1 files changed, 106 insertions, 0 deletions
diff --git a/textproto/catblob.go b/textproto/catblob.go
new file mode 100644
index 0000000..6836689
--- /dev/null
+++ b/textproto/catblob.go
@@ -0,0 +1,106 @@
+// Copyright (C) 2017-2018  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package textproto
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strconv"
+)
+
+// CatBlobReader is a low-level parser of an fast-import auxiliary
+// "cat-blob" stream.
+type CatBlobReader struct {
+	r *bufio.Reader
+}
+
+// NewCatBlobReader creates a new CatBlobReader parser.
+func NewCatBlobReader(r io.Reader) *CatBlobReader {
+	return &CatBlobReader{
+		r: bufio.NewReader(r),
+	}
+}
+
+// ReadLine reads a response from the stream; with special handling
+// for responses to "cat-blob" commands, which contain multiple
+// newline characters.
+func (cbr *CatBlobReader) ReadLine() (line string, err error) {
+	for len(line) <= 1 {
+		line, err = cbr.r.ReadString('\n')
+		if err != nil {
+			return
+		}
+	}
+
+	// get-mark : <sha1> LF
+	// cat-blob : <sha1> SP 'blob' SP <size> LF
+	//            <data> LF
+	// ls       : <mode> SP ('blob' | 'tree' | 'commit') SP <dataref> HT <path> LF
+	// ls       : 'missing' SP <path> LF
+
+	// decide if we have a cat-blob result (return early if we don't)
+	if len(line) <= 46 || line[40:46] != " blob " {
+		return
+	}
+	for _, b := range line[:40] {
+		if !(('0' <= b && b <= '9') || ('a' <= b && b <= 'f')) {
+			return
+		}
+	}
+	// we have a cat-blob result
+	var size int
+	size, err = strconv.Atoi(line[46 : len(line)-1])
+	if err != nil {
+		return
+	}
+	data := make([]byte, size+1)
+	_, err = io.ReadFull(cbr.r, data)
+	line += string(data)
+	return
+}
+
+// CatBlobWriter is a low-level marshaller for an auxiliary cat-blob
+// stream.
+type CatBlobWriter struct {
+	w io.Writer
+}
+
+// NewCatBlobWriter creates a new CatBlobWriter marshaller.
+func NewCatBlobWriter(w io.Writer) *CatBlobWriter {
+	return &CatBlobWriter{
+		w: w,
+	}
+}
+
+// WriteLine writes a response (to a command OTHER THAN "cat-blob") to
+// the stream; arguments are handled similarly to fmt.Println.
+//
+// Use WriteBlob instead to write responses to "cat-blob" commands.
+func (cbw *CatBlobWriter) WriteLine(a ...interface{}) error {
+	_, err := fmt.Fprintln(cbw.w, a...)
+	return err
+}
+
+// WriteBlob writes a response to a "cat-blob" command to the stream.
+func (cbw *CatBlobWriter) WriteBlob(sha1 string, data string) error {
+	err := cbw.WriteLine(sha1, "blob", len(data))
+	if err != nil {
+		return err
+	}
+	_, err = io.WriteString(cbw.w, data)
+	return err
+}