Add hunk/file headers to git_diff_patch_size

This allows git_diff_patch_size to account for hunk headers and
file headers in the returned size.  This required some refactoring
of the code that is used to print file headers so that it could be
invoked by the git_diff_patch_size API.

Also this increases the test coverage and fixes an off-by-one bug
in the size calculation when newline changes happen at the end of
the file.

1 files changed, 7 insertions, 0 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 *);