[fpc-pascal] INVALID_SOCKET constant not defined for Linux

[Ladislav Karrach]

>> This technique is used in fcl-net which should be cross-platform.
>> So I am right, when I say that also in Linux invald socket = -1
>> (in other words: in case of error syscall() returns always -1)
>>
>> Becuase in other place I see another test "if socket < 0 then ..."
>> (which may mean that any negative value can be returned) 
>
> Most likely this is only because "socket < 0" is faster to write than 
> "socket = -1" :-)
>
> From Linux man page for socket:
>
>> RETURN VALUE
>>        On success, a file descriptor for the new socket is returned.  On
>>        error, -1 is returned, and errno is set appropriately.
>
Thanks for all repies.
For now I add to my unit:

{$IFDEF UNIX}
// not defined for POSIX; Linux syscall() returns -1 in case of error
const
   INVALID_SOCKET = -1;
   SOCKET_ERROR = -1;
{$ENDIF}

and later I use (in cross-platform code):
   Fsocket := fpsocket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
   if Fsocket = INVALID_SOCKET then ...

-Laco.