From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Thu, 3 Aug 2017 10:52:49 +0000 (+0100)
Subject: Skeleton: fixed initialization of maximal path length.
X-Git-Tag: 1.0~16
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=dc2495c6807dccbd7fa918fd866ae32194f01edb;p=re2c

Skeleton: fixed initialization of maximal path length.

Broken by commit fffb5932ee52127e03b9f7f5ccca83a421d69061.

Path length were initialized with 0 instead 'DIST_ERROR', which caused
incorrect calculation of maximal path length. This in turn caused errors
in estimating the number of byted necessary to hold keys during data
generation in skeleton. The resulting keys were one-byte while maximal
path length was more than one byte, which (fortunately!) caused runtime
errors in skeleton programs.

Example of program that caused skeleton error:
    /*!re2c
        (@t [\x00] [^]{5,6})* {}
    */

The error was hidden for so long because in practice inputs that need
more than one-byte keys are rare, and fuzzer sets 'ulimit -t 10' when
running re2c, so most of such programs were simply aborted. Those that
were not aborted still had a chance of estimating key size correctly.
---

diff --git a/re2c/src/skeleton/maxpath.cc b/re2c/src/skeleton/maxpath.cc
index c609c215..8fada329 100644
--- a/re2c/src/skeleton/maxpath.cc
+++ b/re2c/src/skeleton/maxpath.cc
@@ -54,7 +54,7 @@ static void calc_dist(
 uint32_t maxpath(const Skeleton &skel)
 {
 	std::vector<uint8_t> loops(skel.nodes_count);
-	std::vector<uint32_t> dists(skel.nodes_count);
+	std::vector<uint32_t> dists(skel.nodes_count, DIST_ERROR);
 	calc_dist(skel, loops, dists, 0);
 	const uint32_t maxlen = dists[0];
 	if (maxlen == DIST_MAX) {