From patchwork Thu Dec  4 18:53:41 2014
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Subject: parsers: ensure revlog index node tree is initialized before insertion
From: adgar@google.com
X-Patchwork-Id: 7008
Message-Id: <4c8cd4678e1cf6992b7d.1417719221@adgar.nyc.corp.google.com>
To: mercurial-devel@selenic.com
Date: Thu, 04 Dec 2014 13:53:41 -0500

# HG changeset patch
# User Mike Edgar <adgar@google.com>
# Date 1417712522 18000
#      Thu Dec 04 12:02:02 2014 -0500
# Node ID 4c8cd4678e1cf6992b7d0a07b87b60775f0dc2c0
# Parent  c237499a7fba65c88a2da721a22b66df4f39cf4e
parsers: ensure revlog index node tree is initialized before insertion

Currently, the revlog index C implementation assumes its node tree will be
initialized before a new element is inserted by revnum. For example, revlog.py
executes 'self.index.insert(-1, e)' in _addrevision(). This is only safe
because the node tree has been initialized by a "node in self.nodemap"
check made in addrevision().

(For context, this was discovered while developing an experimental revlog
mixin which stores "elided nodes" via a separate code path from
_addrevision(); that new code path segfaults without this patch.)

diff -r c237499a7fba -r 4c8cd4678e1c mercurial/parsers.c
--- a/mercurial/parsers.c	Wed Dec 03 22:56:42 2014 +0900
+++ b/mercurial/parsers.c	Thu Dec 04 12:02:02 2014 -0500
@@ -1978,6 +1978,9 @@
 			PyErr_SetString(PyExc_ValueError, "rev out of range");
 		return -1;
 	}
+
+	if (nt_init(self) == -1)
+		return -1;
 	return nt_insert(self, node, (int)rev);
 }