* ext/socket/socket.c (s_recvfrom): alen may be zero with UNIXSocket

too.  (tested on NetBSD 3.0)
  (s_recvfrom_nonblock): extracted from sock_recvfrom_nonblock.
  (sock_recvfrom_nonblock): use s_recvfrom_nonblock.
  (ip_recvfrom_nonblock): new method: IPSocket#recvfrom_nonblock
  (unix_recvfrom_nonblock): new method: UNIXSocket#recvfrom_nonblock
  (s_accept_nonblock): extracted from sock_accept_nonblock.
  (sock_accept_nonblock): use s_accept_nonblock.
  (tcp_accept_nonblock): new method: TCPServer#accept_nonblock
  (unix_accept_nonblock): new method: UNIXServer#accept_nonblock


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@10203 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,16 @@
+Fri Jun  2 00:11:19 2006  Tanaka Akira  <akr@m17n.org>
+
+	* ext/socket/socket.c (s_recvfrom): alen may be zero with UNIXSocket
+	  too.  (tested on NetBSD 3.0)
+	  (s_recvfrom_nonblock): extracted from sock_recvfrom_nonblock.
+	  (sock_recvfrom_nonblock): use s_recvfrom_nonblock.
+	  (ip_recvfrom_nonblock): new method: IPSocket#recvfrom_nonblock
+	  (unix_recvfrom_nonblock): new method: UNIXSocket#recvfrom_nonblock
+	  (s_accept_nonblock): extracted from sock_accept_nonblock.
+	  (sock_accept_nonblock): use s_accept_nonblock.
+	  (tcp_accept_nonblock): new method: TCPServer#accept_nonblock
+	  (unix_accept_nonblock): new method: UNIXServer#accept_nonblock
+	 
 Thu Jun  1 19:12:37 2006  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* win32/win32.c (rb_w32_cmdvector): backslashes inside single-quotes

ext/socket/socket.c

@@ -620,7 +620,10 @@ s_recvfrom(sock, argc, argv, from)
 
 #ifdef HAVE_SYS_UN_H
       case RECV_UNIX:
+        if (alen) /* connection-oriented socket may not return a from result */
             return rb_assoc_new(str, unixaddr((struct sockaddr_un*)buf));
+        else
+            return rb_assoc_new(str, Qnil);
 #endif
       case RECV_SOCKET:
 	return rb_assoc_new(str, rb_str_new(buf, alen));
@@ -629,6 +632,74 @@ s_recvfrom(sock, argc, argv, from)
     }
 }
 
+static VALUE
+s_recvfrom_nonblock(int argc, VALUE *argv, VALUE sock, enum sock_recv_type from)
+{
+    OpenFile *fptr;
+    VALUE str;
+    char buf[1024];
+    socklen_t alen = sizeof buf;
+    VALUE len, flg;
+    long buflen;
+    long slen;
+    int fd, flags;
+    VALUE addr = Qnil;
+
+    rb_scan_args(argc, argv, "11", &len, &flg);
+
+    if (flg == Qnil) flags = 0;
+    else             flags = NUM2INT(flg);
+    buflen = NUM2INT(len);
+
+#ifdef MSG_DONTWAIT
+    /* MSG_DONTWAIT avoids the race condition between fcntl and recvfrom.
+       It is Linux specific, though. */
+    flags |= MSG_DONTWAIT;
+#endif
+
+    GetOpenFile(sock, fptr);
+    if (rb_io_read_pending(fptr)) {
+	rb_raise(rb_eIOError, "recvfrom for buffered IO");
+    }
+    fd = fptr->fd;
+
+    str = rb_tainted_str_new(0, buflen);
+
+    rb_io_check_closed(fptr);
+    rb_io_set_nonblock(fptr);
+    slen = recvfrom(fd, RSTRING(str)->ptr, buflen, flags, (struct sockaddr*)buf, &alen);
+
+    if (slen < 0) {
+	rb_sys_fail("recvfrom(2)");
+    }
+    if (slen < RSTRING(str)->len) {
+	RSTRING(str)->len = slen;
+	RSTRING(str)->ptr[slen] = '\0';
+    }
+    rb_obj_taint(str);
+    switch (from) {
+      case RECV_IP:
+        if (alen) /* connection-oriented socket may not return a from result */
+            addr = ipaddr((struct sockaddr*)buf, fptr->mode & FMODE_NOREVLOOKUP);
+        break;
+
+#ifdef HAVE_SYS_UN_H
+      case RECV_UNIX:
+        if (alen) /* connection-oriented socket may not return a from result */
+            addr = unixaddr((struct sockaddr_un*)buf);
+        break;
+#endif
+
+      case RECV_SOCKET:
+        addr = rb_str_new(buf, alen);
+        break;
+
+      default:
+        rb_bug("s_recvfrom_nonblock called with bad value");
+    }
+    return rb_assoc_new(str, addr);
+}
+
 static VALUE
 bsock_recv(argc, argv, sock)
     int argc;
@@ -1382,6 +1453,20 @@ tcp_svr_init(argc, argv, sock)
 	return init_inetsock(sock, Qnil, arg1, Qnil, Qnil, INET_SERVER);
 }
 
+static VALUE
+s_accept_nonblock(VALUE klass, OpenFile *fptr, struct sockaddr *sockaddr, socklen_t *len)
+{
+    int fd2;
+
+    rb_secure(3);
+    rb_io_set_nonblock(fptr);
+    fd2 = accept(fptr->fd, (struct sockaddr*)sockaddr, len);
+    if (fd2 < 0) {
+        rb_sys_fail("accept(2)");
+    }
+    return init_sock(rb_obj_alloc(klass), fd2);
+}
+
 static VALUE
 s_accept(klass, fd, sockaddr, len)
     VALUE klass;
@@ -1435,6 +1520,49 @@ tcp_accept(sock)
 		    (struct sockaddr*)&from, &fromlen);
 }
 
+/*
+ * call-seq:
+ * 	tcpserver.accept_nonblock => tcpsocket
+ * 
+ * Accepts an incoming connection using accept(2) after
+ * O_NONBLOCK is set for the underlying file descriptor.
+ * It returns an accepted TCPSocket for the incoming connection.
+ * 
+ * === Example
+ * 	require 'socket'
+ * 	serv = TCPServer.new(2202)
+ * 	begin
+ * 	  sock = serv.accept_nonblock
+ * 	rescue Errno::EAGAIN, Errno::ECONNABORTED, Errno::EPROTO, Errno::EINTR
+ * 	  IO.select([serv])
+ * 	  retry
+ * 	end
+ * 	# sock is an accepted socket.
+ * 
+ * Refer to Socket#accept for the exceptions that may be thrown if the call
+ * to TCPServer#accept_nonblock fails. 
+ *
+ * TCPServer#accept_nonblock may raise any error corresponding to accept(2) failure,
+ * including Errno::EAGAIN.
+ * 
+ * === See
+ * * TCPServer#accept
+ * * Socket#accept
+ */
+static VALUE
+tcp_accept_nonblock(sock)
+    VALUE sock;
+{
+    OpenFile *fptr;
+    struct sockaddr_storage from;
+    socklen_t fromlen;
+
+    GetOpenFile(sock, fptr);
+    fromlen = sizeof(from);
+    return s_accept_nonblock(rb_cTCPSocket, fptr,
+                             (struct sockaddr *)&from, &fromlen);
+}
+
 static VALUE
 tcp_sysaccept(sock)
     VALUE sock;
@@ -1551,6 +1679,51 @@ ip_recvfrom(argc, argv, sock)
     return s_recvfrom(sock, argc, argv, RECV_IP);
 }
 
+/*
+ * call-seq:
+ * 	ipsocket.recvfrom_nonblock(len) => [mesg, inet_addr]
+ * 	ipsocket.recvfrom_nonblock(len, flags) => [mesg, inet_addr]
+ * 
+ * Receives up to _len_ bytes from +ipsocket+ using recvfrom(2) after
+ * O_NONBLOCK is set for the underlying file descriptor.
+ * _flags_ is zero or more of the +MSG_+ options.
+ * The first element of the results is the data received.
+ * The second element is an array to represent the sender address.
+ *
+ * When recvfrom(2) returns 0, Socket#recvfrom_nonblock returns
+ * an empty string as data.
+ * The meaning depends on the socket: EOF on TCP, empty packet on UDP, etc.
+ * 
+ * === Parameters
+ * * +len+ - the number of bytes to receive from the socket
+ * * +flags+ - zero or more of the +MSG_+ options 
+ * 
+ * === Example
+ * 	require 'socket'
+ * 	socket = TCPSocket.new("localhost", "daytime")
+ * 	begin
+ * 	  p socket.recvfrom_nonblock(20)
+ * 	rescue Errno::EAGAIN
+ * 	  IO.select([socket])
+ * 	  retry
+ * 	end
+ * 	socket.close
+ * 
+ * Refer to Socket#recvfrom for the exceptions that may be thrown if the call
+ * to _recvfrom_nonblock_ fails. 
+ *
+ * IPSocket#recvfrom_nonblock may raise any error corresponding to recvfrom(2) failure,
+ * including Errno::EAGAIN.
+ *
+ * === See
+ * * Socket#recvfrom
+ */
+static VALUE
+ip_recvfrom_nonblock(int argc, VALUE *argv, VALUE sock)
+{
+    return s_recvfrom_nonblock(argc, argv, sock, RECV_IP);
+}
+
 static VALUE
 ip_s_getaddress(obj, host)
     VALUE obj, host;
@@ -1726,6 +1899,51 @@ unix_recvfrom(argc, argv, sock)
     return s_recvfrom(sock, argc, argv, RECV_UNIX);
 }
 
+/*
+ * call-seq:
+ * 	unixsocket.recvfrom_nonblock(len) => [mesg, unix_addr]
+ * 	unixsocket.recvfrom_nonblock(len, flags) => [mesg, unix_addr]
+ * 
+ * Receives up to _len_ bytes from +unixsocket+ using recvfrom(2) after
+ * O_NONBLOCK is set for the underlying file descriptor.
+ * _flags_ is zero or more of the +MSG_+ options.
+ * The first element of the results is the data received.
+ * The second element is an array to represent the sender address.
+ *
+ * When recvfrom(2) returns 0, UNIXSocket#recvfrom_nonblock returns
+ * an empty string as data.
+ * It means EOF for UNIXSocket#recvfrom_nonblock.
+ * 
+ * === Parameters
+ * * +len+ - the number of bytes to receive from the socket
+ * * +flags+ - zero or more of the +MSG_+ options 
+ * 
+ * === Example
+ * 	require 'socket'
+ * 	socket = UNIXSocket.new("/tmp/sock")
+ * 	begin
+ * 	  p socket.recvfrom_nonblock(20)
+ * 	rescue Errno::EAGAIN
+ * 	  IO.select([socket])
+ * 	  retry
+ * 	end
+ * 	socket.close
+ * 
+ * Refer to Socket#recvfrom for the exceptions that may be thrown if the call
+ * to _recvfrom_nonblock_ fails. 
+ *
+ * IPSocket#recvfrom_nonblock may raise any error corresponding to recvfrom(2) failure,
+ * including Errno::EAGAIN.
+ *
+ * === See
+ * * Socket#recvfrom
+ */
+static VALUE
+unix_recvfrom_nonblock(int argc, VALUE *argv, VALUE sock)
+{
+    return s_recvfrom_nonblock(argc, argv, sock, RECV_UNIX);
+}
+
 #if defined(HAVE_ST_MSG_CONTROL) && defined(SCM_RIGHTS)
 #define FD_PASSING_BY_MSG_CONTROL 1
 #else
@@ -1925,6 +2143,49 @@ unix_accept(sock)
 		    (struct sockaddr*)&from, &fromlen);
 }
 
+/*
+ * call-seq:
+ * 	unixserver.accept_nonblock => unixsocket
+ * 
+ * Accepts an incoming connection using accept(2) after
+ * O_NONBLOCK is set for the underlying file descriptor.
+ * It returns an accepted UNIXSocket for the incoming connection.
+ * 
+ * === Example
+ * 	require 'socket'
+ * 	serv = UNIXServer.new("/tmp/sock")
+ * 	begin
+ * 	  sock = serv.accept_nonblock
+ * 	rescue Errno::EAGAIN, Errno::ECONNABORTED, Errno::EPROTO, Errno::EINTR
+ * 	  IO.select([serv])
+ * 	  retry
+ * 	end
+ * 	# sock is an accepted socket.
+ * 
+ * Refer to Socket#accept for the exceptions that may be thrown if the call
+ * to UNIXServer#accept_nonblock fails. 
+ *
+ * UNIXServer#accept_nonblock may raise any error corresponding to accept(2) failure,
+ * including Errno::EAGAIN.
+ * 
+ * === See
+ * * UNIXServer#accept
+ * * Socket#accept
+ */
+static VALUE
+unix_accept_nonblock(sock)
+    VALUE sock;
+{
+    OpenFile *fptr;
+    struct sockaddr_storage from;
+    socklen_t fromlen;
+
+    GetOpenFile(sock, fptr);
+    fromlen = sizeof(from);
+    return s_accept_nonblock(rb_cUNIXSocket, fptr,
+                             (struct sockaddr *)&from, &fromlen);
+}
+
 static VALUE
 unix_sysaccept(sock)
     VALUE sock;
@@ -2617,8 +2878,8 @@ sock_recvfrom(argc, argv, sock)
 
 /*
  * call-seq:
- * 	socket.recvfrom_nonblock( len ) => [ data, sender ]
+ * 	socket.recvfrom_nonblock(len) => [data, sockaddr]
- * 	socket.recvfrom_nonblock( len, flags ) => [ data, sender ]
+ * 	socket.recvfrom_nonblock(len, flags) => [data, sockaddr]
  * 
  * Receives up to _len_ bytes from +socket+ using recvfrom(2) after
  * O_NONBLOCK is set for the underlying file descriptor.
@@ -2639,13 +2900,13 @@ sock_recvfrom(argc, argv, sock)
  * 	# In one file, start this first
  * 	require 'socket'
  * 	include Socket::Constants
- * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
+ * 	socket = Socket.new(AF_INET, SOCK_STREAM, 0)
- * 	sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
+ * 	sockaddr = Socket.pack_sockaddr_in(2200, 'localhost')
- * 	socket.bind( sockaddr )
+ * 	socket.bind(sockaddr)
- * 	socket.listen( 5 )
+ * 	socket.listen(5)
  * 	client, client_sockaddr = socket.accept
  * 	begin
- * 	  pair = client.recvfrom_nonblock( 20 )
+ * 	  pair = client.recvfrom_nonblock(20)
  * 	rescue Errno::EAGAIN
  * 	  IO.select([client])
  * 	  retry
@@ -2658,9 +2919,9 @@ sock_recvfrom(argc, argv, sock)
  * 	# In another file, start this second
  * 	require 'socket'
  * 	include Socket::Constants
- * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
+ * 	socket = Socket.new(AF_INET, SOCK_STREAM, 0)
- * 	sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
+ * 	sockaddr = Socket.pack_sockaddr_in(2200, 'localhost')
- * 	socket.connect( sockaddr )
+ * 	socket.connect(sockaddr)
  * 	socket.puts "Watch this get cut short!"
  * 	socket.close 
  * 
@@ -2674,47 +2935,9 @@ sock_recvfrom(argc, argv, sock)
  * * Socket#recvfrom
  */
 static VALUE
-sock_recvfrom_nonblock(argc, argv, sock)
+sock_recvfrom_nonblock(int argc, VALUE *argv, VALUE sock)
-    int argc;
-    VALUE *argv;
-    VALUE sock;
 {
-    OpenFile *fptr;
+    return s_recvfrom_nonblock(argc, argv, sock, RECV_SOCKET);
-    VALUE str;
-    char buf[1024];
-    socklen_t alen = sizeof buf;
-    VALUE len, flg;
-    long buflen;
-    long slen;
-    int fd, flags;
-
-    rb_scan_args(argc, argv, "11", &len, &flg);
-
-    if (flg == Qnil) flags = 0;
-    else             flags = NUM2INT(flg);
-    buflen = NUM2INT(len);
-
-    GetOpenFile(sock, fptr);
-    if (rb_io_read_pending(fptr)) {
-	rb_raise(rb_eIOError, "recv for buffered IO");
-    }
-    fd = fptr->fd;
-
-    str = rb_tainted_str_new(0, buflen);
-
-    rb_io_check_closed(fptr);
-    rb_io_set_nonblock(fptr);
-    slen = recvfrom(fd, RSTRING(str)->ptr, buflen, flags, (struct sockaddr*)buf, &alen);
-
-    if (slen < 0) {
-	rb_sys_fail("recvfrom(2)");
-    }
-    if (slen < RSTRING(str)->len) {
-	RSTRING(str)->len = slen;
-	RSTRING(str)->ptr[slen] = '\0';
-    }
-    rb_obj_taint(str);
-    return rb_assoc_new(str, rb_str_new(buf, alen));
 }
 
 static VALUE
@@ -2784,19 +3007,12 @@ sock_accept_nonblock(sock)
     VALUE sock;
 {
     OpenFile *fptr;
-    int fd2;
     VALUE sock2;
     char buf[1024];
     socklen_t len = sizeof buf;
 
     GetOpenFile(sock, fptr);
-    rb_io_set_nonblock(fptr);
+    sock2 = s_accept_nonblock(rb_cSocket, fptr, (struct sockaddr *)buf, &len);
-    fd2 = accept(fptr->fd, (struct sockaddr*)buf, &len);
-    if (fd2 < 0) {
-        rb_sys_fail("accept(2)");
-    }
-    sock2 = init_sock(rb_obj_alloc(rb_cSocket), fd2);
-
     return rb_assoc_new(sock2, rb_str_new(buf, len));
 }
 
@@ -3395,6 +3611,7 @@ Init_socket()
     rb_define_method(rb_cIPSocket, "addr", ip_addr, 0);
     rb_define_method(rb_cIPSocket, "peeraddr", ip_peeraddr, 0);
     rb_define_method(rb_cIPSocket, "recvfrom", ip_recvfrom, -1);
+    rb_define_method(rb_cIPSocket, "recvfrom_nonblock", ip_recvfrom_nonblock, -1);
     rb_define_singleton_method(rb_cIPSocket, "getaddress", ip_s_getaddress, 1);
 
     rb_cTCPSocket = rb_define_class("TCPSocket", rb_cIPSocket);
@@ -3414,6 +3631,7 @@ Init_socket()
     rb_cTCPServer = rb_define_class("TCPServer", rb_cTCPSocket);
     rb_define_global_const("TCPserver", rb_cTCPServer);
     rb_define_method(rb_cTCPServer, "accept", tcp_accept, 0);
+    rb_define_method(rb_cTCPServer, "accept_nonblock", tcp_accept_nonblock, 0);
     rb_define_method(rb_cTCPServer, "sysaccept", tcp_sysaccept, 0);
     rb_define_method(rb_cTCPServer, "initialize", tcp_svr_init, -1);
     rb_define_method(rb_cTCPServer, "listen", sock_listen, 1);
@@ -3433,6 +3651,7 @@ Init_socket()
     rb_define_method(rb_cUNIXSocket, "addr", unix_addr, 0);
     rb_define_method(rb_cUNIXSocket, "peeraddr", unix_peeraddr, 0);
     rb_define_method(rb_cUNIXSocket, "recvfrom", unix_recvfrom, -1);
+    rb_define_method(rb_cUNIXSocket, "recvfrom_nonblock", unix_recvfrom_nonblock, -1);
     rb_define_method(rb_cUNIXSocket, "send_io", unix_send_io, 1);
     rb_define_method(rb_cUNIXSocket, "recv_io", unix_recv_io, -1);
     rb_define_singleton_method(rb_cUNIXSocket, "socketpair", unix_s_socketpair, -1);
@@ -3442,6 +3661,7 @@ Init_socket()
     rb_define_global_const("UNIXserver", rb_cUNIXServer);
     rb_define_method(rb_cUNIXServer, "initialize", unix_svr_init, 1);
     rb_define_method(rb_cUNIXServer, "accept", unix_accept, 0);
+    rb_define_method(rb_cUNIXServer, "accept_nonblock", unix_accept_nonblock, 0);
     rb_define_method(rb_cUNIXServer, "sysaccept", unix_sysaccept, 0);
     rb_define_method(rb_cUNIXServer, "listen", sock_listen, 1);
 #endif

test/socket/test_nonblock.rb

@@ -0,0 +1,171 @@
+begin
+  require "socket"
+rescue LoadError
+end
+
+require "test/unit"
+require "tempfile"
+
+class TestNonblockSocket < Test::Unit::TestCase
+  def test_accept_nonblock
+    serv = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
+    serv.bind(Socket.sockaddr_in(0, "127.0.0.1"))
+    serv.listen(5)
+    assert_raise(Errno::EAGAIN) { serv.accept_nonblock }
+    c = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
+    c.connect(serv.getsockname)
+    s, sockaddr = serv.accept_nonblock
+    assert_equal(c.getsockname, sockaddr)
+  ensure
+    serv.close if serv
+    c.close if c
+    s.close if s
+  end
+
+  def test_connect_nonblock
+    serv = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
+    serv.bind(Socket.sockaddr_in(0, "127.0.0.1"))
+    serv.listen(5)
+    c = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
+    servaddr = serv.getsockname
+    begin
+      c.connect_nonblock(servaddr)
+    rescue Errno::EINPROGRESS
+      IO.select nil, [c]
+      assert_nothing_raised {
+        begin
+          c.connect_nonblock(servaddr)
+        rescue Errno::EISCONN
+        end
+      }
+    end
+    s, sockaddr = serv.accept
+    assert_equal(c.getsockname, sockaddr)
+  ensure
+    serv.close if serv
+    c.close if c
+    s.close if s
+  end
+
+  def test_udp_recvfrom_nonblock
+    u1 = UDPSocket.new
+    u2 = UDPSocket.new
+    u1.bind("127.0.0.1", 0)
+    assert_raise(Errno::EAGAIN) { u1.recvfrom_nonblock(100) }
+    assert_raise(Errno::EAGAIN) { u2.recvfrom_nonblock(100) }
+    u2.send("aaa", 0, u1.getsockname)
+    IO.select [u1]
+    mesg, inet_addr = u1.recvfrom_nonblock(100)
+    assert_equal(4, inet_addr.length)
+    assert_equal("aaa", mesg)
+    af, port, host, addr = inet_addr
+    u2_port, u2_addr = Socket.unpack_sockaddr_in(u2.getsockname)
+    assert_equal(u2_port, port)
+    assert_raise(Errno::EAGAIN) { u1.recvfrom_nonblock(100) }
+    u2.send("", 0, u1.getsockname)
+    IO.select [u1]
+    mesg, inet_addr = u1.recvfrom_nonblock(100)
+    assert_equal("", mesg)
+  ensure
+    u1.close if u1
+    u2.close if u2
+  end
+
+  def bound_unix_socket(klass)
+    tmpfile = Tempfile.new("testrubysock")
+    path = tmpfile.path
+    tmpfile.close(true)
+    return klass.new(path), path
+  end
+
+  def test_unix_recvfrom_nonblock
+    serv, serv_path = bound_unix_socket(UNIXServer)
+    c = UNIXSocket.new(serv_path)
+    s = serv.accept
+    assert_raise(Errno::EAGAIN) { s.recvfrom_nonblock(100) }
+    assert_raise(Errno::EAGAIN) { c.recvfrom_nonblock(100) }
+    s.write "aaa"
+    IO.select [c]
+    mesg, unix_addr = c.recvfrom_nonblock(100)
+    assert_equal("aaa", mesg)
+    if unix_addr != nil # connection-oriented socket may not return the peer address.
+      assert_equal(2, unix_addr.length)
+      af, path = unix_addr
+      assert_equal(serv_path, path)
+    end
+    s.close
+    IO.select [c]
+    mesg, unix_addr = c.recvfrom_nonblock(100)
+    assert_equal("", mesg)
+  ensure
+    File.unlink serv_path if serv_path && File.socket?(serv_path)
+    serv.close if serv
+    c.close if c
+    s.close if s && !s.closed?
+  end
+
+  def test_socket_recvfrom_nonblock
+    s1 = Socket.new(Socket::AF_INET, Socket::SOCK_DGRAM, 0)
+    s1.bind(Socket.sockaddr_in(0, "127.0.0.1"))
+    s2 = Socket.new(Socket::AF_INET, Socket::SOCK_DGRAM, 0)
+    assert_raise(Errno::EAGAIN) { s1.recvfrom_nonblock(100) }
+    assert_raise(Errno::EAGAIN) { s2.recvfrom_nonblock(100) }
+    s2.send("aaa", 0, s1.getsockname)
+    IO.select [s1]
+    mesg, sockaddr = s1.recvfrom_nonblock(100) 
+    assert_equal("aaa", mesg)
+    port, addr = Socket.unpack_sockaddr_in(sockaddr)
+    s2_port, s2_addr = Socket.unpack_sockaddr_in(s2.getsockname)
+    assert_equal(s2_port, port)
+  ensure
+    s1.close if s1
+    s2.close if s2
+  end
+
+  def tcp_pair
+    serv = TCPServer.new("127.0.0.1", 0)
+    af, port, host, addr = serv.addr
+    c = TCPSocket.new(addr, port)
+    s = serv.accept
+    return c, s
+  ensure
+    serv.close if serv
+  end
+
+  def test_read_nonblock
+    c, s = tcp_pair
+    assert_raise(Errno::EAGAIN) { c.read_nonblock(100) }
+    assert_raise(Errno::EAGAIN) { s.read_nonblock(100) }
+    c.write("abc")
+    IO.select [s]
+    assert_equal("a", s.read_nonblock(1))
+    assert_equal("bc", s.read_nonblock(100))
+    assert_raise(Errno::EAGAIN) { s.read_nonblock(100) }
+  ensure
+    c.close if c
+    s.close if s
+  end
+
+  def test_write_nonblock
+    c, s = tcp_pair
+    str = "a" * 10000
+    _, ws, _ = IO.select(nil, [c], nil)
+    assert_equal([c], ws)
+    ret = c.write_nonblock(str)
+    assert_operator(ret, :>, 0)
+    loop {
+      assert_raise(Errno::EAGAIN) {
+        loop {
+          ret = c.write_nonblock(str)
+          assert_operator(ret, :>, 0)
+        }
+      }
+      _, ws, _ = IO.select(nil, [c], nil, 0)
+      break if !ws
+    }
+  ensure
+    c.close if c
+    s.close if s
+  end
+
+end if defined?(Socket)