patch: fix issue libgit2#6294 - unquoted paths with spaces

Author: zawata

src/libgit2/diff_print.c

@@ -441,10 +441,19 @@ int git_diff_delta__format_file_header(
 	if (!id_strlen)
 		id_strlen = GIT_ABBREV_DEFAULT;
 
+	/*
+	 Additional layer of protection against NULL pathnames in addition to the
+	 fix in 'patch_parse.c:check_filenames()' that prevents any of the sides
+	 from having a NULL pathname.
+	 */
 	if ((error = diff_delta_format_path(
-			&old_path, oldpfx, delta->old_file.path)) < 0 ||
+			&old_path,
+			oldpfx,
+			!delta->old_file.path ? delta->new_file.path : delta->old_file.path)) < 0 ||
 		(error = diff_delta_format_path(
-			&new_path, newpfx, delta->new_file.path)) < 0)
+			&new_path,
+			newpfx,
+			!delta->new_file.path ? delta->old_file.path : delta->new_file.path)) < 0)
 		goto done;
 
 	git_str_clear(out);

src/libgit2/parse.c

@@ -32,6 +32,30 @@ void git_parse_ctx_clear(git_parse_ctx *ctx)
 	ctx->content = "";
 }
 
+long git_parse_unescaped_char_offset_in_line(
+	git_parse_ctx *ctx,
+	char char_to_search_for)
+{
+	return git_parse_unescaped_char_offset_in_str(
+		ctx->line,
+		ctx->line_len,
+		char_to_search_for);
+}
+
+long git_parse_unescaped_char_offset_in_str(const char *base, size_t len, char char_to_search_for)
+{
+	bool after_escaping_backslash = false;
+	long offset;
+
+	for (offset = 0; (size_t)offset < len; offset++) {
+		if (!after_escaping_backslash && base[offset] == char_to_search_for) {
+			return offset;
+		}
+		after_escaping_backslash = (!after_escaping_backslash && base[offset] == '\\');
+	}
+	return -1;
+}
+
 void git_parse_advance_line(git_parse_ctx *ctx)
 {
 	ctx->line += ctx->line_len;

src/libgit2/parse.h

@@ -28,6 +28,14 @@ typedef struct {
 int git_parse_ctx_init(git_parse_ctx *ctx, const char *content, size_t content_len);
 void git_parse_ctx_clear(git_parse_ctx *ctx);
 
+long git_parse_unescaped_char_offset_in_line(
+	git_parse_ctx *ctx,
+	char char_to_search_for);
+long git_parse_unescaped_char_offset_in_str(
+	const char *base,
+	size_t len,
+	char char_to_search_for);
+
 #define git_parse_ctx_contains_s(ctx, str) \
 	git_parse_ctx_contains(ctx, str, sizeof(str) - 1)