Support URL when using ros install -c (#2202)

util/util.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io/ioutil"
+	"net/http"
 	"os"
 	"os/exec"
 	"path"
@@ -45,6 +46,19 @@ func FileCopy(src, dest string) error {
 	return WriteFileAtomic(dest, data, 0666)
 }
 
+func HTTPDownloadToFile(url, dest string) error {
+	res, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer res.Body.Close()
+	body, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		return err
+	}
+	return WriteFileAtomic(dest, body, 0666)
+}
+
 func WriteFileAtomic(filename string, data []byte, perm os.FileMode) error {
 	dir, file := path.Split(filename)
 	tempFile, err := ioutil.TempFile(dir, fmt.Sprintf(".%s", file))