1 /* Copyright (C) 2001, 2003, 2004 Free Software Foundation, Inc.
2 Written by Werner Lemberg (wl@gnu.org)
4 This file is part of groff.
6 groff is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 2, or (at your option) any later
11 groff is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License along
17 with groff; see the file COPYING. If not, write to the Free Software
18 Foundation, 51 Franklin St - Fifth Floor, Boston, MA 02110-1301, USA. */
21 /* This file is heavily based on the function __gen_tempname() in the
22 file tempname.c which is part of the fileutils package. */
36 # define TMP_MAX 238328
40 # include <sys/time.h>
43 #ifdef HAVE_GETTIMEOFDAY
44 #ifdef NEED_DECLARATION_GETTIMEOFDAY
46 int gettimeofday(struct timeval *, void *);
51 #if HAVE_CC_INTTYPES_H
52 # include <inttypes.h>
55 /* Use the widest available unsigned type if uint64_t is not
56 available. The algorithm below extracts a number less than 62**6
57 (approximately 2**35.725) from uint64_t, so ancient hosts where
58 uintmax_t is only 32 bits lose about 3.725 bits of randomness,
59 which is better than not having mkstemp at all. */
60 #if !defined UINT64_MAX && !defined uint64_t
61 # define uint64_t uintmax_t
64 /* These are the characters used in temporary filenames. */
65 static const char letters[] =
66 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
68 int gen_tempname(char *tmpl, int dir)
70 static uint64_t value;
72 size_t len = strlen(tmpl);
73 if (len < 6 || strcmp(&tmpl[len - 6], "XXXXXX"))
74 return -1; /* EINVAL */
76 /* This is where the Xs start. */
77 char *XXXXXX = &tmpl[len - 6];
79 /* Get some more or less random data. */
82 gettimeofday(&tv, NULL);
83 uint64_t random_time_bits = ((uint64_t)tv.tv_usec << 16) ^ tv.tv_sec;
85 uint64_t random_time_bits = time(NULL);
87 value += random_time_bits ^ getpid();
89 for (int count = 0; count < TMP_MAX; value += 7777, ++count) {
92 /* Fill in the random bits. */
93 XXXXXX[0] = letters[v % 62];
95 XXXXXX[1] = letters[v % 62];
97 XXXXXX[2] = letters[v % 62];
99 XXXXXX[3] = letters[v % 62];
101 XXXXXX[4] = letters[v % 62];
103 XXXXXX[5] = letters[v % 62];
105 int fd = dir ? mkdir(tmpl, S_IRUSR | S_IWUSR | S_IXUSR)
106 : open(tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
110 else if (errno != EEXIST)
114 /* We got out of the loop because we ran out of combinations to try. */
115 return -1; /* EEXIST */