ec3po: console log printing in py2 and py3

The console log printing needs to work in py2 and py3. For this to work,
the 'data' passed in needs to be treated equally in both cases. Since
mostly what we care about is comparing it to other elements, we simply
ensure that the data becomes a list of integers in both py2 and py3, and
then we compare directly against the integer values of the characters we
want to handle in a special way (\b, \t, etc).

BUG=b:173654272
BRANCH=None
// this shows all the correctly parsed log output from the MCUs (ec, v4,
etc) in the logs
TEST=sudo servod -b scarlet
     cat /var/log/servod_9999/latest.DEBUG

Change-Id: Ibcbb95fd60619dc8234d7dd1f3d5d5c623542ce0
Signed-off-by: Ruben Rodriguez Buchillon <coconutruben@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2576140
Reviewed-by: Matthew Blecker <matthewb@chromium.org>

1 files changed, 19 insertions, 9 deletions

diff --git a/util/ec3po/console.py b/util/ec3po/console.py
index 910e6b9114..5974aaa014 100755
--- a/util/ec3po/console.py
+++ b/util/ec3po/console.py
@@ -215,39 +215,49 @@ class Console(object):
     when it sees backspaces.
 
     Args:
-      data: binary string received from MCU
+      data: bytes - string received from MCU
     """
     data = list(data)
+    # For compatibility with python2 and python3, standardize on the data
+    # being a list of integers. This requires one more transformation in py2
+    if not isinstance(data[0], int):
+      data = [ord(c) for c in data]
 
     # This is a list of already filtered characters (or placeholders).
     line = self.output_line_log_buffer
 
+    # TODO(b/177480273): use raw strings here
     symbols = {
-            b'\n': u'\\n',
-            b'\r': u'\\r',
-            b'\t': u'\\t'
+            ord(b'\n'): u'\\n',
+            ord(b'\r'): u'\\r',
+            ord(b'\t'): u'\\t'
     }
     # self.logger.debug(u'%s + %r', u''.join(line), ''.join(data))
     while data:
+      # Recall, data is a list of integers, namely the byte values sent by
+      # the MCU.
       byte = data.pop(0)
-      if byte == '\n':
+      # This means that |byte| is an int.
+      if byte == ord('\n'):
         line.append(symbols[byte])
         if line:
           self.logger.debug(u'%s', ''.join(line))
         line = []
-      elif byte == b'\b':
+      elif byte == ord('\b'):
         # Backspace: trim the last character off the buffer
         if line:
           line.pop(-1)
       elif byte in symbols:
         line.append(symbols[byte])
-      elif byte < b' ' or byte > b'~':
+      elif byte < ord(' ') or byte > ord('~'):
         # Turn any character that isn't printable ASCII into escaped hex.
         # ' ' is chr(20), and 0-19 are unprintable control characters.
         # '~' is chr(126), and 127 is DELETE.  128-255 are control and Latin-1.
-        line.append(u'\\x%02x' % ord(byte))
+        line.append(u'\\x%02x' % byte)
       else:
-        line.append(u'%s' % byte)
+        # byte is printable. Thus it is safe to use chr() to get the printable
+        # character out of it again.
+        line.append(u'%s' % chr(byte))
     self.output_line_log_buffer = line
 
   def PrintHistory(self):