1 files changed, 72 insertions, 0 deletions
diff --git a/bin/sqfsdiff/compare_files.c b/bin/sqfsdiff/compare_files.c
new file mode 100644
index 0000000..51b66bb
--- /dev/null
+++ b/bin/sqfsdiff/compare_files.c
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * compare_files.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "sqfsdiff.h"
+
+static unsigned char old_buf[MAX_WINDOW_SIZE];
+static unsigned char new_buf[MAX_WINDOW_SIZE];
+
+static int read_blob(const char *prefix, const char *path,
+		     sqfs_data_reader_t *rd, const sqfs_inode_generic_t *inode,
+		     void *buffer, sqfs_u64 offset, size_t size)
+{
+	ssize_t ret;
+
+	ret = sqfs_data_reader_read(rd, inode, offset, buffer, size);
+	ret = (ret < 0 || (size_t)ret < size) ? -1 : 0;
+
+	if (ret) {
+		fprintf(stderr, "Failed to read %s from %s\n",
+			path, prefix);
+		return -1;
+	}
+
+	return 0;
+}
+
+int compare_files(sqfsdiff_t *sd, const sqfs_inode_generic_t *old,
+		  const sqfs_inode_generic_t *new, const char *path)
+{
+	sqfs_u64 offset, diff, oldsz, newsz;
+	int status = 0, ret;
+
+	sqfs_inode_get_file_size(old, &oldsz);
+	sqfs_inode_get_file_size(new, &newsz);
+
+	if (oldsz != newsz)
+		goto out_different;
+
+	if (sd->compare_flags & COMPARE_NO_CONTENTS)
+		return 0;
+
+	for (offset = 0; offset < oldsz; offset += diff) {
+		diff = oldsz - offset;
+
+		if (diff > MAX_WINDOW_SIZE)
+			diff = MAX_WINDOW_SIZE;
+
+		ret = read_blob(sd->old_path, path,
+				sd->sqfs_old.data, old, old_buf, offset, diff);
+		if (ret)
+			return -1;
+
+		ret = read_blob(sd->new_path, path,
+				sd->sqfs_new.data, new, new_buf, offset, diff);
+		if (ret)
+			return -1;
+
+		if (memcmp(old_buf, new_buf, diff) != 0)
+			goto out_different;
+	}
+
+	return status;
+out_different:
+	if (sd->compare_flags & COMPARE_EXTRACT_FILES) {
+		if (extract_files(sd, old, new, path))
+			return -1;
+	}
+	return 1;
+}