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From: "fabio de francesco" <fmdf@tiscali.it>
Newsgroups: comp.lang.ada
Subject: "broken pipe" while reading/writing stream-based sockets
Date: 10 May 2005 16:02:59 -0700
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Date: 2005-05-10T16:02:59-07:00
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Ciao,

I'm still having problems while doing sockets read/write. I have a
server that often crashes with error "Broken Pipe". The server works
always with the same clients and many times it doesn't crash until
something happens that I don't understand.

This is the server code:

-- file tcp_server.adb

with GNAT.Sockets;             use GNAT.Sockets;
with Ada.Text_IO;                use Ada.Text_IO;

procedure TCP_Server is

    Socket : Socket_Type;
    Client : Socket_Type;
    Sock_Addr : Sock_Addr_Type;
    Cli_Addr : Sock_Addr_Type;
    L : constant Positive := 5;
    Channel : Stream_Access;
    S : String( 1 .. 80 );

begin

    Initialize;
    Create_Socket( Socket );
    Set_Socket_Option( Socket, Socket_Level, ( Reuse_Address, True ) );
    Sock_Addr.Addr := Inet_Addr( "127.0.0.1" );
    Sock_Addr.Port := 9876;
    Bind_Socket( Socket, Sock_Addr );
    Listen_Socket( Socket, L );
    Put_Line( "Server in attesa di connessioni..." );

    loop
        Accept_Socket( Socket, Client, Cli_Addr );
        Channel := Stream( Client );
        String'Read( Channel, S );
        String'Write ( Channel, ( "Ricevuto " & S ) );
        Put_Line( "Client ha inviato codice """ & S & """" );
        Free( Channel );
        Close_Socket( Client );
        if S( 1 .. 4 ) = "kill" then
            Put_Line( "Sono stato ucciso" );
            exit;
        end if;
    end loop;

    Close_Socket( Socket );
    Finalize;

end TCP_Server;


And the following is client code:

-- file tcp_client.adb

with GNAT.Sockets;             use GNAT.Sockets;
with Ada.Text_IO;                 use Ada.Text_IO;
with Ada.Strings;                  use Ada.Strings;
with Ada.Strings.Fixed;         use Ada.Strings.Fixed;
with Ada.Command_Line;      use Ada.Command_Line;

procedure TCP_Client is

    Socket : Socket_Type;
    Address : Sock_Addr_Type;
    Channel : Stream_Access;
    S : String( 1 .. 80 );

begin

    if Argument_Count < 1 then
        return;
    end if;

    Initialize;
    Create_Socket( Socket );
    Address.Addr := Addresses( Get_Host_By_Name( "localhost" ), 1 );
    Address.Port := 9876;
    Connect_Socket( Socket, Address );
    Channel := Stream( Socket );

    Move( Argument( 1 ), S );
    if S( 1 .. 4 ) = "kill" then
        Put_Line( "Sto ordinando a Server di fermarsi!" );
    else
        Put_Line( "Sto inviando """ & Trim( S, Both ) & """" );
    end if;

    String'Write( Channel, S );
    String'Read( Channel, S );
    Put_Line( "Server ha risposto """ & Trim( S, Both ) & """" );

    Free( Channel );
    Close_Socket( Socket );
    Finalize;

end TCP_Client;


I usually test the server this way:

$ ./tcp_client abc & ./tcp_client def & ./tcp_client xyz & ./tcp_client
kill

1) Why does this server sometimes crash with "Broken Pipe"?
2) It seems that using Input/Output instead of Read/Write never causes
"Broken Pipe". Why?

Thanks to all of you who will reply,

fabio de francesco