From 4c8f2430e2b226a33b06c725ba90813b8bdc1cf4 Mon Sep 17 00:00:00 2001
From: Douglas RAILLARD <douglas.raillard@arm.com>
Date: Mon, 25 Mar 2019 18:35:44 +0000
Subject: [PATCH] trace: dmesg: Allow using old util-linux binary

Old util-linux binaries don't support --force-prefix. Multi-line entry
parsing will break on these, but at least we can collect the log.

Also decode the raw priority, so only the facility is not decoded in
case busybox or old util-linux is used.
---
 devlib/trace/dmesg.py | 66 +++++++++++++++++++++++++------------------
 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/devlib/trace/dmesg.py b/devlib/trace/dmesg.py
index 90805d6..3887093 100644
--- a/devlib/trace/dmesg.py
+++ b/devlib/trace/dmesg.py
@@ -39,6 +39,8 @@ class KernelLogEntry(object):
     """
 
     _TIMESTAMP_MSG_REGEX = re.compile(r'\[(.*?)\] (.*)')
+    _RAW_LEVEL_REGEX = re.compile(r'<([0-9]+)>(.*)')
+    _PRETTY_LEVEL_REGEX = re.compile(r'\s*([a-z]+)\s*:([a-z]+)\s*:\s*(.*)')
 
     def __init__(self, facility, level, timestamp, msg):
         self.facility = facility
@@ -52,50 +54,57 @@ class KernelLogEntry(object):
         Parses a "dmesg --decode" output line, formatted as following:
         kern  :err   : [3618282.310743] nouveau 0000:01:00.0: systemd-logind[988]: nv50cal_space: -16
 
-        Or the more basic output:
-        [3618282.310743] nouveau 0000:01:00.0: systemd-logind[988]: nv50cal_space: -16
+        Or the more basic output given by "dmesg -r":
+        <3>[3618282.310743] nouveau 0000:01:00.0: systemd-logind[988]: nv50cal_space: -16
 
         """
 
-        def parse_timestamp_msg(line):
-            match = cls._TIMESTAMP_MSG_REGEX.match(line.strip())
+        def parse_raw_level(line):
+            match = cls._RAW_LEVEL_REGEX.match(line)
             if not match:
                 raise ValueError('dmesg entry format not recognized: {}'.format(line))
+            level, remainder = match.groups()
+            levels = DmesgCollector.LOG_LEVELS
+            # BusyBox dmesg can output numbers that need to wrap around
+            level = levels[int(level) % len(levels)]
+            return level, remainder
+
+        def parse_pretty_level(line):
+            match = cls._PRETTY_LEVEL_REGEX.match(line)
+            facility, level, remainder = match.groups()
+            return facility, level, remainder
+
+        def parse_timestamp_msg(line):
+            match = cls._TIMESTAMP_MSG_REGEX.match(line)
             timestamp, msg = match.groups()
+            timestamp = timedelta(seconds=float(timestamp.strip()))
             return timestamp, msg
 
-        # If we can parse the timestamp directly, that is a basic line
+        line = line.strip()
+
+        # If we can parse the raw prio directly, that is a basic line
         try:
-            timestamp, msg = parse_timestamp_msg(line)
-        except ValueError:
-            facility, level, remainder = line.split(':', 2)
-            timestamp, msg = parse_timestamp_msg(remainder)
-            facility = facility.strip()
-            level = level.strip()
-        else:
+            level, remainder = parse_raw_level(line)
             facility = None
-            level = None
+        except ValueError:
+            facility, level, remainder = parse_pretty_level(line)
+
+        timestamp, msg = parse_timestamp_msg(remainder)
 
         return cls(
             facility=facility,
             level=level,
-            timestamp=timedelta(seconds=float(timestamp.strip())),
+            timestamp=timestamp,
             msg=msg.strip(),
         )
 
     def __str__(self):
-        if self.facility and self.level:
-            prefix = '{facility}:{level}:'.format(
-                facility=self.facility,
-                level=self.level,
-            )
-        else:
-            prefix = ''
-
-        return '{prefix}[{timestamp}] {msg}'.format(
+        facility = self.facility + ': ' if self.facility else ''
+        return '{facility}{level}: [{timestamp}] {msg}'.format(
+            facility=facility,
+            level=self.level,
             timestamp=self.timestamp.total_seconds(),
             msg=self.msg,
-            prefix=prefix,
         )
 
 
@@ -136,11 +145,12 @@ class DmesgCollector(TraceCollector):
             ))
         self.level = level
 
-        # Check if dmesg is the BusyBox one, or the one from util-linux.
+        # Check if dmesg is the BusyBox one, or the one from util-linux in a
+        # recent version.
         # Note: BusyBox dmesg does not support -h, but will still print the
         # help with an exit code of 1
-        self.basic_dmesg = 'BusyBox' in self.target.execute('dmesg -h',
-                                                        check_exit_code=False)
+        self.basic_dmesg = '--force-prefix' not in \
+                self.target.execute('dmesg -h', check_exit_code=False)
         self.facility = facility
         self.reset()
 
@@ -173,7 +183,7 @@ class DmesgCollector(TraceCollector):
         ))
         levels_list.append(self.level)
         if self.basic_dmesg:
-            cmd = 'dmesg'
+            cmd = 'dmesg -r'
         else:
             cmd = 'dmesg --facility={facility} --force-prefix --decode --level={levels}'.format(
                 levels=','.join(levels_list),