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[gdb.git] / libiberty / mkstemps.c
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1 /* Copyright (C) 1991, 1992, 1996, 1998, 2004 Free Software Foundation, Inc.
2 This file is derived from mkstemp.c from the GNU C Library.
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.
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.
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. */
19 #ifdef HAVE_CONFIG_H
20 #include "config.h"
21 #endif
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 #endif
39 #include "ansidecl.h"
41 /* We need to provide a type for gcc_uint64_t. */
42 #ifdef __GNUC__
43 __extension__ typedef unsigned long long gcc_uint64_t;
44 #else
45 typedef unsigned long gcc_uint64_t;
46 #endif
48 #ifndef TMP_MAX
49 #define TMP_MAX 16384
50 #endif
52 #ifndef O_BINARY
53 # define O_BINARY 0
54 #endif
58 @deftypefn Replacement int mkstemps (char *@var{pattern}, int @var{suffix_len})
60 Generate a unique temporary file name from @var{pattern}.
61 @var{pattern} has the form:
63 @example
64 @var{path}/ccXXXXXX@var{suffix}
65 @end example
67 @var{suffix_len} tells us how long @var{suffix} is (it can be zero
68 length). The last six characters of @var{pattern} before @var{suffix}
69 must be @samp{XXXXXX}; they are replaced with a string that makes the
70 filename unique. Returns a file descriptor open on the file for
71 reading and writing.
73 @end deftypefn
77 int
78 mkstemps (char *pattern, int suffix_len)
80 static const char letters[]
81 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
82 static gcc_uint64_t value;
83 #ifdef HAVE_GETTIMEOFDAY
84 struct timeval tv;
85 #endif
86 char *XXXXXX;
87 size_t len;
88 int count;
90 len = strlen (pattern);
92 if ((int) len < 6 + suffix_len
93 || strncmp (&pattern[len - 6 - suffix_len], "XXXXXX", 6))
95 return -1;
98 XXXXXX = &pattern[len - 6 - suffix_len];
100 #ifdef HAVE_GETTIMEOFDAY
101 /* Get some more or less random data. */
102 gettimeofday (&tv, NULL);
103 value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
104 #else
105 value += getpid ();
106 #endif
108 for (count = 0; count < TMP_MAX; ++count)
110 gcc_uint64_t v = value;
111 int fd;
113 /* Fill in the random bits. */
114 XXXXXX[0] = letters[v % 62];
115 v /= 62;
116 XXXXXX[1] = letters[v % 62];
117 v /= 62;
118 XXXXXX[2] = letters[v % 62];
119 v /= 62;
120 XXXXXX[3] = letters[v % 62];
121 v /= 62;
122 XXXXXX[4] = letters[v % 62];
123 v /= 62;
124 XXXXXX[5] = letters[v % 62];
126 fd = open (pattern, O_BINARY|O_RDWR|O_CREAT|O_EXCL, 0600);
127 if (fd >= 0)
128 /* The file does not exist. */
129 return fd;
131 /* This is a random value. It is only necessary that the next
132 TMP_MAX values generated by adding 7777 to VALUE are different
133 with (module 2^32). */
134 value += 7777;
137 /* We return the null string if we can't find a unique file name. */
138 pattern[0] = '\0';
139 return -1;