Fix tmpfile(3).
This could be better, but at least now it works.
Change-Id: I88b7cf3f7ce8e5fa0b3fe678b7d1679a68ffffc9
diff --git a/libc/bionic/tmpfile.cpp b/libc/bionic/tmpfile.cpp
new file mode 100644
index 0000000..ad58a92
--- /dev/null
+++ b/libc/bionic/tmpfile.cpp
@@ -0,0 +1,113 @@
+/*-
+ * Copyright (c) 1990, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+class ScopedSignalBlocker {
+ public:
+ ScopedSignalBlocker() {
+ sigset_t set;
+ sigfillset(&set);
+ sigprocmask(SIG_BLOCK, &set, &old_set_);
+ }
+
+ ~ScopedSignalBlocker() {
+ sigprocmask(SIG_SETMASK, &old_set_, NULL);
+ }
+
+ private:
+ sigset_t old_set_;
+};
+
+static FILE* __tmpfile_dir(const char* tmp_dir) {
+ char buf[PATH_MAX];
+ int path_length = snprintf(buf, sizeof(buf), "%s/tmp.XXXXXXXXXX", tmp_dir);
+ if (path_length >= sizeof(buf)) {
+ return NULL;
+ }
+
+ int fd;
+ {
+ ScopedSignalBlocker ssb;
+ fd = mkstemp(buf);
+ if (fd == -1) {
+ return NULL;
+ }
+
+ // Unlink the file now so that it's removed when closed.
+ unlink(buf);
+
+ // Can we still use the file now it's unlinked?
+ // File systems without hard link support won't have the usual Unix semantics.
+ struct stat sb;
+ int rc = fstat(fd, &sb);
+ if (rc == -1) {
+ int old_errno = errno;
+ close(fd);
+ errno = old_errno;
+ return NULL;
+ }
+ }
+
+ // Turn the file descriptor into a FILE*.
+ FILE* fp = fdopen(fd, "w+");
+ if (fp != NULL) {
+ return fp;
+ }
+
+ // Failure. Clean up. We already unlinked, so we just need to close.
+ int old_errno = errno;
+ close(fd);
+ errno = old_errno;
+ return NULL;
+}
+
+FILE* tmpfile() {
+ // TODO: get this app's temporary directory from the framework ("/data/data/app/cache").
+
+ // $EXTERNAL_STORAGE turns out not to be very useful because it doesn't support hard links.
+ // This means we can't do the usual trick of calling unlink before handing the file back.
+
+ FILE* fp = __tmpfile_dir("/data/local/tmp");
+ if (fp == NULL) {
+ // P_tmpdir is "/tmp/", but POSIX explicitly says that tmpdir(3) should try P_tmpdir before
+ // giving up. This is potentially useful for bionic on the host anyway.
+ fp = __tmpfile_dir(P_tmpdir);
+ }
+ return fp;
+}