-- --
-- B o d y --
-- --
--- Copyright (C) 2001-2006, AdaCore --
+-- Copyright (C) 2001-2008, AdaCore --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- Note: this code used to be in GNAT.Sockets, but has been moved to a
-- platform-specific file. It is now used only for non-UNIX platforms.
-separate
- (GNAT.Sockets.Thin)
+separate (GNAT.Sockets.Thin)
package body Signalling_Fds is
+ -----------
+ -- Close --
+ -----------
+
+ procedure Close (Sig : C.int) is
+ Res : C.int;
+ pragma Unreferenced (Res);
+ -- Res is assigned but never read, because we purposefully ignore
+ -- any error returned by the C_Close system call, as per the spec
+ -- of this procedure.
+ begin
+ Res := C_Close (Sig);
+ end Close;
+
------------
-- Create --
------------
-- Listening socket, read socket and write socket
Sin : aliased Sockaddr_In;
- Len : aliased C.int := Sin'Size / 8;
+ Len : aliased C.int;
-- Address of listening socket
Res : C.int;
- -- Return status of system calls
-
- Err : Integer;
- -- Saved errno value
+ pragma Warnings (Off, Res);
+ -- Return status of system calls (usually ignored, hence warnings off)
begin
- Fds (Read_End) := Failure;
- Fds (Write_End) := Failure;
+ Fds.all := (Read_End | Write_End => Failure);
-- We open two signalling sockets. One of them is used to send data
-- to the other, which is included in a C_Select socket set. The
-- communication is used to force the call to C_Select to complete,
-- and the waiting task to resume its execution.
- -- Create a listening socket
+ loop
+ -- Retry loop, in case the C_Connect below fails
- L_Sock := C_Socket (Constants.AF_INET, Constants.SOCK_STREAM, 0);
+ -- Create a listening socket
- if L_Sock = Failure then
- goto Fail;
- end if;
+ L_Sock := C_Socket (SOSC.AF_INET, SOSC.SOCK_STREAM, 0);
- -- Bind the socket to an available port on localhost
+ if L_Sock = Failure then
+ goto Fail;
+ end if;
- Sin.Sin_Addr.S_B1 := 127;
- Sin.Sin_Addr.S_B2 := 0;
- Sin.Sin_Addr.S_B3 := 0;
- Sin.Sin_Addr.S_B4 := 1;
- Sin.Sin_Port := 0;
+ -- Bind the socket to an available port on localhost
- Res := C_Bind (L_Sock, Sin'Address, Len);
+ Set_Family (Sin.Sin_Family, Family_Inet);
+ Sin.Sin_Addr.S_B1 := 127;
+ Sin.Sin_Addr.S_B2 := 0;
+ Sin.Sin_Addr.S_B3 := 0;
+ Sin.Sin_Addr.S_B4 := 1;
+ Sin.Sin_Port := 0;
- if Res = Failure then
- goto Fail;
- end if;
+ Len := C.int (Lengths (Family_Inet));
+ Res := C_Bind (L_Sock, Sin'Address, Len);
- -- Get assigned port
+ if Res = Failure then
+ goto Fail;
+ end if;
- Res := C_Getsockname (L_Sock, Sin'Address, Len'Access);
- if Res = Failure then
- goto Fail;
- end if;
+ -- Get assigned port
- -- Set socket to listen mode, with a backlog of 1 to guarantee that
- -- exactly one call to connect(2) succeeds.
+ Res := C_Getsockname (L_Sock, Sin'Address, Len'Access);
+ if Res = Failure then
+ goto Fail;
+ end if;
- Res := C_Listen (L_Sock, 1);
+ -- Set socket to listen mode, with a backlog of 1 to guarantee that
+ -- exactly one call to connect(2) succeeds.
- if Res = Failure then
- goto Fail;
- end if;
+ Res := C_Listen (L_Sock, 1);
- -- Create read end (client) socket
+ if Res = Failure then
+ goto Fail;
+ end if;
- R_Sock := C_Socket (Constants.AF_INET, Constants.SOCK_STREAM, 0);
+ -- Create read end (client) socket
- if R_Sock = Failure then
- goto Fail;
- end if;
+ R_Sock := C_Socket (SOSC.AF_INET, SOSC.SOCK_STREAM, 0);
- -- Connect listening socket
+ if R_Sock = Failure then
+ goto Fail;
+ end if;
- Res := C_Connect (R_Sock, Sin'Address, Len);
+ -- Connect listening socket
- if Res = Failure then
- goto Fail;
- end if;
+ Res := C_Connect (R_Sock, Sin'Address, Len);
+
+ exit when Res /= Failure;
- -- Since the call to connect(2) has suceeded and the backlog limit on
+ if Socket_Errno /= SOSC.EADDRINUSE then
+ goto Fail;
+ end if;
+
+ -- In rare cases, the above C_Bind chooses a port that is still
+ -- marked "in use", even though it has been closed (perhaps by some
+ -- other process that has already exited). This causes the above
+ -- C_Connect to fail with EADDRINUSE. In this case, we close the
+ -- ports, and loop back to try again. This mysterious Windows
+ -- behavior is documented. See, for example:
+ -- http://msdn2.microsoft.com/en-us/library/ms737625.aspx
+ -- In an experiment with 2000 calls, 21 required exactly one retry, 7
+ -- required two, and none required three or more. Note that no delay
+ -- is needed between retries; retrying C_Bind will typically produce
+ -- a different port.
+
+ pragma Assert (Res = Failure
+ and then
+ Socket_Errno = SOSC.EADDRINUSE);
+ Res := C_Close (W_Sock);
+ W_Sock := Failure;
+ Res := C_Close (R_Sock);
+ R_Sock := Failure;
+ end loop;
+
+ -- Since the call to connect(2) has succeeded and the backlog limit on
-- the listening socket is 1, we know that there is now exactly one
-- pending connection on L_Sock, which is the one from R_Sock.
W_Sock := C_Accept (L_Sock, Sin'Address, Len'Access);
+
if W_Sock = Failure then
goto Fail;
end if;
Res := C_Close (L_Sock);
- Fds (Read_End) := R_Sock;
- Fds (Write_End) := W_Sock;
+ Fds.all := (Read_End => R_Sock, Write_End => W_Sock);
- return Success;
+ return Thin_Common.Success;
<<Fail>>
- Err := Socket_Errno;
+ declare
+ Saved_Errno : constant Integer := Socket_Errno;
- if W_Sock /= Failure then
- Res := C_Close (W_Sock);
- end if;
+ begin
+ if W_Sock /= Failure then
+ Res := C_Close (W_Sock);
+ end if;
- if R_Sock /= Failure then
- Res := C_Close (R_Sock);
- end if;
+ if R_Sock /= Failure then
+ Res := C_Close (R_Sock);
+ end if;
- if L_Sock /= Failure then
- Res := C_Close (L_Sock);
- end if;
+ if L_Sock /= Failure then
+ Res := C_Close (L_Sock);
+ end if;
- Set_Socket_Errno (Err);
+ Set_Socket_Errno (Saved_Errno);
+ end;
return Failure;
end Create;
function Read (Rsig : C.int) return C.int is
Buf : aliased Character;
begin
- return C_Recv (Rsig, Buf'Address, 1, Constants.MSG_Forced_Flags);
+ return C_Recv (Rsig, Buf'Address, 1, SOSC.MSG_Forced_Flags);
end Read;
-----------
function Write (Wsig : C.int) return C.int is
Buf : aliased Character := ASCII.NUL;
begin
- return C_Send (Wsig, Buf'Address, 1, Constants.MSG_Forced_Flags);
+ return C_Sendto
+ (Wsig, Buf'Address, 1,
+ Flags => SOSC.MSG_Forced_Flags,
+ To => System.Null_Address,
+ Tolen => 0);
end Write;
end Signalling_Fds;
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