Address non-Close errors identified by errcheck

app/api_topology.go

@@ -59,7 +59,10 @@ func makeTopologyHandlers(
 
 	// Websocket for the full topology. This route overlaps with the next.
 	get.HandleFunc(base+"/ws", func(w http.ResponseWriter, r *http.Request) {
-		r.ParseForm()
+		if err := r.ParseForm(); err != nil {
+			respondWith(w, http.StatusInternalServerError, err.Error())
+			return
+		}
 		loop := websocketLoop
 		if t := r.Form.Get("t"); t != "" {
 			var err error
@@ -140,7 +143,9 @@ func handleWebsocket(
 		diff := report.TopoDiff(previousTopo, newTopo)
 		previousTopo = newTopo
 
-		conn.SetWriteDeadline(time.Now().Add(websocketTimeout))
+		if err := conn.SetWriteDeadline(time.Now().Add(websocketTimeout)); err != nil {
+			return
+		}
 		if err := conn.WriteJSON(diff); err != nil {
 			return
 		}

app/main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"log/syslog"
 	"net/http"
@@ -28,7 +27,6 @@ func main() {
 		probes        = flag.String("probes", strings.Join(defaultProbes, ","), "list of probe endpoints, comma separated")
 		batch         = flag.Duration("batch", 1*time.Second, "batch interval")
 		window        = flag.Duration("window", 15*time.Second, "window")
-		pidfile       = flag.String("pidfile", "", "write PID file")
 		listen        = flag.String("http.address", ":"+strconv.Itoa(xfer.AppPort), "webserver listen address")
 	)
 	flag.Parse()
@@ -57,15 +55,6 @@ func main() {
 		log.SetOutput(f)
 	}
 
-	if *pidfile != "" {
-		err := ioutil.WriteFile(*pidfile, []byte(fmt.Sprint(os.Getpid())), 0644)
-		if err != nil {
-			log.Print(err)
-			return
-		}
-		defer os.Remove(*pidfile)
-	}
-
 	log.Printf("app starting, version %s", version)
 
 	// Collector deals with the probes, and generates merged reports.

app/server_helpers.go

@@ -2,12 +2,15 @@ package main
 
 import (
 	"encoding/json"
+	"log"
 	"net/http"
 )
 
 func respondWith(w http.ResponseWriter, code int, response interface{}) {
 	w.Header().Set("Content-Type", "application/json")
 	w.Header().Add("Cache-Control", "no-cache")
 	w.WriteHeader(code)
-	json.NewEncoder(w).Encode(response)
+	if err := json.NewEncoder(w).Encode(response); err != nil {
+		log.Print(err)
+	}
 }

experimental/example/goapp/app.go

@@ -82,9 +82,12 @@ func get(target string) {
 		log.Printf("%s: %v", target, err)
 		return
 	}
+	defer resp.Body.Close()
 	log.Printf("%s: %s", target, resp.Status)
-	io.Copy(ioutil.Discard, resp.Body)
-	resp.Body.Close()
+	if _, err := io.Copy(ioutil.Discard, resp.Body); err != nil {
+		log.Printf("%s: %v", target, err)
+		return
+	}
 }
 
 func interrupt() error {

experimental/genreport/main.go

@@ -3,11 +3,14 @@ package main
 import (
 	"encoding/json"
 	"flag"
+	"log"
 	"os"
 )
 
 func main() {
 	nodes := flag.Int("nodes", 10, "node count")
 	flag.Parse()
-	json.NewEncoder(os.Stdout).Encode(DemoReport(*nodes))
+	if err := json.NewEncoder(os.Stdout).Encode(DemoReport(*nodes)); err != nil {
+		log.Print(err)
+	}
 }

probe/main.go

@@ -53,7 +53,7 @@ func main() {
 			log.Printf("exposing Prometheus endpoint at %s%s", *httpListen, *prometheusEndpoint)
 			http.Handle(*prometheusEndpoint, makePrometheusHandler())
 		}
-		go http.ListenAndServe(*httpListen, nil)
+		go func(err error) { log.Print(err) }(http.ListenAndServe(*httpListen, nil))
 	}
 
 	if *spyProcs && os.Getegid() != 0 {

probe/process_mapper_test.go

@@ -17,7 +17,7 @@ func TestCgroupMapper(t *testing.T) {
 		"/netscape/notify_on_release": "0\n",
 		"/weirdfile":                  "",
 	})
-	defer os.RemoveAll(tmp)
+	defer removeAll(t, tmp)
 
 	m := newCgroupMapper(tmp, 1*time.Second)
 	for pid, want := range map[uint]string{
@@ -44,14 +44,20 @@ func setupTmpFS(t *testing.T, fs map[string]string) string {
 	for file, content := range fs {
 		dir := path.Dir(file)
 		if err := os.MkdirAll(filepath.Join(tmp, dir), 0777); err != nil {
-			os.RemoveAll(tmp)
+			removeAll(t, tmp)
 			t.Fatalf("MkdirAll: %v", err)
 		}
 
 		if err := ioutil.WriteFile(filepath.Join(tmp, file), []byte(content), 0655); err != nil {
-			os.RemoveAll(tmp)
+			removeAll(t, tmp)
 			t.Fatalf("WriteFile: %v", err)
 		}
 	}
 	return tmp
 }
+
+func removeAll(t *testing.T, path string) {
+	if err := os.RemoveAll(path); err != nil {
+		t.Error(err)
+	}
+}