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authorMáximo Cuadros <mcuadros@gmail.com>2016-11-08 23:46:38 +0100
committerGitHub <noreply@github.com>2016-11-08 23:46:38 +0100
commitac095bb12c4d29722b60ba9f20590fa7cfa6bc7d (patch)
tree223f36f336ba3414b1e45cac8af6c4744a5d7ef6 /plumbing/format/objfile/writer.go
parente523701393598f4fa241dd407af9ff8925507a1a (diff)
downloadgo-git-ac095bb12c4d29722b60ba9f20590fa7cfa6bc7d.tar.gz
new plumbing package (#118)
* plumbing: now core was renamed to core, and formats and clients moved inside
Diffstat (limited to 'plumbing/format/objfile/writer.go')
-rw-r--r--plumbing/format/objfile/writer.go109
1 files changed, 109 insertions, 0 deletions
diff --git a/plumbing/format/objfile/writer.go b/plumbing/format/objfile/writer.go
new file mode 100644
index 0000000..44563d2
--- /dev/null
+++ b/plumbing/format/objfile/writer.go
@@ -0,0 +1,109 @@
+package objfile
+
+import (
+ "compress/zlib"
+ "errors"
+ "io"
+ "strconv"
+
+ "gopkg.in/src-d/go-git.v4/plumbing"
+)
+
+var (
+ ErrOverflow = errors.New("objfile: declared data length exceeded (overflow)")
+)
+
+// Writer writes and encodes data in compressed objfile format to a provided
+// io.Writerº. Close should be called when finished with the Writer. Close will
+// not close the underlying io.Writer.
+type Writer struct {
+ raw io.Writer
+ zlib io.WriteCloser
+ hasher plumbing.Hasher
+ multi io.Writer
+
+ closed bool
+ pending int64 // number of unwritten bytes
+}
+
+// NewWriter returns a new Writer writing to w.
+//
+// The returned Writer implements io.WriteCloser. Close should be called when
+// finished with the Writer. Close will not close the underlying io.Writer.
+func NewWriter(w io.Writer) *Writer {
+ return &Writer{
+ raw: w,
+ zlib: zlib.NewWriter(w),
+ }
+}
+
+// WriteHeader writes the type and the size and prepares to accept the object's
+// contents. If an invalid t is provided, plumbing.ErrInvalidType is returned. If a
+// negative size is provided, ErrNegativeSize is returned.
+func (w *Writer) WriteHeader(t plumbing.ObjectType, size int64) error {
+ if !t.Valid() {
+ return plumbing.ErrInvalidType
+ }
+ if size < 0 {
+ return ErrNegativeSize
+ }
+
+ b := t.Bytes()
+ b = append(b, ' ')
+ b = append(b, []byte(strconv.FormatInt(size, 10))...)
+ b = append(b, 0)
+
+ defer w.prepareForWrite(t, size)
+ _, err := w.zlib.Write(b)
+
+ return err
+}
+
+func (w *Writer) prepareForWrite(t plumbing.ObjectType, size int64) {
+ w.pending = size
+
+ w.hasher = plumbing.NewHasher(t, size)
+ w.multi = io.MultiWriter(w.zlib, w.hasher)
+}
+
+// Write writes the object's contents. Write returns the error ErrOverflow if
+// more than size bytes are written after WriteHeader.
+func (w *Writer) Write(p []byte) (n int, err error) {
+ if w.closed {
+ return 0, ErrClosed
+ }
+
+ overwrite := false
+ if int64(len(p)) > w.pending {
+ p = p[0:w.pending]
+ overwrite = true
+ }
+
+ n, err = w.multi.Write(p)
+ w.pending -= int64(n)
+ if err == nil && overwrite {
+ err = ErrOverflow
+ return
+ }
+
+ return
+}
+
+// Hash returns the hash of the object data stream that has been written so far.
+// It can be called before or after Close.
+func (w *Writer) Hash() plumbing.Hash {
+ return w.hasher.Sum() // Not yet closed, return hash of data written so far
+}
+
+// Close releases any resources consumed by the Writer.
+//
+// Calling Close does not close the wrapped io.Writer originally passed to
+// NewWriter.
+func (w *Writer) Close() error {
+ if err := w.zlib.Close(); err != nil {
+ return err
+ }
+
+ w.closed = true
+ return nil
+}