This is code that was born while working on https://stackoverflow.com/questions/34504970/non-blocking-read-on-os-pipe-on-windows
It consists of ospipen.py module with a sigle function:
def pipe_no_wait(pipefd):
""" pipefd is a integer as returned by os.pipe """
ossub.py that tests the concept on subprocess.PIPE, and Go program for that subprocess.
Everything is in public domain.
| package main | |
| import ( | |
| "fmt" | |
| "time" | |
| ) | |
| func main() { | |
| fmt.Print("Heya! Two seconds..\n") | |
| time.Sleep(2000 * time.Millisecond) | |
| fmt.Print("Heya! One more..\n") | |
| time.Sleep(1000 * time.Millisecond) | |
| fmt.Print("Heya! Done.") | |
| } |
| import msvcrt | |
| import os | |
| from ctypes import windll, byref, wintypes, GetLastError, WinError | |
| from ctypes.wintypes import HANDLE, DWORD, POINTER, BOOL | |
| LPDWORD = POINTER(DWORD) | |
| PIPE_NOWAIT = wintypes.DWORD(0x00000001) | |
| ERROR_NO_DATA = 232 | |
| def pipe_no_wait(pipefd): | |
| """ pipefd is a integer as returned by os.pipe """ | |
| SetNamedPipeHandleState = windll.kernel32.SetNamedPipeHandleState | |
| SetNamedPipeHandleState.argtypes = [HANDLE, LPDWORD, LPDWORD, LPDWORD] | |
| SetNamedPipeHandleState.restype = BOOL | |
| h = msvcrt.get_osfhandle(pipefd) | |
| res = windll.kernel32.SetNamedPipeHandleState(h, byref(PIPE_NOWAIT), None, None) | |
| if res == 0: | |
| print(WinError()) | |
| return False | |
| return True | |
| if __name__ == '__main__': | |
| # CreatePipe | |
| r, w = os.pipe() | |
| pipe_no_wait(r) | |
| print os.write(w, 'xxx') | |
| print os.read(r, 1024) | |
| try: | |
| print os.write(w, 'yyy') | |
| print os.read(r, 1024) | |
| print os.read(r, 1024) | |
| except OSError as e: | |
| print dir(e), e.errno, GetLastError() | |
| print(WinError()) | |
| if GetLastError() != ERROR_NO_DATA: | |
| raise | |
| print os.write(w, 'zzz') | |
| print os.read(r, 1024) |
| import subprocess | |
| """ | |
| p = subprocess.Popen('python.exe -c "import time; print(\\"xxx\\"); time.sleep(2); print(\\"yyy\\")', stdout = subprocess.PIPE) | |
| print p.stdout | |
| print p.stdout.fileno() | |
| print p.stdout.read()""" | |
| # ^ blocking read, reads xxx\nyyy after 2 seconds. probably due to buffering | |
| from ospipen import pipe_no_wait | |
| #p = subprocess.Popen('python.exe -c "import time; print(\\"xxx\\"); time.sleep(2); print(\\"yyy\\")', stdout = subprocess.PIPE) | |
| p = subprocess.Popen('osgo.exe', stdout = subprocess.PIPE) | |
| pipe_no_wait(p.stdout.fileno()) | |
| print p.stdout | |
| print p.stdout.fileno() | |
| import time | |
| while True: | |
| try: | |
| print ".", p.stdout.read(), ".", time.time(), p.stdout.closed, p.poll() | |
| except IOError as e: | |
| print e | |
| time.sleep(0.1) |
Good to know. As I don't use Windows anymore, feel free to fork it and place a link here so that people know where to find maintained version.
Nice solution, you might have just saved me few days..:)
In Python3 LPDWORD is already defined, so I changed ospipen.py from:
to: