Fix race condition on httpSmartSubTransport

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

Author: Paulo Gomes

pkg/git/libgit2/managed/http.go

@@ -217,6 +217,7 @@ type httpSmartSubtransportStream struct {
 	sentRequest bool
 	recvReply   sync.WaitGroup
 	httpError   error
+	m           sync.RWMutex
 }
 
 func newManagedHttpStream(owner *httpSmartSubtransport, req *http.Request, client *http.Client) *httpSmartSubtransportStream {
@@ -244,6 +245,8 @@ func (self *httpSmartSubtransportStream) Read(buf []byte) (int, error) {
 
 	self.recvReply.Wait()
 
+	self.m.RLock()
+	defer self.m.RUnlock()
 	if self.httpError != nil {
 		return 0, self.httpError
 	}
@@ -252,6 +255,8 @@ func (self *httpSmartSubtransportStream) Read(buf []byte) (int, error) {
 }
 
 func (self *httpSmartSubtransportStream) Write(buf []byte) (int, error) {
+	self.m.RLock()
+	defer self.m.RUnlock()
 	if self.httpError != nil {
 		return 0, self.httpError
 	}
@@ -266,7 +271,11 @@ func (self *httpSmartSubtransportStream) Free() {
 
 func (self *httpSmartSubtransportStream) sendRequestBackground() {
 	go func() {
-		self.httpError = self.sendRequest()
+		err := self.sendRequest()
+
+		self.m.Lock()
+		self.httpError = err
+		self.m.Unlock()
 	}()
 	self.sentRequest = true
 }
@@ -299,33 +308,29 @@ func (self *httpSmartSubtransportStream) sendRequest() error {
 		}
 	}
 
-	for {
-		req := &http.Request{
-			Method: self.req.Method,
-			URL:    self.req.URL,
-			Header: self.req.Header,
-		}
-		if req.Method == "POST" {
-			req.Body = self.reader
-			req.ContentLength = -1
-		}
-
-		req.SetBasicAuth(userName, password)
-		resp, err = self.client.Do(req)
-		if err != nil {
-			return err
-		}
+	req := &http.Request{
+		Method: self.req.Method,
+		URL:    self.req.URL,
+		Header: self.req.Header,
+	}
+	if req.Method == "POST" {
+		req.Body = self.reader
+		req.ContentLength = -1
+	}
 
-		if resp.StatusCode == http.StatusOK {
-			break
-		}
+	req.SetBasicAuth(userName, password)
+	resp, err = self.client.Do(req)
+	if err != nil {
+		return err
+	}
 
-		io.Copy(ioutil.Discard, resp.Body)
-		resp.Body.Close()
-		return fmt.Errorf("Unhandled HTTP error %s", resp.Status)
+	if resp.StatusCode == http.StatusOK {
+		self.resp = resp
+		self.sentRequest = true
+		return nil
 	}
 
-	self.sentRequest = true
-	self.resp = resp
-	return nil
+	io.Copy(ioutil.Discard, resp.Body)
+	defer resp.Body.Close()
+	return fmt.Errorf("Unhandled HTTP error %s", resp.Status)
 }