Extend filesystem diff utility to work on squashfs images

Since it already works on an fstree_t instance (constructed from the
input paths), and we now have a handy sqfs_reader_t, it is quite simple
to extend.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 45 insertions, 0 deletions

diff --git a/difftool/compare_files_sqfs.c b/difftool/compare_files_sqfs.c
new file mode 100644
index 0000000..d8bef83
--- /dev/null
+++ b/difftool/compare_files_sqfs.c
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * compare_file_sfqs.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "difftool.h"
+
+static unsigned char a_buf[MAX_WINDOW_SIZE];
+static unsigned char b_buf[MAX_WINDOW_SIZE];
+
+int compare_files(file_info_t *a, file_info_t *b, const char *path)
+{
+	uint64_t offset, diff;
+	ssize_t ret;
+
+	if (a->size != b->size)
+		return 1;
+
+	for (offset = 0; offset < a->size; offset += diff) {
+		diff = a->size - offset;
+
+		if (diff > MAX_WINDOW_SIZE)
+			diff = MAX_WINDOW_SIZE;
+
+		ret = data_reader_read(sqfs_a.data, a, offset, a_buf, diff);
+		if (ret < 0 || (size_t)ret < diff) {
+			fprintf(stderr, "Failed to read %s from %s\n",
+				path, first_path);
+			return -1;
+		}
+
+		ret = data_reader_read(sqfs_b.data, b, offset, b_buf, diff);
+		if (ret < 0 || (size_t)ret < diff) {
+			fprintf(stderr, "Failed to read %s from %s\n",
+				path, second_path);
+			return -1;
+		}
+
+		if (memcmp(a_buf, b_buf, diff) != 0)
+			return 1;
+	}
+
+	return 0;
+}