From 299afd25fd6dead39bf5c78572782db885579911 Mon Sep 17 00:00:00 2001
From: jilles <jilles@FreeBSD.org>
Date: Wed, 1 May 2013 20:10:21 +0000
Subject: Add accept4() system call.

The accept4() function, compared to accept(), allows setting the new file
descriptor atomically close-on-exec and explicitly controlling the
non-blocking status on the new socket. (Note that the latter point means
that accept() is not equivalent to any form of accept4().)

The linuxulator's accept4 implementation leaves a race window where the new
file descriptor is not close-on-exec because it calls sys_accept(). This
implementation leaves no such race window (by using falloc() flags). The
linuxulator could be fixed and simplified by using the new code.

Like accept(), accept4() is async-signal-safe, a cancellation point and
permitted in capability mode.
---
 lib/libthr/pthread.map           |  5 +++++
 lib/libthr/thread/thr_syscalls.c | 22 ++++++++++++++++++++++
 2 files changed, 27 insertions(+)

(limited to 'lib/libthr')

diff --git a/lib/libthr/pthread.map b/lib/libthr/pthread.map
index 355edea..bbbd930e 100644
--- a/lib/libthr/pthread.map
+++ b/lib/libthr/pthread.map
@@ -181,6 +181,7 @@ FBSDprivate_1.0 {
 	___wait;
 	___waitpid;
 	__accept;
+	__accept4;
 	__aio_suspend;
 	__close;
 	__connect;
@@ -408,3 +409,7 @@ FBSD_1.2 {
 	setcontext;
 	swapcontext;
 };
+
+FBSD_1.3 {
+	accept4;
+};
diff --git a/lib/libthr/thread/thr_syscalls.c b/lib/libthr/thread/thr_syscalls.c
index 2327d74..7a08302 100644
--- a/lib/libthr/thread/thr_syscalls.c
+++ b/lib/libthr/thread/thr_syscalls.c
@@ -101,6 +101,7 @@ extern pid_t	__waitpid(pid_t, int *, int);
 extern int	__sys_aio_suspend(const struct aiocb * const[], int,
 			const struct timespec *);
 extern int	__sys_accept(int, struct sockaddr *, socklen_t *);
+extern int	__sys_accept4(int, struct sockaddr *, socklen_t *, int);
 extern int	__sys_connect(int, const struct sockaddr *, socklen_t);
 extern int	__sys_fsync(int);
 extern int	__sys_msync(void *, size_t, int);
@@ -129,6 +130,7 @@ int	___usleep(useconds_t useconds);
 pid_t	___wait(int *);
 pid_t	___waitpid(pid_t, int *, int);
 int	__accept(int, struct sockaddr *, socklen_t *);
+int	__accept4(int, struct sockaddr *, socklen_t *, int);
 int	__aio_suspend(const struct aiocb * const iocbs[], int,
 		const struct timespec *);
 int	__close(int);
@@ -176,6 +178,26 @@ __accept(int s, struct sockaddr *addr, socklen_t *addrlen)
  	return (ret);
 }
 
+__weak_reference(__accept4, accept4);
+
+/*
+ * Cancellation behavior:
+ *   If thread is canceled, no socket is created.
+ */
+int
+__accept4(int s, struct sockaddr *addr, socklen_t *addrlen, int flags)
+{
+	struct pthread *curthread;
+	int ret;
+
+	curthread = _get_curthread();
+	_thr_cancel_enter(curthread);
+	ret = __sys_accept4(s, addr, addrlen, flags);
+	_thr_cancel_leave(curthread, ret == -1);
+
+ 	return (ret);
+}
+
 __weak_reference(__aio_suspend, aio_suspend);
 
 int
-- 
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