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lglaf.py: do not hang forever on reads

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Use 5 second timeout for the initial hello and 60 seconds for other
cases. Maybe a --read-timeout option should be added in case you need
more time...
This commit is contained in:
Peter Wu 2015-12-29 18:40:46 +01:00
parent fe75d2108f
commit e71375d6cc
1 changed files with 14 additions and 10 deletions
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24
lglaf.py
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@ -138,18 +138,18 @@ def make_exec_request(shell_command):
class Communication(object):
def __init__(self):
self.read_buffer = b''
def read(self, n):
def read(self, n, timeout=None):
"""Reads exactly n bytes."""
need = n - len(self.read_buffer)
while need > 0:
buff = self._read(need)
buff = self._read(need, timeout=timeout)
self.read_buffer += buff
if not buff:
raise EOFError
need -= len(buff)
data, self.read_buffer = self.read_buffer[0:n], self.read_buffer[n:]
return data
def _read(self, n):
def _read(self, n, timeout=None):
"""Try one read, possibly returning less or more than n bytes."""
raise NotImplementedError
def write(self, data):
@ -182,7 +182,7 @@ class FileCommunication(Communication):
self.f = open(file_path, 'r+b', buffering=0)
else:
self.f = open(file_path, 'r+b')
def _read(self, n):
def _read(self, n, timeout=None):
return self.f.read(n)
def write(self, data):
self.f.write(data)
@ -194,7 +194,7 @@ class USBCommunication(Communication):
EP_OUT = 3
VENDOR_ID_LG = 0x1004
# Read timeout. Set to 0 to disable timeouts
READ_TIMEOUT_MS = 0
READ_TIMEOUT_MS = 60000
def __init__(self):
super(USBCommunication, self).__init__()
# Match device using heuristics on the interface/endpoint descriptors,
@ -217,9 +217,9 @@ class USBCommunication(Communication):
usb.util.ENDPOINT_TYPE_BULK
for ep in intf
)
def _read(self, n):
def _read(self, n, timeout=READ_TIMEOUT_MS):
# device seems to use 16 KiB buffers.
array = self.usbdev.read(self.EP_IN, 2**14, timeout=self.READ_TIMEOUT_MS)
array = self.usbdev.read(self.EP_IN, 2**14, timeout=timeout)
try: return array.tobytes()
except: return array.tostring()
def write(self, data):
@ -236,20 +236,24 @@ def try_hello(comm):
Tests whether the device speaks the expected protocol. If desynchronization
is detected, tries to read as much data as possible.
"""
# Wait for at most 5 seconds for a response... it shouldn't take that long
# and otherwise something is wrong.
HELLO_READ_TIMEOUT = 5000
hello_request = make_request(b'HELO', args=[b'\1\0\0\1'])
comm.write(hello_request)
data = comm.read(0x20)
data = comm.read(0x20, timeout=HELLO_READ_TIMEOUT)
if data[0:4] != b'HELO':
# Unexpected response, maybe some stale data from a previous execution?
while data[0:4] != b'HELO':
try:
validate_message(data, ignore_crc=True)
size = struct.unpack_from('<I', data, 0x14)[0]
comm.read(size)
comm.read(size, timeout=HELLO_READ_TIMEOUT)
except RuntimeError: pass
# Flush read buffer
comm.reset()
data = comm.read(0x20)
data = comm.read(0x20, timeout=HELLO_READ_TIMEOUT)
# Just to be sure, send another HELO request.
comm.call(hello_request)