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[Bug regex/6395] New: regex ^$ is not detected as anchored
- From: "bonzini at gnu dot org" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: 11 Apr 2008 12:44:30 -0000
- Subject: [Bug regex/6395] New: regex ^$ is not detected as anchored
- Reply-to: sourceware-bugzilla at sourceware dot org
Regex matching has an optimization where only one match is tried for a regex
anchored to the beginning of the buffer. While other anchors are resolved with
the fastmap, this one allows further optimization and is special cased. However,
because of a bug in create_cd_newstate, ^$ would be mistakenly treated as a
non-anchoring match, and re_search_internal would try matching it at every position.
In fact, the bug is (almost) fixed by this hunk:
@@ -1682,8 +1680,6 @@ create_cd_newstate (const re_dfa_t *dfa,
newstate->halt = 1;
else if (type == OP_BACK_REF)
newstate->has_backref = 1;
- else if (type == ANCHOR)
- constraint = node->opr.ctx_type;
if (constraint)
{
However, some complications in building the NFA prevent this from fixing the
problem. Therefore, this patch cleans up the handling of anchors so that tests
on type == ANCHOR are not necessary anymore. When creating the NFA (calc_first),
I move the opr.ctx_type to the constraint field of re_token_t, and then I always
look at it unconditionally, without special-casing ANCHORs. This also allows
some simplification of duplicate_node_closure.
--
Summary: regex ^$ is not detected as anchored
Product: glibc
Version: unspecified
Status: NEW
Severity: enhancement
Priority: P2
Component: regex
AssignedTo: bonzini at gnu dot org
ReportedBy: bonzini at gnu dot org
CC: glibc-bugs-regex at sources dot redhat dot com,glibc-
bugs at sources dot redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=6395
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