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
54 // O_TMPFILE isn't available until Linux 3.11, so we fall back to this on
55 // older kernels. AOSP was on a new enough kernel in the Lollipop timeframe,
56 // so this code should be obsolete by 2025.
__tmpfile_dir_legacy(const char * tmp_dir)57 static FILE* __tmpfile_dir_legacy(const char* tmp_dir) {
58 char* path = nullptr;
59 if (asprintf(&path, "%s/tmp.XXXXXXXXXX", tmp_dir) == -1) {
60 return nullptr;
61 }
62
63 int fd = mkstemp(path);
64 if (fd == -1) {
65 free(path);
66 return nullptr;
67 }
68
69 // Unlink the file now so that it's removed when closed.
70 unlink(path);
71 free(path);
72
73 // Can we still use the file now it's unlinked?
74 // File systems without hard link support won't have the usual Unix semantics.
75 struct stat sb;
76 if (fstat(fd, &sb) == -1) {
77 ErrnoRestorer errno_restorer;
78 close(fd);
79 return nullptr;
80 }
81
82 return __fd_to_fp(fd);
83 }
84
__get_TMPDIR()85 const char* __get_TMPDIR() {
86 // Use $TMPDIR if set, or fall back to /data/local/tmp otherwise.
87 // Useless for apps, but good enough for the shell.
88 const char* tmpdir = getenv("TMPDIR");
89 return (tmpdir == nullptr) ? "/data/local/tmp" : tmpdir;
90 }
91
tmpfile()92 FILE* tmpfile() {
93 const char* tmpdir = __get_TMPDIR();
94 int fd = open(tmpdir, O_TMPFILE | O_RDWR, S_IRUSR | S_IWUSR);
95 if (fd == -1) return __tmpfile_dir_legacy(tmpdir);
96 return __fd_to_fp(fd);
97 }
98 __strong_alias(tmpfile64, tmpfile);
99
tempnam(const char * dir,const char * prefix)100 char* tempnam(const char* dir, const char* prefix) {
101 // This function is a terrible idea, marked deprecated in our headers,
102 // and marked obsolescent by POSIX.1-2008, but we make some effort anyway
103 // since we can't easily remove it...
104
105 // $TMPDIR overrides any directory passed in.
106 const char* tmpdir = getenv("TMPDIR");
107 if (tmpdir != nullptr) dir = tmpdir;
108
109 // If we still have no directory, we'll give you a default.
110 // It's useless for apps, but good enough for the shell.
111 if (dir == nullptr) dir = "/data/local/tmp";
112
113 // Default prefix?
114 if (prefix == nullptr) prefix = "tempnam.";
115
116 // Make up a mktemp(3) template and defer to it for the real work.
117 char* path = nullptr;
118 if (asprintf(&path, "%s/%sXXXXXXXXXX", dir, prefix) == -1) return nullptr;
119 if (mktemp(path) == nullptr) {
120 free(path);
121 return nullptr;
122 }
123 return path;
124 }
125
tmpnam(char * s)126 char* tmpnam(char* s) {
127 // This function is a terrible idea, marked deprecated in our headers,
128 // and marked obsolescent by POSIX-1.2008, but we make some effort anyway
129 // since we can't easily remove it...
130
131 // Default buffer?
132 static char buf[L_tmpnam];
133 if (s == nullptr) s = buf;
134
135 // Make up a mktemp(3) template and defer to it for the real work.
136 snprintf(s, L_tmpnam, "%s/tmpnam.XXXXXXXXXX", __get_TMPDIR());
137 return mktemp(s);
138 }
139