Add functionality for converting Diff objects to a buffer and back

diff.go

@@ -3,6 +3,7 @@ package git
 /*
 #include <git2.h>
 
+extern void _go_git_apply_init_options(git_apply_options *options);
 extern int _go_git_diff_foreach(git_diff *diff, int eachFile, int eachHunk, int eachLine, void *payload);
 extern void _go_git_setup_diff_notify_callbacks(git_diff_options* opts);
 extern int _go_git_diff_blobs(git_blob *old, const char *old_path, git_blob *new, const char *new_path, git_diff_options *opts, int eachFile, int eachHunk, int eachLine, void *payload);
@@ -847,3 +848,76 @@ func DiffBlobs(oldBlob *Blob, oldAsPath string, newBlob *Blob, newAsPath string,
 
 	return nil
 }
+
+type ApplyOptions struct {
+	Version uint
+	Flags   uint
+	// TODO: there are some more flags, not currently used
+}
+
+func DefaultApplyOptions() (*ApplyOptions, error) {
+	opts := C.git_apply_options{}
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	C._go_git_apply_init_options(&opts)
+
+	return applyOptionsFromC(&opts), nil
+}
+
+func (a *ApplyOptions) toC() *C.git_apply_options {
+	if a == nil {
+		return nil
+	}
+
+	opts := &C.git_apply_options{
+		version: C.uint(a.Version),
+		flags:   C.uint(a.Flags),
+	}
+
+	return opts
+}
+
+func applyOptionsFromC(opts *C.git_apply_options) *ApplyOptions {
+	return &ApplyOptions{
+		Version: uint(opts.version),
+		Flags:   uint(opts.flags),
+	}
+}
+
+type GitApplyLocation int
+
+const (
+	GitApplyLocationWorkdir GitApplyLocation = C.GIT_APPLY_LOCATION_WORKDIR
+	GitApplyLocationIndex   GitApplyLocation = C.GIT_APPLY_LOCATION_INDEX
+	GitApplyLocationBoth    GitApplyLocation = C.GIT_APPLY_LOCATION_BOTH
+)
+
+func (v *Repository) ApplyDiff(diff *Diff, location GitApplyLocation, opts *ApplyOptions) error {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ecode := C.git_apply(v.ptr, diff.ptr, C.git_apply_location_t(location), opts.toC())
+	runtime.KeepAlive(v)
+	if ecode < 0 {
+		return MakeGitError(ecode)
+	}
+
+	return nil
+}
+
+func DiffFromBuffer(buffer []byte, repo *Repository) (*Diff, error) {
+	var diff *C.git_diff
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ecode := C.git_diff_from_buffer(&diff, C.CString(string(buffer)), C.size_t(len(buffer)))
+	if ecode < 0 {
+		return nil, MakeGitError(ecode)
+	}
+	runtime.KeepAlive(diff)
+
+	return newDiffFromC(diff, repo), nil
+}

diff_test.go

@@ -236,3 +236,65 @@ func TestDiffBlobs(t *testing.T) {
 		t.Fatalf("Bad number of lines iterated")
 	}
 }
+
+func Test_ApplyDiff_Addfile(t *testing.T) {
+	repo := createTestRepo(t)
+	defer cleanupTestRepo(t, repo)
+
+	seedTestRepo(t, repo)
+
+	addFirstFileCommit, addFileTree := addAndGetTree(t, repo, "file1", `hello`)
+	addSecondFileCommit, addSecondFileTree := addAndGetTree(t, repo, "file2", `hello2`)
+
+	diff, err := repo.DiffTreeToTree(addFileTree, addSecondFileTree, nil)
+	checkFatal(t, err)
+
+	t.Run("check does not apply to current tree because file exists", func(t *testing.T) {
+		err = repo.ResetToCommit(addSecondFileCommit, ResetHard, &CheckoutOpts{})
+		checkFatal(t, err)
+
+		err = repo.ApplyDiff(diff, GitApplyLocationBoth, nil)
+		if err == nil {
+			t.Error("expecting applying patch to current repo to fail")
+		}
+	})
+
+	t.Run("check apply to correct commit", func(t *testing.T) {
+		err = repo.ResetToCommit(addFirstFileCommit, ResetHard, &CheckoutOpts{})
+		checkFatal(t, err)
+
+		err = repo.ApplyDiff(diff, GitApplyLocationBoth, nil)
+		checkFatal(t, err)
+	})
+
+	t.Run("check convert to raw buffer and apply", func(t *testing.T) {
+		err = repo.ResetToCommit(addFirstFileCommit, ResetHard, &CheckoutOpts{})
+		checkFatal(t, err)
+
+		raw, err := diff.ToBuf(DiffFormatPatch)
+		checkFatal(t, err)
+
+		if len(raw) == 0 {
+			t.Error("empty diff created")
+		}
+
+		diff2, err := DiffFromBuffer(raw, repo)
+		checkFatal(t, err)
+
+		err = repo.ApplyDiff(diff2, GitApplyLocationBoth, nil)
+		checkFatal(t, err)
+	})
+}
+
+func addAndGetTree(t *testing.T, repo *Repository, filename string, content string) (*Commit, *Tree) {
+	commitId, err := commitSomething(repo, filename, content)
+	checkFatal(t, err)
+
+	commit, err := repo.LookupCommit(commitId)
+	checkFatal(t, err)
+
+	tree, err := commit.Tree()
+	checkFatal(t, err)
+
+	return commit, tree
+}