Merge functionality of file on disk and file in sqfs compare functions

Moving towards unified sqfs vs sqfs, sqfs vs dir, dir vs sqfs
comparisions.

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

1 files changed, 97 insertions, 0 deletions

diff --git a/difftool/compare_files.c b/difftool/compare_files.c
new file mode 100644
index 0000000..89c5f5c
--- /dev/null
+++ b/difftool/compare_files.c
@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * compare_files.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)
+{
+	char second_name[strlen(second_path) + strlen(path) + 2];
+	char first_name[strlen(first_path) + strlen(path) + 2];
+	int afd = -1, bfd = -1, status = 0;
+	uint64_t offset, diff;
+	ssize_t ret;
+
+	if (a->size != b->size)
+		goto out_different;
+
+	if (compare_flags & COMPARE_NO_CONTENTS)
+		return 0;
+
+	if (a_is_dir) {
+		sprintf(first_name, "%s/%s", first_path, path);
+
+		afd = open(first_name, O_RDONLY);
+		if (afd < 0) {
+			perror(first_name);
+			goto fail;
+		}
+	}
+
+	if (b_is_dir) {
+		sprintf(second_name, "%s/%s", second_path, path);
+
+		bfd = open(second_name, O_RDONLY);
+		if (bfd < 0) {
+			perror(second_name);
+			goto fail;
+		}
+	}
+
+	for (offset = 0; offset < a->size; offset += diff) {
+		diff = a->size - offset;
+
+		if (diff > MAX_WINDOW_SIZE)
+			diff = MAX_WINDOW_SIZE;
+
+		if (a_is_dir) {
+			if (read_data_at(first_name, offset, afd, a_buf, diff))
+				goto out;
+		} else {
+			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;
+			}
+		}
+
+		if (b_is_dir) {
+			if (read_data_at(second_name, offset, bfd, b_buf, diff))
+				goto out;
+		} else {
+			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)
+			goto out_different;
+	}
+out:
+	if (afd >= 0)
+		close(afd);
+	if (bfd >= 0)
+		close(bfd);
+	return status;
+fail:
+	status = -1;
+	goto out;
+out_different:
+	if (compare_flags & COMPARE_EXTRACT_FILES) {
+		if (extract_files(a, b, path))
+			goto fail;
+	}
+	status = 1;
+	goto out;
+}