| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- G N A T . S O C K E T S . T H I N . S I G N A L L I N G _ F D S -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 2001-2010, 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- -- |
| -- ware Foundation; either version 3, or (at your option) any later ver- -- |
| -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- |
| -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- |
| -- or FITNESS FOR A PARTICULAR PURPOSE. -- |
| -- -- |
| -- As a special exception under Section 7 of GPL version 3, you are granted -- |
| -- additional permissions described in the GCC Runtime Library Exception, -- |
| -- version 3.1, as published by the Free Software Foundation. -- |
| -- -- |
| -- You should have received a copy of the GNU General Public License and -- |
| -- a copy of the GCC Runtime Library Exception along with this program; -- |
| -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- |
| -- <http://www.gnu.org/licenses/>. -- |
| -- -- |
| -- GNAT was originally developed by the GNAT team at New York University. -- |
| -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- Portable sockets-based implementation of GNAT.Sockets.Thin.Signalling_Fds |
| -- used for platforms that do not support UNIX pipes. |
| |
| -- 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) |
| 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 -- |
| ------------ |
| |
| function Create (Fds : not null access Fd_Pair) return C.int is |
| L_Sock, R_Sock, W_Sock : C.int := Failure; |
| -- Listening socket, read socket and write socket |
| |
| Sin : aliased Sockaddr_In; |
| Len : aliased C.int; |
| -- Address of listening socket |
| |
| Res : C.int; |
| pragma Warnings (Off, Res); |
| -- Return status of system calls (usually ignored, hence warnings off) |
| |
| begin |
| 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. |
| |
| loop |
| -- Retry loop, in case the C_Connect below fails |
| |
| -- Create a listening socket |
| |
| L_Sock := C_Socket (SOSC.AF_INET, SOSC.SOCK_STREAM, 0); |
| |
| if L_Sock = Failure then |
| goto Fail; |
| end if; |
| |
| -- Bind the socket to an available port on localhost |
| |
| 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; |
| |
| Len := C.int (Lengths (Family_Inet)); |
| Res := C_Bind (L_Sock, Sin'Address, Len); |
| |
| if Res = Failure then |
| goto Fail; |
| end if; |
| |
| -- Get assigned port |
| |
| Res := C_Getsockname (L_Sock, Sin'Address, Len'Access); |
| if Res = Failure then |
| goto Fail; |
| end if; |
| |
| -- Set socket to listen mode, with a backlog of 1 to guarantee that |
| -- exactly one call to connect(2) succeeds. |
| |
| Res := C_Listen (L_Sock, 1); |
| |
| if Res = Failure then |
| goto Fail; |
| end if; |
| |
| -- Create read end (client) socket |
| |
| R_Sock := C_Socket (SOSC.AF_INET, SOSC.SOCK_STREAM, 0); |
| |
| if R_Sock = Failure then |
| goto Fail; |
| end if; |
| |
| -- Connect listening socket |
| |
| Res := C_Connect (R_Sock, Sin'Address, Len); |
| |
| exit when Res /= Failure; |
| |
| 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; |
| |
| -- Set TCP_NODELAY on W_Sock, since we always want to send the data out |
| -- immediately. |
| |
| Set_Socket_Option |
| (Socket => Socket_Type (W_Sock), |
| Level => IP_Protocol_For_TCP_Level, |
| Option => (Name => No_Delay, Enabled => True)); |
| |
| -- Close listening socket (ignore exit status) |
| |
| Res := C_Close (L_Sock); |
| |
| Fds.all := (Read_End => R_Sock, Write_End => W_Sock); |
| |
| return Thin_Common.Success; |
| |
| <<Fail>> |
| declare |
| Saved_Errno : constant Integer := Socket_Errno; |
| |
| 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 L_Sock /= Failure then |
| Res := C_Close (L_Sock); |
| end if; |
| |
| Set_Socket_Errno (Saved_Errno); |
| end; |
| |
| return Failure; |
| end Create; |
| |
| ---------- |
| -- Read -- |
| ---------- |
| |
| function Read (Rsig : C.int) return C.int is |
| Buf : aliased Character; |
| begin |
| return C_Recv (Rsig, Buf'Address, 1, SOSC.MSG_Forced_Flags); |
| end Read; |
| |
| ----------- |
| -- Write -- |
| ----------- |
| |
| function Write (Wsig : C.int) return C.int is |
| Buf : aliased Character := ASCII.NUL; |
| begin |
| return C_Sendto |
| (Wsig, Buf'Address, 1, |
| Flags => SOSC.MSG_Forced_Flags, |
| To => System.Null_Address, |
| Tolen => 0); |
| end Write; |
| |
| end Signalling_Fds; |
