bobby wrote:
Michalis Kamburelis wrote:
bobby wrote:
Hi everyone,
I'm stuck with an assignment for my studies.
My assignment is to make a GUI for a disassembler.
Now, the professor want it to be multi-platform (Win32/Linux).
I saw a output-redirection example in Lazarus WIKI (one with memory
stream), but the problem is that it's limited to very small amount
of data.
I don't have a clue how to make it to deal with more amount of data.
I've try to clean the memory stream when it's going to be full, but
it seems that I didn't do it like it should be done.
The example from wiki is at:
http://wiki.lazarus.freepascal.org/index.php/Executing_External_Programs
Can somebody help me with redirecting the output to SynMemo
component? I need it to work on both Win32 and Linux.
As for now, the following lines gives me 106kb (same amount like
example from the wiki), but the output should be 800kb (amount of
data from 'disasm.exe test.exe > output.txt').
with TProcess.Create(self) do begin
Options := [poUsePipes];
CommandLine := 'disasm.exe test.exe';
Execute;
while running do
begin
S := TStringList.Create;
S.LoadFromStream(OutPut);
for n := 0 to S.Count - 1 do
SynMemo1.Lines.Add(S[n]);
S.Free;
end;
After a lot of experimenting, only clue a got is that the pipes are
somehow limited, not the other components. The previous example has
proved that the StringLists are not the ones who make that
limitation (created and destroyed on every cycle of the loop).
Where is the problem?
Thanks in advance for every clue/advice you can give me.
If someone can give me the example of executing the external file,
and redirecting the stdout to text file, also, working on both Win
and Lin, that will also solve my problem.
On the page
[http://wiki.lazarus.freepascal.org/index.php/Executing_External_Programs]
the example "Reading large output" looks suited for reading large
data. Are you sure you're using the exact code from this example, and
you still don't get the full output ?
In particular, see the section "// read last part" in that example:
when program ends, you must read remaining data from the pipe. This
is something that is missing from your snippet above: you do
while running do
begin
... read next chunk from Output ...
end;
but *after* this loop terminates (when Running = false) you must
remember to read the rest of Output. In other words, the process may
(and often will) terminate *before* you finished reading the pipe.
Michalis
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This code gives the same result as the previous code:
begin
with TProcess.Create(self) do begin
Options := [poUsePipes];
CommandLine := 'disasm.exe test.exe';
Execute;
while running do
begin
S := TStringList.Create;
S.LoadFromStream(OutPut);
for n := 0 to S.Count - 1 do
SynMemo1.Lines.Add(S[n]);
S.Free;
end;
S := TStringList.Create;
S.LoadFromStream(OutPut);
for n := 0 to S.Count - 1 do
SynMemo1.Lines.Add(S[n]);
S.Free;
end;
end;
The received data is still 106kb (it should be 800kb). Is there any
possibility that the pipe is waiting for some signal /command to resume?
About the example from wiki, the process will never terminate under
Win32, and also the writeln commands throws errors. Deleting all
writeln commands will make example working, but as I've mentioned, the
child process will never terminate, I must close the console window
manually.
After doing so, the piped data is also 106kb, and not the expected 800kb.
I am just guessing but doesn't S.LoadFromStream block until the Program
exits?
You should create a buffer and a MemoryStream. then use
var
Buffer: array [0..2047] of byte;
MemoryStream: TMemoryStream;
S: TStringList;
begin
.....
MemoryStream := TMemoryStream.Create;
while Running or (DataCount > 0) do begin
DataCount := Output.Read(Buffer, 2048);
MemoryStream.Write(Buffer, DataCount);
end;
S := TStringList.Create;
S.LoadFromStream(MemoryStream);
...
end;
I am not extremely familiar with how streams work, but using
LoadFromStream(Output) may not "Read" the data so it can be replaced
with new data. Also as I said I think S.LoadFromStream is blocking until
the end of the stream is reached, which can't happen until the program
has ended possibly resulting in lost data. Someone please correct me if
I am wrong ;)
HTH
Andrew
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