Move some diff helpers into separate file

2 files changed, 433 insertions, 422 deletions

diff --git a/src/diff_output.c b/src/diff_output.c
index bcd39f093..9a5be2a10 100644
--- a/src/diff_output.c
+++ b/src/diff_output.c
@@ -207,6 +207,8 @@ static long diff_context_find(
 	const char *scan;
 	bool found_paren = false;
 
+	GIT_UNUSED(ctxt);
+
 	if (line_len > 0 && line[line_len - 1] == '\n')
 		line_len--;
 	if (line_len > 0 && line[line_len - 1] == '\r')
@@ -1064,359 +1066,6 @@ int git_diff_foreach(
 	return error;
 }
 
-
-typedef struct {
-	git_diff_list *diff;
-	git_diff_data_cb print_cb;
-	void *payload;
-	git_buf *buf;
-	int oid_strlen;
-} diff_print_info;
-
-static int diff_print_info_init(
-	diff_print_info *pi,
-	git_buf *out, git_diff_list *diff, git_diff_data_cb cb, void *payload)
-{
-	assert(diff && diff->repo);
-
-	pi->diff     = diff;
-	pi->print_cb = cb;
-	pi->payload  = payload;
-	pi->buf      = out;
-
-	if (git_repository__cvar(&pi->oid_strlen, diff->repo, GIT_CVAR_ABBREV) < 0)
-		return -1;
-
-	pi->oid_strlen += 1; /* for NUL byte */
-
-	if (pi->oid_strlen < 2)
-		pi->oid_strlen = 2;
-	else if (pi->oid_strlen > GIT_OID_HEXSZ + 1)
-		pi->oid_strlen = GIT_OID_HEXSZ + 1;
-
-	return 0;
-}
-
-static char pick_suffix(int mode)
-{
-	if (S_ISDIR(mode))
-		return '/';
-	else if (mode & 0100) //-V536
-		/* in git, modes are very regular, so we must have 0100755 mode */
-		return '*';
-	else
-		return ' ';
-}
-
-char git_diff_status_char(git_delta_t status)
-{
-	char code;
-
-	switch (status) {
-	case GIT_DELTA_ADDED:     code = 'A'; break;
-	case GIT_DELTA_DELETED:   code = 'D'; break;
-	case GIT_DELTA_MODIFIED:  code = 'M'; break;
-	case GIT_DELTA_RENAMED:   code = 'R'; break;
-	case GIT_DELTA_COPIED:    code = 'C'; break;
-	case GIT_DELTA_IGNORED:   code = 'I'; break;
-	case GIT_DELTA_UNTRACKED: code = '?'; break;
-	default:                  code = ' '; break;
-	}
-
-	return code;
-}
-
-static int callback_error(void)
-{
-	giterr_clear();
-	return GIT_EUSER;
-}
-
-static int print_compact(
-	const git_diff_delta *delta, float progress, void *data)
-{
-	diff_print_info *pi = data;
-	char old_suffix, new_suffix, code = git_diff_status_char(delta->status);
-
-	GIT_UNUSED(progress);
-
-	if (code == ' ')
-		return 0;
-
-	old_suffix = pick_suffix(delta->old_file.mode);
-	new_suffix = pick_suffix(delta->new_file.mode);
-
-	git_buf_clear(pi->buf);
-
-	if (delta->old_file.path != delta->new_file.path &&
-		pi->diff->strcomp(delta->old_file.path,delta->new_file.path) != 0)
-		git_buf_printf(pi->buf, "%c\t%s%c -> %s%c\n", code,
-			delta->old_file.path, old_suffix, delta->new_file.path, new_suffix);
-	else if (delta->old_file.mode != delta->new_file.mode &&
-		delta->old_file.mode != 0 && delta->new_file.mode != 0)
-		git_buf_printf(pi->buf, "%c\t%s%c (%o -> %o)\n", code,
-			delta->old_file.path, new_suffix, delta->old_file.mode, delta->new_file.mode);
-	else if (old_suffix != ' ')
-		git_buf_printf(pi->buf, "%c\t%s%c\n", code, delta->old_file.path, old_suffix);
-	else
-		git_buf_printf(pi->buf, "%c\t%s\n", code, delta->old_file.path);
-
-	if (git_buf_oom(pi->buf))
-		return -1;
-
-	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_FILE_HDR,
-			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
-		return callback_error();
-
-	return 0;
-}
-
-int git_diff_print_compact(
-	git_diff_list *diff,
-	git_diff_data_cb print_cb,
-	void *payload)
-{
-	int error;
-	git_buf buf = GIT_BUF_INIT;
-	diff_print_info pi;
-
-	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
-		error = git_diff_foreach(diff, print_compact, NULL, NULL, &pi);
-
-	git_buf_free(&buf);
-
-	return error;
-}
-
-static int print_raw(
-	const git_diff_delta *delta, float progress, void *data)
-{
-	diff_print_info *pi = data;
-	char code = git_diff_status_char(delta->status);
-	char start_oid[GIT_OID_HEXSZ+1], end_oid[GIT_OID_HEXSZ+1];
-
-	GIT_UNUSED(progress);
-
-	if (code == ' ')
-		return 0;
-
-	git_buf_clear(pi->buf);
-
-	git_oid_tostr(start_oid, pi->oid_strlen, &delta->old_file.oid);
-	git_oid_tostr(end_oid, pi->oid_strlen, &delta->new_file.oid);
-
-	git_buf_printf(
-		pi->buf, ":%06o %06o %s... %s... %c",
-		delta->old_file.mode, delta->new_file.mode, start_oid, end_oid, code);
-
-	if (delta->similarity > 0)
-		git_buf_printf(pi->buf, "%03u", delta->similarity);
-
-	if (delta->status == GIT_DELTA_RENAMED || delta->status == GIT_DELTA_COPIED)
-		git_buf_printf(
-			pi->buf, "\t%s %s\n", delta->old_file.path, delta->new_file.path);
-	else
-		git_buf_printf(
-			pi->buf, "\t%s\n", delta->old_file.path ?
-			delta->old_file.path : delta->new_file.path);
-
-	if (git_buf_oom(pi->buf))
-		return -1;
-
-	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_FILE_HDR,
-			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
-		return callback_error();
-
-	return 0;
-}
-
-int git_diff_print_raw(
-	git_diff_list *diff,
-	git_diff_data_cb print_cb,
-	void *payload)
-{
-	int error;
-	git_buf buf = GIT_BUF_INIT;
-	diff_print_info pi;
-
-	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
-		error = git_diff_foreach(diff, print_raw, NULL, NULL, &pi);
-
-	git_buf_free(&buf);
-
-	return error;
-}
-
-static int print_oid_range(diff_print_info *pi, const git_diff_delta *delta)
-{
-	char start_oid[GIT_OID_HEXSZ+1], end_oid[GIT_OID_HEXSZ+1];
-
-	git_oid_tostr(start_oid, pi->oid_strlen, &delta->old_file.oid);
-	git_oid_tostr(end_oid, pi->oid_strlen, &delta->new_file.oid);
-
-	/* TODO: Match git diff more closely */
-	if (delta->old_file.mode == delta->new_file.mode) {
-		git_buf_printf(pi->buf, "index %s..%s %o\n",
-			start_oid, end_oid, delta->old_file.mode);
-	} else {
-		if (delta->old_file.mode == 0) {
-			git_buf_printf(pi->buf, "new file mode %o\n", delta->new_file.mode);
-		} else if (delta->new_file.mode == 0) {
-			git_buf_printf(pi->buf, "deleted file mode %o\n", delta->old_file.mode);
-		} else {
-			git_buf_printf(pi->buf, "old mode %o\n", delta->old_file.mode);
-			git_buf_printf(pi->buf, "new mode %o\n", delta->new_file.mode);
-		}
-		git_buf_printf(pi->buf, "index %s..%s\n", start_oid, end_oid);
-	}
-
-	if (git_buf_oom(pi->buf))
-		return -1;
-
-	return 0;
-}
-
-static int print_patch_file(
-	const git_diff_delta *delta, float progress, void *data)
-{
-	diff_print_info *pi = data;
-	const char *oldpfx = pi->diff->opts.old_prefix;
-	const char *oldpath = delta->old_file.path;
-	const char *newpfx = pi->diff->opts.new_prefix;
-	const char *newpath = delta->new_file.path;
-
-	GIT_UNUSED(progress);
-
-	if (S_ISDIR(delta->new_file.mode) ||
-		delta->status == GIT_DELTA_UNMODIFIED ||
-		delta->status == GIT_DELTA_IGNORED ||
-		(delta->status == GIT_DELTA_UNTRACKED &&
-		 (pi->diff->opts.flags & GIT_DIFF_INCLUDE_UNTRACKED_CONTENT) == 0))
-		return 0;
-
-	if (!oldpfx)
-		oldpfx = DIFF_OLD_PREFIX_DEFAULT;
-
-	if (!newpfx)
-		newpfx = DIFF_NEW_PREFIX_DEFAULT;
-
-	git_buf_clear(pi->buf);
-	git_buf_printf(pi->buf, "diff --git %s%s %s%s\n", oldpfx, delta->old_file.path, newpfx, delta->new_file.path);
-
-	if (print_oid_range(pi, delta) < 0)
-		return -1;
-
-	if (git_oid_iszero(&delta->old_file.oid)) {
-		oldpfx = "";
-		oldpath = "/dev/null";
-	}
-	if (git_oid_iszero(&delta->new_file.oid)) {
-		newpfx = "";
-		newpath = "/dev/null";
-	}
-
-	if ((delta->flags & GIT_DIFF_FLAG_BINARY) == 0) {
-		git_buf_printf(pi->buf, "--- %s%s\n", oldpfx, oldpath);
-		git_buf_printf(pi->buf, "+++ %s%s\n", newpfx, newpath);
-	}
-
-	if (git_buf_oom(pi->buf))
-		return -1;
-
-	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_FILE_HDR,
-			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
-		return callback_error();
-
-	if ((delta->flags & GIT_DIFF_FLAG_BINARY) == 0)
-		return 0;
-
-	git_buf_clear(pi->buf);
-	git_buf_printf(
-		pi->buf, "Binary files %s%s and %s%s differ\n",
-		oldpfx, oldpath, newpfx, newpath);
-	if (git_buf_oom(pi->buf))
-		return -1;
-
-	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_BINARY,
-			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
-		return callback_error();
-
-	return 0;
-}
-
-static int print_patch_hunk(
-	const git_diff_delta *d,
-	const git_diff_range *r,
-	const char *header,
-	size_t header_len,
-	void *data)
-{
-	diff_print_info *pi = data;
-
-	if (S_ISDIR(d->new_file.mode))
-		return 0;
-
-	git_buf_clear(pi->buf);
-	if (git_buf_printf(pi->buf, "%.*s", (int)header_len, header) < 0)
-		return -1;
-
-	if (pi->print_cb(d, r, GIT_DIFF_LINE_HUNK_HDR,
-			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
-		return callback_error();
-
-	return 0;
-}
-
-static int print_patch_line(
-	const git_diff_delta *delta,
-	const git_diff_range *range,
-	char line_origin, /* GIT_DIFF_LINE value from above */
-	const char *content,
-	size_t content_len,
-	void *data)
-{
-	diff_print_info *pi = data;
-
-	if (S_ISDIR(delta->new_file.mode))
-		return 0;
-
-	git_buf_clear(pi->buf);
-
-	if (line_origin == GIT_DIFF_LINE_ADDITION ||
-		line_origin == GIT_DIFF_LINE_DELETION ||
-		line_origin == GIT_DIFF_LINE_CONTEXT)
-		git_buf_printf(pi->buf, "%c%.*s", line_origin, (int)content_len, content);
-	else if (content_len > 0)
-		git_buf_printf(pi->buf, "%.*s", (int)content_len, content);
-
-	if (git_buf_oom(pi->buf))
-		return -1;
-
-	if (pi->print_cb(delta, range, line_origin,
-			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
-		return callback_error();
-
-	return 0;
-}
-
-int git_diff_print_patch(
-	git_diff_list *diff,
-	git_diff_data_cb print_cb,
-	void *payload)
-{
-	int error;
-	git_buf buf = GIT_BUF_INIT;
-	diff_print_info pi;
-
-	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
-		error = git_diff_foreach(
-			diff, print_patch_file, print_patch_hunk, print_patch_line, &pi);
-
-	git_buf_free(&buf);
-
-	return error;
-}
-
 static void set_data_from_blob(
 	const git_blob *blob, git_map *map, git_diff_file *file)
 {
@@ -1826,75 +1475,6 @@ notfound:
 	return diff_error_outofrange(thing);
 }
 
-static int print_to_buffer_cb(
-	const git_diff_delta *delta,
-	const git_diff_range *range,
-	char line_origin,
-	const char *content,
-	size_t content_len,
-	void *payload)
-{
-	git_buf *output = payload;
-	GIT_UNUSED(delta); GIT_UNUSED(range); GIT_UNUSED(line_origin);
-	return git_buf_put(output, content, content_len);
-}
-
-int git_diff_patch_print(
-	git_diff_patch *patch,
-	git_diff_data_cb print_cb,
-	void *payload)
-{
-	int error;
-	git_buf temp = GIT_BUF_INIT;
-	diff_print_info pi;
-	size_t h, l;
-
-	assert(patch && print_cb);
-
-	if (!(error = diff_print_info_init(
-			&pi, &temp, patch->diff, print_cb, payload)))
-		error = print_patch_file(patch->delta, 0, &pi);
-
-	for (h = 0; h < patch->hunks_size && !error; ++h) {
-		diff_patch_hunk *hunk = &patch->hunks[h];
-
-		error = print_patch_hunk(
-			patch->delta, &hunk->range, hunk->header, hunk->header_len, &pi);
-
-		for (l = 0; l < hunk->line_count && !error; ++l) {
-			diff_patch_line *line = &patch->lines[hunk->line_start + l];
-
-			error = print_patch_line(
-				patch->delta, &hunk->range,
-				line->origin, line->ptr, line->len, &pi);
-		}
-	}
-
-	git_buf_free(&temp);
-
-	return error;
-}
-
-int git_diff_patch_to_str(
-	char **string,
-	git_diff_patch *patch)
-{
-	int error;
-	git_buf output = GIT_BUF_INIT;
-
-	error = git_diff_patch_print(patch, print_to_buffer_cb, &output);
-
-	/* GIT_EUSER means git_buf_put in print_to_buffer_cb returned -1,
-	 * meaning a memory allocation failure, so just map to -1...
-	 */
-	if (error == GIT_EUSER)
-		error = -1;
-
-	*string = git_buf_detach(&output);
-
-	return error;
-}
-
 int git_diff__paired_foreach(
 	git_diff_list *idx2head,
 	git_diff_list *wd2idx,
diff --git a/src/diff_print.c b/src/diff_print.c
new file mode 100644
index 000000000..b6fbec829
--- /dev/null
+++ b/src/diff_print.c
@@ -0,0 +1,431 @@
+/*
+ * 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 "diff.h"
+#include "diff_output.h"
+
+typedef struct {
+	git_diff_list *diff;
+	git_diff_data_cb print_cb;
+	void *payload;
+	git_buf *buf;
+	int oid_strlen;
+} diff_print_info;
+
+static int diff_print_info_init(
+	diff_print_info *pi,
+	git_buf *out, git_diff_list *diff, git_diff_data_cb cb, void *payload)
+{
+	assert(diff && diff->repo);
+
+	pi->diff     = diff;
+	pi->print_cb = cb;
+	pi->payload  = payload;
+	pi->buf      = out;
+
+	if (git_repository__cvar(&pi->oid_strlen, diff->repo, GIT_CVAR_ABBREV) < 0)
+		return -1;
+
+	pi->oid_strlen += 1; /* for NUL byte */
+
+	if (pi->oid_strlen < 2)
+		pi->oid_strlen = 2;
+	else if (pi->oid_strlen > GIT_OID_HEXSZ + 1)
+		pi->oid_strlen = GIT_OID_HEXSZ + 1;
+
+	return 0;
+}
+
+static char pick_suffix(int mode)
+{
+	if (S_ISDIR(mode))
+		return '/';
+	else if (mode & 0100) //-V536
+		/* in git, modes are very regular, so we must have 0100755 mode */
+		return '*';
+	else
+		return ' ';
+}
+
+char git_diff_status_char(git_delta_t status)
+{
+	char code;
+
+	switch (status) {
+	case GIT_DELTA_ADDED:     code = 'A'; break;
+	case GIT_DELTA_DELETED:   code = 'D'; break;
+	case GIT_DELTA_MODIFIED:  code = 'M'; break;
+	case GIT_DELTA_RENAMED:   code = 'R'; break;
+	case GIT_DELTA_COPIED:    code = 'C'; break;
+	case GIT_DELTA_IGNORED:   code = 'I'; break;
+	case GIT_DELTA_UNTRACKED: code = '?'; break;
+	default:                  code = ' '; break;
+	}
+
+	return code;
+}
+
+static int callback_error(void)
+{
+	giterr_clear();
+	return GIT_EUSER;
+}
+
+static int print_compact(
+	const git_diff_delta *delta, float progress, void *data)
+{
+	diff_print_info *pi = data;
+	char old_suffix, new_suffix, code = git_diff_status_char(delta->status);
+
+	GIT_UNUSED(progress);
+
+	if (code == ' ')
+		return 0;
+
+	old_suffix = pick_suffix(delta->old_file.mode);
+	new_suffix = pick_suffix(delta->new_file.mode);
+
+	git_buf_clear(pi->buf);
+
+	if (delta->old_file.path != delta->new_file.path &&
+		pi->diff->strcomp(delta->old_file.path,delta->new_file.path) != 0)
+		git_buf_printf(pi->buf, "%c\t%s%c -> %s%c\n", code,
+			delta->old_file.path, old_suffix, delta->new_file.path, new_suffix);
+	else if (delta->old_file.mode != delta->new_file.mode &&
+		delta->old_file.mode != 0 && delta->new_file.mode != 0)
+		git_buf_printf(pi->buf, "%c\t%s%c (%o -> %o)\n", code,
+			delta->old_file.path, new_suffix, delta->old_file.mode, delta->new_file.mode);
+	else if (old_suffix != ' ')
+		git_buf_printf(pi->buf, "%c\t%s%c\n", code, delta->old_file.path, old_suffix);
+	else
+		git_buf_printf(pi->buf, "%c\t%s\n", code, delta->old_file.path);
+
+	if (git_buf_oom(pi->buf))
+		return -1;
+
+	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_FILE_HDR,
+			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
+		return callback_error();
+
+	return 0;
+}
+
+int git_diff_print_compact(
+	git_diff_list *diff,
+	git_diff_data_cb print_cb,
+	void *payload)
+{
+	int error;
+	git_buf buf = GIT_BUF_INIT;
+	diff_print_info pi;
+
+	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
+		error = git_diff_foreach(diff, print_compact, NULL, NULL, &pi);
+
+	git_buf_free(&buf);
+
+	return error;
+}
+
+static int print_raw(
+	const git_diff_delta *delta, float progress, void *data)
+{
+	diff_print_info *pi = data;
+	char code = git_diff_status_char(delta->status);
+	char start_oid[GIT_OID_HEXSZ+1], end_oid[GIT_OID_HEXSZ+1];
+
+	GIT_UNUSED(progress);
+
+	if (code == ' ')
+		return 0;
+
+	git_buf_clear(pi->buf);
+
+	git_oid_tostr(start_oid, pi->oid_strlen, &delta->old_file.oid);
+	git_oid_tostr(end_oid, pi->oid_strlen, &delta->new_file.oid);
+
+	git_buf_printf(
+		pi->buf, ":%06o %06o %s... %s... %c",
+		delta->old_file.mode, delta->new_file.mode, start_oid, end_oid, code);
+
+	if (delta->similarity > 0)
+		git_buf_printf(pi->buf, "%03u", delta->similarity);
+
+	if (delta->status == GIT_DELTA_RENAMED || delta->status == GIT_DELTA_COPIED)
+		git_buf_printf(
+			pi->buf, "\t%s %s\n", delta->old_file.path, delta->new_file.path);
+	else
+		git_buf_printf(
+			pi->buf, "\t%s\n", delta->old_file.path ?
+			delta->old_file.path : delta->new_file.path);
+
+	if (git_buf_oom(pi->buf))
+		return -1;
+
+	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_FILE_HDR,
+			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
+		return callback_error();
+
+	return 0;
+}
+
+int git_diff_print_raw(
+	git_diff_list *diff,
+	git_diff_data_cb print_cb,
+	void *payload)
+{
+	int error;
+	git_buf buf = GIT_BUF_INIT;
+	diff_print_info pi;
+
+	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
+		error = git_diff_foreach(diff, print_raw, NULL, NULL, &pi);
+
+	git_buf_free(&buf);
+
+	return error;
+}
+
+static int print_oid_range(diff_print_info *pi, const git_diff_delta *delta)
+{
+	char start_oid[GIT_OID_HEXSZ+1], end_oid[GIT_OID_HEXSZ+1];
+
+	git_oid_tostr(start_oid, pi->oid_strlen, &delta->old_file.oid);
+	git_oid_tostr(end_oid, pi->oid_strlen, &delta->new_file.oid);
+
+	/* TODO: Match git diff more closely */
+	if (delta->old_file.mode == delta->new_file.mode) {
+		git_buf_printf(pi->buf, "index %s..%s %o\n",
+			start_oid, end_oid, delta->old_file.mode);
+	} else {
+		if (delta->old_file.mode == 0) {
+			git_buf_printf(pi->buf, "new file mode %o\n", delta->new_file.mode);
+		} else if (delta->new_file.mode == 0) {
+			git_buf_printf(pi->buf, "deleted file mode %o\n", delta->old_file.mode);
+		} else {
+			git_buf_printf(pi->buf, "old mode %o\n", delta->old_file.mode);
+			git_buf_printf(pi->buf, "new mode %o\n", delta->new_file.mode);
+		}
+		git_buf_printf(pi->buf, "index %s..%s\n", start_oid, end_oid);
+	}
+
+	if (git_buf_oom(pi->buf))
+		return -1;
+
+	return 0;
+}
+
+static int print_patch_file(
+	const git_diff_delta *delta, float progress, void *data)
+{
+	diff_print_info *pi = data;
+	const char *oldpfx = pi->diff->opts.old_prefix;
+	const char *oldpath = delta->old_file.path;
+	const char *newpfx = pi->diff->opts.new_prefix;
+	const char *newpath = delta->new_file.path;
+
+	GIT_UNUSED(progress);
+
+	if (S_ISDIR(delta->new_file.mode) ||
+		delta->status == GIT_DELTA_UNMODIFIED ||
+		delta->status == GIT_DELTA_IGNORED ||
+		(delta->status == GIT_DELTA_UNTRACKED &&
+		 (pi->diff->opts.flags & GIT_DIFF_INCLUDE_UNTRACKED_CONTENT) == 0))
+		return 0;
+
+	if (!oldpfx)
+		oldpfx = DIFF_OLD_PREFIX_DEFAULT;
+
+	if (!newpfx)
+		newpfx = DIFF_NEW_PREFIX_DEFAULT;
+
+	git_buf_clear(pi->buf);
+	git_buf_printf(pi->buf, "diff --git %s%s %s%s\n", oldpfx, delta->old_file.path, newpfx, delta->new_file.path);
+
+	if (print_oid_range(pi, delta) < 0)
+		return -1;
+
+	if (git_oid_iszero(&delta->old_file.oid)) {
+		oldpfx = "";
+		oldpath = "/dev/null";
+	}
+	if (git_oid_iszero(&delta->new_file.oid)) {
+		newpfx = "";
+		newpath = "/dev/null";
+	}
+
+	if ((delta->flags & GIT_DIFF_FLAG_BINARY) == 0) {
+		git_buf_printf(pi->buf, "--- %s%s\n", oldpfx, oldpath);
+		git_buf_printf(pi->buf, "+++ %s%s\n", newpfx, newpath);
+	}
+
+	if (git_buf_oom(pi->buf))
+		return -1;
+
+	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_FILE_HDR,
+			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
+		return callback_error();
+
+	if ((delta->flags & GIT_DIFF_FLAG_BINARY) == 0)
+		return 0;
+
+	git_buf_clear(pi->buf);
+	git_buf_printf(
+		pi->buf, "Binary files %s%s and %s%s differ\n",
+		oldpfx, oldpath, newpfx, newpath);
+	if (git_buf_oom(pi->buf))
+		return -1;
+
+	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_BINARY,
+			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
+		return callback_error();
+
+	return 0;
+}
+
+static int print_patch_hunk(
+	const git_diff_delta *d,
+	const git_diff_range *r,
+	const char *header,
+	size_t header_len,
+	void *data)
+{
+	diff_print_info *pi = data;
+
+	if (S_ISDIR(d->new_file.mode))
+		return 0;
+
+	git_buf_clear(pi->buf);
+	if (git_buf_printf(pi->buf, "%.*s", (int)header_len, header) < 0)
+		return -1;
+
+	if (pi->print_cb(d, r, GIT_DIFF_LINE_HUNK_HDR,
+			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
+		return callback_error();
+
+	return 0;
+}
+
+static int print_patch_line(
+	const git_diff_delta *delta,
+	const git_diff_range *range,
+	char line_origin, /* GIT_DIFF_LINE value from above */
+	const char *content,
+	size_t content_len,
+	void *data)
+{
+	diff_print_info *pi = data;
+
+	if (S_ISDIR(delta->new_file.mode))
+		return 0;
+
+	git_buf_clear(pi->buf);
+
+	if (line_origin == GIT_DIFF_LINE_ADDITION ||
+		line_origin == GIT_DIFF_LINE_DELETION ||
+		line_origin == GIT_DIFF_LINE_CONTEXT)
+		git_buf_printf(pi->buf, "%c%.*s", line_origin, (int)content_len, content);
+	else if (content_len > 0)
+		git_buf_printf(pi->buf, "%.*s", (int)content_len, content);
+
+	if (git_buf_oom(pi->buf))
+		return -1;
+
+	if (pi->print_cb(delta, range, line_origin,
+			git_buf_cstr(pi->buf), git_buf_len(pi->buf), pi->payload))
+		return callback_error();
+
+	return 0;
+}
+
+int git_diff_print_patch(
+	git_diff_list *diff,
+	git_diff_data_cb print_cb,
+	void *payload)
+{
+	int error;
+	git_buf buf = GIT_BUF_INIT;
+	diff_print_info pi;
+
+	if (!(error = diff_print_info_init(&pi, &buf, diff, print_cb, payload)))
+		error = git_diff_foreach(
+			diff, print_patch_file, print_patch_hunk, print_patch_line, &pi);
+
+	git_buf_free(&buf);
+
+	return error;
+}
+
+
+static int print_to_buffer_cb(
+	const git_diff_delta *delta,
+	const git_diff_range *range,
+	char line_origin,
+	const char *content,
+	size_t content_len,
+	void *payload)
+{
+	git_buf *output = payload;
+	GIT_UNUSED(delta); GIT_UNUSED(range); GIT_UNUSED(line_origin);
+	return git_buf_put(output, content, content_len);
+}
+
+int git_diff_patch_print(
+	git_diff_patch *patch,
+	git_diff_data_cb print_cb,
+	void *payload)
+{
+	int error;
+	git_buf temp = GIT_BUF_INIT;
+	diff_print_info pi;
+	size_t h, l;
+
+	assert(patch && print_cb);
+
+	if (!(error = diff_print_info_init(
+			&pi, &temp, patch->diff, print_cb, payload)))
+		error = print_patch_file(patch->delta, 0, &pi);
+
+	for (h = 0; h < patch->hunks_size && !error; ++h) {
+		diff_patch_hunk *hunk = &patch->hunks[h];
+
+		error = print_patch_hunk(
+			patch->delta, &hunk->range, hunk->header, hunk->header_len, &pi);
+
+		for (l = 0; l < hunk->line_count && !error; ++l) {
+			diff_patch_line *line = &patch->lines[hunk->line_start + l];
+
+			error = print_patch_line(
+				patch->delta, &hunk->range,
+				line->origin, line->ptr, line->len, &pi);
+		}
+	}
+
+	git_buf_free(&temp);
+
+	return error;
+}
+
+int git_diff_patch_to_str(
+	char **string,
+	git_diff_patch *patch)
+{
+	int error;
+	git_buf output = GIT_BUF_INIT;
+
+	error = git_diff_patch_print(patch, print_to_buffer_cb, &output);
+
+	/* GIT_EUSER means git_buf_put in print_to_buffer_cb returned -1,
+	 * meaning a memory allocation failure, so just map to -1...
+	 */
+	if (error == GIT_EUSER)
+		error = -1;
+
+	*string = git_buf_detach(&output);
+
+	return error;
+}