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, 121 insertions, 0 deletions

diff --git a/difftool/sqfsdiff.c b/difftool/sqfsdiff.c
new file mode 100644
index 0000000..2fc10a1
--- /dev/null
+++ b/difftool/sqfsdiff.c
@@ -0,0 +1,121 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * sqfsdiff.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "difftool.h"
+
+static struct option long_opts[] = {
+	{ "no-owner", no_argument, NULL, 'O' },
+	{ "no-permissions", no_argument, NULL, 'P' },
+	{ "help", no_argument, NULL, 'h' },
+	{ "version", no_argument, NULL, 'V' },
+};
+
+static const char *short_opts = "OPhV";
+
+static const char *usagestr =
+"Usage: sqfsdiff [OPTIONS...] <first> <second>\n"
+"\n"
+"Compare the contents of two squashfs images. In contrast to doing a direct\n"
+"diff of the images, this actually recovers the file system trees and\n"
+"recursively compares them against each other.\n"
+"\n"
+"Any differences in packed file layout, ordering, compression, inode\n"
+"allocation and so on is ignored, only the contents are compared.\n"
+"\n"
+"The two images are considered equal if each directory contains the same\n"
+"entries, symlink with the same paths have the same targets, device nodes\n"
+"the same device number and files the same size and contents.\n"
+"\n"
+"A report of any difference is printed to stdout. The exit status is similar\n"
+"that of diff(1): 0 means equal, 1 means different, 2 means problem.\n"
+"\n"
+"Possible options:\n"
+"\n"
+"  --no-owner, -O              Do not compare file owners.\n"
+"  --no-permissions, -P        Do not compare permission bits.\n"
+"\n"
+"  --help, -h                  Print help text and exit.\n"
+"  --version, -V               Print version information and exit.\n"
+"\n";
+
+int compare_flags = 0;
+const char *first_path;
+const char *second_path;
+sqfs_reader_t sqfs_a;
+sqfs_reader_t sqfs_b;
+
+static void process_options(int argc, char **argv)
+{
+	int i;
+
+	for (;;) {
+		i = getopt_long(argc, argv, short_opts, long_opts, NULL);
+		if (i == -1)
+			break;
+
+		switch (i) {
+		case 'O':
+			compare_flags |= COMPARE_NO_OWNER;
+			break;
+		case 'P':
+			compare_flags |= COMPARE_NO_PERM;
+			break;
+		case 'h':
+			fputs(usagestr, stdout);
+			exit(EXIT_SUCCESS);
+		case 'V':
+			print_version();
+			exit(EXIT_SUCCESS);
+		default:
+			goto fail_arg;
+		}
+	}
+
+	if (optind >= argc) {
+		fputs("Missing arguments: first filesystem\n", stderr);
+		goto fail_arg;
+	}
+
+	first_path = argv[optind++];
+
+	if (optind >= argc) {
+		fputs("Missing arguments: second filesystem\n", stderr);
+		goto fail_arg;
+	}
+
+	second_path = argv[optind++];
+
+	if (optind < argc) {
+		fputs("Unknown extra arguments\n", stderr);
+		goto fail_arg;
+	}
+	return;
+fail_arg:
+	fprintf(stderr, "Try `sqfsdiff --help' for more information.\n");
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char **argv)
+{
+	int ret = EXIT_FAILURE;
+
+	process_options(argc, argv);
+
+	if (sqfs_reader_open(&sqfs_a, first_path, 0))
+		return EXIT_FAILURE;
+
+	if (sqfs_reader_open(&sqfs_b, second_path, 0))
+		goto out_sqfs_a;
+
+	ret = node_compare(sqfs_a.fs.root, sqfs_b.fs.root);
+	if (ret < 0)
+		ret = 2;
+
+	sqfs_reader_close(&sqfs_b);
+out_sqfs_a:
+	sqfs_reader_close(&sqfs_a);
+	return ret;
+}