wip

mmap/file.go

@@ -0,0 +1,100 @@
+package mmap
+
+import "os"
+
+type File struct {
+	f   *os.File
+	Map []byte
+}
+
+func Create(path string, size int64) (*File, error) {
+	f, err := os.Create(path)
+	if err != nil {
+		return nil, err
+	}
+	if err := f.Truncate(size); err != nil {
+		f.Close()
+		return nil, err
+	}
+	m, err := Map(f, PROT_READ|PROT_WRITE)
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+	return &File{f, m}, nil
+}
+
+// Opens a mapped file in read-only mode.
+func Open(path string) (*File, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	m, err := Map(f, PROT_READ)
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+	return &File{f, m}, nil
+}
+
+func OpenFile(
+	path string,
+	fileFlags int,
+	perm os.FileMode,
+	size int64, // -1 for file size.
+) (*File, error) {
+	f, err := os.OpenFile(path, fileFlags, perm)
+	if err != nil {
+		return nil, err
+	}
+
+	writable := fileFlags|os.O_RDWR != 0 || fileFlags|os.O_WRONLY != 0
+
+	fi, err := f.Stat()
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+
+	if writable && size > 0 && size != fi.Size() {
+		if err := f.Truncate(size); err != nil {
+			f.Close()
+			return nil, err
+		}
+	}
+
+	mapFlags := PROT_READ
+	if writable {
+		mapFlags |= PROT_WRITE
+	}
+
+	m, err := Map(f, mapFlags)
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+
+	return &File{f, m}, nil
+}
+
+func (f *File) Sync() error {
+	return Sync(f.Map)
+}
+
+func (f *File) Close() error {
+	if f.Map != nil {
+		if err := Unmap(f.Map); err != nil {
+			return err
+		}
+		f.Map = nil
+	}
+
+	if f.f != nil {
+		if err := f.f.Close(); err != nil {
+			return err
+		}
+		f.f = nil
+	}
+	return nil
+}