From d9498148b860252c6f80eb6cd5acbd9fe07b2b8b Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Fri, 17 Nov 2017 16:29:37 -0500
Subject: error callbacks

---
 backend.go  | 54 ++++++++++++++++++++++++++++++++++++++----------------
 frontend.go |  5 ++++-
 2 files changed, 42 insertions(+), 17 deletions(-)

diff --git a/backend.go b/backend.go
index 3bf07b5..b91ee88 100644
--- a/backend.go
+++ b/backend.go
@@ -13,58 +13,80 @@ type Backend struct {
 	w   *bufio.Writer
 	fiw *textproto.FIWriter
 	cbr *textproto.CatBlobReader
+
+	onErr func(error) error
 }
 
-func NewBackend(fastImport io.Writer, catBlob io.Reader) *Backend {
-	ret := Backend{}
+func NewBackend(fastImport io.Writer, catBlob io.Reader, onErr func(error) error) *Backend {
+	ret := &Backend{}
 	ret.w = bufio.NewWriter(fastImport)
 	ret.fiw = textproto.NewFIWriter(ret.w)
 	if catBlob != nil {
 		ret.cbr = textproto.NewCatBlobReader(catBlob)
 	}
-	return &ret
+	ret.onErr = onErr
+	return ret
 }
 
 func (b *Backend) Do(cmd Cmd) error {
 	err := cmd.fiWriteCmd(b.fiw)
 	if err != nil {
-		return err
+		return b.onErr(err)
+	}
+	err = b.w.Flush()
+	if err != nil {
+		return b.onErr(err)
 	}
-	return b.w.Flush()
+	return nil
 }
 
-func (b *Backend) GetMark(cmd CmdGetMark) (string, error) {
-	err := b.Do(cmd)
+func (b *Backend) GetMark(cmd CmdGetMark) (sha1 string, err error) {
+	err = b.Do(cmd)
 	if err != nil {
-		return "", err
+		return
 	}
 	line, err := b.cbr.ReadLine()
 	if err != nil {
-		return "", err
+		err = b.onErr(err)
+		return
+	}
+	sha1, err = cbpGetMark(line)
+	if err != nil {
+		err = b.onErr(err)
 	}
-	return cbpGetMark(line)
+	return
 }
 
 func (b *Backend) CatBlob(cmd CmdCatBlob) (sha1 string, data string, err error) {
 	err = b.Do(cmd)
 	if err != nil {
-		return "", "", err
+		return
 	}
 	line, err := b.cbr.ReadLine()
 	if err != nil {
-		return "", "", err
+		err = b.onErr(err)
+		return
+	}
+	sha1, data, err = cbpCatBlob(line)
+	if err != nil {
+		err = b.onErr(err)
 	}
-	return cbpCatBlob(line)
+	return
 }
 
 func (b *Backend) Ls(cmd CmdLs) (mode textproto.Mode, dataref string, path textproto.Path, err error) {
 	err = b.Do(cmd)
 	if err != nil {
-		return 0, "", "", err
+		return
 	}
 	line, err := b.cbr.ReadLine()
 	if err != nil {
-		return 0, "", "", err
+		err = b.onErr(err)
+		return
+	}
+	mode, dataref, path, err = cbpLs(line)
+	if err != nil {
+		err = b.onErr(err)
 	}
-	return cbpLs(line)
+	return
 }
diff --git a/frontend.go b/frontend.go
index 0b10f65..2150a35 100644
--- a/frontend.go
+++ b/frontend.go
@@ -38,7 +38,7 @@ type Frontend struct {
 	err error
 }
 
-func NewFrontend(fastImport io.Reader, catBlob io.Writer) *Frontend {
+func NewFrontend(fastImport io.Reader, catBlob io.Writer, onErr func(error) error) *Frontend {
 	ret := &Frontend{}
 	ret.fir = textproto.NewFIReader(fastImport)
 	if catBlob == nil {
@@ -49,6 +49,9 @@ func NewFrontend(fastImport io.Reader, catBlob io.Writer) *Frontend {
 	ret.cmd = make(chan Cmd)
 	go func() {
 		ret.err = ret.parse()
+		if onErr != nil {
+			ret.err = onErr(ret.err)
+		}
 		close(ret.cmd)
 	}()
 	return ret
-- 
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