commit b210f39f074eef565d2f2d23e95547ebb42d2ab2
Author: icedream <icedream@icedream.pw>
Date:   Tue Feb 21 08:26:46 2017 +0100

    Initial commit.

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..2d3d068
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "bsdiff"]
+	path = bsdiff
+	url = https://github.com/mendsley/bsdiff.git
diff --git a/bsdiff b/bsdiff
new file mode 160000
index 0000000..7d70d8f
--- /dev/null
+++ b/bsdiff
@@ -0,0 +1 @@
+Subproject commit 7d70d8f4ff48345bc76e314c9d98da91f78873fa
diff --git a/cmd/bsdiff/main.go b/cmd/bsdiff/main.go
new file mode 100644
index 0000000..77cf81a
--- /dev/null
+++ b/cmd/bsdiff/main.go
@@ -0,0 +1,31 @@
+package main
+
+import (
+	"log"
+	"os"
+
+	"github.com/icedream/go-bsdiff"
+)
+
+func must(err error) {
+	if err == nil {
+		return
+	}
+
+	log.Fatal(err)
+}
+
+func main() {
+	oldFile, err := os.Open("test.txt")
+	must(err)
+
+	newFile, err := os.Open("test_new.txt")
+	must(err)
+
+	patchFile, err := os.Create("test.patch")
+	must(err)
+
+	must(bsdiff.Diff(oldFile, newFile, patchFile))
+
+	log.Println("Done.")
+}
diff --git a/diff.go b/diff.go
new file mode 100644
index 0000000..5e1de99
--- /dev/null
+++ b/diff.go
@@ -0,0 +1,33 @@
+package bsdiff
+
+import (
+	"io"
+	"io/ioutil"
+
+	"github.com/dsnet/compress/bzip2"
+	"github.com/icedream/go-bsdiff/internal/native"
+)
+
+func Diff(oldReader, newReader io.Reader, patchWriter io.Writer) (err error) {
+	oldBytes, err := ioutil.ReadAll(oldReader)
+	if err != nil {
+		return
+	}
+	newBytes, err := ioutil.ReadAll(newReader)
+	if err != nil {
+		return
+	}
+
+	if err = writeHeader(patchWriter, uint64(len(newBytes))); err != nil {
+		return
+	}
+
+	// Compression
+	bz2Writer, err := bzip2.NewWriter(patchWriter, nil)
+	if err != nil {
+		return
+	}
+	defer bz2Writer.Close()
+
+	return native.Diff(oldBytes, newBytes, bz2Writer)
+}
diff --git a/internal/native/cgo.c b/internal/native/cgo.c
new file mode 100644
index 0000000..576101c
--- /dev/null
+++ b/internal/native/cgo.c
@@ -0,0 +1,56 @@
+#include "cgo.h"
+
+#include "bsdiff.h"
+#include "bspatch.h"
+
+extern int cgo_write_buffer(int bufferIndex, void* buf, int size);
+
+int cgo_write(struct bsdiff_stream* stream,
+	const void* buf, int size) {
+	struct buffer_table_index* bufferEntry;
+	
+	bufferEntry = (struct buffer_table_index*)stream->opaque;
+
+	return cgo_write_buffer(bufferEntry->index, (void*)buf, size);
+}
+
+extern int cgo_read_buffer(int bufferIndex, void* buf, int size);
+
+int cgo_read(const struct bspatch_stream* stream,
+	void* buf, int size) {
+		struct buffer_table_index* bufferEntry;
+		
+		bufferEntry = (struct buffer_table_index*)stream->opaque;
+		
+	return cgo_read_buffer(bufferEntry->index, buf, size) ;
+}
+
+int bsdiff_cgo(uint8_t* oldptr, int64_t oldsize,
+	uint8_t* newptr, int64_t newsize,
+	int bufferIndex)
+{
+	struct bsdiff_stream stream;
+	stream.malloc = malloc;
+	stream.free = free;
+	stream.write = cgo_write;
+
+	struct buffer_table_index bufferEntry;
+	bufferEntry.index = bufferIndex;
+	stream.opaque = &bufferEntry;
+
+	return bsdiff(oldptr, oldsize, newptr, newsize, &stream);
+}
+
+int bspatch_cgo(uint8_t* oldptr, int64_t oldsize,
+	uint8_t* newptr, int64_t newsize,
+	int bufferIndex)
+{
+	struct bspatch_stream stream;
+	stream.read = cgo_read;
+	
+	struct buffer_table_index bufferEntry;
+	bufferEntry.index = bufferIndex;
+	stream.opaque = &bufferEntry;
+	
+	return bspatch(oldptr, oldsize, newptr, newsize, &stream);
+}
\ No newline at end of file
diff --git a/internal/native/cgo.h b/internal/native/cgo.h
new file mode 100644
index 0000000..cf692e8
--- /dev/null
+++ b/internal/native/cgo.h
@@ -0,0 +1,15 @@
+#include <stdlib.h>
+#include "stdint.h"
+
+struct buffer_table_index
+{
+	int index;
+};
+
+int bsdiff_cgo(uint8_t* oldptr, int64_t oldsize,
+	uint8_t* newptr, int64_t newsize,
+	int bufferIndex);
+	
+int bspatch_cgo(uint8_t* oldptr, int64_t oldsize,
+	uint8_t* newptr, int64_t newsize,
+	int bufferIndex);
diff --git a/internal/native/cgo_read.go b/internal/native/cgo_read.go
new file mode 100644
index 0000000..4e4967a
--- /dev/null
+++ b/internal/native/cgo_read.go
@@ -0,0 +1,43 @@
+package native
+
+/*
+#include "bspatch.h"
+*/
+import "C"
+import (
+	"io"
+	"log"
+	"unsafe"
+)
+
+//export cgo_read_buffer
+func cgo_read_buffer(bufferIndex C.int,
+	bufPtr unsafe.Pointer, length C.int) C.int {
+	goLength := int(length)
+
+	if goLength == 0 {
+		return 0
+	}
+
+	sourceBuffer := readers.Get(int(bufferIndex))
+	targetBuffer := cPtrToSlice(bufPtr, goLength)
+
+	errCode := 0
+	offset := 0
+	for offset < goLength {
+		n, err := sourceBuffer.Read(targetBuffer)
+
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			log.Println("cgo_read_buffer failed:", err)
+			errCode = 1
+			break
+		}
+
+		offset += n
+		targetBuffer = targetBuffer[n:]
+	}
+
+	return C.int(errCode)
+}
diff --git a/internal/native/cgo_write.go b/internal/native/cgo_write.go
new file mode 100644
index 0000000..1a4e6bd
--- /dev/null
+++ b/internal/native/cgo_write.go
@@ -0,0 +1,18 @@
+package native
+
+/*
+#include "bsdiff.h"
+*/
+import "C"
+import "unsafe"
+
+//export cgo_write_buffer
+func cgo_write_buffer(bufferIndex C.int,
+	dataPtr unsafe.Pointer, size C.int) C.int {
+	buffer := writers.Get(int(bufferIndex))
+	errCode := 0
+	if _, err := buffer.Write(cPtrToSlice(dataPtr, int(size))); err != nil {
+		errCode = 1
+	}
+	return C.int(errCode)
+}
diff --git a/internal/native/diff.go b/internal/native/diff.go
new file mode 100644
index 0000000..97b78e5
--- /dev/null
+++ b/internal/native/diff.go
@@ -0,0 +1,28 @@
+package native
+
+/*
+#cgo CFLAGS: -I../../bsdiff
+
+#include "bsdiff.h"
+#include "cgo.h"
+*/
+import "C"
+import (
+	"errors"
+	"io"
+)
+
+func Diff(oldbytes, newbytes []byte, patch io.Writer) (err error) {
+	oldptr, oldsize := bytesToUint8PtrAndSize(oldbytes)
+	newptr, newsize := bytesToUint8PtrAndSize(newbytes)
+
+	bufferIndex := writers.Add(patch)
+
+	errCode := int(C.bsdiff_cgo(oldptr, oldsize, newptr, newsize, C.int(bufferIndex)))
+	if errCode != 0 {
+		err = errors.New("bsdiff failed")
+		return
+	}
+
+	return
+}
diff --git a/internal/native/ext_bsdiff.c b/internal/native/ext_bsdiff.c
new file mode 100644
index 0000000..a9558c1
--- /dev/null
+++ b/internal/native/ext_bsdiff.c
@@ -0,0 +1,2 @@
+#include "bsdiff.c"
+#include "bspatch.c"
\ No newline at end of file
diff --git a/internal/native/native.go b/internal/native/native.go
new file mode 100644
index 0000000..8a9348f
--- /dev/null
+++ b/internal/native/native.go
@@ -0,0 +1,31 @@
+package native
+
+/*
+#include <stdint.h>
+*/
+import "C"
+import (
+	"reflect"
+	"unsafe"
+)
+
+var (
+	writers = writerTable{}
+	readers = readerTable{}
+)
+
+func bytesToUint8PtrAndSize(bytes []byte) (ptr *C.uint8_t, size C.int64_t) {
+	ptr = (*C.uint8_t)(unsafe.Pointer(&bytes[0]))
+	size = C.int64_t(int64(len(bytes)))
+	return
+}
+
+func cPtrToSlice(ptr unsafe.Pointer, size int) []byte {
+	var slice []byte
+	sliceHeader := (*reflect.SliceHeader)(unsafe.Pointer(&slice))
+	sliceHeader.Cap = size
+	sliceHeader.Len = size
+	sliceHeader.Data = uintptr(ptr)
+
+	return slice
+}
diff --git a/internal/native/patch.go b/internal/native/patch.go
new file mode 100644
index 0000000..f797cf5
--- /dev/null
+++ b/internal/native/patch.go
@@ -0,0 +1,29 @@
+package native
+
+/*
+#cgo CFLAGS: -I../../bsdiff
+
+#include "bspatch.h"
+#include "cgo.h"
+*/
+import "C"
+import (
+	"errors"
+	"io"
+	"strconv"
+)
+
+func Patch(oldbytes, newbytes []byte, patch io.Reader) (err error) {
+	oldptr, oldsize := bytesToUint8PtrAndSize(oldbytes)
+	newptr, newsize := bytesToUint8PtrAndSize(newbytes)
+
+	bufferIndex := readers.Add(patch)
+
+	errCode := int(C.bspatch_cgo(oldptr, oldsize, newptr, newsize, C.int(bufferIndex)))
+	if errCode != 0 {
+		err = errors.New("bspatch failed with code " + strconv.Itoa(errCode))
+		return
+	}
+
+	return
+}
diff --git a/internal/native/table_reader.go b/internal/native/table_reader.go
new file mode 100644
index 0000000..620e683
--- /dev/null
+++ b/internal/native/table_reader.go
@@ -0,0 +1,37 @@
+package native
+
+import (
+	"io"
+	"sync"
+)
+
+type readerTable struct {
+	nextIndex int
+	table     map[int]io.Reader
+	mutex     sync.Mutex
+}
+
+func (bt *readerTable) Add(reader io.Reader) (index int) {
+	bt.mutex.Lock()
+	defer bt.mutex.Unlock()
+
+	if bt.table == nil {
+		bt.table = map[int]io.Reader{}
+	}
+
+	index = bt.nextIndex
+	bt.table[index] = reader
+
+	// TODO - Handle int overflow
+
+	bt.nextIndex++
+
+	return
+}
+
+func (bt *readerTable) Get(index int) io.Reader {
+	bt.mutex.Lock()
+	defer bt.mutex.Unlock()
+
+	return bt.table[index]
+}
diff --git a/internal/native/table_writer.go b/internal/native/table_writer.go
new file mode 100644
index 0000000..42b57c2
--- /dev/null
+++ b/internal/native/table_writer.go
@@ -0,0 +1,37 @@
+package native
+
+import (
+	"io"
+	"sync"
+)
+
+type writerTable struct {
+	nextIndex int
+	table     map[int]io.Writer
+	mutex     sync.Mutex
+}
+
+func (bt *writerTable) Add(writer io.Writer) (index int) {
+	bt.mutex.Lock()
+	defer bt.mutex.Unlock()
+
+	if bt.table == nil {
+		bt.table = map[int]io.Writer{}
+	}
+
+	index = bt.nextIndex
+	bt.table[index] = writer
+
+	// TODO - Handle int overflow
+
+	bt.nextIndex++
+
+	return
+}
+
+func (bt *writerTable) Get(index int) io.Writer {
+	bt.mutex.Lock()
+	defer bt.mutex.Unlock()
+
+	return bt.table[index]
+}
diff --git a/magic.go b/magic.go
new file mode 100644
index 0000000..b64530e
--- /dev/null
+++ b/magic.go
@@ -0,0 +1,39 @@
+package bsdiff
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+)
+
+var (
+	ErrInvalidMagic = errors.New("Invalid magic")
+
+	sizeEncoding = binary.BigEndian
+
+	magicText = []byte("ENDSLEY/BSDIFF43")
+)
+
+func writeHeader(w io.Writer, size uint64) (err error) {
+	if _, err = w.Write(magicText); err != nil {
+		return
+	}
+	err = binary.Write(w, sizeEncoding, size)
+	return
+}
+
+func readHeader(r io.Reader) (size uint64, err error) {
+	magicBuf := make([]byte, len(magicText))
+	n, err := r.Read(magicBuf)
+	if err != nil {
+		return
+	}
+	if n < len(magicText) {
+		err = ErrInvalidMagic
+		return
+	}
+
+	err = binary.Read(r, sizeEncoding, &size)
+
+	return
+}
diff --git a/patch.go b/patch.go
new file mode 100644
index 0000000..f2a0dde
--- /dev/null
+++ b/patch.go
@@ -0,0 +1,33 @@
+package bsdiff
+
+import (
+	"compress/bzip2"
+	"io"
+	"io/ioutil"
+	"log"
+
+	"github.com/icedream/go-bsdiff/internal/native"
+)
+
+func Patch(oldReader io.Reader, newWriter io.Writer, patchReader io.Reader) (err error) {
+	oldBytes, err := ioutil.ReadAll(oldReader)
+	if err != nil {
+		return
+	}
+
+	newLen, err := readHeader(patchReader)
+	if err != nil {
+		return
+	}
+	newBytes := make([]byte, newLen)
+
+	log.Printf("Going to create a file of %d bytes.", newLen)
+
+	// Decompression
+	bz2Reader := bzip2.NewReader(patchReader)
+
+	err = native.Patch(oldBytes, newBytes, bz2Reader)
+
+	newWriter.Write(newBytes)
+	return
+}