patch: `patch_diff` -> `patch_generated`

1 files changed, 953 insertions, 0 deletions

diff --git a/src/patch_generate.c b/src/patch_generate.c
new file mode 100644
index 000000000..80a5a552a
--- /dev/null
+++ b/src/patch_generate.c
@@ -0,0 +1,953 @@
+/*
+ * 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 "git2/blob.h"
+#include "diff.h"
+#include "diff_file.h"
+#include "diff_driver.h"
+#include "patch_generate.h"
+#include "diff_xdiff.h"
+#include "delta.h"
+#include "zstream.h"
+#include "fileops.h"
+
+static void diff_output_init(
+	git_patch_generated_output *, const git_diff_options *, git_diff_file_cb,
+	git_diff_binary_cb, git_diff_hunk_cb, git_diff_line_cb, void*);
+
+static void diff_output_to_patch(
+	git_patch_generated_output *, git_patch_generated *);
+
+static void patch_generated_free(git_patch *p)
+{
+	git_patch_generated *patch = (git_patch_generated *)p;
+
+	git_array_clear(patch->base.lines);
+	git_array_clear(patch->base.hunks);
+
+	git__free((char *)patch->base.binary.old_file.data);
+	git__free((char *)patch->base.binary.new_file.data);
+
+	git_diff_file_content__clear(&patch->ofile);
+	git_diff_file_content__clear(&patch->nfile);
+
+	git_diff_free(patch->diff); /* decrements refcount */
+	patch->diff = NULL;
+
+	git_pool_clear(&patch->flattened);
+
+	git__free((char *)patch->base.diff_opts.old_prefix);
+	git__free((char *)patch->base.diff_opts.new_prefix);
+
+	if (patch->flags & GIT_PATCH_GENERATED_ALLOCATED)
+		git__free(patch);
+}
+
+static void patch_generated_update_binary(git_patch_generated *patch)
+{
+	if ((patch->base.delta->flags & DIFF_FLAGS_KNOWN_BINARY) != 0)
+		return;
+
+	if ((patch->ofile.file->flags & GIT_DIFF_FLAG_BINARY) != 0 ||
+		(patch->nfile.file->flags & GIT_DIFF_FLAG_BINARY) != 0)
+		patch->base.delta->flags |= GIT_DIFF_FLAG_BINARY;
+
+	else if (patch->ofile.file->size > GIT_XDIFF_MAX_SIZE ||
+		patch->nfile.file->size > GIT_XDIFF_MAX_SIZE)
+		patch->base.delta->flags |= GIT_DIFF_FLAG_BINARY;
+
+	else if ((patch->ofile.file->flags & DIFF_FLAGS_NOT_BINARY) != 0 &&
+		(patch->nfile.file->flags & DIFF_FLAGS_NOT_BINARY) != 0)
+		patch->base.delta->flags |= GIT_DIFF_FLAG_NOT_BINARY;
+}
+
+static void patch_generated_init_common(git_patch_generated *patch)
+{
+	patch->base.free_fn = patch_generated_free;
+
+	patch_generated_update_binary(patch);
+
+	patch->flags |= GIT_PATCH_GENERATED_INITIALIZED;
+
+	if (patch->diff)
+		git_diff_addref(patch->diff);
+}
+
+static int patch_generated_normalize_options(
+	git_diff_options *out,
+	const git_diff_options *opts)
+{
+	if (opts) {
+		GITERR_CHECK_VERSION(opts, GIT_DIFF_OPTIONS_VERSION, "git_diff_options");
+		memcpy(out, opts, sizeof(git_diff_options));
+	} else {
+		git_diff_options default_opts = GIT_DIFF_OPTIONS_INIT;
+		memcpy(out, &default_opts, sizeof(git_diff_options));
+	}
+
+	out->old_prefix = opts && opts->old_prefix ?
+		git__strdup(opts->old_prefix) :
+		git__strdup(DIFF_OLD_PREFIX_DEFAULT);
+
+	out->new_prefix = opts && opts->new_prefix ?
+		git__strdup(opts->new_prefix) :
+		git__strdup(DIFF_NEW_PREFIX_DEFAULT);
+
+	GITERR_CHECK_ALLOC(out->old_prefix);
+	GITERR_CHECK_ALLOC(out->new_prefix);
+
+	return 0;
+}
+
+static int patch_generated_init(
+	git_patch_generated *patch, git_diff *diff, size_t delta_index)
+{
+	int error = 0;
+
+	memset(patch, 0, sizeof(*patch));
+
+	patch->diff = diff;
+	patch->base.repo = diff->repo;
+	patch->base.delta = git_vector_get(&diff->deltas, delta_index);
+	patch->delta_index = delta_index;
+
+	if ((error = patch_generated_normalize_options(
+			&patch->base.diff_opts, &diff->opts)) < 0 ||
+		(error = git_diff_file_content__init_from_diff(
+			&patch->ofile, diff, patch->base.delta, true)) < 0 ||
+		(error = git_diff_file_content__init_from_diff(
+			&patch->nfile, diff, patch->base.delta, false)) < 0)
+		return error;
+
+	patch_generated_init_common(patch);
+
+	return 0;
+}
+
+static int patch_generated_alloc_from_diff(
+	git_patch_generated **out, git_diff *diff, size_t delta_index)
+{
+	int error;
+	git_patch_generated *patch = git__calloc(1, sizeof(git_patch_generated));
+	GITERR_CHECK_ALLOC(patch);
+
+	if (!(error = patch_generated_init(patch, diff, delta_index))) {
+		patch->flags |= GIT_PATCH_GENERATED_ALLOCATED;
+		GIT_REFCOUNT_INC(patch);
+	} else {
+		git__free(patch);
+		patch = NULL;
+	}
+
+	*out = patch;
+	return error;
+}
+
+GIT_INLINE(bool) should_skip_binary(git_patch_generated *patch, git_diff_file *file)
+{
+	if ((patch->base.diff_opts.flags & GIT_DIFF_SHOW_BINARY) != 0)
+		return false;
+
+	return (file->flags & GIT_DIFF_FLAG_BINARY) != 0;
+}
+
+static bool patch_generated_diffable(git_patch_generated *patch)
+{
+	size_t olen, nlen;
+
+	if (patch->base.delta->status == GIT_DELTA_UNMODIFIED)
+		return false;
+
+	/* if we've determined this to be binary (and we are not showing binary
+	 * data) then we have skipped loading the map data.  instead, query the
+	 * file data itself.
+	 */
+	if ((patch->base.delta->flags & GIT_DIFF_FLAG_BINARY) != 0 &&
+		(patch->base.diff_opts.flags & GIT_DIFF_SHOW_BINARY) == 0) {
+		olen = (size_t)patch->ofile.file->size;
+		nlen = (size_t)patch->nfile.file->size;
+	} else {
+		olen = patch->ofile.map.len;
+		nlen = patch->nfile.map.len;
+	}
+
+	/* if both sides are empty, files are identical */
+	if (!olen && !nlen)
+		return false;
+
+	/* otherwise, check the file sizes and the oid */
+	return (olen != nlen ||
+		!git_oid_equal(&patch->ofile.file->id, &patch->nfile.file->id));
+}
+
+static int patch_generated_load(git_patch_generated *patch, git_patch_generated_output *output)
+{
+	int error = 0;
+	bool incomplete_data;
+
+	if ((patch->flags & GIT_PATCH_GENERATED_LOADED) != 0)
+		return 0;
+
+	/* if no hunk and data callbacks and user doesn't care if data looks
+	 * binary, then there is no need to actually load the data
+	 */
+	if ((patch->ofile.opts_flags & GIT_DIFF_SKIP_BINARY_CHECK) != 0 &&
+		output && !output->binary_cb && !output->hunk_cb && !output->data_cb)
+		return 0;
+
+	incomplete_data =
+		(((patch->ofile.flags & GIT_DIFF_FLAG__NO_DATA) != 0 ||
+		  (patch->ofile.file->flags & GIT_DIFF_FLAG_VALID_ID) != 0) &&
+		 ((patch->nfile.flags & GIT_DIFF_FLAG__NO_DATA) != 0 ||
+		  (patch->nfile.file->flags & GIT_DIFF_FLAG_VALID_ID) != 0));
+
+	/* always try to load workdir content first because filtering may
+	 * need 2x data size and this minimizes peak memory footprint
+	 */
+	if (patch->ofile.src == GIT_ITERATOR_TYPE_WORKDIR) {
+		if ((error = git_diff_file_content__load(
+				&patch->ofile, &patch->base.diff_opts)) < 0 ||
+			should_skip_binary(patch, patch->ofile.file))
+			goto cleanup;
+	}
+	if (patch->nfile.src == GIT_ITERATOR_TYPE_WORKDIR) {
+		if ((error = git_diff_file_content__load(
+				&patch->nfile, &patch->base.diff_opts)) < 0 ||
+			should_skip_binary(patch, patch->nfile.file))
+			goto cleanup;
+	}
+
+	/* once workdir has been tried, load other data as needed */
+	if (patch->ofile.src != GIT_ITERATOR_TYPE_WORKDIR) {
+		if ((error = git_diff_file_content__load(
+				&patch->ofile, &patch->base.diff_opts)) < 0 ||
+			should_skip_binary(patch, patch->ofile.file))
+			goto cleanup;
+	}
+	if (patch->nfile.src != GIT_ITERATOR_TYPE_WORKDIR) {
+		if ((error = git_diff_file_content__load(
+				&patch->nfile, &patch->base.diff_opts)) < 0 ||
+			should_skip_binary(patch, patch->nfile.file))
+			goto cleanup;
+	}
+
+	/* if previously missing an oid, and now that we have it the two sides
+	 * are the same (and not submodules), update MODIFIED -> UNMODIFIED
+	 */
+	if (incomplete_data &&
+		patch->ofile.file->mode == patch->nfile.file->mode &&
+		patch->ofile.file->mode != GIT_FILEMODE_COMMIT &&
+		git_oid_equal(&patch->ofile.file->id, &patch->nfile.file->id) &&
+		patch->base.delta->status == GIT_DELTA_MODIFIED) /* not RENAMED/COPIED! */
+		patch->base.delta->status = GIT_DELTA_UNMODIFIED;
+
+cleanup:
+	patch_generated_update_binary(patch);
+
+	if (!error) {
+		if (patch_generated_diffable(patch))
+			patch->flags |= GIT_PATCH_GENERATED_DIFFABLE;
+
+		patch->flags |= GIT_PATCH_GENERATED_LOADED;
+	}
+
+	return error;
+}
+
+static int patch_generated_invoke_file_callback(
+	git_patch_generated *patch, git_patch_generated_output *output)
+{
+	float progress = patch->diff ?
+		((float)patch->delta_index / patch->diff->deltas.length) : 1.0f;
+
+	if (!output->file_cb)
+		return 0;
+
+	return giterr_set_after_callback_function(
+		output->file_cb(patch->base.delta, progress, output->payload),
+		"git_patch");
+}
+
+static int create_binary(
+	git_diff_binary_t *out_type,
+	char **out_data,
+	size_t *out_datalen,
+	size_t *out_inflatedlen,
+	const char *a_data,
+	size_t a_datalen,
+	const char *b_data,
+	size_t b_datalen)
+{
+	git_buf deflate = GIT_BUF_INIT, delta = GIT_BUF_INIT;
+	unsigned long delta_data_len;
+	int error;
+
+	/* The git_delta function accepts unsigned long only */
+	if (!git__is_ulong(a_datalen) || !git__is_ulong(b_datalen))
+		return GIT_EBUFS;
+
+	if ((error = git_zstream_deflatebuf(&deflate, b_data, b_datalen)) < 0)
+		goto done;
+
+	/* The git_delta function accepts unsigned long only */
+	if (!git__is_ulong(deflate.size)) {
+		error = GIT_EBUFS;
+		goto done;
+	}
+
+	if (a_datalen && b_datalen) {
+		void *delta_data;
+
+		error = git_delta(&delta_data, &delta_data_len,
+			a_data, a_datalen,
+			b_data, b_datalen,
+			deflate.size);
+
+		if (error == 0) {
+			error = git_zstream_deflatebuf(
+				&delta, delta_data, (size_t)delta_data_len);
+
+			git__free(delta_data);
+		} else if (error == GIT_EBUFS) {
+			error = 0;
+		}
+
+		if (error < 0)
+			goto done;
+	}
+
+	if (delta.size && delta.size < deflate.size) {
+		*out_type = GIT_DIFF_BINARY_DELTA;
+		*out_datalen = delta.size;
+		*out_data = git_buf_detach(&delta);
+		*out_inflatedlen = delta_data_len;
+	} else {
+		*out_type = GIT_DIFF_BINARY_LITERAL;
+		*out_datalen = deflate.size;
+		*out_data = git_buf_detach(&deflate);
+		*out_inflatedlen = b_datalen;
+	}
+
+done:
+	git_buf_free(&deflate);
+	git_buf_free(&delta);
+
+	return error;
+}
+
+static int diff_binary(git_patch_generated_output *output, git_patch_generated *patch)
+{
+	git_diff_binary binary = {{0}};
+	const char *old_data = patch->ofile.map.data;
+	const char *new_data = patch->nfile.map.data;
+	size_t old_len = patch->ofile.map.len,
+		new_len = patch->nfile.map.len;
+	int error;
+
+	/* Create the old->new delta (as the "new" side of the patch),
+	 * and the new->old delta (as the "old" side)
+	 */
+	if ((error = create_binary(&binary.old_file.type,
+			(char **)&binary.old_file.data,
+			&binary.old_file.datalen,
+			&binary.old_file.inflatedlen,
+			new_data, new_len, old_data, old_len)) < 0 ||
+		(error = create_binary(&binary.new_file.type,
+			(char **)&binary.new_file.data,
+			&binary.new_file.datalen,
+			&binary.new_file.inflatedlen,
+			old_data, old_len, new_data, new_len)) < 0)
+		return error;
+
+	error = giterr_set_after_callback_function(
+		output->binary_cb(patch->base.delta, &binary, output->payload),
+		"git_patch");
+
+	git__free((char *) binary.old_file.data);
+	git__free((char *) binary.new_file.data);
+
+	return error;
+}
+
+static int patch_generated_create(
+	git_patch_generated *patch,
+	git_patch_generated_output *output)
+{
+	int error = 0;
+
+	if ((patch->flags & GIT_PATCH_GENERATED_DIFFED) != 0)
+		return 0;
+
+	/* if we are not looking at the binary or text data, don't do the diff */
+	if (!output->binary_cb && !output->hunk_cb && !output->data_cb)
+		return 0;
+
+	if ((patch->flags & GIT_PATCH_GENERATED_LOADED) == 0 &&
+		(error = patch_generated_load(patch, output)) < 0)
+		return error;
+
+	if ((patch->flags & GIT_PATCH_GENERATED_DIFFABLE) == 0)
+		return 0;
+
+	if ((patch->base.delta->flags & GIT_DIFF_FLAG_BINARY) != 0) {
+		if (output->binary_cb)
+			error = diff_binary(output, patch);
+	}
+	else {
+		if (output->diff_cb)
+			error = output->diff_cb(output, patch);
+	}
+
+	patch->flags |= GIT_PATCH_GENERATED_DIFFED;
+	return error;
+}
+
+static int diff_required(git_diff *diff, const char *action)
+{
+	if (diff)
+		return 0;
+	giterr_set(GITERR_INVALID, "Must provide valid diff to %s", action);
+	return -1;
+}
+
+int git_diff_foreach(
+	git_diff *diff,
+	git_diff_file_cb file_cb,
+	git_diff_binary_cb binary_cb,
+	git_diff_hunk_cb hunk_cb,
+	git_diff_line_cb data_cb,
+	void *payload)
+{
+	int error = 0;
+	git_xdiff_output xo;
+	size_t idx;
+	git_patch_generated patch;
+
+	if ((error = diff_required(diff, "git_diff_foreach")) < 0)
+		return error;
+
+	memset(&xo, 0, sizeof(xo));
+	memset(&patch, 0, sizeof(patch));
+	diff_output_init(
+		&xo.output, &diff->opts, file_cb, binary_cb, hunk_cb, data_cb, payload);
+	git_xdiff_init(&xo, &diff->opts);
+
+	git_vector_foreach(&diff->deltas, idx, patch.base.delta) {
+
+		/* check flags against patch status */
+		if (git_diff_delta__should_skip(&diff->opts, patch.base.delta))
+			continue;
+
+		if (binary_cb || hunk_cb || data_cb) {
+			if ((error = patch_generated_init(&patch, diff, idx)) != 0 ||
+				(error = patch_generated_load(&patch, &xo.output)) != 0)
+				return error;
+		}
+
+		if ((error = patch_generated_invoke_file_callback(&patch, &xo.output)) == 0) {
+			if (binary_cb || hunk_cb || data_cb)
+					error = patch_generated_create(&patch, &xo.output);
+		}
+
+		git_patch_free(&patch.base);
+
+		if (error)
+			break;
+	}
+
+	return error;
+}
+
+typedef struct {
+	git_patch_generated patch;
+	git_diff_delta delta;
+	char paths[GIT_FLEX_ARRAY];
+} patch_generated_with_delta;
+
+static int diff_single_generate(patch_generated_with_delta *pd, git_xdiff_output *xo)
+{
+	int error = 0;
+	git_patch_generated *patch = &pd->patch;
+	bool has_old = ((patch->ofile.flags & GIT_DIFF_FLAG__NO_DATA) == 0);
+	bool has_new = ((patch->nfile.flags & GIT_DIFF_FLAG__NO_DATA) == 0);
+
+	pd->delta.status = has_new ?
+		(has_old ? GIT_DELTA_MODIFIED : GIT_DELTA_ADDED) :
+		(has_old ? GIT_DELTA_DELETED : GIT_DELTA_UNTRACKED);
+
+	if (git_oid_equal(&patch->nfile.file->id, &patch->ofile.file->id))
+		pd->delta.status = GIT_DELTA_UNMODIFIED;
+
+	patch->base.delta = &pd->delta;
+
+	patch_generated_init_common(patch);
+
+	if (pd->delta.status == GIT_DELTA_UNMODIFIED &&
+		!(patch->ofile.opts_flags & GIT_DIFF_INCLUDE_UNMODIFIED))
+		return error;
+
+	error = patch_generated_invoke_file_callback(patch, (git_patch_generated_output *)xo);
+
+	if (!error)
+		error = patch_generated_create(patch, (git_patch_generated_output *)xo);
+
+	return error;
+}
+
+static int patch_generated_from_sources(
+	patch_generated_with_delta *pd,
+	git_xdiff_output *xo,
+	git_diff_file_content_src *oldsrc,
+	git_diff_file_content_src *newsrc,
+	const git_diff_options *opts)
+{
+	int error = 0;
+	git_repository *repo =
+		oldsrc->blob ? git_blob_owner(oldsrc->blob) :
+		newsrc->blob ? git_blob_owner(newsrc->blob) : NULL;
+	git_diff_file *lfile = &pd->delta.old_file, *rfile = &pd->delta.new_file;
+	git_diff_file_content *ldata = &pd->patch.ofile, *rdata = &pd->patch.nfile;
+
+	if ((error = patch_generated_normalize_options(&pd->patch.base.diff_opts, opts)) < 0)
+		return error;
+
+	if (opts && (opts->flags & GIT_DIFF_REVERSE) != 0) {
+		void *tmp = lfile; lfile = rfile; rfile = tmp;
+		tmp = ldata; ldata = rdata; rdata = tmp;
+	}
+
+	pd->patch.base.delta = &pd->delta;
+
+	if (!oldsrc->as_path) {
+		if (newsrc->as_path)
+			oldsrc->as_path = newsrc->as_path;
+		else
+			oldsrc->as_path = newsrc->as_path = "file";
+	}
+	else if (!newsrc->as_path)
+		newsrc->as_path = oldsrc->as_path;
+
+	lfile->path = oldsrc->as_path;
+	rfile->path = newsrc->as_path;
+
+	if ((error = git_diff_file_content__init_from_src(
+			ldata, repo, opts, oldsrc, lfile)) < 0 ||
+		(error = git_diff_file_content__init_from_src(
+			rdata, repo, opts, newsrc, rfile)) < 0)
+		return error;
+
+	return diff_single_generate(pd, xo);
+}
+
+static int patch_generated_with_delta_alloc(
+	patch_generated_with_delta **out,
+	const char **old_path,
+	const char **new_path)
+{
+	patch_generated_with_delta *pd;
+	size_t old_len = *old_path ? strlen(*old_path) : 0;
+	size_t new_len = *new_path ? strlen(*new_path) : 0;
+	size_t alloc_len;
+
+	GITERR_CHECK_ALLOC_ADD(&alloc_len, sizeof(*pd), old_len);
+	GITERR_CHECK_ALLOC_ADD(&alloc_len, alloc_len, new_len);
+	GITERR_CHECK_ALLOC_ADD(&alloc_len, alloc_len, 2);
+
+	*out = pd = git__calloc(1, alloc_len);
+	GITERR_CHECK_ALLOC(pd);
+
+	pd->patch.flags = GIT_PATCH_GENERATED_ALLOCATED;
+
+	if (*old_path) {
+		memcpy(&pd->paths[0], *old_path, old_len);
+		*old_path = &pd->paths[0];
+	} else if (*new_path)
+		*old_path = &pd->paths[old_len + 1];
+
+	if (*new_path) {
+		memcpy(&pd->paths[old_len + 1], *new_path, new_len);
+		*new_path = &pd->paths[old_len + 1];
+	} else if (*old_path)
+		*new_path = &pd->paths[0];
+
+	return 0;
+}
+
+static int diff_from_sources(
+	git_diff_file_content_src *oldsrc,
+	git_diff_file_content_src *newsrc,
+	const git_diff_options *opts,
+	git_diff_file_cb file_cb,
+	git_diff_binary_cb binary_cb,
+	git_diff_hunk_cb hunk_cb,
+	git_diff_line_cb data_cb,
+	void *payload)
+{
+	int error = 0;
+	patch_generated_with_delta pd;
+	git_xdiff_output xo;
+
+	memset(&xo, 0, sizeof(xo));
+	diff_output_init(
+		&xo.output, opts, file_cb, binary_cb, hunk_cb, data_cb, payload);
+	git_xdiff_init(&xo, opts);
+
+	memset(&pd, 0, sizeof(pd));
+
+	error = patch_generated_from_sources(&pd, &xo, oldsrc, newsrc, opts);
+
+	git_patch_free(&pd.patch.base);
+
+	return error;
+}
+
+static int patch_from_sources(
+	git_patch **out,
+	git_diff_file_content_src *oldsrc,
+	git_diff_file_content_src *newsrc,
+	const git_diff_options *opts)
+{
+	int error = 0;
+	patch_generated_with_delta *pd;
+	git_xdiff_output xo;
+
+	assert(out);
+	*out = NULL;
+
+	if ((error = patch_generated_with_delta_alloc(
+			&pd, &oldsrc->as_path, &newsrc->as_path)) < 0)
+		return error;
+
+	memset(&xo, 0, sizeof(xo));
+	diff_output_to_patch(&xo.output, &pd->patch);
+	git_xdiff_init(&xo, opts);
+
+	if (!(error = patch_generated_from_sources(pd, &xo, oldsrc, newsrc, opts)))
+		*out = (git_patch *)pd;
+	else
+		git_patch_free((git_patch *)pd);
+
+	return error;
+}
+
+int git_diff_blobs(
+	const git_blob *old_blob,
+	const char *old_path,
+	const git_blob *new_blob,
+	const char *new_path,
+	const git_diff_options *opts,
+	git_diff_file_cb file_cb,
+	git_diff_binary_cb binary_cb,
+	git_diff_hunk_cb hunk_cb,
+	git_diff_line_cb data_cb,
+	void *payload)
+{
+	git_diff_file_content_src osrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BLOB(old_blob, old_path);
+	git_diff_file_content_src nsrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BLOB(new_blob, new_path);
+	return diff_from_sources(
+		&osrc, &nsrc, opts, file_cb, binary_cb, hunk_cb, data_cb, payload);
+}
+
+int git_patch_from_blobs(
+	git_patch **out,
+	const git_blob *old_blob,
+	const char *old_path,
+	const git_blob *new_blob,
+	const char *new_path,
+	const git_diff_options *opts)
+{
+	git_diff_file_content_src osrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BLOB(old_blob, old_path);
+	git_diff_file_content_src nsrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BLOB(new_blob, new_path);
+	return patch_from_sources(out, &osrc, &nsrc, opts);
+}
+
+int git_diff_blob_to_buffer(
+	const git_blob *old_blob,
+	const char *old_path,
+	const char *buf,
+	size_t buflen,
+	const char *buf_path,
+	const git_diff_options *opts,
+	git_diff_file_cb file_cb,
+	git_diff_binary_cb binary_cb,
+	git_diff_hunk_cb hunk_cb,
+	git_diff_line_cb data_cb,
+	void *payload)
+{
+	git_diff_file_content_src osrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BLOB(old_blob, old_path);
+	git_diff_file_content_src nsrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BUF(buf, buflen, buf_path);
+	return diff_from_sources(
+		&osrc, &nsrc, opts, file_cb, binary_cb, hunk_cb, data_cb, payload);
+}
+
+int git_patch_from_blob_and_buffer(
+	git_patch **out,
+	const git_blob *old_blob,
+	const char *old_path,
+	const char *buf,
+	size_t buflen,
+	const char *buf_path,
+	const git_diff_options *opts)
+{
+	git_diff_file_content_src osrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BLOB(old_blob, old_path);
+	git_diff_file_content_src nsrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BUF(buf, buflen, buf_path);
+	return patch_from_sources(out, &osrc, &nsrc, opts);
+}
+
+int git_diff_buffers(
+	const void *old_buf,
+	size_t old_len,
+	const char *old_path,
+	const void *new_buf,
+	size_t new_len,
+	const char *new_path,
+	const git_diff_options *opts,
+	git_diff_file_cb file_cb,
+	git_diff_binary_cb binary_cb,
+	git_diff_hunk_cb hunk_cb,
+	git_diff_line_cb data_cb,
+	void *payload)
+{
+	git_diff_file_content_src osrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BUF(old_buf, old_len, old_path);
+	git_diff_file_content_src nsrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BUF(new_buf, new_len, new_path);
+	return diff_from_sources(
+		&osrc, &nsrc, opts, file_cb, binary_cb, hunk_cb, data_cb, payload);
+}
+
+int git_patch_from_buffers(
+	git_patch **out,
+	const void *old_buf,
+	size_t old_len,
+	const char *old_path,
+	const char *new_buf,
+	size_t new_len,
+	const char *new_path,
+	const git_diff_options *opts)
+{
+	git_diff_file_content_src osrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BUF(old_buf, old_len, old_path);
+	git_diff_file_content_src nsrc =
+		GIT_DIFF_FILE_CONTENT_SRC__BUF(new_buf, new_len, new_path);
+	return patch_from_sources(out, &osrc, &nsrc, opts);
+}
+
+int git_patch_from_diff(
+	git_patch **patch_ptr, git_diff *diff, size_t idx)
+{
+	int error = 0;
+	git_xdiff_output xo;
+	git_diff_delta *delta = NULL;
+	git_patch_generated *patch = NULL;
+
+	if (patch_ptr) *patch_ptr = NULL;
+
+	if (diff_required(diff, "git_patch_from_diff") < 0)
+		return -1;
+
+	delta = git_vector_get(&diff->deltas, idx);
+	if (!delta) {
+		giterr_set(GITERR_INVALID, "Index out of range for delta in diff");
+		return GIT_ENOTFOUND;
+	}
+
+	if (git_diff_delta__should_skip(&diff->opts, delta))
+		return 0;
+
+	/* don't load the patch data unless we need it for binary check */
+	if (!patch_ptr &&
+		((delta->flags & DIFF_FLAGS_KNOWN_BINARY) != 0 ||
+		 (diff->opts.flags & GIT_DIFF_SKIP_BINARY_CHECK) != 0))
+		return 0;
+
+	if ((error = patch_generated_alloc_from_diff(&patch, diff, idx)) < 0)
+		return error;
+
+	memset(&xo, 0, sizeof(xo));
+	diff_output_to_patch(&xo.output, patch);
+	git_xdiff_init(&xo, &diff->opts);
+
+	error = patch_generated_invoke_file_callback(patch, &xo.output);
+
+	if (!error)
+		error = patch_generated_create(patch, &xo.output);
+
+	if (!error) {
+		/* TODO: if cumulative diff size is < 0.5 total size, flatten patch */
+		/* TODO: and unload the file content */
+	}
+
+	if (error || !patch_ptr)
+		git_patch_free(&patch->base);
+	else
+		*patch_ptr = &patch->base;
+
+	return error;
+}
+
+git_diff_driver *git_patch_generated_driver(git_patch_generated *patch)
+{
+	/* ofile driver is representative for whole patch */
+	return patch->ofile.driver;
+}
+
+void git_patch_generated_old_data(
+	char **ptr, size_t *len, git_patch_generated *patch)
+{
+	*ptr = patch->ofile.map.data;
+	*len = patch->ofile.map.len;
+}
+
+void git_patch_generated_new_data(
+	char **ptr, size_t *len, git_patch_generated *patch)
+{
+	*ptr = patch->nfile.map.data;
+	*len = patch->nfile.map.len;
+}
+
+static int patch_generated_file_cb(
+	const git_diff_delta *delta,
+	float progress,
+	void *payload)
+{
+	GIT_UNUSED(delta); GIT_UNUSED(progress); GIT_UNUSED(payload);
+	return 0;
+}
+
+static int patch_generated_binary_cb(
+	const git_diff_delta *delta,
+	const git_diff_binary *binary,
+	void *payload)
+{
+	git_patch *patch = payload;
+
+	GIT_UNUSED(delta);
+
+	memcpy(&patch->binary, binary, sizeof(git_diff_binary));
+
+	if (binary->old_file.data) {
+		patch->binary.old_file.data = git__malloc(binary->old_file.datalen);
+		GITERR_CHECK_ALLOC(patch->binary.old_file.data);
+
+		memcpy((char *)patch->binary.old_file.data,
+			binary->old_file.data, binary->old_file.datalen);
+	}
+
+	if (binary->new_file.data) {
+		patch->binary.new_file.data = git__malloc(binary->new_file.datalen);
+		GITERR_CHECK_ALLOC(patch->binary.new_file.data);
+
+		memcpy((char *)patch->binary.new_file.data,
+			binary->new_file.data, binary->new_file.datalen);
+	}
+
+	return 0;
+}
+
+static int git_patch_hunk_cb(
+	const git_diff_delta *delta,
+	const git_diff_hunk *hunk_,
+	void *payload)
+{
+	git_patch_generated  *patch = payload;
+	git_patch_hunk *hunk;
+
+	GIT_UNUSED(delta);
+
+	hunk = git_array_alloc(patch->base.hunks);
+	GITERR_CHECK_ALLOC(hunk);
+
+	memcpy(&hunk->hunk, hunk_, sizeof(hunk->hunk));
+
+	patch->base.header_size += hunk_->header_len;
+
+	hunk->line_start = git_array_size(patch->base.lines);
+	hunk->line_count = 0;
+
+	return 0;
+}
+
+static int patch_generated_line_cb(
+	const git_diff_delta *delta,
+	const git_diff_hunk *hunk_,
+	const git_diff_line *line_,
+	void *payload)
+{
+	git_patch_generated  *patch = payload;
+	git_patch_hunk *hunk;
+	git_diff_line   *line;
+
+	GIT_UNUSED(delta);
+	GIT_UNUSED(hunk_);
+
+	hunk = git_array_last(patch->base.hunks);
+	assert(hunk); /* programmer error if no hunk is available */
+
+	line = git_array_alloc(patch->base.lines);
+	GITERR_CHECK_ALLOC(line);
+
+	memcpy(line, line_, sizeof(*line));
+
+	/* do some bookkeeping so we can provide old/new line numbers */
+
+	patch->base.content_size += line->content_len;
+
+	if (line->origin == GIT_DIFF_LINE_ADDITION ||
+		line->origin == GIT_DIFF_LINE_DELETION)
+		patch->base.content_size += 1;
+	else if (line->origin == GIT_DIFF_LINE_CONTEXT) {
+		patch->base.content_size += 1;
+		patch->base.context_size += line->content_len + 1;
+	} else if (line->origin == GIT_DIFF_LINE_CONTEXT_EOFNL)
+		patch->base.context_size += line->content_len;
+
+	hunk->line_count++;
+
+	return 0;
+}
+
+static void diff_output_init(
+	git_patch_generated_output *out,
+	const git_diff_options *opts,
+	git_diff_file_cb file_cb,
+	git_diff_binary_cb binary_cb,
+	git_diff_hunk_cb hunk_cb,
+	git_diff_line_cb data_cb,
+	void *payload)
+{
+	GIT_UNUSED(opts);
+
+	memset(out, 0, sizeof(*out));
+
+	out->file_cb = file_cb;
+	out->binary_cb = binary_cb;
+	out->hunk_cb = hunk_cb;
+	out->data_cb = data_cb;
+	out->payload = payload;
+}
+
+static void diff_output_to_patch(
+	git_patch_generated_output *out, git_patch_generated *patch)
+{
+	diff_output_init(
+		out,
+		NULL,
+		patch_generated_file_cb,
+		patch_generated_binary_cb,
+		git_patch_hunk_cb,
+		patch_generated_line_cb,
+		patch);
+}