1 /*-
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <errno.h>
34 #include <fcntl.h>
35 #include <signal.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <sys/stat.h>
40 #include <sys/types.h>
41 #include <unistd.h>
42
43 #include "private/ErrnoRestorer.h"
44
__fd_to_fp(int fd)45 static FILE* __fd_to_fp(int fd) {
46 FILE* fp = fdopen(fd, "w+");
47 if (fp != nullptr) return fp;
48
49 ErrnoRestorer errno_restorer;
50 close(fd);
51 return nullptr;
52 }
53
__tmpfile_dir_legacy(const char * tmp_dir)54 static FILE* __tmpfile_dir_legacy(const char* tmp_dir) {
55 char* path = nullptr;
56 if (asprintf(&path, "%s/tmp.XXXXXXXXXX", tmp_dir) == -1) {
57 return nullptr;
58 }
59
60 int fd = mkstemp(path);
61 if (fd == -1) {
62 free(path);
63 return nullptr;
64 }
65
66 // Unlink the file now so that it's removed when closed.
67 unlink(path);
68 free(path);
69
70 // Can we still use the file now it's unlinked?
71 // File systems without hard link support won't have the usual Unix semantics.
72 struct stat sb;
73 if (fstat(fd, &sb) == -1) {
74 ErrnoRestorer errno_restorer;
75 close(fd);
76 return nullptr;
77 }
78
79 return __fd_to_fp(fd);
80 }
81
__tmpfile_dir(const char * tmp_dir)82 static FILE* __tmpfile_dir(const char* tmp_dir) {
83 int fd = open(tmp_dir, O_TMPFILE | O_RDWR, S_IRUSR | S_IWUSR);
84 if (fd == -1) return __tmpfile_dir_legacy(tmp_dir);
85 return __fd_to_fp(fd);
86 }
87
tmpfile()88 FILE* tmpfile() {
89 // TODO: get this app's temporary directory from the framework ("/data/data/app/cache").
90
91 // $EXTERNAL_STORAGE turns out not to be very useful because it doesn't support hard links.
92 // This means we can't do the usual trick of calling unlink before handing the file back.
93
94 FILE* fp = __tmpfile_dir("/data/local/tmp");
95 if (fp == nullptr) {
96 // P_tmpdir is "/tmp/", but POSIX explicitly says that tmpdir(3) should try P_tmpdir before
97 // giving up. This is potentially useful for bionic on the host anyway.
98 fp = __tmpfile_dir(P_tmpdir);
99 }
100 return fp;
101 }
102 __strong_alias(tmpfile64, tmpfile);
103
tempnam(const char * dir,const char * prefix)104 char* tempnam(const char* dir, const char* prefix) {
105 // This function is a terrible idea, marked deprecated in our headers,
106 // and marked obsolescent by POSIX.1-2008, but we make some effort anyway
107 // since we can't easily remove it...
108
109 // $TMPDIR overrides any directory passed in.
110 char* tmpdir = getenv("TMPDIR");
111 if (tmpdir != nullptr) dir = tmpdir;
112
113 // If we still have no directory, we'll give you a default.
114 // It's useless for apps, but good enough for the shell.
115 if (dir == nullptr) dir = "/data/local/tmp";
116
117 // Default prefix?
118 if (prefix == nullptr) prefix = "tempnam.";
119
120 // Make up a mktemp(3) template and defer to it for the real work.
121 char* path = nullptr;
122 if (asprintf(&path, "%s/%sXXXXXXXXXX", dir, prefix) == -1) return nullptr;
123 if (mktemp(path) == nullptr) {
124 free(path);
125 return nullptr;
126 }
127 return path;
128 }
129
tmpnam(char * s)130 char* tmpnam(char* s) {
131 // This function is a terrible idea, marked deprecated in our headers,
132 // and marked obsolescent by POSIX-1.2008, but we make some effort anyway
133 // since we can't easily remove it...
134
135 // Default buffer?
136 static char buf[L_tmpnam];
137 if (s == nullptr) s = buf;
138
139 // Use $TMPDIR if set, or fall back to /data/local/tmp otherwise.
140 // Useless for apps, but good enough for the shell.
141 const char* dir = getenv("TMPDIR");
142 if (dir == nullptr) dir = "/data/local/tmp";
143
144 // Make up a mktemp(3) template and defer to it for the real work.
145 snprintf(s, L_tmpnam, "%s/tmpnam.XXXXXXXXXX", dir);
146 return mktemp(s);
147 }
148