import os import sys import string MAXFD = 256 # Max number of file descriptors (os.getdtablesize()???) _active = [] def _cleanup(): for inst in _active[:]: inst.poll() class Popen3: def __init__(self, cmd, capturestderr=0): cmd = ['/bin/sh', '-c', cmd] p2cread, p2cwrite = os.pipe() c2pread, c2pwrite = os.pipe() if capturestderr: errout, errin = os.pipe() self.pid = os.fork() if self.pid == 0: # Child os.close(0) os.close(1) if os.dup(p2cread) <> 0: sys.stderr.write('popen2: bad read dup\n') if os.dup(c2pwrite) <> 1: sys.stderr.write('popen2: bad write dup\n') if capturestderr: os.close(2) if os.dup(errin) <> 2: pass for i in range(3, MAXFD): try: os.close(i) except: pass try: os.execv(cmd[0], cmd) finally: os._exit(1) # Shouldn't come here, I guess os._exit(1) os.close(p2cread) self.tochild = os.fdopen(p2cwrite, 'w') os.close(c2pwrite) self.fromchild = os.fdopen(c2pread, 'r') if capturestderr: os.close(errin) self.childerr = os.fdopen(errout, 'r') else: self.childerr = None self.sts = -1 # Child not completed yet _active.append(self) def poll(self): if self.sts < 0: try: pid, sts = os.waitpid(self.pid, os.WNOHANG) if pid == self.pid: self.sts = sts _active.remove(self) except os.error: pass return self.sts def wait(self): pid, sts = os.waitpid(self.pid, 0) if pid == self.pid: self.sts = sts _active.remove(self) return self.sts def popen2(cmd): _cleanup() inst = Popen3(cmd, 0) return inst.fromchild, inst.tochild def popen3(cmd): _cleanup() inst = Popen3(cmd, 1) return inst.fromchild, inst.tochild, inst.childerr def _test(): teststr = "abc\n" print "testing popen2..." r, w = popen2('cat') w.write(teststr) w.close() assert r.read() == teststr print "testing popen3..." r, w, e = popen3('cat') w.write(teststr) w.close() assert r.read() == teststr assert e.read() == "" _cleanup() assert not _active print "All OK" if __name__ == '__main__': _test()