I think I understand that the _pipeOpen(), _pipeRead(), and _pipeWrite() are equivalent to C's popen(), pread(), and pwrite(), respectively.

But, popen() wants either a "r" or a "w" argument for reading _or_ writing.  It can't do both.  So, I need two separate _pipeOpen() calls -- one for the read pipe and one for the write pipe.  I'd like to do this with only one program running -- I'd rather not pipe the output into a temporary file and then cat that file for the second _pipeOpen().  Also, this would eventually fill up the file.

I've seen some implementations of popen2() in C, which provides a read file descriptor and a write file descriptor for one program.  But, I don't see how to use that same model in Flash.

I wasn't sure whether the ASnative() calls were put in by Adobe or chumby.  If it were the chumby folks, I guess I'm asking whether they think bidirectional pipe support is worth adding.

The web page: http://snippets.dzone.com/posts/show/1134

shows a C implementation of popen2() (I think the correct implementation is about a 1/3 of the way down the page), so it looks like it is possible to do.

Are named pipes available ? Those should be bidirectional.

Redge

I got some email from Henry Groover that provided the answer.  Code snippet is below, where mycmd is an executable that takes stdin and provides stdout:

_backtick = ASnative(5, 52);
_pipeOpen = ASnative(5, 191);
_pipeRead = ASnative(5, 193);
_pipeWrite = ASnative(5, 194);
_pipeClose = ASnative(5, 195);

_backtick("mkfifo /tmp/.outpipe"); // Create named pipe

/* You need to create the read pipe before creating the write pipe, otherwise your process will block until there's a process reading. */
rHandle = _pipeOpen("cat - </tmp/.outpipe", "r"); // Create read pipe

/* If you read at this time, you'll block.  So, no reading until the write pipe is created and mycmd is executed. */
wHandle = _pipeOpen("mycmd >/tmp/.outpipe", "w"); // Create write pipe

/* Now it's safe to read and write.  To avoid deadlocks, it's best if mycmd doesn't depend on getting data on stdin to generate data on stdout. */
_pipeWrite(wHandle, "this will be sent to stdin of mycmd");
s = _pipeRead(rHandle); // Read from stdout of mycmd

_pipeClose(wHandle);
_pipeClose(rHandle);

It could be that you're running into privilege problems, where the master widget has access to many more functions than the slave widget.  Try creating /psp/flashplayer.cfg and adding the following line:

PrivilegedCallExceptions 0x8000

Then restart flashplayer.  That should give slave widgets permission to use pipe calls.

Note that this could present a security risk.  Any widget could then make calls to pipe objects, which is why we normally have it turned off.