Merge pull request 'Add error handling and improve comments' (#7) from fix-1.9.x into master

Reviewed-on: #7

versionedTerraform.go

@@ -5,6 +5,7 @@ import (
 	"bufio"
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -90,51 +91,54 @@ func (v *Version) InstallTerraformVersion() error {
 	if v.Version.IsLessThan(*minV) {
 		suffix = alternateSuffix
 	}
-	resp, err := http.Get(hashicorpUrl +
+	url := hashicorpUrl +
 		v.Version.ToString() +
 		"/" + terraformPrefix +
 		v.Version.ToString() +
-		suffix)
+		suffix
+
+	resp, err := http.Get(url)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to download Terraform: %v", err)
 	}
 	defer resp.Body.Close()
 
 	body, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to read response body: %v", err)
 	}
 
 	zipReader, err := zip.NewReader(bytes.NewReader(body), int64(len(body)))
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to create zip reader: %v", err)
 	}
+
 	versionedFileName := homeDir + versionedTerraformFolder + "/" + terraformPrefix + v.Version.ToString()
-	versionedFile, err := os.OpenFile(versionedFileName, os.O_WRONLY, 0755)
-	if os.IsNotExist(err) {
-		versionedFile, err = os.OpenFile(versionedFileName, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0755)
+	versionedFile, err := os.OpenFile(versionedFileName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
 	if err != nil {
-			return err
-		}
-	}
-	if err != nil {
-		return err
+		return fmt.Errorf("failed to create output file: %v", err)
 	}
 	defer versionedFile.Close()
 
 	for _, zipFile := range zipReader.File {
+		if zipFile.Name != "terraform" {
+			continue
+		}
+
 		zr, err := zipFile.Open()
 		if err != nil {
-			return err
+			return fmt.Errorf("failed to open zip file: %v", err)
 		}
-		unzippedFileBytes, _ := ioutil.ReadAll(zr)
+		defer zr.Close()
 
-		_, err = versionedFile.Write(unzippedFileBytes)
+		_, err = io.Copy(versionedFile, zr)
 		if err != nil {
-			return err
+			return fmt.Errorf("failed to write terraform binary: %v", err)
 		}
-		zr.Close()
+
+		break
 	}
+
 	return nil
 }