On 08/05/11 05:38, Anton Shepelev wrote:
Hello all,
I have been experimenting with redirection of stan-
dard I/O of child processes using FreePascal 2.4.2
on Windows. I have succeeded in capturing standard
input and standard output, but failed to feed my own
data to the child's standard input.
The child process doesn't seem to receive any input
at all, staying blocked forever.
At first I thought it was a problem with my usage of
WinApi, so I rewrote my program using the TProcess
class... just to get the same result. The program
feeds 'Anton' to the more.com program and captures
part of its output:
Program StrRedir;
uses Classes, Process, Sysutils;
const MaxByte = 255;
type
TStrBuf = packed record {As a way to read buffers into strings}
case Boolean of
true: ( size: Byte;
buf: array[0..MaxByte] of Char;
);
false:( txt: ShortString; );
end;
var
MoreProcess: TProcess;
readCount: integer;
strBuf: TStrBuf;
begin
MoreProcess := TProcess.Create(nil);
MoreProcess.CommandLine := 'C:\WINDOWS\system32\cmd.exe /C more';
MoreProcess.Options := [poUsePipes];
MoreProcess.Execute;
strBuf.txt := 'Anton';
MoreProcess.Input.Write(strBuf.buf, strBuf.size);
MoreProcess.CloseInput();
writeLn('Waiting...'); //This never ends
while MoreProcess.Running do begin Sleep(50); end;
writeLn('Wait finished.');
Sleep(100);
strBuf.size := MoreProcess.Output.Read(strBuf.buf, 255);
writeLn(strBuf.txt);
end.
Could you please help me to make it work?
Thanks in advance,
Anton
Anton - I have attached an extract from some working code (hopefully I
didnt remove anything necessary)
It may help you move on a bit further
SteveG
Process.Execute
// capture all proc output (if required) - watch for proc ending quickly,
but data still waiting
while ( Process.Running )
// cycle whilst process active
OR ( (poUsePipes IN Process.Options) AND
(Process.Output.NumBytesAvailable > 0) )
// OR finished already, still data waiting
do begin
Sleep(1);
if Terminated then break;
// no pipes - not past here as causes exceptions to read process pipes if
not enabled
if NOT (poUsePipes IN Process.Options) then continue;
// read output
BytesAvailable := Process.Output.NumBytesAvailable;
if BytesAvailable > 0 then begin
SetLength(str1, BytesAvailable);
Process.OutPut.Read(str1[1], BytesAvailable);
StdOutStore += str1;
end;
// read errors
BytesAvailable := Process.Stderr.NumBytesAvailable;
if BytesAvailable > 0 then begin
SetLength(str1, BytesAvailable);
Process.Stderr.Read(str1[1], BytesAvailable);
StdErrStore += str1;
end;
// send input
if UsrSendMsg > '' then begin
Process.Input.Write(UsrSendMsg[1], Length(UsrSendMsg));
UsrSendMsg := '';
end;
end;
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