how to know there is data in the buffer using sockets unit

[arturogr]

Hello:

 I am using windows, and I want to know if there is an option (function), to know if there is data in the in-buffer socket of a connection; so I can call the fpRecv funtion to read the data in the in-buffer.

If I call fpRecv, the program halts, wainting for information to reach the program. But I want to do some thing else in a loop, while wainting for data.

I found something like fpSelect() in the forum, but that function is not recognized in sockets unit, and I do not find any documentation for that:

Code: Pascal  [Select][+][-]

1. if(fpSelect(FSocket + 1,@RTFD,nil,nil,@Timeout) > 0) then
2.        begin
3.          Len := fpRecv(FSocket,@Bytes_In,256,0);
4.        end;

By the other hand, I have read something like "ioctl", but with no examples to handle the same goal.

thank you.

[olly]

Take a look at https://gitlab.com/freepascal.org/fpc/source/-/blob/main/packages/fcl-net/src/ssockets.pp#L306 lots of cross platform examples there.

For Windows you'll want the winsock2 unit to get access for ioctlsocket and select functions.

[MarkMLl]

Use the FIONREAD ioctl. Example below was originally written for serial data but should be about right

Code: Pascal  [Select][+][-]

1. FUNCTION MinDataAvailable(handle: INTEGER): INTEGER;
2.  
3. begin
4.  
5. (* If the handle is invalid (port not open) or there is an error then return < 0. *)
6.  
7.   if handle = InvalidSerialHandle then
8.     result := -1
9.   else begin
10.     if fpIoctl(handle, FIONREAD, @result) <> 0 then
11.       result := -1
12.   end
13. end { MinDataAvailable } ;
14.  

MarkMLl