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Fix flow of ACKs to ensure we do not hang on final buf write #155

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Fix flow of ACKs to ensure we do not hang on final buf write #155

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19792d9
Fix flow of ACKs to ensure we do not hang on final buf write
shaunrs Apr 14, 2021
9da4ca1
Add DC1 for start of transmission
shaunrs Aug 9, 2021
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30 changes: 22 additions & 8 deletions rshell/main.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1092,9 +1092,11 @@ def recv_file_from_host(src_file, dst_filename, filesize, dst_mode='wb'):
buf_size = BUFFER_SIZE
write_buf = bytearray(buf_size)
read_buf = bytearray(buf_size)

# Send XON (DC1) signal to the host to inform it we are ready to receive new data
sys.stdout.write('\x11')

while bytes_remaining > 0:
# Send back an ack as a form of flow control
sys.stdout.write('\x06')
read_size = min(bytes_remaining, buf_size)
buf_remaining = read_size
buf_index = 0
Expand All @@ -1116,6 +1118,10 @@ def recv_file_from_host(src_file, dst_filename, filesize, dst_mode='wb'):
if hasattr(os, 'sync'):
os.sync()
bytes_remaining -= read_size

# Send back an ack as a form of flow control
sys.stdout.write('\x06')

return True
except:
return False
Expand All @@ -1128,13 +1134,14 @@ def send_file_to_remote(dev, src_file, dst_filename, filesize, dst_mode='wb'):
bytes_remaining = filesize
save_timeout = dev.timeout
dev.timeout = 2
while bytes_remaining > 0:
# Wait for ack so we don't get too far ahead of the remote
ack = dev.read(1)
if ack is None or ack != b'\x06':
sys.stderr.write("timed out or error in transfer to remote: {!r}\n".format(ack))
sys.exit(2)

# Block waiting for XON (DC1) signal from remote before sending data
xon = dev.read(1)
if not xon or xon != b'\x11':
sys.stderr.write("timed out expecting XON signal from remote, received: {!r}\n".format(xon))
sys.exit(2)

while bytes_remaining > 0:
if HAS_BUFFER:
buf_size = BUFFER_SIZE
else:
Expand All @@ -1147,6 +1154,13 @@ def send_file_to_remote(dev, src_file, dst_filename, filesize, dst_mode='wb'):
dev.write(buf)
else:
dev.write(binascii.hexlify(buf))

# Wait for ack so we don't get too far ahead of the remote
ack = dev.read(1)
if ack is None or ack != b'\x06':
sys.stderr.write("timed out or error in transfer to remote: {!r}\n".format(ack))
sys.exit(2)

bytes_remaining -= read_size
#sys.stdout.write('\r')
dev.timeout = save_timeout
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