Revert to mustOpen(api()) by retrieving GOROOT value correctly.

Author: dmitshur

playground/imports/mkstdlib.go

@@ -14,30 +14,17 @@ import (
 	"io"
 	"io/ioutil"
 	"log"
-	"net/http"
 	"os"
 	"path"
 	"path/filepath"
 	"regexp"
+	"runtime"
 	"sort"
 	"strings"
 )
 
 var outputFlag = flag.String("output", "", "output file name without extension; if empty, then print to stdout")
 
-func mustOpenAPI(base string) io.Reader {
-	resp, err := http.Get("https://raw.githubusercontent.com/golang/go/master/api/" + base)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer resp.Body.Close()
-	body, err := ioutil.ReadAll(resp.Body)
-	if err != nil {
-		log.Fatal(err)
-	}
-	return bytes.NewReader(body)
-}
-
 func mustOpen(name string) io.Reader {
 	f, err := os.Open(name)
 	if err != nil {
@@ -47,7 +34,7 @@ func mustOpen(name string) io.Reader {
 }
 
 func api(base string) string {
-	return filepath.Join(os.Getenv("GOROOT"), "api", base)
+	return filepath.Join(runtime.GOROOT(), "api", base)
 }
 
 var sym = regexp.MustCompile(`^pkg (\S+).*?, (?:var|func|type|const) ([A-Z]\w*)`)
@@ -69,12 +56,12 @@ func main() {
 	outf("package imports\n")
 	outf("var stdlib = map[string]string{\n")
 	f := io.MultiReader(
-		mustOpenAPI("go1.txt"),
-		mustOpenAPI("go1.1.txt"),
-		mustOpenAPI("go1.2.txt"),
-		mustOpenAPI("go1.3.txt"),
-		mustOpenAPI("go1.4.txt"),
-		mustOpenAPI("go1.5.txt"),
+		mustOpen(api("go1.txt")),
+		mustOpen(api("go1.1.txt")),
+		mustOpen(api("go1.2.txt")),
+		mustOpen(api("go1.3.txt")),
+		mustOpen(api("go1.4.txt")),
+		mustOpen(api("go1.5.txt")),
 	)
 	sc := bufio.NewScanner(f)
 	fullImport := map[string]string{} // "zip.NewReader" => "archive/zip"