Debian control file parser.

debian/format.go

@@ -0,0 +1,82 @@
+package debian
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"strings"
+)
+
+// Stanza or paragraph of Debian control file
+type Stanza map[string]string
+
+// Parsing errors
+var (
+	ErrMalformedStanza = errors.New("malformed stanza syntax")
+)
+
+var multilineFields = make(map[string]bool)
+
+func init() {
+	multilineFields["Description"] = true
+	multilineFields["Files"] = true
+	multilineFields["Changes"] = true
+	multilineFields["Checksums-Sha1"] = true
+	multilineFields["Checksums-Sha256"] = true
+	multilineFields["Package-List"] = true
+	multilineFields["SHA256"] = true
+	multilineFields["SHA1"] = true
+	multilineFields["MD5Sum"] = true
+}
+
+// ControlFileReader implements reading of control files stanza by stanza
+type ControlFileReader struct {
+	scanner *bufio.Scanner
+}
+
+// NewControlFileReader creates ControlFileReader, it wraps with buffering
+func NewControlFileReader(r io.Reader) *ControlFileReader {
+	return &ControlFileReader{scanner: bufio.NewScanner(bufio.NewReaderSize(r, 32768))}
+}
+
+// ReadStanza reeads one stanza from control file
+func (c *ControlFileReader) ReadStanza() (Stanza, error) {
+	stanza := make(Stanza, 32)
+	lastField := ""
+	lastFieldMultiline := false
+
+	for c.scanner.Scan() {
+		line := c.scanner.Text()
+
+		// Current stanza ends with empty line
+		if line == "" {
+			if len(stanza) > 0 {
+				return stanza, nil
+			}
+			continue
+		}
+
+		if line[0] == ' ' || line[0] == '\t' {
+			if lastFieldMultiline {
+				stanza[lastField] += line + "\n"
+			} else {
+				stanza[lastField] += strings.TrimSpace(line)
+			}
+		} else {
+			parts := strings.SplitN(line, ":", 2)
+			if len(parts) != 2 {
+				return nil, ErrMalformedStanza
+			}
+			lastField = parts[0]
+			stanza[lastField] = strings.TrimSpace(parts[1])
+			_, lastFieldMultiline = multilineFields[lastField]
+		}
+	}
+	if err := c.scanner.Err(); err != nil {
+		return nil, err
+	}
+	if len(stanza) > 0 {
+		return stanza, nil
+	}
+	return nil, nil
+}