[PATCH v2 2/2] bitbake: Remove custom exception backtrace formatting

["'Felix Moessbauer' via isar-users" <isar-users@googlegroups.com>]

Backport of upstream bitbake patch c25e7ed128b9fd5b53d28d678238e2f3af52ef8b.

Removes the code in bitbake to show custom backtrace formatting for
exceptions. In particular, the bitbake exception code prints function
arguments, which while helpful is a security problem when passwords and
other secrets can be passed as function arguments.

As it turns out, the handling of the custom serialized exception stack
frames was pretty much made obsolete by d7db75020ed ("event/msg: Pass
formatted exceptions"), which changed the events to pass a preformatted
stacktrack list of strings, but the passing of the serialized data was
never removed.

Change all the code to use the python traceback API to format exceptions
instead of the custom code; conveniently traceback.format_exception()
also returns a list of stack trace strings, so it can be used as a drop
in replacement for bb.exception.format_exception()

[Felix: adjusted to bitbake path in isar repo]

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 bitbake/lib/bb/cooker.py      | 32 +++++++++---
 bitbake/lib/bb/event.py       |  9 +---
 bitbake/lib/bb/exceptions.py  | 96 -----------------------------------
 bitbake/lib/bb/msg.py         |  4 --
 bitbake/lib/bb/ui/teamcity.py |  5 --
 5 files changed, 25 insertions(+), 121 deletions(-)
 delete mode 100644 bitbake/lib/bb/exceptions.py

diff --git a/bitbake/lib/bb/cooker.py b/bitbake/lib/bb/cooker.py
index c5bfef55..701cf51b 100644
--- a/bitbake/lib/bb/cooker.py
+++ b/bitbake/lib/bb/cooker.py
@@ -17,7 +17,7 @@ import threading
 from io import StringIO, UnsupportedOperation
 from contextlib import closing
 from collections import defaultdict, namedtuple
-import bb, bb.exceptions, bb.command
+import bb, bb.command
 from bb import utils, data, parse, event, cache, providers, taskdata, runqueue, build
 import queue
 import signal
@@ -2098,7 +2098,6 @@ class Parser(multiprocessing.Process):
         except Exception as exc:
             tb = sys.exc_info()[2]
             exc.recipe = filename
-            exc.traceback = list(bb.exceptions.extract_traceback(tb, context=3))
             return True, None, exc
         # Need to turn BaseExceptions into Exceptions here so we gracefully shutdown
         # and for example a worker thread doesn't just exit on its own in response to
@@ -2299,8 +2298,12 @@ class CookerParser(object):
             return False
         except ParsingFailure as exc:
             self.error += 1
-            logger.error('Unable to parse %s: %s' %
-                     (exc.recipe, bb.exceptions.to_string(exc.realexception)))
+
+            exc_desc = str(exc)
+            if isinstance(exc, SystemExit) and not isinstance(exc.code, str):
+                exc_desc = 'Exited with "%d"' % exc.code
+
+            logger.error('Unable to parse %s: %s' % (exc.recipe, exc_desc))
             self.shutdown(clean=False)
             return False
         except bb.parse.ParseError as exc:
@@ -2309,20 +2312,33 @@ class CookerParser(object):
             self.shutdown(clean=False, eventmsg=str(exc))
             return False
         except bb.data_smart.ExpansionError as exc:
+            def skip_frames(f, fn_prefix):
+                while f and f.tb_frame.f_code.co_filename.startswith(fn_prefix):
+                    f = f.tb_next
+                return f
+
             self.error += 1
             bbdir = os.path.dirname(__file__) + os.sep
-            etype, value, _ = sys.exc_info()
-            tb = list(itertools.dropwhile(lambda e: e.filename.startswith(bbdir), exc.traceback))
+            etype, value, tb = sys.exc_info()
+
+            # Remove any frames where the code comes from bitbake. This
+            # prevents deep (and pretty useless) backtraces for expansion error
+            tb = skip_frames(tb, bbdir)
+            cur = tb
+            while cur:
+                cur.tb_next = skip_frames(cur.tb_next, bbdir)
+                cur = cur.tb_next
+
             logger.error('ExpansionError during parsing %s', value.recipe,
                          exc_info=(etype, value, tb))
             self.shutdown(clean=False)
             return False
         except Exception as exc:
             self.error += 1
-            etype, value, tb = sys.exc_info()
+            _, value, _ = sys.exc_info()
             if hasattr(value, "recipe"):
                 logger.error('Unable to parse %s' % value.recipe,
-                            exc_info=(etype, value, exc.traceback))
+                            exc_info=sys.exc_info())
             else:
                 # Most likely, an exception occurred during raising an exception
                 import traceback
diff --git a/bitbake/lib/bb/event.py b/bitbake/lib/bb/event.py
index 4761c868..952c85c0 100644
--- a/bitbake/lib/bb/event.py
+++ b/bitbake/lib/bb/event.py
@@ -19,7 +19,6 @@ import sys
 import threading
 import traceback
 
-import bb.exceptions
 import bb.utils
 
 # This is the pid for which we should generate the event. This is set when
@@ -759,13 +758,7 @@ class LogHandler(logging.Handler):
 
     def emit(self, record):
         if record.exc_info:
-            etype, value, tb = record.exc_info
-            if hasattr(tb, 'tb_next'):
-                tb = list(bb.exceptions.extract_traceback(tb, context=3))
-            # Need to turn the value into something the logging system can pickle
-            record.bb_exc_info = (etype, value, tb)
-            record.bb_exc_formatted = bb.exceptions.format_exception(etype, value, tb, limit=5)
-            value = str(value)
+            record.bb_exc_formatted = traceback.format_exception(*record.exc_info)
             record.exc_info = None
         fire(record, None)
 
diff --git a/bitbake/lib/bb/exceptions.py b/bitbake/lib/bb/exceptions.py
deleted file mode 100644
index 801db9c8..00000000
--- a/bitbake/lib/bb/exceptions.py
+++ /dev/null
@@ -1,96 +0,0 @@
-#
-# Copyright BitBake Contributors
-#
-# SPDX-License-Identifier: GPL-2.0-only
-#
-
-import inspect
-import traceback
-import bb.namedtuple_with_abc
-from collections import namedtuple
-
-
-class TracebackEntry(namedtuple.abc):
-    """Pickleable representation of a traceback entry"""
-    _fields = 'filename lineno function args code_context index'
-    _header = '  File "{0.filename}", line {0.lineno}, in {0.function}{0.args}'
-
-    def format(self, formatter=None):
-        if not self.code_context:
-            return self._header.format(self) + '\n'
-
-        formatted = [self._header.format(self) + ':\n']
-
-        for lineindex, line in enumerate(self.code_context):
-            if formatter:
-                line = formatter(line)
-
-            if lineindex == self.index:
-                formatted.append('    >%s' % line)
-            else:
-                formatted.append('     %s' % line)
-        return formatted
-
-    def __str__(self):
-        return ''.join(self.format())
-
-def _get_frame_args(frame):
-    """Get the formatted arguments and class (if available) for a frame"""
-    arginfo = inspect.getargvalues(frame)
-
-    try:
-        if not arginfo.args:
-            return '', None
-    # There have been reports from the field of python 2.6 which doesn't 
-    # return a namedtuple here but simply a tuple so fallback gracefully if
-    # args isn't present.
-    except AttributeError:
-        return '', None
-
-    firstarg = arginfo.args[0]
-    if firstarg == 'self':
-        self = arginfo.locals['self']
-        cls = self.__class__.__name__
-
-        arginfo.args.pop(0)
-        del arginfo.locals['self']
-    else:
-        cls = None
-
-    formatted = inspect.formatargvalues(*arginfo)
-    return formatted, cls
-
-def extract_traceback(tb, context=1):
-    frames = inspect.getinnerframes(tb, context)
-    for frame, filename, lineno, function, code_context, index in frames:
-        formatted_args, cls = _get_frame_args(frame)
-        if cls:
-            function = '%s.%s' % (cls, function)
-        yield TracebackEntry(filename, lineno, function, formatted_args,
-                             code_context, index)
-
-def format_extracted(extracted, formatter=None, limit=None):
-    if limit:
-        extracted = extracted[-limit:]
-
-    formatted = []
-    for tracebackinfo in extracted:
-        formatted.extend(tracebackinfo.format(formatter))
-    return formatted
-
-
-def format_exception(etype, value, tb, context=1, limit=None, formatter=None):
-    formatted = ['Traceback (most recent call last):\n']
-
-    if hasattr(tb, 'tb_next'):
-        tb = extract_traceback(tb, context)
-
-    formatted.extend(format_extracted(tb, formatter, limit))
-    formatted.extend(traceback.format_exception_only(etype, value))
-    return formatted
-
-def to_string(exc):
-    if isinstance(exc, SystemExit):
-        if not isinstance(exc.code, str):
-            return 'Exited with "%d"' % exc.code
-    return str(exc)
diff --git a/bitbake/lib/bb/msg.py b/bitbake/lib/bb/msg.py
index 3e18596f..4f616ff4 100644
--- a/bitbake/lib/bb/msg.py
+++ b/bitbake/lib/bb/msg.py
@@ -89,10 +89,6 @@ class BBLogFormatter(logging.Formatter):
             msg = logging.Formatter.format(self, record)
         if hasattr(record, 'bb_exc_formatted'):
             msg += '\n' + ''.join(record.bb_exc_formatted)
-        elif hasattr(record, 'bb_exc_info'):
-            etype, value, tb = record.bb_exc_info
-            formatted = bb.exceptions.format_exception(etype, value, tb, limit=5)
-            msg += '\n' + ''.join(formatted)
         return msg
 
     def colorize(self, record):
diff --git a/bitbake/lib/bb/ui/teamcity.py b/bitbake/lib/bb/ui/teamcity.py
index fca46c28..7eeaab8d 100644
--- a/bitbake/lib/bb/ui/teamcity.py
+++ b/bitbake/lib/bb/ui/teamcity.py
@@ -30,7 +30,6 @@ import bb.build
 import bb.command
 import bb.cooker
 import bb.event
-import bb.exceptions
 import bb.runqueue
 from bb.ui import uihelper
 
@@ -102,10 +101,6 @@ class TeamcityLogFormatter(logging.Formatter):
         details = ""
         if hasattr(record, 'bb_exc_formatted'):
             details = ''.join(record.bb_exc_formatted)
-        elif hasattr(record, 'bb_exc_info'):
-            etype, value, tb = record.bb_exc_info
-            formatted = bb.exceptions.format_exception(etype, value, tb, limit=5)
-            details = ''.join(formatted)
 
         if record.levelno in [bb.msg.BBLogFormatter.ERROR, bb.msg.BBLogFormatter.CRITICAL]:
             # ERROR gets a separate errorDetails field
-- 
2.53.0

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