fix PR#7 comments

1 files changed, 16 insertions, 0 deletions

diff --git a/commit.go b/commit.go
index afd67ab..99dbf37 100644
--- a/commit.go
+++ b/commit.go
@@ -3,12 +3,16 @@ package git
 import (
 	"bufio"
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 
 	"gopkg.in/src-d/go-git.v2/core"
 )
 
+// New errors defined by this package.
+var ErrFileNotFound = errors.New("file not found")
+
 type Hash core.Hash
 
 // Commit points to a single tree, marking it as what the project looked like
@@ -50,6 +54,18 @@ func (c *Commit) NumParents() int {
 	return len(c.parents)
 }
 
+// File returns the file with the specified "path" in the commit and a
+// nil error if the file exists. If the file does not exists, it returns
+// a nil file and the ErrFileNotFound error.
+func (c *Commit) File(path string) (file *File, err error) {
+	for file := range c.Tree().Files() {
+		if file.Name == path {
+			return file, nil
+		}
+	}
+	return nil, ErrFileNotFound
+}
+
 // Decode transform an core.Object into a Blob struct
 func (c *Commit) Decode(o core.Object) error {
 	c.Hash = o.Hash()