pkg/subsystem: add the MAINTAINERS file parsing code

1 files changed, 144 insertions, 0 deletions

diff --git a/pkg/subsystem/linux/maintainers.go b/pkg/subsystem/linux/maintainers.go
new file mode 100644
index 000000000..ce692bfd4
--- /dev/null
+++ b/pkg/subsystem/linux/maintainers.go
@@ -0,0 +1,144 @@
+// Copyright 2023 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package linux
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"net/mail"
+	"regexp"
+	"strings"
+	"unicode"
+)
+
+// maintainersRecord represents a single raw record in the MAINTAINERS file.
+type maintainersRecord struct {
+	name            string
+	includePatterns []string
+	excludePatterns []string
+	regexps         []string
+	lists           []string
+	maintainers     []string
+}
+
+func parseLinuxMaintainers(content io.Reader) ([]*maintainersRecord, error) {
+	scanner := bufio.NewScanner(content)
+	// First skip the headers.
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "Maintainers List" {
+			// Also skip ------.
+			scanner.Scan()
+			break
+		}
+	}
+	ml := &maintainersLexer{scanner: scanner}
+	ret := []*maintainersRecord{}
+loop:
+	for {
+		item := ml.next()
+		switch v := item.(type) {
+		case recordTitle:
+			// The new subsystem begins.
+			ret = append(ret, &maintainersRecord{name: string(v)})
+		case recordProperty:
+			if len(ret) == 0 {
+				return nil, fmt.Errorf("line %d: property without subsystem", ml.currentLine)
+			}
+			err := applyProperty(ret[len(ret)-1], &v)
+			if err != nil {
+				return nil, fmt.Errorf("line %d: failed to apply the property %#v: %w",
+					ml.currentLine, v, err)
+			}
+		case endOfFile:
+			break loop
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+	return ret, nil
+}
+
+type maintainersLexer struct {
+	scanner     *bufio.Scanner
+	currentLine int
+	inComment   bool
+}
+
+type recordTitle string
+type recordProperty struct {
+	key   string
+	value string
+}
+type endOfFile struct{}
+
+var propertyRe = regexp.MustCompile(`^([[:alpha:]]):\s+(.*).*$`)
+
+func (ml *maintainersLexer) next() interface{} {
+	for ml.scanner.Scan() {
+		ml.currentLine++
+		rawLine := ml.scanner.Text()
+		line := strings.TrimSpace(rawLine)
+		if strings.HasPrefix(line, ".") {
+			ml.inComment = true
+			continue
+		}
+		// A comment continues to the next line(s) if they begin with a space character.
+		if ml.inComment && (line == "" || !unicode.IsSpace(rune(rawLine[0]))) {
+			ml.inComment = false
+		}
+		if ml.inComment || line == "" {
+			continue
+		}
+		// Now let's consider the possible line types.
+		if matches := propertyRe.FindStringSubmatch(line); matches != nil {
+			return recordProperty{key: matches[1], value: matches[2]}
+		}
+		return recordTitle(line)
+	}
+	return endOfFile{}
+}
+
+func applyProperty(record *maintainersRecord, property *recordProperty) error {
+	switch property.key {
+	case "F":
+		record.includePatterns = append(record.includePatterns, property.value)
+	case "X":
+		record.excludePatterns = append(record.excludePatterns, property.value)
+	case "N":
+		if _, err := regexp.Compile(property.value); err != nil {
+			return fmt.Errorf("invalid regexp: %s", property.value)
+		}
+		record.regexps = append(record.regexps, property.value)
+	case "M":
+		value, err := parseEmail(property.value)
+		if err != nil {
+			return err
+		}
+		record.maintainers = append(record.maintainers, value)
+	case "L":
+		value, err := parseEmail(property.value)
+		if err != nil {
+			return err
+		}
+		record.lists = append(record.lists, value)
+	}
+	return nil
+}
+
+func parseEmail(value string) (string, error) {
+	// Sometimes there happen extra symbols at the end of the line,
+	// let's make this parser more error tolerant.
+	pos := strings.LastIndexAny(value, ">)")
+	if pos >= 0 {
+		value = value[:pos+1]
+	}
+	addr, err := mail.ParseAddress(value)
+	if err != nil {
+		return "", err
+	}
+	return addr.Address, nil
+}