set the close-on-exec flag on all file descriptors

Added the "fd_util" library, which attempts to use the new thread-safe
Linux system calls pipe2(), accept4() and the options O_CLOEXEC,
SOCK_CLOEXEC.  Without these, it falls back to FD_CLOEXEC, which is
not thread safe.

This is particularly important for the "pipe" output plugin (and
others, such as JACK/PulseAudio), because we were heavily leaking file
descriptors to child processes.

1 files changed, 53 insertions, 0 deletions

diff --git a/src/fd_util.h b/src/fd_util.h
new file mode 100644
index 00000000..805d1cc3
--- /dev/null
+++ b/src/fd_util.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * This library provides easy helper functions for working with file
+ * descriptors.  It has wrappers for taking advantage of Linux 2.6
+ * specific features like O_CLOEXEC.
+ *
+ */
+
+#ifndef FD_UTIL_H
+#define FD_UTIL_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct sockaddr;
+
+int
+fd_set_cloexec(int fd, bool enable);
+
+int
+open_cloexec(const char *path_fs, int flags);
+
+int
+creat_cloexec(const char *path_fs, int mode);
+
+int
+pipe_cloexec(int fd[2]);
+
+int
+socket_cloexec(int domain, int type, int protocol);
+
+int
+accept_cloexec(int fd, struct sockaddr *address, size_t *address_length_r);
+
+#endif