feat: support parse png icon from pe file

icon.go

@@ -0,0 +1,46 @@
+package pe
+
+import (
+	"bytes"
+	"errors"
+	"image/png"
+)
+
+func (pe *File) ParsePngIcon() ([]byte, error) {
+	var iconEntry *ResourceDirectoryEntry
+	for _, e := range pe.Resources.Entries {
+		if e.ID != RTIcon {
+			continue
+		}
+		if len(e.Directory.Entries) == 0 {
+			return nil, errors.New("no entries found in resource directory")
+		}
+		iconEntry = &e
+		break
+	}
+	if iconEntry == nil {
+		return nil, errors.New("no icon found in resource directory")
+	}
+
+	for _, iconItem := range iconEntry.Directory.Entries {
+		if len(iconItem.Directory.Entries) == 0 {
+			continue
+		}
+
+		iconData := &iconItem.Directory.Entries[0]
+
+		offset, size := pe.GetOffsetFromRva(iconData.Data.Struct.OffsetToData), iconData.Data.Struct.Size
+
+		b, err := pe.ReadBytesAtOffset(offset, size)
+		if err != nil {
+			return nil, err
+		}
+
+		_, err = png.Decode(bytes.NewBuffer(b))
+		if err != nil {
+			continue
+		}
+		return b, nil
+	}
+	return nil, errors.New("no valid png icon found")
+}

icon_test.go

@@ -0,0 +1,30 @@
+package pe
+
+import (
+	"os"
+	"testing"
+)
+
+func Test_ParseIcon(t *testing.T) {
+	file, err := New("/Users/dafenghuang/Downloads/WeChatSetup.exe", &Options{})
+	if err != nil {
+		t.Errorf("open file failed, err %v", err)
+		return
+	}
+
+	err = file.Parse()
+	if err != nil {
+		t.Errorf("parse file failed, err %v", err)
+		return
+	}
+
+	iconBytes, err := file.ParsePngIcon()
+	if err != nil {
+		t.Errorf("parse icon failed, err %v", err)
+		return
+	}
+
+	os.WriteFile("test.png", iconBytes, 0644)
+
+	t.Logf("length %d", len(iconBytes))
+}