Merge pull request #4 from github/check-repo-exists

Check that `git` can be run and that the repository exists

Author: mhagger

README.md

@@ -80,9 +80,9 @@ Is your Git repository bursting at the seams?
 
     *   On other platforms: TBD
 
-3.  Run:
+3.  Change to the directory containing the Git repository, then run
 
-        git sizer [<opt>...] [<path-to-git-repository>]
+        git sizer [<opt>...]
 
     To get a summary of the current repository, all you need is
 

git-sizer.go

@@ -43,7 +43,7 @@ func (v *NegatedBoolValue) IsBoolFlag() bool {
 func main() {
 	err := mainImplementation()
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "%s\n", err)
+		fmt.Fprintf(os.Stderr, "error: %s\n", err)
 		os.Exit(1)
 	}
 }
@@ -107,19 +107,13 @@ func mainImplementation() error {
 
 	args := flag.Args()
 
-	var path string
-	switch len(args) {
-	case 0:
-		path = "."
-	case 1:
-		path = args[0]
-	default:
+	if len(args) != 0 {
 		return errors.New("excess arguments")
 	}
 
-	repo, err := sizes.NewRepository(path)
+	repo, err := sizes.NewRepository(".")
 	if err != nil {
-		return fmt.Errorf("couldn't open %v: %s", path, err)
+		return fmt.Errorf("couldn't open Git repository: %s", err)
 	}
 	defer repo.Close()
 

sizes/git.go

@@ -57,9 +57,35 @@ type Repository struct {
 }
 
 func NewRepository(path string) (*Repository, error) {
-	return &Repository{
-		path: path,
-	}, nil
+	command := exec.Command(
+		"git", "-C", path,
+		"rev-parse", "--git-dir",
+	)
+	out, err := command.Output()
+	if err != nil {
+		switch err := err.(type) {
+		case *exec.Error:
+			return nil, errors.New(
+				fmt.Sprintf(
+					"could not run git (is it in your PATH?): %s",
+					err.Err,
+				),
+			)
+		case *exec.ExitError:
+			return nil, errors.New(
+				fmt.Sprintf(
+					"git rev-parse failed: %s",
+					err.Stderr,
+				),
+			)
+		default:
+			return nil, err
+		}
+	}
+	repo := &Repository{
+		path: string(bytes.TrimSpace(out)),
+	}
+	return repo, nil
 }
 
 func (repo *Repository) Close() error {

sizes/graph.go

@@ -26,13 +26,21 @@ func ScanRepositoryUsingGraph(
 	if err != nil {
 		return HistorySize{}, err
 	}
-	defer refIter.Close()
+	defer func() {
+		if refIter != nil {
+			refIter.Close()
+		}
+	}()
 
 	iter, in, err := repo.NewObjectIter("--stdin", "--date-order")
 	if err != nil {
 		return HistorySize{}, err
 	}
-	defer iter.Close()
+	defer func() {
+		if iter != nil {
+			iter.Close()
+		}
+	}()
 
 	errChan := make(chan error, 1)
 	var refs []Reference
@@ -67,7 +75,9 @@ func ScanRepositoryUsingGraph(
 				return
 			}
 		}
-		errChan <- nil
+		err := refIter.Close()
+		refIter = nil
+		errChan <- err
 	}()
 
 	type ObjectHeader struct {
@@ -154,11 +164,21 @@ func ScanRepositoryUsingGraph(
 		return HistorySize{}, err
 	}
 
+	err = iter.Close()
+	iter = nil
+	if err != nil {
+		return HistorySize{}, err
+	}
+
 	objectIter, objectIn, err := repo.NewBatchObjectIter()
 	if err != nil {
 		return HistorySize{}, err
 	}
-	defer objectIter.Close()
+	defer func() {
+		if objectIter != nil {
+			objectIter.Close()
+		}
+	}()
 
 	go func() {
 		defer objectIn.Close()
@@ -297,6 +317,12 @@ func ScanRepositoryUsingGraph(
 		return HistorySize{}, err
 	}
 
+	err = objectIter.Close()
+	objectIter = nil
+	if err != nil {
+		return HistorySize{}, err
+	}
+
 	progressMeter.Start("Processing references: %d")
 	for _, ref := range refs {
 		progressMeter.Inc()