238328
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| 38 | #endif
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| 39 | #ifndef __GT_FILE
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| 40 | # define __GT_FILE 0
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| 41 | # define __GT_BIGFILE 1
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| 42 | # define __GT_DIR 2
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| 43 | # define __GT_NOCREATE 3
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| 44 | #endif
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| 45 |
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| 46 | #include <stddef.h>
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| 47 | #include <stdlib.h>
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| 48 | #include <string.h>
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| 49 |
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| 50 | #if HAVE_FCNTL_H || _LIBC
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| 51 | # include <fcntl.h>
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| 52 | #endif
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| 53 |
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| 54 | #if HAVE_SYS_TIME_H || _LIBC
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| 55 | # include <sys/time.h>
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| 56 | #endif
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| 57 |
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| 58 | #if HAVE_STDINT_H || _LIBC
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| 59 | # include <stdint.h>
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| 60 | #endif
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| 61 | #if HAVE_INTTYPES_H
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| 62 | # include <inttypes.h>
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| 63 | #endif
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| 64 |
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| 65 | #if HAVE_UNISTD_H || _LIBC
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| 66 | # include <unistd.h>
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| 67 | #endif
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| 68 |
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| 69 | #include <sys/stat.h>
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| 70 | #if STAT_MACROS_BROKEN
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| 71 | # undef S_ISDIR
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| 72 | #endif
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| 73 | #if !defined S_ISDIR && defined S_IFDIR
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| 74 | # define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
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| 75 | #endif
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| 76 | #if !S_IRUSR && S_IREAD
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| 77 | # define S_IRUSR S_IREAD
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| 78 | #endif
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| 79 | #if !S_IRUSR
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| 80 | # define S_IRUSR 00400
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| 81 | #endif
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| 82 | #if !S_IWUSR && S_IWRITE
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| 83 | # define S_IWUSR S_IWRITE
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| 84 | #endif
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| 85 | #if !S_IWUSR
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| 86 | # define S_IWUSR 00200
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| 87 | #endif
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| 88 | #if !S_IXUSR && S_IEXEC
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| 89 | # define S_IXUSR S_IEXEC
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| 90 | #endif
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| 91 | #if !S_IXUSR
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| 92 | # define S_IXUSR 00100
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| 93 | #endif
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| 94 |
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| 95 | #if _LIBC
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| 96 | # define struct_stat64 struct stat64
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| 97 | #else
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| 98 | # define struct_stat64 struct stat
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| 99 | # define __getpid getpid
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| 100 | # define __gettimeofday gettimeofday
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| 101 | # define __mkdir mkdir
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| 102 | # define __open open
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| 103 | # define __open64 open
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| 104 | # define __lxstat64(version, path, buf) lstat (path, buf)
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| 105 | # define __xstat64(version, path, buf) stat (path, buf)
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| 106 | #endif
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| 107 |
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| 108 | #if ! (HAVE___SECURE_GETENV || _LIBC)
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| 109 | # define __secure_getenv getenv
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| 110 | #endif
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| 111 |
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| 112 | #ifdef _LIBC
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| 113 | # include <hp-timing.h>
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| 114 | # if HP_TIMING_AVAIL
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| 115 | # define RANDOM_BITS(Var) \
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| 116 | if (__builtin_expect (value == UINT64_C (0), 0)) \
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| 117 | { \
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| 118 | /* If this is the first time this function is used initialize \
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| 119 | the variable we accumulate the value in to some somewhat \
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| 120 | random value. If we'd not do this programs at startup time \
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| 121 | might have a reduced set of possible names, at least on slow \
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| 122 | machines. */ \
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| 123 | struct timeval tv; \
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| 124 | __gettimeofday (&tv, NULL); \
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| 125 | value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec; \
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| 126 | } \
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| 127 | HP_TIMING_NOW (Var)
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| 128 | # endif
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| 129 | #endif
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| 130 |
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| 131 | /* Use the widest available unsigned type if uint64_t is not
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| 132 | available. The algorithm below extracts a number less than 62**6
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| 133 | (approximately 2**35.725) from uint64_t, so ancient hosts where
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| 134 | uintmax_t is only 32 bits lose about 3.725 bits of randomness,
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| 135 | which is better than not having mkstemp at all. */
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| 136 | #if !defined UINT64_MAX && !defined uint64_t
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| 137 | # define uint64_t uintmax_t
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| 138 | #endif
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| 139 |
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| 140 | /* Return nonzero if DIR is an existent directory. */
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| 141 | static int
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| 142 | direxists (const char *dir)
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| 143 | {
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| 144 | struct_stat64 buf;
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| 145 | return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
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| 146 | }
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| 147 |
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| 148 | /* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is
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| 149 | non-null and exists, uses it; otherwise uses the first of $TMPDIR,
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| 150 | P_tmpdir, /tmp that exists. Copies into TMPL a template suitable
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| 151 | for use with mk[s]temp. Will fail (-1) if DIR is non-null and
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| 152 | doesn't exist, none of the searched dirs exists, or there's not
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| 153 | enough space in TMPL. */
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| 154 | int
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| 155 | __path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
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| 156 | int try_tmpdir)
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| 157 | {
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| 158 | const char *d;
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| 159 | size_t dlen, plen;
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| 160 |
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| 161 | if (!pfx || !pfx[0])
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| 162 | {
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| 163 | pfx = "file";
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| 164 | plen = 4;
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| 165 | }
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| 166 | else
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| 167 | {
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| 168 | plen = strlen (pfx);
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| 169 | if (plen > 5)
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| 170 | plen = 5;
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| 171 | }
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| 172 |
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| 173 | if (try_tmpdir)
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| 174 | {
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| 175 | d = __secure_getenv ("TMPDIR");
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| 176 | if (d != NULL && direxists (d))
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| 177 | dir = d;
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| 178 | else if (dir != NULL && direxists (dir))
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| 179 | /* nothing */ ;
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| 180 | else
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| 181 | dir = NULL;
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| 182 | }
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| 183 | if (dir == NULL)
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| 184 | {
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| 185 | if (direxists (P_tmpdir))
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| 186 | dir = P_tmpdir;
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| 187 | else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
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| 188 | dir = "/tmp";
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| 189 | else
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| 190 | {
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| 191 | __set_errno (ENOENT);
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| 192 | return -1;
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| 193 | }
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| 194 | }
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| 195 |
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| 196 | dlen = strlen (dir);
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| 197 | while (dlen > 1 && dir[dlen - 1] == '/')
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| 198 | dlen--; /* remove trailing slashes */
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| 199 |
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| 200 | /* check we have room for "${dir}/${pfx}XXXXXX\0" */
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| 201 | if (tmpl_len < dlen + 1 + plen + 6 + 1)
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| 202 | {
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| 203 | __set_errno (EINVAL);
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| 204 | return -1;
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| 205 | }
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| 206 |
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| 207 | sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx);
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| 208 | return 0;
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| 209 | }
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| 210 |
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| 211 | /* These are the characters used in temporary filenames. */
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| 212 | static const char letters[] =
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| 213 | "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
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| 214 |
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| 215 | /* Generate a temporary file name based on TMPL. TMPL must match the
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| 216 | rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed
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| 217 | does not exist at the time of the call to __gen_tempname. TMPL is
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| 218 | overwritten with the result.
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| 219 |
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| 220 | KIND may be one of:
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| 221 | __GT_NOCREATE: simply verify that the name does not exist
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| 222 | at the time of the call.
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| 223 | __GT_FILE: create the file using open(O_CREAT|O_EXCL)
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| 224 | and return a read-write fd. The file is mode 0600.
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| 225 | __GT_BIGFILE: same as __GT_FILE but use open64().
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| 226 | __GT_DIR: create a directory, which will be mode 0700.
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| 227 |
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| 228 | We use a clever algorithm to get hard-to-predict names. */
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| 229 | int
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| 230 | __gen_tempname (char *tmpl, int kind)
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| 231 | {
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| 232 | int len;
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| 233 | char *XXXXXX;
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| 234 | static uint64_t value;
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| 235 | uint64_t random_time_bits;
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| 236 | unsigned int count;
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| 237 | int fd = -1;
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| 238 | int save_errno = errno;
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| 239 | struct_stat64 st;
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| 240 |
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| 241 | /* A lower bound on the number of temporary files to attempt to
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| 242 | generate. The maximum total number of temporary file names that
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| 243 | can exist for a given template is 62**6. It should never be
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| 244 | necessary to try all these combinations. Instead if a reasonable
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| 245 | number of names is tried (we define reasonable as 62**3) fail to
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| 246 | give the system administrator the chance to remove the problems. */
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| 247 | unsigned int attempts_min = 62 * 62 * 62;
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| 248 |
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| 249 | /* The number of times to attempt to generate a temporary file. To
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| 250 | conform to POSIX, this must be no smaller than TMP_MAX. */
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| 251 | unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min;
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| 252 |
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| 253 | len = strlen (tmpl);
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| 254 | if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
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| 255 | {
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| 256 | __set_errno (EINVAL);
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| 257 | return -1;
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| 258 | }
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| 259 |
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| 260 | /* This is where the Xs start. */
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| 261 | XXXXXX = &tmpl[len - 6];
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| 262 |
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| 263 | /* Get some more or less random data. */
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| 264 | #ifdef RANDOM_BITS
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| 265 | RANDOM_BITS (random_time_bits);
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| 266 | #else
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| 267 | # if HAVE_GETTIMEOFDAY || _LIBC
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| 268 | {
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| 269 | struct timeval tv;
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| 270 | __gettimeofday (&tv, NULL);
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| 271 | random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
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| 272 | }
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| 273 | # else
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| 274 | random_time_bits = time (NULL);
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| 275 | # endif
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| 276 | #endif
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| 277 | value += random_time_bits ^ __getpid ();
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| 278 |
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| 279 | for (count = 0; count < attempts; value += 7777, ++count)
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| 280 | {
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| 281 | uint64_t v = value;
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| 282 |
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| 283 | /* Fill in the random bits. */
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| 284 | XXXXXX[0] = letters[v % 62];
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| 285 | v /= 62;
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| 286 | XXXXXX[1] = letters[v % 62];
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| 287 | v /= 62;
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| 288 | XXXXXX[2] = letters[v % 62];
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| 289 | v /= 62;
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| 290 | XXXXXX[3] = letters[v % 62];
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| 291 | v /= 62;
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| 292 | XXXXXX[4] = letters[v % 62];
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| 293 | v /= 62;
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| 294 | XXXXXX[5] = letters[v % 62];
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| 295 |
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| 296 | switch (kind)
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| 297 | {
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| 298 | case __GT_FILE:
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| 299 | fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
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| 300 | break;
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| 301 |
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| 302 | case __GT_BIGFILE:
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| 303 | fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
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| 304 | break;
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| 305 |
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| 306 | case __GT_DIR:
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| 307 | fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
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| 308 | break;
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| 309 |
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| 310 | case __GT_NOCREATE:
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| 311 | /* This case is backward from the other three. __gen_tempname
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| 312 | succeeds if __xstat fails because the name does not exist.
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| 313 | Note the continue to bypass the common logic at the bottom
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| 314 | of the loop. */
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| 315 | if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
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| 316 | {
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| 317 | if (errno == ENOENT)
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| 318 | {
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| 319 | __set_errno (save_errno);
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| 320 | return 0;
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| 321 | }
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| 322 | else
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| 323 | /* Give up now. */
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| 324 | return -1;
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| 325 | }
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| 326 | continue;
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| 327 |
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| 328 | default:
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| 329 | assert (! "invalid KIND in __gen_tempname");
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| 330 | }
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| 331 |
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| 332 | if (fd >= 0)
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| 333 | {
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| 334 | __set_errno (save_errno);
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| 335 | return fd;
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| 336 | }
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| 337 | else if (errno != EEXIST)
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| 338 | return -1;
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| 339 | }
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| 340 |
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| 341 | /* We got out of the loop because we ran out of combinations to try. */
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| 342 | __set_errno (EEXIST);
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| 343 | return -1;
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| 344 | }
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