Fix panic for incomplete demos (fixes #3)

Return io.ErrUnexpectedEOF instead

Author: markus-wa

packet_handlers.go

@@ -17,6 +17,10 @@ import (
 const entitySentinel = 9999
 
 func (p *Parser) handlePacketEntities(pe *msg.CSVCMsg_PacketEntities) {
+	defer func() {
+		p.setError(recoverFromPanic(recover()))
+	}()
+
 	r := bit.NewSmallBitReader(bytes.NewReader(pe.EntityData))
 
 	currentEntity := -1
@@ -80,13 +84,21 @@ func (p *Parser) readEnterPVS(reader *bit.BitReader, entityID int) *st.Entity {
 }
 
 func (p *Parser) handleGameEventList(gel *msg.CSVCMsg_GameEventList) {
+	defer func() {
+		p.setError(recoverFromPanic(recover()))
+	}()
+
 	p.gehDescriptors = make(map[int32]*msg.CSVCMsg_GameEventListDescriptorT)
 	for _, d := range gel.GetDescriptors() {
 		p.gehDescriptors[d.GetEventid()] = d
 	}
 }
 
 func (p *Parser) handleGameEvent(ge *msg.CSVCMsg_GameEvent) {
+	defer func() {
+		p.setError(recoverFromPanic(recover()))
+	}()
+
 	if p.gehDescriptors == nil {
 		p.warn("Received GameEvent but event descriptors are missing")
 		return
@@ -517,6 +529,10 @@ func getCommunityID(guid string) int64 {
 }
 
 func (p *Parser) handleUpdateStringTable(tab *msg.CSVCMsg_UpdateStringTable) {
+	defer func() {
+		p.setError(recoverFromPanic(recover()))
+	}()
+
 	cTab := p.stringTables[tab.TableId]
 	switch cTab.Name {
 	case stNameUserInfo:
@@ -527,10 +543,13 @@ func (p *Parser) handleUpdateStringTable(tab *msg.CSVCMsg_UpdateStringTable) {
 		// Only handle updates for the above types
 		p.handleCreateStringTable(cTab)
 	}
-
 }
 
 func (p *Parser) handleCreateStringTable(tab *msg.CSVCMsg_CreateStringTable) {
+	defer func() {
+		p.setError(recoverFromPanic(recover()))
+	}()
+
 	if tab.Name == stNameModelPreCache {
 		for i := len(p.modelPreCache); i < int(tab.MaxEntries); i++ {
 			p.modelPreCache = append(p.modelPreCache, "")
@@ -617,6 +636,10 @@ func (p *Parser) handleCreateStringTable(tab *msg.CSVCMsg_CreateStringTable) {
 }
 
 func (p *Parser) handleUserMessage(um *msg.CSVCMsg_UserMessage) {
+	defer func() {
+		p.setError(recoverFromPanic(recover()))
+	}()
+
 	switch msg.ECstrike15UserMessages(um.MsgType) {
 	case msg.ECstrike15UserMessages_CS_UM_SayText:
 		st := new(msg.CCSUsrMsg_SayText)
@@ -679,6 +702,10 @@ type frameParsedTokenType struct{}
 var frameParsedToken = new(frameParsedTokenType)
 
 func (p *Parser) handleFrameParsed(*frameParsedTokenType) {
+	defer func() {
+		p.setError(recoverFromPanic(recover()))
+	}()
+
 	for k, rp := range p.rawPlayers {
 		if rp == nil {
 			continue

parser.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sync"
 
 	dp "github.com/markus-wa/godispatch"
 
@@ -48,6 +49,8 @@ type Parser struct {
 	stringTables          []*msg.CSVCMsg_CreateStringTable
 	cancelChan            chan struct{}
 	warn                  WarnHandler
+	err                   error
+	errLock               sync.Mutex
 }
 
 // Map returns the map name. E.g. de_dust2 or de_inferno.
@@ -133,6 +136,21 @@ func (p *Parser) TState() *TeamState {
 	return &p.tState
 }
 
+func (p *Parser) error() (err error) {
+	p.errLock.Lock()
+	err = p.err
+	p.errLock.Unlock()
+	return
+}
+
+func (p *Parser) setError(err error) {
+	if err != nil {
+		p.errLock.Lock()
+		p.err = err
+		p.errLock.Unlock()
+	}
+}
+
 // TeamState contains a team's ID, score, clan name & country flag.
 type TeamState struct {
 	id       int

parsing.go

@@ -3,6 +3,7 @@ package demoinfocs
 import (
 	"errors"
 	"fmt"
+	"io"
 
 	common "github.com/markus-wa/demoinfocs-golang/common"
 	events "github.com/markus-wa/demoinfocs-golang/events"
@@ -53,7 +54,13 @@ func (p *Parser) ParseHeader() error {
 // ParseToEnd attempts to parse the demo until the end.
 // Aborts and returns an error if Cancel() is called before the end.
 // May panic if the demo is corrupt in some way.
-func (p *Parser) ParseToEnd() error {
+func (p *Parser) ParseToEnd() (err error) {
+	defer func() {
+		if err == nil {
+			err = recoverFromPanic(recover())
+		}
+	}()
+
 	if p.header == nil {
 		panic(msgHeaderNotParsed)
 	}
@@ -70,12 +77,28 @@ func (p *Parser) ParseToEnd() error {
 
 				// Close msgQueue
 				close(p.msgQueue)
-				return nil
+
+				return p.error()
 			}
 		}
+
+		if pErr := p.error(); pErr != nil {
+			return pErr
+		}
 	}
 }
 
+func recoverFromPanic(r interface{}) error {
+	if r != nil {
+		if r == io.ErrUnexpectedEOF {
+			return io.ErrUnexpectedEOF
+		} else {
+			panic(r)
+		}
+	}
+	return nil
+}
+
 // Cancel aborts ParseToEnd(). All information that was already read
 // up to this point will still be used (and new events may still be sent).
 func (p *Parser) Cancel() {
@@ -85,12 +108,18 @@ func (p *Parser) Cancel() {
 // ParseNextFrame attempts to parse the next frame / demo-tick (not ingame tick).
 // Returns true unless the demo command 'stop' was encountered.
 // Panics if header hasn't been parsed yet - see Parser.ParseHeader().
-func (p *Parser) ParseNextFrame() bool {
+func (p *Parser) ParseNextFrame() (b bool, err error) {
+	defer func() {
+		if err == nil {
+			err = recoverFromPanic(recover())
+		}
+	}()
+
 	if p.header == nil {
 		panic(msgHeaderNotParsed)
 	}
 
-	b := p.parseFrame()
+	b = p.parseFrame()
 
 	// Make sure all the messages of the frame are handled
 	p.msgDispatcher.SyncQueues(p.msgQueue)
@@ -99,7 +128,9 @@ func (p *Parser) ParseNextFrame() bool {
 	if !b {
 		close(p.msgQueue)
 	}
-	return b
+
+	err = p.error()
+	return
 }
 
 func (p *Parser) parseFrame() bool {