1 /* Copyright (C) 1991-2023 Free Software Foundation, Inc.
2 This file is derived from mkstemp.c from the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Library General Public License for more details.
13
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If not,
16 write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
17 Boston, MA 02110-1301, USA. */
18
19 #ifdef HAVE_CONFIG_H
20 #include "config.h"
21 #endif
22
23 #include <sys/types.h>
24 #ifdef HAVE_STDLIB_H
25 #include <stdlib.h>
26 #endif
27 #ifdef HAVE_STRING_H
28 #include <string.h>
29 #endif
30 #include <errno.h>
31 #include <stdio.h>
32 #include <fcntl.h>
33 #ifdef HAVE_UNISTD_H
34 #include <unistd.h>
35 #endif
36 #ifdef HAVE_SYS_TIME_H
37 #include <sys/time.h>
38 #elif HAVE_TIME_H
39 #include <time.h>
40 #endif
41 #include "ansidecl.h"
42
43 /* We need to provide a type for gcc_uint64_t. */
44 #ifdef __GNUC__
45 __extension__ typedef unsigned long long gcc_uint64_t;
46 #else
47 typedef unsigned long gcc_uint64_t;
48 #endif
49
50 #ifndef TMP_MAX
51 #define TMP_MAX 16384
52 #endif
53
54 #ifndef O_BINARY
55 # define O_BINARY 0
56 #endif
57
58 /*
59
60 @deftypefn Replacement int mkstemps (char *@var{pattern}, int @var{suffix_len})
61
62 Generate a unique temporary file name from @var{pattern}.
63 @var{pattern} has the form:
64
65 @example
66 @var{path}/ccXXXXXX@var{suffix}
67 @end example
68
69 @var{suffix_len} tells us how long @var{suffix} is (it can be zero
70 length). The last six characters of @var{pattern} before @var{suffix}
71 must be @samp{XXXXXX}; they are replaced with a string that makes the
72 filename unique. Returns a file descriptor open on the file for
73 reading and writing.
74
75 @end deftypefn
76
77 */
78
79 int
80 mkstemps (char *pattern, int suffix_len)
81 {
82 static const char letters[]
83 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
84 static gcc_uint64_t value;
85 #ifdef HAVE_GETTIMEOFDAY
86 struct timeval tv;
87 #endif
88 char *XXXXXX;
89 size_t len;
90 int count;
91
92 len = strlen (pattern);
93
94 if ((int) len < 6 + suffix_len
95 || strncmp (&pattern[len - 6 - suffix_len], "XXXXXX", 6))
96 {
97 return -1;
98 }
99
100 XXXXXX = &pattern[len - 6 - suffix_len];
101
102 #ifdef HAVE_GETTIMEOFDAY
103 /* Get some more or less random data. */
104 gettimeofday (&tv, NULL);
105 value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
106 #else
107 value += getpid ();
108 #endif
109
110 for (count = 0; count < TMP_MAX; ++count)
111 {
112 gcc_uint64_t v = value;
113 int fd;
114
115 /* Fill in the random bits. */
116 XXXXXX[0] = letters[v % 62];
117 v /= 62;
118 XXXXXX[1] = letters[v % 62];
119 v /= 62;
120 XXXXXX[2] = letters[v % 62];
121 v /= 62;
122 XXXXXX[3] = letters[v % 62];
123 v /= 62;
124 XXXXXX[4] = letters[v % 62];
125 v /= 62;
126 XXXXXX[5] = letters[v % 62];
127
128 fd = open (pattern, O_BINARY|O_RDWR|O_CREAT|O_EXCL, 0600);
129 if (fd >= 0)
130 /* The file does not exist. */
131 return fd;
132 if (errno != EEXIST
133 #ifdef EISDIR
134 && errno != EISDIR
135 #endif
136 )
137 /* Fatal error (EPERM, ENOSPC etc). Doesn't make sense to loop. */
138 break;
139
140 /* This is a random value. It is only necessary that the next
141 TMP_MAX values generated by adding 7777 to VALUE are different
142 with (module 2^32). */
143 value += 7777;
144 }
145
146 /* We return the null string if we can't find a unique file name. */
147 pattern[0] = '\0';
148 return -1;
149 }