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, 38 insertions, 11 deletions

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++;