Assume that accept4 is always available and works

Simplify the Linux accept4 implementation based on the assumption
that it is available in some way.  __ASSUME_ACCEPT4_SOCKETCALL was
previously unused, so remove it.

For ia64, the accept4 system call (and socket call) were backported
in kernel version 3.2.18.  Reflect this in the installation
instructions.

2 files changed, 133 insertions, 0 deletions

diff --git a/socket/Makefile b/socket/Makefile
index 25d4f68578..1e2555d66d 100644
--- a/socket/Makefile
+++ b/socket/Makefile
@@ -31,6 +31,8 @@ routines := accept bind connect getpeername getsockname getsockopt	\
 	    setsockopt shutdown socket socketpair isfdtype opensock	\
 	    sockatmark accept4 recvmmsg sendmmsg
 
+tests := tst-accept4
+
 aux	 := sa_len
 
 include ../Rules
diff --git a/socket/tst-accept4.c b/socket/tst-accept4.c
new file mode 100644
index 0000000000..a5cf3a237b
--- /dev/null
+++ b/socket/tst-accept4.c
@@ -0,0 +1,131 @@
+/* Test the accept4 function with differing flags arguments.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <support/check.h>
+#include <support/xsocket.h>
+#include <support/xunistd.h>
+#include <sys/socket.h>
+
+static bool
+is_nonblocking (int fd)
+{
+  int status = fcntl (fd, F_GETFL);
+  if (status < 0)
+    FAIL_EXIT1 ("fcntl (F_GETFL): %m");
+  return status & O_NONBLOCK;
+}
+
+static bool
+is_cloexec (int fd)
+{
+  int status = fcntl (fd, F_GETFD);
+  if (status < 0)
+    FAIL_EXIT1 ("fcntl (F_GETFD): %m");
+  return status & FD_CLOEXEC;
+}
+
+struct client
+{
+  int socket;
+  struct sockaddr_in address;
+};
+
+/* Perform a non-blocking connect to *SERVER_ADDRESS.  */
+static struct client
+client_connect (const struct sockaddr_in *server_address)
+{
+  struct client result;
+  result.socket = xsocket (AF_INET,
+                           SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
+  TEST_VERIFY (is_nonblocking (result.socket));
+  TEST_VERIFY (is_cloexec (result.socket));
+  int ret = connect (result.socket, (const struct sockaddr *) server_address,
+                     sizeof (*server_address));
+  if (ret < 0 && errno != EINPROGRESS)
+    FAIL_EXIT1 ("client connect: %m");
+  socklen_t sa_len = sizeof (result.address);
+  xgetsockname (result.socket, (struct sockaddr *) &result.address,
+                &sa_len);
+  TEST_VERIFY (sa_len == sizeof (result.address));
+  return result;
+}
+
+static void
+check_same_address (const struct sockaddr_in *left,
+                    const struct sockaddr_in *right)
+{
+  TEST_VERIFY (left->sin_family == AF_INET);
+  TEST_VERIFY (right->sin_family == AF_INET);
+  TEST_VERIFY (left->sin_addr.s_addr == right->sin_addr.s_addr);
+  TEST_VERIFY (left->sin_port == right->sin_port);
+}
+
+static int
+do_test (void)
+{
+  /* Create server socket.  */
+  int server_socket = xsocket (AF_INET, SOCK_STREAM, 0);
+  TEST_VERIFY (!is_nonblocking (server_socket));
+  TEST_VERIFY (!is_cloexec (server_socket));
+  struct sockaddr_in server_address =
+    {
+      .sin_family = AF_INET,
+      .sin_addr = {.s_addr = htonl (INADDR_LOOPBACK) },
+    };
+  xbind (server_socket,
+         (struct sockaddr *) &server_address, sizeof (server_address));
+  {
+    socklen_t sa_len = sizeof (server_address);
+    xgetsockname (server_socket, (struct sockaddr *) &server_address,
+                  &sa_len);
+    TEST_VERIFY (sa_len == sizeof (server_address));
+  }
+  xlisten (server_socket, 5);
+
+  for (int do_nonblock = 0; do_nonblock < 2; ++do_nonblock)
+    for (int do_cloexec = 0; do_cloexec < 2; ++do_cloexec)
+      {
+        int sockflags = 0;
+        if (do_nonblock)
+          sockflags |= SOCK_NONBLOCK;
+        if (do_cloexec)
+          sockflags |= SOCK_CLOEXEC;
+
+        struct client client = client_connect (&server_address);
+        struct sockaddr_in client_address;
+        socklen_t sa_len = sizeof (client_address);
+        int client_socket = xaccept4 (server_socket,
+                                      (struct sockaddr *) &client_address,
+                                      &sa_len, sockflags);
+        TEST_VERIFY (sa_len == sizeof (client_address));
+        TEST_VERIFY (is_nonblocking (client_socket) == do_nonblock);
+        TEST_VERIFY (is_cloexec (client_socket) == do_cloexec);
+        check_same_address (&client.address, &client_address);
+        xclose (client_socket);
+        xclose (client.socket);
+      }
+
+  xclose (server_socket);
+  return 0;
+}
+
+#include <support/test-driver.c>