start implementing fileblockdevice

README.md

@@ -4,6 +4,12 @@
 [![Coverage Status](https://coveralls.io/repos/Knio/everdb-go/badge.svg)](https://coveralls.io/r/Knio/everdb-go)
 
 
+`EverDB-go` is a `Go` language port of [EverDB](https://github.com/Knio/everdb)
+
+
+`EverDB-go` is currently a work in progress and is *unfinished* and *not fit for use*.
+
+
 ## Docs
 
 http://godoc.org/github.com/Knio/everdb-go

everdb.go

@@ -1,8 +1,8 @@
 package everdb
 
-type Helloer struct {
+type Database struct {
 }
 
-func (h Helloer) HelloWorld() int {
+func (h Database) HelloWorld() int {
 	return 5
 }

everdb_test.go

@@ -5,7 +5,7 @@ import "testing"
 func TestHelloer(t *testing.T) {
 	t.Parallel()
 
-	h := Helloer{}
+	h := Database{}
 	if val := h.HelloWorld(); val != 5 {
 		t.Error("Value was wrong:", val)
 	}

fileblockdevice.go

@@ -0,0 +1,81 @@
+package everdb
+
+import "errors"
+import "os"
+
+const BLOCK_SIZE = 4096
+
+type FileBlockDevice struct {
+	file *os.File
+	len  uint32
+}
+
+func NewFileBlockDevice(fname string, readonly bool, overwrite bool) (*FileBlockDevice, error) {
+	if readonly && overwrite {
+		return nil, errors.New("Both overwrite and readonly specified")
+	}
+
+	f := new(FileBlockDevice)
+	var err error
+
+	if readonly {
+		f.file, err = os.OpenFile(fname, os.O_RDONLY, 0)
+	} else if overwrite {
+		f.file, err = os.OpenFile(fname, os.O_CREATE|os.O_RDWR|os.O_TRUNC, 0666)
+	} else {
+		f.file, err = os.OpenFile(fname, os.O_CREATE|os.O_RDWR, 0666)
+	}
+
+	if nil != err {
+		return nil, err
+	}
+
+	fi, err := f.file.Stat()
+	if nil != err {
+		return nil, errors.New("Failed to stat file")
+	}
+
+	if fi.Size()%BLOCK_SIZE != 0 {
+		return nil, errors.New("File is corrupt (not a multiple of BLOCK_SIZE")
+	}
+
+	f.len = (uint32)(fi.Size() / BLOCK_SIZE)
+
+	return f, nil
+}
+
+func (f *FileBlockDevice) Len() uint32 {
+	return f.len
+}
+
+func (f *FileBlockDevice) Resize(len uint32) error {
+	sz := (int64)(len) * BLOCK_SIZE
+
+	err := f.file.Truncate(sz)
+	if nil != err {
+		return err
+	}
+
+	fi, err := f.file.Stat()
+	if nil != err {
+		return errors.New("Failed to stat file")
+	}
+	if fi.Size() != sz {
+		return errors.New("Failed to reize file")
+	}
+	f.len = len
+
+	return nil
+}
+
+func (f *FileBlockDevice) Get(block int) ([]byte, error) {
+	b := make([]byte, BLOCK_SIZE)
+	n, err := f.file.ReadAt(b, (int64)(block)*BLOCK_SIZE)
+	if nil != err {
+		return nil, err
+	}
+	if n != BLOCK_SIZE {
+		return nil, errors.New("Failed to read BLOCK_SIZE bytes")
+	}
+	return b, nil
+}

fileblockdevice_test.go

@@ -0,0 +1,64 @@
+package everdb
+
+import "testing"
+import "os"
+
+func TestMain(m *testing.M) {
+	code := m.Run()
+
+	os.Remove("test.db")
+	os.Exit(code)
+}
+
+func equals(a, b []byte) bool {
+	l := len(a)
+	if l != len(b) {
+		return false
+	}
+	for i := 0; i < l; i++ {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func TestFileBlockDevice(t *testing.T) {
+	t.Parallel()
+
+	h, err := NewFileBlockDevice("test.db", false, true)
+
+	if nil != err {
+		t.Error(err)
+	}
+
+	if val := h.Len(); val != 0 {
+		t.Error("Initial block device was not empty", val)
+	}
+
+	err = h.Resize(1)
+
+	if nil != err {
+		t.Errorf("Resize failed: %v", err)
+	}
+
+	if h.Len() != 1 {
+		t.Error("Resize failed")
+	}
+
+	zero := make([]byte, BLOCK_SIZE)
+	for i := 0; i < BLOCK_SIZE; i++ {
+		zero[i] = 0
+	}
+
+	b, err := h.Get(0)
+
+	if nil != err {
+		t.Error("Failed to get block")
+	}
+
+	if !equals(b, zero) {
+		t.Error("fresh block is not zeroed")
+	}
+
+}