how to know there is data in the buffer using sockets unit
lazarus / 38-Networking and Web Programming

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arturogr · 2023-12-12 02:43

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][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
if(fpSelect(FSocket + 1,@RTFD,nil,nil,@Timeout) > 0) then       begin 
       Len := fpRecv(FSocket,@Bytes_In,256,0);       end;
By the other hand, I have read something like "ioctl", but with no
examples to handle the same goal.

thank you.

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olly · 2023-12-12 03:02

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.

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MarkMLl · 2023-12-12 08:13

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

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i FUNCTION
MinDataAvailable(handle: INTEGER): INTEGER; begin (* If the handle is
invalid (port not open) or there is an error then return < 0. *)   if
handle = InvalidSerialHandle then    result := -1  else begin    if
fpIoctl(handle, FIONREAD, @result) <> 0 then      result := -1  endend
{ MinDataAvailable } ; 
MarkMLl