fix: don't assume the header count will be positive (#882)

Achille · web-flow · commit 94daae277a52 · 2022-04-11T10:15:45.000-07:00
diff --git a/message_reader.go b/message_reader.go
@@ -318,10 +318,12 @@ func (r *messageSetReader) readMessageV2(_ int64, key readBytesFunc, val readByt
 	if err = r.readVarInt(&headerCount); err != nil {
 		return
 	}
-	headers = make([]Header, headerCount)
-	for i := 0; i < int(headerCount); i++ {
-		if err = r.readMessageHeader(&headers[i]); err != nil {
-			return
+	if headerCount > 0 {
+		headers = make([]Header, headerCount)
+		for i := range headers {
+			if err = r.readMessageHeader(&headers[i]); err != nil {
+				return
+			}
 		}
 	}
 	lastOffset = r.header.firstOffset + int64(r.header.v2.lastOffsetDelta)

Original file line number	Diff line number	Diff line change
`@@ -318,10 +318,12 @@ func (r *messageSetReader) readMessageV2(_ int64, key readBytesFunc, val readByt`
`318`	`318`	`if err = r.readVarInt(&headerCount); err != nil {`
`319`	`319`	`return`
`320`	`320`	`}`
`321`		`- headers = make([]Header, headerCount)`
`322`		`- for i := 0; i < int(headerCount); i++ {`
`323`		`- if err = r.readMessageHeader(&headers[i]); err != nil {`
`324`		`- return`
	`321`	`+ if headerCount > 0 {`
	`322`	`+ headers = make([]Header, headerCount)`
	`323`	`+ for i := range headers {`
	`324`	`+ if err = r.readMessageHeader(&headers[i]); err != nil {`
	`325`	`+ return`
	`326`	`+ }`
`325`	`327`	`}`
`326`	`328`	`}`
`327`	`329`	`lastOffset = r.header.firstOffset + int64(r.header.v2.lastOffsetDelta)`