Initial commit of PakGo. TODO: HTTP filesysystem / os.file stuff

PakGo.go

@@ -0,0 +1,109 @@
+package PakGo
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+
+	"os"
+	"reflect"
+	"strings"
+)
+
+type pakHeader struct {
+	Id     [4]byte
+	Offset uint32
+	Size   uint32
+}
+
+type pakFileEntry struct {
+	Name   [56]byte
+	Offset uint32
+	Size   uint32
+}
+
+type pakFileEntryNative struct {
+	Name   string
+	Offset int64
+	Size   int
+}
+
+type PakFile struct {
+	filetable  []pakFileEntryNative
+	filehandle *os.File
+}
+
+func (pak PakFile) fileid(filename string, filetable []pakFileEntryNative) (int, error) {
+	for id, file := range filetable {
+		if filename == file.Name {
+			return id, nil
+		}
+	}
+	return -1, errors.New("the system cannot find the file specified")
+}
+
+func (pak PakFile) ReadFile(filename string) ([]byte, error) {
+	i, err := pak.fileid(filename, pak.filetable)
+	if err != nil {
+		return nil, err
+	}
+
+	data := make([]byte, pak.filetable[i].Size)
+	pak.filehandle.Seek(pak.filetable[i].Offset, 0)
+	pak.filehandle.Read(data)
+
+	return data, nil
+}
+
+func (pak PakFile) PakClose() {
+	pak.filehandle.Close()
+}
+
+func PakLoad(filename string) (PakFile, error) {
+	var filetable []pakFileEntryNative
+
+	f, err := os.Open(filename)
+	if err != nil {
+		return PakFile{}, err
+	}
+
+	header := pakHeader{}
+	binary.Read(f, binary.LittleEndian, &header.Id)
+	binary.Read(f, binary.LittleEndian, &header.Offset)
+	binary.Read(f, binary.LittleEndian, &header.Size)
+
+	validheader := []byte{'P', 'A', 'C', 'K'}
+	valid := bytes.Compare(validheader, header.Id[:])
+	if valid != 0 {
+		return PakFile{}, errors.New("not a valid .PAK file")
+	}
+
+	size := reflect.TypeOf(pakFileEntry{}).Size()
+	filecount := int(header.Size / uint32(size))
+
+	f.Seek(int64(header.Offset), 0)
+
+	for i := 1; i <= filecount; i++ {
+		file := pakFileEntry{}
+
+		binary.Read(f, binary.LittleEndian, &file.Name)
+		binary.Read(f, binary.LittleEndian, &file.Offset)
+		binary.Read(f, binary.LittleEndian, &file.Size)
+
+		filename := string(file.Name[:])
+		filename = string(file.Name[:strings.Index(filename, "\x00")])
+
+		nativefile := pakFileEntryNative{
+			Name:   filename,
+			Offset: int64(file.Offset),
+			Size:   int(file.Size),
+		}
+		filetable = append(filetable, nativefile)
+
+	}
+
+	return PakFile{
+		filetable:  filetable,
+		filehandle: f,
+	}, nil
+}

README.md

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+Docs coming in next couple of days..

go.mod

@@ -0,0 +1,3 @@
+module github.com/stevenhowes/PakGo
+
+go 1.17