diff mercurial/util.py @ 43494:5d40317d42b7

dirs: reject consecutive slashes in paths

We shouldn't ever see those, and the fuzzer go really excited that if
it gives us a 65k string with 55k slashes in it we use a lot of RAM.

This is a better fix than what I tried in D7105. It was suggested by
Yuya, and I verified it does in fact cause the fuzzer to not OOM.

This is a revision of D7234, but with the missing set of an error
added. I added a unit test of the dirs behavior because I needed to
reason more carefully about the failure modes around consecutive
slashes.

Differential Revision: https://phab.mercurial-scm.org/D7252

--- a/mercurial/util.py	Tue Nov 05 22:56:12 2019 -0500
+++ b/mercurial/util.py	Thu Oct 17 19:29:22 2019 -0400
@@ -3515,6 +3515,10 @@
     def addpath(self, path):
         dirs = self._dirs
         for base in finddirs(path):
+            if base.endswith(b'/'):
+                raise ValueError(
+                    "found invalid consecutive slashes in path: %r" % base
+                )
             if base in dirs:
                 dirs[base] += 1
                 return