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authorMax Kellermann <max@duempel.org>2009-11-07 18:55:16 +0100
committerMax Kellermann <max@duempel.org>2009-11-07 18:55:16 +0100
commite3af0032b236dc52d4a74c4d740e57a1f6d520aa (patch)
tree3984233a9b639e71ad80b4f6598539de3a27a008 /src/fd_util.c
parent9b21152600071ec46c021c8ba3b2ef69c90f039f (diff)
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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.
Diffstat (limited to '')
-rw-r--r--src/fd_util.c171
1 files changed, 171 insertions, 0 deletions
diff --git a/src/fd_util.c b/src/fd_util.c
new file mode 100644
index 000000000..b6593d919
--- /dev/null
+++ b/src/fd_util.c
@@ -0,0 +1,171 @@
+/*
+ * 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.
+ */
+
+#include "fd_util.h"
+#include "config.h"
+
+#if !defined(_GNU_SOURCE) && (defined(HAVE_PIPE2) || defined(HAVE_ACCEPT4))
+#define _GNU_SOURCE
+#endif
+
+#include <assert.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#ifdef WIN32
+#include <winsock2.h>
+#else
+#include <sys/socket.h>
+#endif
+
+#ifndef WIN32
+
+static int
+fd_mask_flags(int fd, int and_mask, int xor_mask)
+{
+ int ret;
+
+ assert(fd >= 0);
+
+ ret = fcntl(fd, F_GETFD, 0);
+ if (ret < 0)
+ return ret;
+
+ return fcntl(fd, F_SETFD, (ret & and_mask) ^ xor_mask);
+}
+
+#endif /* !WIN32 */
+
+int
+fd_set_cloexec(int fd, bool enable)
+{
+#ifndef WIN32
+ return fd_mask_flags(fd, ~FD_CLOEXEC, enable ? FD_CLOEXEC : 0);
+#else
+ (void)fd;
+ (void)enable;
+#endif
+}
+
+int
+open_cloexec(const char *path_fs, int flags)
+{
+ int fd;
+
+#ifdef O_CLOEXEC
+ flags |= O_CLOEXEC;
+#endif
+
+#ifdef O_NOCTTY
+ flags |= O_NOCTTY;
+#endif
+
+ fd = open(path_fs, flags, 0666);
+ fd_set_cloexec(fd, true);
+
+ return fd;
+}
+
+int
+creat_cloexec(const char *path_fs, int mode)
+{
+ int flags = O_CREAT|O_WRONLY|O_TRUNC;
+ int fd;
+
+#ifdef O_CLOEXEC
+ flags |= O_CLOEXEC;
+#endif
+
+#ifdef O_NOCTTY
+ flags |= O_NOCTTY;
+#endif
+
+ fd = open(path_fs, flags, mode);
+ fd_set_cloexec(fd, true);
+
+ return fd;
+}
+
+int
+pipe_cloexec(int fd[2])
+{
+#ifdef WIN32
+ return _pipe(event_pipe, 512, _O_BINARY);
+#else
+ int ret;
+
+#ifdef HAVE_PIPE2
+ ret = pipe2(fd, O_CLOEXEC);
+ if (ret >= 0 || errno != ENOSYS)
+ return ret;
+#endif
+
+ ret = pipe(fd);
+ if (ret >= 0) {
+ fd_set_cloexec(fd[0], true);
+ fd_set_cloexec(fd[1], true);
+ }
+
+ return ret;
+#endif
+}
+
+int
+socket_cloexec(int domain, int type, int protocol)
+{
+ int fd;
+
+#ifdef SOCK_CLOEXEC
+ fd = socket(domain, type | SOCK_CLOEXEC, protocol);
+ if (fd >= 0 || errno != EINVAL)
+ return fd;
+#endif
+
+ fd = socket(domain, type, protocol);
+ if (fd >= 0)
+ fd_set_cloexec(fd, true);
+
+ return fd;
+}
+
+int
+accept_cloexec(int fd, struct sockaddr *address, size_t *address_length_r)
+{
+ int ret;
+ socklen_t address_length = *address_length_r;
+
+#ifdef HAVE_ACCEPT4
+ ret = accept4(fd, address, &address_length, SOCK_CLOEXEC);
+ if (ret >= 0 || errno != ENOSYS) {
+ if (ret >= 0)
+ *address_length_r = address_length;
+
+ return ret;
+ }
+#endif
+
+ ret = accept(fd, address, &address_length);
+ if (ret >= 0) {
+ fd_set_cloexec(ret, true);
+ *address_length_r = address_length;
+ }
+
+ return ret;
+}