quark created this revision. Herald added a subscriber: mercurial-devel. Herald added a reviewer: hg-reviewers.
REVISION SUMMARY Checking `len(lines)` is not a great way of detecting infinite loops, as demonstrated in the added test. Therefore check instruction count instead. The original C implementation does not have this problem. There are a few other places where the C implementation enforces more strictly, like `a1 <= a2 <= len(lines)`, `b1 <= b2`, `rev > 0`. But they are optional. TEST PLAN Add a test. The old code forces the test to time out. REPOSITORY rHG Mercurial REVISION DETAIL https://phab.mercurial-scm.org/D4151 AFFECTED FILES mercurial/linelog.py tests/test-linelog.py CHANGE DETAILS diff --git a/tests/test-linelog.py b/tests/test-linelog.py --- a/tests/test-linelog.py +++ b/tests/test-linelog.py @@ -179,6 +179,15 @@ ar = ll.annotate(rev) self.assertEqual([(l.rev, l.linenum) for l in ar], lines) + def testinfinitebadprogram(self): + ll = linelog.linelog.fromdata( + b'\x00\x00\x00\x00\x00\x00\x00' # header + b'\x02\x00\x00\x00\x00\x00\x00\x00\x01' # JUMP to self + ) + with self.assertRaises(linelog.LineLogError): + # should not be an infinite loop and raise + ll.annotate(1) + if __name__ == '__main__': import silenttestrunner silenttestrunner.main(__name__) diff --git a/mercurial/linelog.py b/mercurial/linelog.py --- a/mercurial/linelog.py +++ b/mercurial/linelog.py @@ -373,13 +373,15 @@ def annotate(self, rev): pc = 1 lines = [] - # Sanity check: if len(lines) is longer than len(program), we + executed = 0 + # Sanity check: if instructions executed exceeds len(program), we # hit an infinite loop in the linelog program somehow and we # should stop. - while pc is not None and len(lines) < len(self._program): + while pc is not None and executed < len(self._program): inst = self._program[pc] lastpc = pc pc = inst.execute(rev, pc, lines.append) + executed += 1 if pc is not None: raise LineLogError( 'Probably hit an infinite loop in linelog. Program:\n' + To: quark, #hg-reviewers Cc: mercurial-devel _______________________________________________ Mercurial-devel mailing list Mercurial-devel@mercurial-scm.org https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
