Fix GetFile support for GitHub getter

This change fixes support for getting single files from GitHub.

While this worked fine for other Git repositories, it did not work for GitHub, because the getter tried to clone a wrong URL. For example, if a GitHub URL of "https://github.com/owner/repo/subdir/file.txt" would be given to "GetFile", it would clone "https://github.com/owner/repo/subdir" instead of cloning "https://github.com/owner/repo" and extracting "subdir/file.txt".

get_git.go

@@ -141,8 +141,15 @@ func (g *GitGetter) GetFile(ctx context.Context, req *Request) error {
 
 	// Get the filename, and strip the filename from the URL so we can
 	// just get the repository directly.
-	filename := filepath.Base(req.u.Path)
-	req.u.Path = filepath.Dir(req.u.Path)
+	var filename string
+	if req.u.Host == "github.com" {
+		tokens := strings.SplitN(req.u.Path[1:], "/", 3)
+		req.u.Path = "/" + tokens[0] + "/" + tokens[1]
+		filename = tokens[2]
+	} else {
+		filename = filepath.Base(req.u.Path)
+		req.u.Path = filepath.Dir(req.u.Path)
+	}
 	dst := req.Dst
 	req.Dst = td
 

get_git_test.go

@@ -313,6 +313,61 @@ func TestGitGetter_GetFile(t *testing.T) {
 	testing_helper.AssertContents(t, dst, "hello")
 }
 
+func TestGitGetter_githubGetWithFileMode(t *testing.T) {
+	if !testHasGit {
+		t.Skip("git not found, skipping")
+	}
+
+	ctx := context.Background()
+	dst := testing_helper.TempTestFile(t)
+	defer os.RemoveAll(filepath.Dir(dst))
+
+	req := Request{
+		Src:     "git::https://github.com/arikkfir/go-getter/testdata/basic/foo/main.tf?ref=master",
+		Dst:     dst,
+		GetMode: ModeFile,
+	}
+
+	var result *GetResult
+	var err error
+	var c Client
+	if result, err = c.Get(ctx, &req); err != nil {
+		t.Fatalf("err: %s", err)
+	} else if result.Dst != dst {
+		t.Errorf("result.Dst != dst (%s != %s)", result.Dst, dst)
+	}
+
+	// Verify the main file exists
+	if _, err := os.Stat(dst); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	testing_helper.AssertContents(t, dst, "# Hello\n")
+}
+
+func TestGitGetter_githubGetFile(t *testing.T) {
+	if !testHasGit {
+		t.Skip("git not found, skipping")
+	}
+
+	ctx := context.Background()
+	dst := testing_helper.TempTestFile(t)
+	defer os.RemoveAll(filepath.Dir(dst))
+
+	var result *GetResult
+	var err error
+	if result, err = GetFile(ctx, dst, "git::https://github.com/arikkfir/go-getter/testdata/basic/foo/main.tf?ref=master"); err != nil {
+		t.Fatalf("err: %s", err)
+	} else if result.Dst != dst {
+		t.Errorf("result.Dst != dst (%s != %s)", result.Dst, dst)
+	}
+
+	// Verify the main file exists
+	if _, err := os.Stat(dst); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	testing_helper.AssertContents(t, dst, "# Hello\n")
+}
+
 func TestGitGetter_gitVersion(t *testing.T) {
 	if !testHasGit {
 		t.Skip("git not found, skipping")