1 files changed, 327 insertions, 0 deletions
diff --git a/src/libgit2/merge_file.c b/src/libgit2/merge_file.c
new file mode 100644
index 000000000..732a047b1
--- /dev/null
+++ b/src/libgit2/merge_file.c
@@ -0,0 +1,327 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "common.h"
+
+#include "repository.h"
+#include "posix.h"
+#include "futils.h"
+#include "index.h"
+#include "diff_xdiff.h"
+#include "merge.h"
+
+#include "git2/repository.h"
+#include "git2/object.h"
+#include "git2/index.h"
+#include "git2/merge.h"
+
+#include "xdiff/xdiff.h"
+
+/* only examine the first 8000 bytes for binaryness.
+ * https://github.com/git/git/blob/77bd3ea9f54f1584147b594abc04c26ca516d987/xdiff-interface.c#L197
+ */
+#define GIT_MERGE_FILE_BINARY_SIZE 8000
+
+#define GIT_MERGE_FILE_SIDE_EXISTS(X)	((X)->mode != 0)
+
+static int merge_file_input_from_index(
+	git_merge_file_input *input_out,
+	git_odb_object **odb_object_out,
+	git_odb *odb,
+	const git_index_entry *entry)
+{
+	int error = 0;
+
+	GIT_ASSERT_ARG(input_out);
+	GIT_ASSERT_ARG(odb_object_out);
+	GIT_ASSERT_ARG(odb);
+	GIT_ASSERT_ARG(entry);
+
+	if ((error = git_odb_read(odb_object_out, odb, &entry->id)) < 0)
+		goto done;
+
+	input_out->path = entry->path;
+	input_out->mode = entry->mode;
+	input_out->ptr = (char *)git_odb_object_data(*odb_object_out);
+	input_out->size = git_odb_object_size(*odb_object_out);
+
+done:
+	return error;
+}
+
+static void merge_file_normalize_opts(
+	git_merge_file_options *out,
+	const git_merge_file_options *given_opts)
+{
+	if (given_opts)
+		memcpy(out, given_opts, sizeof(git_merge_file_options));
+	else {
+		git_merge_file_options default_opts = GIT_MERGE_FILE_OPTIONS_INIT;
+		memcpy(out, &default_opts, sizeof(git_merge_file_options));
+	}
+}
+
+static int merge_file__xdiff(
+	git_merge_file_result *out,
+	const git_merge_file_input *ancestor,
+	const git_merge_file_input *ours,
+	const git_merge_file_input *theirs,
+	const git_merge_file_options *given_opts)
+{
+	xmparam_t xmparam;
+	mmfile_t ancestor_mmfile = {0}, our_mmfile = {0}, their_mmfile = {0};
+	mmbuffer_t mmbuffer;
+	git_merge_file_options options = GIT_MERGE_FILE_OPTIONS_INIT;
+	const char *path;
+	int xdl_result;
+	int error = 0;
+
+	memset(out, 0x0, sizeof(git_merge_file_result));
+
+	merge_file_normalize_opts(&options, given_opts);
+
+	memset(&xmparam, 0x0, sizeof(xmparam_t));
+
+	if (ours->size > LONG_MAX ||
+	    theirs->size > LONG_MAX ||
+	    (ancestor && ancestor->size > LONG_MAX)) {
+		git_error_set(GIT_ERROR_MERGE, "failed to merge files");
+		error = -1;
+		goto done;
+	}
+
+	if (ancestor) {
+		xmparam.ancestor = (options.ancestor_label) ?
+			options.ancestor_label : ancestor->path;
+		ancestor_mmfile.ptr = (char *)ancestor->ptr;
+		ancestor_mmfile.size = (long)ancestor->size;
+	}
+
+	xmparam.file1 = (options.our_label) ?
+		options.our_label : ours->path;
+	our_mmfile.ptr = (char *)ours->ptr;
+	our_mmfile.size = (long)ours->size;
+
+	xmparam.file2 = (options.their_label) ?
+		options.their_label : theirs->path;
+	their_mmfile.ptr = (char *)theirs->ptr;
+	their_mmfile.size = (long)theirs->size;
+
+	if (options.favor == GIT_MERGE_FILE_FAVOR_OURS)
+		xmparam.favor = XDL_MERGE_FAVOR_OURS;
+	else if (options.favor == GIT_MERGE_FILE_FAVOR_THEIRS)
+		xmparam.favor = XDL_MERGE_FAVOR_THEIRS;
+	else if (options.favor == GIT_MERGE_FILE_FAVOR_UNION)
+		xmparam.favor = XDL_MERGE_FAVOR_UNION;
+
+	xmparam.level = (options.flags & GIT_MERGE_FILE_SIMPLIFY_ALNUM) ?
+		XDL_MERGE_ZEALOUS_ALNUM : XDL_MERGE_ZEALOUS;
+
+	if (options.flags & GIT_MERGE_FILE_STYLE_DIFF3)
+		xmparam.style = XDL_MERGE_DIFF3;
+	if (options.flags & GIT_MERGE_FILE_STYLE_ZDIFF3)
+		xmparam.style = XDL_MERGE_ZEALOUS_DIFF3;
+
+	if (options.flags & GIT_MERGE_FILE_IGNORE_WHITESPACE)
+		xmparam.xpp.flags |= XDF_IGNORE_WHITESPACE;
+	if (options.flags & GIT_MERGE_FILE_IGNORE_WHITESPACE_CHANGE)
+		xmparam.xpp.flags |= XDF_IGNORE_WHITESPACE_CHANGE;
+	if (options.flags & GIT_MERGE_FILE_IGNORE_WHITESPACE_EOL)
+		xmparam.xpp.flags |= XDF_IGNORE_WHITESPACE_AT_EOL;
+
+	if (options.flags & GIT_MERGE_FILE_DIFF_PATIENCE)
+		xmparam.xpp.flags |= XDF_PATIENCE_DIFF;
+
+	if (options.flags & GIT_MERGE_FILE_DIFF_MINIMAL)
+		xmparam.xpp.flags |= XDF_NEED_MINIMAL;
+
+	xmparam.marker_size = options.marker_size;
+
+	if ((xdl_result = xdl_merge(&ancestor_mmfile, &our_mmfile,
+		&their_mmfile, &xmparam, &mmbuffer)) < 0) {
+		git_error_set(GIT_ERROR_MERGE, "failed to merge files");
+		error = -1;
+		goto done;
+	}
+
+	path = git_merge_file__best_path(
+		ancestor ? ancestor->path : NULL,
+		ours->path,
+		theirs->path);
+
+	if (path != NULL && (out->path = git__strdup(path)) == NULL) {
+		error = -1;
+		goto done;
+	}
+
+	out->automergeable = (xdl_result == 0);
+	out->ptr = (const char *)mmbuffer.ptr;
+	out->len = mmbuffer.size;
+	out->mode = git_merge_file__best_mode(
+		ancestor ? ancestor->mode : 0,
+		ours->mode,
+		theirs->mode);
+
+done:
+	if (error < 0)
+		git_merge_file_result_free(out);
+
+	return error;
+}
+
+static bool merge_file__is_binary(const git_merge_file_input *file)
+{
+	size_t len = file ? file->size : 0;
+
+	if (len > GIT_XDIFF_MAX_SIZE)
+		return true;
+	if (len > GIT_MERGE_FILE_BINARY_SIZE)
+		len = GIT_MERGE_FILE_BINARY_SIZE;
+
+	return len ? (memchr(file->ptr, 0, len) != NULL) : false;
+}
+
+static int merge_file__binary(
+	git_merge_file_result *out,
+	const git_merge_file_input *ours,
+	const git_merge_file_input *theirs,
+	const git_merge_file_options *given_opts)
+{
+	const git_merge_file_input *favored = NULL;
+
+	memset(out, 0x0, sizeof(git_merge_file_result));
+
+	if (given_opts && given_opts->favor == GIT_MERGE_FILE_FAVOR_OURS)
+		favored = ours;
+	else if (given_opts && given_opts->favor == GIT_MERGE_FILE_FAVOR_THEIRS)
+		favored = theirs;
+	else
+		goto done;
+
+	if ((out->path = git__strdup(favored->path)) == NULL ||
+		(out->ptr = git__malloc(favored->size)) == NULL)
+		goto done;
+
+	memcpy((char *)out->ptr, favored->ptr, favored->size);
+	out->len = favored->size;
+	out->mode = favored->mode;
+	out->automergeable = 1;
+
+done:
+	return 0;
+}
+
+static int merge_file__from_inputs(
+	git_merge_file_result *out,
+	const git_merge_file_input *ancestor,
+	const git_merge_file_input *ours,
+	const git_merge_file_input *theirs,
+	const git_merge_file_options *given_opts)
+{
+	if (merge_file__is_binary(ancestor) ||
+		merge_file__is_binary(ours) ||
+		merge_file__is_binary(theirs))
+		return merge_file__binary(out, ours, theirs, given_opts);
+
+	return merge_file__xdiff(out, ancestor, ours, theirs, given_opts);
+}
+
+static git_merge_file_input *git_merge_file__normalize_inputs(
+	git_merge_file_input *out,
+	const git_merge_file_input *given)
+{
+	memcpy(out, given, sizeof(git_merge_file_input));
+
+	if (!out->path)
+		out->path = "file.txt";
+
+	if (!out->mode)
+		out->mode = 0100644;
+
+	return out;
+}
+
+int git_merge_file(
+	git_merge_file_result *out,
+	const git_merge_file_input *ancestor,
+	const git_merge_file_input *ours,
+	const git_merge_file_input *theirs,
+	const git_merge_file_options *options)
+{
+	git_merge_file_input inputs[3] = { {0} };
+
+	GIT_ASSERT_ARG(out);
+	GIT_ASSERT_ARG(ours);
+	GIT_ASSERT_ARG(theirs);
+
+	memset(out, 0x0, sizeof(git_merge_file_result));
+
+	if (ancestor)
+		ancestor = git_merge_file__normalize_inputs(&inputs[0], ancestor);
+
+	ours = git_merge_file__normalize_inputs(&inputs[1], ours);
+	theirs = git_merge_file__normalize_inputs(&inputs[2], theirs);
+
+	return merge_file__from_inputs(out, ancestor, ours, theirs, options);
+}
+
+int git_merge_file_from_index(
+	git_merge_file_result *out,
+	git_repository *repo,
+	const git_index_entry *ancestor,
+	const git_index_entry *ours,
+	const git_index_entry *theirs,
+	const git_merge_file_options *options)
+{
+	git_merge_file_input *ancestor_ptr = NULL,
+		ancestor_input = {0}, our_input = {0}, their_input = {0};
+	git_odb *odb = NULL;
+	git_odb_object *odb_object[3] = { 0 };
+	int error = 0;
+
+	GIT_ASSERT_ARG(out);
+	GIT_ASSERT_ARG(repo);
+	GIT_ASSERT_ARG(ours);
+	GIT_ASSERT_ARG(theirs);
+
+	memset(out, 0x0, sizeof(git_merge_file_result));
+
+	if ((error = git_repository_odb(&odb, repo)) < 0)
+		goto done;
+
+	if (ancestor) {
+		if ((error = merge_file_input_from_index(
+			&ancestor_input, &odb_object[0], odb, ancestor)) < 0)
+			goto done;
+
+		ancestor_ptr = &ancestor_input;
+	}
+
+	if ((error = merge_file_input_from_index(&our_input, &odb_object[1], odb, ours)) < 0 ||
+	    (error = merge_file_input_from_index(&their_input, &odb_object[2], odb, theirs)) < 0)
+		goto done;
+
+	error = merge_file__from_inputs(out,
+		ancestor_ptr, &our_input, &their_input, options);
+
+done:
+	git_odb_object_free(odb_object[0]);
+	git_odb_object_free(odb_object[1]);
+	git_odb_object_free(odb_object[2]);
+	git_odb_free(odb);
+
+	return error;
+}
+
+void git_merge_file_result_free(git_merge_file_result *result)
+{
+	if (result == NULL)
+		return;
+
+	git__free((char *)result->path);
+	git__free((char *)result->ptr);
+}