1 /* $NetBSD: tmpname.cpp,v 1.1.1.1 2016/01/13 18:41:48 christos Exp $ */
2
3 /* Copyright (C) 2001, 2003, 2004 Free Software Foundation, Inc.
4 Written by Werner Lemberg (wl@gnu.org)
5
6 This file is part of groff.
7
8 groff is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
11 version.
12
13 groff is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License along
19 with groff; see the file COPYING. If not, write to the Free Software
20 Foundation, 51 Franklin St - Fifth Floor, Boston, MA 02110-1301, USA. */
21
22
23 /* This file is heavily based on the function __gen_tempname() in the
24 file tempname.c which is part of the fileutils package. */
25
26
27 #include "lib.h"
28
29 #include <stddef.h>
30 #include <stdlib.h>
31 #include <errno.h>
32 #include <time.h>
33
34 #include "posix.h"
35 #include "nonposix.h"
36
37 #ifndef TMP_MAX
38 # define TMP_MAX 238328
39 #endif
40
41 #if HAVE_SYS_TIME_H
42 # include <sys/time.h>
43 #endif
44
45 #ifdef HAVE_GETTIMEOFDAY
46 #ifdef NEED_DECLARATION_GETTIMEOFDAY
47 extern "C" {
48 int gettimeofday(struct timeval *, void *);
49 }
50 #endif
51 #endif
52
53 #if HAVE_CC_INTTYPES_H
54 # include <inttypes.h>
55 #endif
56
57 /* Use the widest available unsigned type if uint64_t is not
58 available. The algorithm below extracts a number less than 62**6
59 (approximately 2**35.725) from uint64_t, so ancient hosts where
60 uintmax_t is only 32 bits lose about 3.725 bits of randomness,
61 which is better than not having mkstemp at all. */
62 #if !defined UINT64_MAX && !defined uint64_t
63 # define uint64_t uintmax_t
64 #endif
65
66 /* These are the characters used in temporary filenames. */
67 static const char letters[] =
68 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
69
gen_tempname(char * tmpl,int dir)70 int gen_tempname(char *tmpl, int dir)
71 {
72 static uint64_t value;
73
74 size_t len = strlen(tmpl);
75 if (len < 6 || strcmp(&tmpl[len - 6], "XXXXXX"))
76 return -1; /* EINVAL */
77
78 /* This is where the Xs start. */
79 char *XXXXXX = &tmpl[len - 6];
80
81 /* Get some more or less random data. */
82 #if HAVE_GETTIMEOFDAY
83 timeval tv;
84 gettimeofday(&tv, NULL);
85 uint64_t random_time_bits = ((uint64_t)tv.tv_usec << 16) ^ tv.tv_sec;
86 #else
87 uint64_t random_time_bits = time(NULL);
88 #endif
89 value += random_time_bits ^ getpid();
90
91 for (int count = 0; count < TMP_MAX; value += 7777, ++count) {
92 uint64_t v = value;
93
94 /* Fill in the random bits. */
95 XXXXXX[0] = letters[v % 62];
96 v /= 62;
97 XXXXXX[1] = letters[v % 62];
98 v /= 62;
99 XXXXXX[2] = letters[v % 62];
100 v /= 62;
101 XXXXXX[3] = letters[v % 62];
102 v /= 62;
103 XXXXXX[4] = letters[v % 62];
104 v /= 62;
105 XXXXXX[5] = letters[v % 62];
106
107 int fd = dir ? mkdir(tmpl, S_IRUSR | S_IWUSR | S_IXUSR)
108 : open(tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
109
110 if (fd >= 0)
111 return fd;
112 else if (errno != EEXIST)
113 return -1;
114 }
115
116 /* We got out of the loop because we ran out of combinations to try. */
117 return -1; /* EEXIST */
118 }
119