1/* Utility to pick a temporary filename prefix.
2 Copyright (C) 1996-2025 Free Software Foundation, Inc.
3
4This file is part of the libiberty library.
5Libiberty is free software; you can redistribute it and/or
6modify it under the terms of the GNU Library General Public
7License as published by the Free Software Foundation; either
8version 2 of the License, or (at your option) any later version.
9
10Libiberty is distributed in the hope that it will be useful,
11but WITHOUT ANY WARRANTY; without even the implied warranty of
12MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13Library General Public License for more details.
14
15You should have received a copy of the GNU Library General Public
16License along with libiberty; see the file COPYING.LIB. If not,
17write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
18Boston, MA 02110-1301, USA. */
19
20#ifdef HAVE_CONFIG_H
21#include "config.h"
22#endif
23
24#include <stdio.h> /* May get P_tmpdir. */
25#include <sys/types.h>
26#include <errno.h>
27#ifdef HAVE_UNISTD_H
28#include <unistd.h>
29#endif
30#ifdef HAVE_STDLIB_H
31#include <stdlib.h>
32#endif
33#ifdef HAVE_STRING_H
34#include <string.h>
35#endif
36#ifdef HAVE_SYS_FILE_H
37#include <sys/file.h> /* May get R_OK, etc. on some systems. */
38#endif
39#if defined(_WIN32) && !defined(__CYGWIN__)
40#define WIN32_LEAN_AND_MEAN
41#include <windows.h>
42#endif
43#if HAVE_SYS_STAT_H
44#include <sys/stat.h>
45#endif
46
47
48#ifndef R_OK
49#define R_OK 4
50#define W_OK 2
51#define X_OK 1
52#endif
53
54#include "libiberty.h"
55extern int mkstemps (char *, int);
56
57/* '/' works just fine on MS-DOS based systems. */
58#ifndef DIR_SEPARATOR
59#define DIR_SEPARATOR '/'
60#endif
61
62/* Name of temporary file.
63 mktemp requires 6 trailing X's. */
64#define TEMP_FILE "XXXXXX"
65#define TEMP_FILE_LEN (sizeof(TEMP_FILE) - 1)
66
67#if !defined(_WIN32) || defined(__CYGWIN__)
68
69/* Subroutine of choose_tmpdir.
70 If BASE is non-NULL, return it.
71 Otherwise it checks if DIR is a usable directory.
72 If success, DIR is returned.
73 Otherwise NULL is returned. */
74
75static inline const char *try_dir (const char *, const char *);
76
77static inline const char *
78try_dir (const char *dir, const char *base)
79{
80 if (base != 0)
81 return base;
82 if (dir != 0
83 && access (name: dir, R_OK | W_OK | X_OK) == 0)
84 {
85 /* Check to make sure dir is actually a directory. */
86#ifdef S_ISDIR
87 struct stat s;
88 if (stat (file: dir, buf: &s))
89 return NULL;
90 if (!S_ISDIR (s.st_mode))
91 return NULL;
92#endif
93 return dir;
94 }
95 return 0;
96}
97
98static const char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
99static const char vartmp[] =
100{ DIR_SEPARATOR, 'v', 'a', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
101
102#endif
103
104static char *memoized_tmpdir;
105
106/*
107
108@deftypefn Replacement const char* choose_tmpdir ()
109
110Returns a pointer to a directory path suitable for creating temporary
111files in.
112
113@end deftypefn
114
115*/
116
117const char *
118choose_tmpdir (void)
119{
120 if (!memoized_tmpdir)
121 {
122#if !defined(_WIN32) || defined(__CYGWIN__)
123 const char *base = 0;
124 char *tmpdir;
125 unsigned int len;
126
127#ifdef VMS
128 /* Try VMS standard temp logical. */
129 base = try_dir ("/sys$scratch", base);
130#else
131 base = try_dir (dir: getenv (name: "TMPDIR"), base);
132 base = try_dir (dir: getenv (name: "TMP"), base);
133 base = try_dir (dir: getenv (name: "TEMP"), base);
134#endif
135
136#ifdef P_tmpdir
137 /* We really want a directory name here as if concatenated with say \dir
138 we do not end up with a double \\ which defines an UNC path. */
139 if (strcmp (P_tmpdir, s2: "\\") == 0)
140 base = try_dir (dir: "\\.", base);
141 else
142 base = try_dir (P_tmpdir, base);
143#endif
144
145 /* Try /var/tmp, then /tmp. */
146 base = try_dir (dir: vartmp, base);
147 base = try_dir (dir: tmp, base);
148
149 /* If all else fails, use the current directory! */
150 if (base == 0)
151 base = ".";
152 /* Append DIR_SEPARATOR to the directory we've chosen
153 and return it. */
154 len = strlen (s: base);
155 tmpdir = XNEWVEC (char, len + 2);
156 strcpy (dest: tmpdir, src: base);
157 tmpdir[len] = DIR_SEPARATOR;
158 tmpdir[len+1] = '\0';
159 memoized_tmpdir = tmpdir;
160#else /* defined(_WIN32) && !defined(__CYGWIN__) */
161 DWORD len;
162
163 /* Figure out how much space we need. */
164 len = GetTempPath(0, NULL);
165 if (len)
166 {
167 memoized_tmpdir = XNEWVEC (char, len);
168 if (!GetTempPath(len, memoized_tmpdir))
169 {
170 XDELETEVEC (memoized_tmpdir);
171 memoized_tmpdir = NULL;
172 }
173 }
174 if (!memoized_tmpdir)
175 /* If all else fails, use the current directory. */
176 memoized_tmpdir = xstrdup (".\\");
177#endif /* defined(_WIN32) && !defined(__CYGWIN__) */
178 }
179
180 return memoized_tmpdir;
181}
182
183/*
184
185@deftypefn Replacement char* make_temp_file (const char *@var{suffix})
186
187Return a temporary file name (as a string) or @code{NULL} if unable to
188create one. @var{suffix} is a suffix to append to the file name. The
189string is @code{malloc}ed, and the temporary file has been created.
190
191@end deftypefn
192
193*/
194
195char *
196make_temp_file_with_prefix (const char *prefix, const char *suffix)
197{
198 const char *base = choose_tmpdir ();
199 char *temp_filename;
200 int base_len, suffix_len, prefix_len;
201 int fd;
202
203 if (prefix == 0)
204 prefix = "cc";
205
206 if (suffix == 0)
207 suffix = "";
208
209 base_len = strlen (s: base);
210 prefix_len = strlen (s: prefix);
211 suffix_len = strlen (s: suffix);
212
213 temp_filename = XNEWVEC (char, base_len
214 + TEMP_FILE_LEN
215 + suffix_len
216 + prefix_len + 1);
217 strcpy (dest: temp_filename, src: base);
218 strcpy (dest: temp_filename + base_len, src: prefix);
219 strcpy (dest: temp_filename + base_len + prefix_len, TEMP_FILE);
220 strcpy (dest: temp_filename + base_len + prefix_len + TEMP_FILE_LEN, src: suffix);
221
222 fd = mkstemps (temp_filename, suffix_len);
223 /* Mkstemps failed. It may be EPERM, ENOSPC etc. */
224 if (fd == -1)
225 {
226 fprintf (stderr, format: "Cannot create temporary file in %s: %s\n",
227 base, strerror (errno));
228 abort ();
229 }
230 /* We abort on failed close out of sheer paranoia. */
231 if (close (fd: fd))
232 abort ();
233 return temp_filename;
234}
235
236char *
237make_temp_file (const char *suffix)
238{
239 return make_temp_file_with_prefix (NULL, suffix);
240}
241

source code of libiberty/make-temp-file.c