3 files changed, 87 insertions, 48 deletions

diff --git a/src/diff.h b/src/diff.h
index d09a130bc..ff480324f 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -81,6 +81,13 @@ extern const char *git_diff_delta__path(const git_diff_delta *delta);
 extern bool git_diff_delta__should_skip(
 	const git_diff_options *opts, const git_diff_delta *delta);
 
+extern int git_diff_delta__format_file_header(
+	git_buf *out,
+	const git_diff_delta *delta,
+	const char *oldpfx,
+	const char *newpfx,
+	int oid_strlen);
+
 extern int git_diff__oid_for_file(
 	git_repository *, const char *, uint16_t, git_off_t, git_oid *);
 
diff --git a/src/diff_patch.c b/src/diff_patch.c
index 5febc883c..6f8ea2d3d 100644
--- a/src/diff_patch.c
+++ b/src/diff_patch.c
@@ -42,7 +42,7 @@ struct git_diff_patch {
 	git_array_t(diff_patch_hunk) hunks;
 	git_array_t(diff_patch_line) lines;
 	size_t oldno, newno;
-	size_t content_size, context_size;
+	size_t content_size, context_size, header_size;
 	git_pool flattened;
 };
 
@@ -806,7 +806,11 @@ notfound:
 	return diff_error_outofrange(thing);
 }
 
-size_t git_diff_patch_size(git_diff_patch *patch, int include_context)
+size_t git_diff_patch_size(
+	git_diff_patch *patch,
+	int include_context,
+	int include_hunk_headers,
+	int include_file_headers)
 {
 	size_t out;
 
@@ -817,6 +821,21 @@ size_t git_diff_patch_size(git_diff_patch *patch, int include_context)
 	if (!include_context)
 		out -= patch->context_size;
 
+	if (include_hunk_headers)
+		out += patch->header_size;
+
+	if (include_file_headers) {
+		git_buf file_header = GIT_BUF_INIT;
+
+		if (git_diff_delta__format_file_header(
+				&file_header, patch->delta, NULL, NULL, 0) < 0)
+			giterr_clear();
+		else
+			out += git_buf_len(&file_header);
+
+		git_buf_free(&file_header);
+	}
+
 	return out;
 }
 
@@ -914,6 +933,8 @@ static int diff_patch_hunk_cb(
 	hunk->header[header_len] = '\0';
 	hunk->header_len = header_len;
 
+	patch->header_size += header_len;
+
 	hunk->line_start = git_array_size(patch->lines);
 	hunk->line_count = 0;
 
@@ -934,6 +955,7 @@ static int diff_patch_line_cb(
 	git_diff_patch *patch = payload;
 	diff_patch_hunk *hunk;
 	diff_patch_line *line;
+	const char *content_end = content + content_len;
 
 	GIT_UNUSED(delta);
 	GIT_UNUSED(range);
@@ -948,38 +970,43 @@ static int diff_patch_line_cb(
 	line->len = content_len;
 	line->origin = line_origin;
 
-	patch->content_size += content_len + 1; /* +1 for line_origin */
-
-	if (line_origin == GIT_DIFF_LINE_CONTEXT ||
-		line_origin == GIT_DIFF_LINE_CONTEXT_EOFNL)
-		patch->context_size += content_len + 1;
-
 	/* do some bookkeeping so we can provide old/new line numbers */
 
-	for (line->lines = 0; content_len > 0; --content_len) {
+	line->lines = 0;
+	while (content < content_end)
 		if (*content++ == '\n')
 			++line->lines;
-	}
+
+	patch->content_size += content_len;
 
 	switch (line_origin) {
 	case GIT_DIFF_LINE_ADDITION:
+		patch->content_size += 1;
 	case GIT_DIFF_LINE_DEL_EOFNL:
 		line->oldno = -1;
 		line->newno = patch->newno;
 		patch->newno += line->lines;
 		break;
 	case GIT_DIFF_LINE_DELETION:
+		patch->content_size += 1;
 	case GIT_DIFF_LINE_ADD_EOFNL:
 		line->oldno = patch->oldno;
 		line->newno = -1;
 		patch->oldno += line->lines;
 		break;
-	default:
+	case GIT_DIFF_LINE_CONTEXT:
+		patch->content_size += 1;
+		patch->context_size += 1;
+	case GIT_DIFF_LINE_CONTEXT_EOFNL:
+		patch->context_size += content_len;
 		line->oldno = patch->oldno;
 		line->newno = patch->newno;
 		patch->oldno += line->lines;
 		patch->newno += line->lines;
 		break;
+	default:
+		assert(false);
+		break;
 	}
 
 	hunk->line_count++;
diff --git a/src/diff_print.c b/src/diff_print.c
index 0de548813..cdb813176 100644
--- a/src/diff_print.c
+++ b/src/diff_print.c
@@ -198,13 +198,13 @@ int git_diff_print_raw(
 	return error;
 }
 
-static int diff_print_oid_range(diff_print_info *pi, const git_diff_delta *delta)
+static int diff_print_oid_range(
+	git_buf *out, const git_diff_delta *delta, int oid_strlen)
 {
-	git_buf *out = pi->buf;
 	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);
+	git_oid_tostr(start_oid, oid_strlen, &delta->old_file.oid);
+	git_oid_tostr(end_oid, oid_strlen, &delta->new_file.oid);
 
 	/* TODO: Match git diff more closely */
 	if (delta->old_file.mode == delta->new_file.mode) {
@@ -228,35 +228,29 @@ static int diff_print_oid_range(diff_print_info *pi, const git_diff_delta *delta
 	return 0;
 }
 
-static int diff_print_patch_file(
-	const git_diff_delta *delta, float progress, void *data)
+int git_diff_delta__format_file_header(
+	git_buf *out,
+	const git_diff_delta *delta,
+	const char *oldpfx,
+	const char *newpfx,
+	int oid_strlen)
 {
-	diff_print_info *pi = data;
-	const char *oldpfx = pi->diff ? pi->diff->opts.old_prefix : NULL;
 	const char *oldpath = delta->old_file.path;
-	const char *newpfx = pi->diff ? pi->diff->opts.new_prefix : NULL;
 	const char *newpath = delta->new_file.path;
-	uint32_t opts_flags = pi->diff ? pi->diff->opts.flags : GIT_DIFF_NORMAL;
-
-	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 &&
-		 (opts_flags & GIT_DIFF_INCLUDE_UNTRACKED_CONTENT) == 0))
-		return 0;
 
 	if (!oldpfx)
 		oldpfx = DIFF_OLD_PREFIX_DEFAULT;
 	if (!newpfx)
 		newpfx = DIFF_NEW_PREFIX_DEFAULT;
+	if (!oid_strlen)
+		oid_strlen = GIT_ABBREV_DEFAULT + 1;
 
-	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);
+	git_buf_clear(out);
+
+	git_buf_printf(out, "diff --git %s%s %s%s\n",
+		oldpfx, oldpath, newpfx, newpath);
 
-	if (diff_print_oid_range(pi, delta) < 0)
+	if (diff_print_oid_range(out, delta, oid_strlen) < 0)
 		return -1;
 
 	if (git_oid_iszero(&delta->old_file.oid)) {
@@ -269,28 +263,39 @@ static int diff_print_patch_file(
 	}
 
 	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);
+		git_buf_printf(out, "--- %s%s\n", oldpfx, oldpath);
+		git_buf_printf(out, "+++ %s%s\n", newpfx, newpath);
+	} else {
+		git_buf_printf(
+			out, "Binary files %s%s and %s%s differ\n",
+			oldpfx, oldpath, newpfx, newpath);
 	}
 
-	if (git_buf_oom(pi->buf))
-		return -1;
+	return git_buf_oom(out) ? -1 : 0;
+}
 
-	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();
+static int diff_print_patch_file(
+	const git_diff_delta *delta, float progress, void *data)
+{
+	diff_print_info *pi = data;
+	const char *oldpfx = pi->diff ? pi->diff->opts.old_prefix : NULL;
+	const char *newpfx = pi->diff ? pi->diff->opts.new_prefix : NULL;
+	uint32_t opts_flags = pi->diff ? pi->diff->opts.flags : GIT_DIFF_NORMAL;
 
-	if ((delta->flags & GIT_DIFF_FLAG_BINARY) == 0)
+	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 &&
+		 (opts_flags & GIT_DIFF_INCLUDE_UNTRACKED_CONTENT) == 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))
+	if (git_diff_delta__format_file_header(
+			pi->buf, delta, oldpfx, newpfx, pi->oid_strlen) < 0)
 		return -1;
 
-	if (pi->print_cb(delta, NULL, GIT_DIFF_LINE_BINARY,
+	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();