Add a helper utility to compare filesystem trees

The intended use case is to compare two mounted or unpacke squashfs
images, so a repacked test image can be compared against its original
or an image unpacked with unsquashfs can be compared with an image
unpacked by rdsquashfs or sqfs2tar.

Since the tool is only intended to aid development (specifically
automated testing), it is not installed by `make install`.

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

1 files changed, 118 insertions, 0 deletions

diff --git a/difftool/fscompare.c b/difftool/fscompare.c
new file mode 100644
index 0000000..c925adc
--- /dev/null
+++ b/difftool/fscompare.c
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * fscompare.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: fscompare [OPTIONS...] <first> <second>\n"
+"\n"
+"Compare two directories, making sure that each contains the same entries.\n"
+"If an entry is a directory, comparison recurses into the directory.\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";
+
+const char *first_path;
+const char *second_path;
+int compare_flags = 0;
+
+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 directory\n", stderr);
+		goto fail_arg;
+	}
+
+	first_path = argv[optind++];
+
+	if (optind >= argc) {
+		fputs("Missing arguments: second directory\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 `fscompare --help' for more information.\n");
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char **argv)
+{
+	int ret = EXIT_FAILURE;
+	fstree_t afs, bfs;
+
+	process_options(argc, argv);
+
+	if (fstree_init(&afs, 512, NULL))
+		return EXIT_FAILURE;
+
+	if (fstree_init(&bfs, 512, NULL))
+		goto out_afs;
+
+	if (fstree_from_dir(&afs, first_path, false))
+		goto out_bfs;
+
+	if (fstree_from_dir(&bfs, second_path, false))
+		goto out_bfs;
+
+	tree_node_sort_recursive(afs.root);
+	tree_node_sort_recursive(bfs.root);
+
+	if (node_compare(afs.root, bfs.root) == 0)
+		ret = EXIT_SUCCESS;
+
+out_bfs:
+	fstree_cleanup(&bfs);
+out_afs:
+	fstree_cleanup(&afs);
+	return ret;
+}