Makes serialposix.Serial.write() respect write_timeout=0 to be non-blocking.
diff --git a/serial/serialposix.py b/serial/serialposix.py
index 70fb241..c99dc0e 100644
--- a/serial/serialposix.py
+++ b/serial/serialposix.py
@@ -521,14 +521,17 @@
raise portNotOpenError
d = to_bytes(data)
tx_len = len(d)
- if self._write_timeout is not None and self._write_timeout > 0:
- timeout = time.time() + self._write_timeout
- else:
- timeout = None
+ timeout = self._write_timeout
+ if timeout and timeout > 0: # Avoid comparing None with zero
+ timeout += time.time()
while tx_len > 0:
try:
n = os.write(self.fd, d)
- if timeout:
+ if timeout == 0:
+ # Zero timeout indicates non-blocking - simply return the
+ # number of bytes of data actually written
+ return n
+ elif timeout and timeout > 0: # Avoid comparing None with zero
# when timeout is set, use select to wait for being ready
# with the time left as timeout
timeleft = timeout - time.time()
@@ -538,6 +541,7 @@
if not ready:
raise writeTimeoutError
else:
+ assert timeout is None
# wait for write operation
_, ready, _ = select.select([], [self.fd], [], None)
if not ready: