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 <signal.h> 35#include <stdio.h> 36#include <stdlib.h> 37#include <sys/stat.h> 38#include <sys/types.h> 39#include <unistd.h> 40 41#include "private/ErrnoRestorer.h" 42 43class ScopedSignalBlocker { 44 public: 45 ScopedSignalBlocker() { 46 sigset_t set; 47 sigfillset(&set); 48 sigprocmask(SIG_BLOCK, &set, &old_set_); 49 } 50 51 ~ScopedSignalBlocker() { 52 sigprocmask(SIG_SETMASK, &old_set_, NULL); 53 } 54 55 private: 56 sigset_t old_set_; 57}; 58 59static FILE* __tmpfile_dir(const char* tmp_dir) { 60 char buf[PATH_MAX]; 61 int path_length = snprintf(buf, sizeof(buf), "%s/tmp.XXXXXXXXXX", tmp_dir); 62 if (path_length >= static_cast<int>(sizeof(buf))) { 63 return NULL; 64 } 65 66 int fd; 67 { 68 ScopedSignalBlocker ssb; 69 fd = mkstemp(buf); 70 if (fd == -1) { 71 return NULL; 72 } 73 74 // Unlink the file now so that it's removed when closed. 75 unlink(buf); 76 77 // Can we still use the file now it's unlinked? 78 // File systems without hard link support won't have the usual Unix semantics. 79 struct stat sb; 80 int rc = fstat(fd, &sb); 81 if (rc == -1) { 82 ErrnoRestorer errno_restorer; 83 close(fd); 84 return NULL; 85 } 86 } 87 88 // Turn the file descriptor into a FILE*. 89 FILE* fp = fdopen(fd, "w+"); 90 if (fp != NULL) { 91 return fp; 92 } 93 94 // Failure. Clean up. We already unlinked, so we just need to close. 95 ErrnoRestorer errno_restorer; 96 close(fd); 97 return NULL; 98} 99 100FILE* tmpfile() { 101 // TODO: get this app's temporary directory from the framework ("/data/data/app/cache"). 102 103 // $EXTERNAL_STORAGE turns out not to be very useful because it doesn't support hard links. 104 // This means we can't do the usual trick of calling unlink before handing the file back. 105 106 FILE* fp = __tmpfile_dir("/data/local/tmp"); 107 if (fp == NULL) { 108 // P_tmpdir is "/tmp/", but POSIX explicitly says that tmpdir(3) should try P_tmpdir before 109 // giving up. This is potentially useful for bionic on the host anyway. 110 fp = __tmpfile_dir(P_tmpdir); 111 } 112 return fp; 113} 114