From 1da8f12f5e783fade177c7547f4e1a601c489c7f Mon Sep 17 00:00:00 2001
From: Patrick Ohly <patrick.ohly@intel.com>
Date: Wed, 23 Mar 2022 13:24:30 +0100
Subject: [PATCH] logcheck: fix detection of invalid * regexp in filter

Extending the user-supplied regular expression to match the entire string by
adding ^ and $ turned invalid regular expressions like * into valid
ones (`^*$`) and thus didn't flag them as error.

It's better to compile the string exactly as supplied by the user (better error
message, properly detects this case) and then checking later whether the entire
string was matched.
---
 logcheck/pkg/filter.go      | 19 ++++++++++++++++---
 logcheck/pkg/filter_test.go |  6 +++++-
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/logcheck/pkg/filter.go b/logcheck/pkg/filter.go
index 231a38c..c2ad909 100644
--- a/logcheck/pkg/filter.go
+++ b/logcheck/pkg/filter.go
@@ -88,8 +88,7 @@ func (f *RegexpFilter) Set(filename string) error {
 			line.enabled[c] = enabled
 		}
 
-		// Must match entire string.
-		re, err := regexp.Compile("^" + parts[1] + "$")
+		re, err := regexp.Compile(parts[1])
 		if err != nil {
 			return fmt.Errorf("%s:%d: %v", filename, lineNr, err)
 		}
@@ -106,7 +105,8 @@ func (f *RegexpFilter) Set(filename string) error {
 // Enabled checks whether a certain check is enabled for a file.
 func (f *RegexpFilter) Enabled(check string, enabled bool, filename string) bool {
 	for _, l := range f.lines {
-		if l.match.MatchString(filename) {
+		// Must match entire string.
+		if matchFullString(filename, l.match) {
 			if e, ok := l.enabled[check]; ok {
 				enabled = e
 			}
@@ -114,3 +114,16 @@ func (f *RegexpFilter) Enabled(check string, enabled bool, filename string) bool
 	}
 	return enabled
 }
+
+func matchFullString(str string, re *regexp.Regexp) bool {
+	loc := re.FindStringIndex(str)
+	if loc == nil {
+		// No match at all.
+		return false
+	}
+	if loc[1]-loc[0] < len(str) {
+		// Only matches a substring.
+		return false
+	}
+	return true
+}
diff --git a/logcheck/pkg/filter_test.go b/logcheck/pkg/filter_test.go
index 115af49..eee829a 100644
--- a/logcheck/pkg/filter_test.go
+++ b/logcheck/pkg/filter_test.go
@@ -116,7 +116,11 @@ func TestParsing(t *testing.T) {
 	}{
 		"invalid-regexp": {
 			content:     `structured [`,
-			expectError: filename + ":0: error parsing regexp: missing closing ]: `[$`",
+			expectError: filename + ":0: error parsing regexp: missing closing ]: `[`",
+		},
+		"wildcard": {
+			content:     `structured *`,
+			expectError: filename + ":0: error parsing regexp: missing argument to repetition operator: `*`",
 		},
 		"invalid-line": {
 			content: `structured .