Question

I use winsock to receive a 1024byte buffer like this:

var
 buffer    : array[0..1023] of byte; 
 endarray  : array of byte;
 hFile     : THandle;
 dwWritten : DWORD;
 dwRead    : DWORD;
begin
 SetLength (endarray, 3000); //fixxed size (doesn't really matter here, cause I know the size)
 hFile := CreateFileW('test.bin', GENERIC_WRITE, FILE_SHARE_WRITE, nil, CREATE_NEW, 0, 0);
 SetFilePointer(hFile, 0, nil, FILE_BEGIN);
 repeat
 dwRead := recv(MySock, Buffer, 1024, 0);
 WriteFile(hFile, buffer[0], dwRead, dwWritten, nil); // works fine!
 // Add the buffer to the endarray but how?
 until (dwRead = 0) or (dwRead = -1)
 [...]
 CloseHandle (hFile);
end;

How can I add the buffer to the endarray automatically so it actually gets appended to the end?

Answer 1

Like this:

var
  PrevLen: Integer;
....
dwRead := recv(MySock, Buffer, 1024, 0);
if dwRead>0 then
begin
  PrevLen := Length(endarray);
  SetLength(endarray, PrevLen+dwRead);
  Move(Buffer[0], endarray[PrevLen], dwRead);
end;

And also remove the first line of code from your function that pre-allocates endarray.

If you’d rather allocate the buffer once (as per the code in the question) then you can code it like this:

var
  endarrayLen: Integer;
.....
endarrayLen := 0;
repeat
  dwRead := recv(MySock, Buffer, 1024, 0);
  if dwRead>0 then
  begin
    Move(Buffer[0], endarray[endarrayLen], dwRead);
    inc(endarrayLen, dwRead);
  end;
  .....
until ...

But that’s a buffer overrun waiting to happen!