getNEVRA refactor and cleanup

pkg/entry.go

@@ -3,7 +3,9 @@ package rpmdb
 import (
  "bytes"
  "encoding/binary"
+ "fmt"
  "io"
+ "strings"
  "unsafe"
 
  "golang.org/x/xerrors"
@@ -67,6 +69,24 @@ type entryInfo struct {
  Count uint32 /*!< Number of tag elements. */
 }
 
+func (ei entryInfo) TagName() string {
+ tagname, ok := tagNames[ei.Tag]
+ if !ok {
+ tagname = fmt.Sprintf("tag#%v", ei.Tag)
+ }
+
+ return tagname
+}
+
+func (ei entryInfo) TypeName() string {
+ typename, ok := typeNames[ei.Tag]
+ if !ok {
+ typename = fmt.Sprintf("type#%v", ei.Tag)
+ }
+
+ return typename
+}
+
 // ref. https://github.com/rpm-software-management/rpm/blob/rpm-4.14.3-release/lib/header.c#L88-L94
 type indexEntry struct {
  Info entryInfo
@@ -75,6 +95,98 @@ type indexEntry struct {
  Data []byte
 }
 
+const (
+ sizeOfInt32 = 4
+ sizeOfUInt16 = 2
+)
+
+func (ie indexEntry) ParseString() (string, error) {
+ if ie.Info.Type != RPM_STRING_TYPE {
+ return "", xerrors.Errorf("invalid tag type for string field: %v", ie.Info.TypeName())
+ }
+
+ result := string(bytes.TrimRight(ie.Data, "\x00"))
+
+ switch (ie.Info.Tag) {
+ case RPMTAG_SOURCERPM, RPMTAG_LICENSE, RPMTAG_VENDOR:
+ if result == "(none)" {
+ result = ""
+ }
+ }
+
+ return result, nil
+}
+
+func (ie indexEntry) ParseI18nString() (string, error) {
+ // some libraries have a string value instead of international string,
+ // so accounting for both
+ if ie.Info.Type != RPM_I18NSTRING_TYPE && ie.Info.Type != RPM_STRING_TYPE {
+ return "", xerrors.Errorf("invalid tag type for international string field: %v",
+ ie.Info.TypeName())
+ }
+
+ // since this is an international string, getting the first null terminated string
+ return string(bytes.Split(ie.Data, []byte{0})[0]), nil
+}
+
+func (ie indexEntry) ParseStringArray() ([]string, error) {
+ if ie.Info.Type != RPM_STRING_ARRAY_TYPE {
+ return nil, xerrors.Errorf("invalid tag type for string array field: %v",
+ ie.Info.TypeName())
+ }
+
+ return strings.Split(string(bytes.TrimRight(ie.Data, "\x00")), "\x00"), nil
+}
+
+func (ie indexEntry) ParseUint16Array() ([]uint16, error) {
+ length := ie.Length / sizeOfUInt16
+ values := make([]uint16, length)
+ reader := bytes.NewReader(ie.Data)
+ if err := binary.Read(reader, binary.BigEndian, &values); err != nil {
+ return nil, xerrors.Errorf("failed to read binary: %w", err)
+ }
+ return values, nil
+}
+
+func (ie indexEntry) ParseInt32() (int, error) {
+ if ie.Info.Type != RPM_INT32_TYPE {
+ return 0, xerrors.Errorf("invalid tag type for int32 field: %v",
+ ie.Info.TypeName())
+ }
+
+ var value int32
+ reader := bytes.NewReader(ie.Data)
+ if err := binary.Read(reader, binary.BigEndian, &value); err != nil {
+ return 0, xerrors.Errorf("failed to read binary: %w", err)
+ }
+ return int(value), nil
+}
+
+func (ie indexEntry) ParseInt32Array() ([]int32, error) {
+ if ie.Info.Type != RPM_INT32_TYPE {
+ return nil, xerrors.Errorf("invalid tag type for int32 array field: %v",
+ ie.Info.TypeName())
+ }
+
+ length := ie.Length / sizeOfInt32
+ values := make([]int32, length)
+ reader := bytes.NewReader(ie.Data)
+ if err := binary.Read(reader, binary.BigEndian, &values); err != nil {
+ return nil, xerrors.Errorf("failed to read binary: %w", err)
+ }
+ return values, nil
+}
+
+func (ie indexEntry) ParseInt64() (int, error) {
+ var value int64
+
+ reader := bytes.NewReader(ie.Data)
+ if err := binary.Read(reader, binary.BigEndian, &value); err != nil {
+ return 0, xerrors.Errorf("failed to read binary: %w", err)
+ }
+ return int(value), nil
+}
+
 // ref. https://github.com/rpm-software-management/rpm/blob/rpm-4.14.3-release/lib/header_internal.h#L23
 type hdrblob struct {
  peList []entryInfo