1 /* Copyright (C) 2001, 2003, 2004, 2009 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 3 of the License, or
9 (at your option) any later version.
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
17 along with this program. If not, see <http://www.gnu.org/licenses/>. */
20 /* This file is heavily based on the function __gen_tempname() in the
21 file tempname.c which is part of the fileutils package. */
35 # define TMP_MAX 238328
39 # include <sys/time.h>
42 #ifdef HAVE_GETTIMEOFDAY
43 #ifdef NEED_DECLARATION_GETTIMEOFDAY
45 int gettimeofday(struct timeval *, void *);
50 #if HAVE_CC_INTTYPES_H
51 # include <inttypes.h>
54 /* Use the widest available unsigned type if uint64_t is not
55 available. The algorithm below extracts a number less than 62**6
56 (approximately 2**35.725) from uint64_t, so ancient hosts where
57 uintmax_t is only 32 bits lose about 3.725 bits of randomness,
58 which is better than not having mkstemp at all. */
59 #if !defined UINT64_MAX && !defined uint64_t
60 # define uint64_t uintmax_t
63 /* These are the characters used in temporary filenames. */
64 static const char letters[] =
65 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
67 int gen_tempname(char *tmpl, int dir)
69 static uint64_t value;
71 size_t len = strlen(tmpl);
72 if (len < 6 || strcmp(&tmpl[len - 6], "XXXXXX"))
73 return -1; /* EINVAL */
75 /* This is where the Xs start. */
76 char *XXXXXX = &tmpl[len - 6];
78 /* Get some more or less random data. */
81 gettimeofday(&tv, NULL);
82 uint64_t random_time_bits = ((uint64_t)tv.tv_usec << 16) ^ tv.tv_sec;
84 uint64_t random_time_bits = time(NULL);
86 value += random_time_bits ^ getpid();
88 for (int count = 0; count < TMP_MAX; value += 7777, ++count) {
91 /* Fill in the random bits. */
92 XXXXXX[0] = letters[v % 62];
94 XXXXXX[1] = letters[v % 62];
96 XXXXXX[2] = letters[v % 62];
98 XXXXXX[3] = letters[v % 62];
100 XXXXXX[4] = letters[v % 62];
102 XXXXXX[5] = letters[v % 62];
104 int fd = dir ? mkdir(tmpl, S_IRUSR | S_IWUSR | S_IXUSR)
105 : open(tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
109 else if (errno != EEXIST)
113 /* We got out of the loop because we ran out of combinations to try. */
114 return -1; /* EEXIST */