messageWriter: don't ignore error in writeString

cryptix · ivy · commit a0242b2233b4 · 2018-07-31T14:36:49.000-07:00
fixes #30 [Ivy: add changelog entry]
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -13,6 +13,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 - #26: Fixes RFC 1341 compliance by properly capitalizing the
   `MIME-Version` header.
+- #30: Fixes IO errors being silently dropped in `Message.WriteTo`.
 
 ## [2.2.0] - 2018-03-01
 
diff --git a/writeto.go b/writeto.go
@@ -161,7 +161,11 @@ func (w *messageWriter) Write(p []byte) (int, error) {
 }
 
 func (w *messageWriter) writeString(s string) {
-	n, _ := io.WriteString(w.w, s)
+	if w.err != nil { // do nothing when in error
+		return
+	}
+	var n int
+	n, w.err = io.WriteString(w.w, s)
 	w.n += int64(n)
 }
 

Original file line number	Diff line number	Diff line change
`@@ -161,7 +161,11 @@ func (w *messageWriter) Write(p []byte) (int, error) {`
`161`	`161`	`}`
`162`	`162`
`163`	`163`	`func (w *messageWriter) writeString(s string) {`
`164`		`- n, _ := io.WriteString(w.w, s)`
	`164`	`+ if w.err != nil { // do nothing when in error`
	`165`	`+ return`
	`166`	`+ }`
	`167`	`+ var n int`
	`168`	`+ n, w.err = io.WriteString(w.w, s)`
`165`	`169`	`w.n += int64(n)`
`166`	`170`	`}`
`167`	`171`