Add flag to sqfsdiff to compare the fields in the super block

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

4 files changed, 155 insertions, 8 deletions

diff --git a/difftool/Makemodule.am b/difftool/Makemodule.am
index 62c9197..1b0011b 100644
--- a/difftool/Makemodule.am
+++ b/difftool/Makemodule.am
@@ -5,7 +5,7 @@ fscompare_LDADD = libfstree.a libutil.a
 
 sqfsdiff_SOURCES = difftool/sqfsdiff.c difftool/difftool.h difftool/util.c
 sqfsdiff_SOURCES += difftool/compare_dir.c difftool/node_compare.c
-sqfsdiff_SOURCES += difftool/compare_files_sqfs.c
+sqfsdiff_SOURCES += difftool/compare_files_sqfs.c difftool/super.c
 sqfsdiff_LDADD = libsquashfs.a libfstree.a libcompress.a libutil.a
 sqfsdiff_LDADD += $(XZ_LIBS) $(ZLIB_LIBS) $(LZO_LIBS) $(LZ4_LIBS) $(ZSTD_LIBS)
 
diff --git a/difftool/difftool.h b/difftool/difftool.h
index 4b6173a..23a161c 100644
--- a/difftool/difftool.h
+++ b/difftool/difftool.h
@@ -45,4 +45,6 @@ int compare_files(file_info_t *a, file_info_t *b, const char *path);
 
 int node_compare(tree_node_t *a, tree_node_t *b);
 
+int compare_super_blocks(const sqfs_super_t *a, const sqfs_super_t *b);
+
 #endif /* DIFFTOOL_H */
diff --git a/difftool/sqfsdiff.c b/difftool/sqfsdiff.c
index 96a8f31..8818a37 100644
--- a/difftool/sqfsdiff.c
+++ b/difftool/sqfsdiff.c
@@ -12,11 +12,12 @@ static struct option long_opts[] = {
 	{ "no-contents", no_argument, NULL, 'C' },
 	{ "timestamps", no_argument, NULL, 'T' },
 	{ "inode-num", no_argument, NULL, 'I' },
+	{ "super", no_argument, NULL, 'S' },
 	{ "help", no_argument, NULL, 'h' },
 	{ "version", no_argument, NULL, 'V' },
 };
 
-static const char *short_opts = "OPCTIhV";
+static const char *short_opts = "OPCTIShV";
 
 static const char *usagestr =
 "Usage: sqfsdiff [OPTIONS...] <first> <second>\n"
@@ -42,6 +43,7 @@ static const char *usagestr =
 "\n"
 "  --timestamps, -T            Compare file timestamps.\n"
 "  --inode-num, -I             Compare inode numbers of all files.\n"
+"  --super, -S                 Also compare metadata in super blocks.\n"
 "\n"
 "  --help, -h                  Print help text and exit.\n"
 "  --version, -V               Print version information and exit.\n"
@@ -52,6 +54,7 @@ const char *first_path;
 const char *second_path;
 sqfs_reader_t sqfs_a;
 sqfs_reader_t sqfs_b;
+static bool compare_super = false;
 
 static void process_options(int argc, char **argv)
 {
@@ -78,6 +81,9 @@ static void process_options(int argc, char **argv)
 		case 'I':
 			compare_flags |= COMPARE_INODE_NUM;
 			break;
+		case 'S':
+			compare_super = true;
+			break;
 		case 'h':
 			fputs(usagestr, stdout);
 			exit(EXIT_SUCCESS);
@@ -115,22 +121,37 @@ fail_arg:
 
 int main(int argc, char **argv)
 {
-	int ret = EXIT_FAILURE;
+	int status, ret = 0;
 
 	process_options(argc, argv);
 
 	if (sqfs_reader_open(&sqfs_a, first_path, 0))
-		return EXIT_FAILURE;
+		return 2;
 
-	if (sqfs_reader_open(&sqfs_b, second_path, 0))
+	if (sqfs_reader_open(&sqfs_b, second_path, 0)) {
+		status = 2;
 		goto out_sqfs_a;
+	}
 
 	ret = node_compare(sqfs_a.fs.root, sqfs_b.fs.root);
-	if (ret < 0)
-		ret = 2;
+	if (ret != 0)
+		goto out;
 
+	if (compare_super) {
+		ret = compare_super_blocks(&sqfs_a.super, &sqfs_b.super);
+		if (ret != 0)
+			goto out;
+	}
+out:
+	if (ret < 0) {
+		status = 2;
+	} else if (ret > 0) {
+		status = 1;
+	} else {
+		status = 0;
+	}
 	sqfs_reader_close(&sqfs_b);
 out_sqfs_a:
 	sqfs_reader_close(&sqfs_a);
-	return ret;
+	return status;
 }
diff --git a/difftool/super.c b/difftool/super.c
new file mode 100644
index 0000000..7bda728
--- /dev/null
+++ b/difftool/super.c
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * super.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "difftool.h"
+
+static const struct {
+	uint16_t mask;
+	const char *name;
+} sqfs_flags[] = {
+	{ SQFS_FLAG_UNCOMPRESSED_INODES, "uncompressed inodes" },
+	{ SQFS_FLAG_UNCOMPRESSED_DATA, "uncompressed data" },
+	{ SQFS_FLAG_UNCOMPRESSED_FRAGMENTS, "uncompressed fragments" },
+	{ SQFS_FLAG_NO_FRAGMENTS, "no fragments" },
+	{ SQFS_FLAG_ALWAYS_FRAGMENTS, "always fragments" },
+	{ SQFS_FLAG_DUPLICATES, "duplicates" },
+	{ SQFS_FLAG_EXPORTABLE, "exportable" },
+	{ SQFS_FLAG_UNCOMPRESSED_XATTRS, "uncompressed xattrs" },
+	{ SQFS_FLAG_NO_XATTRS, "no xattrs" },
+	{ SQFS_FLAG_COMPRESSOR_OPTIONS, "compressor options" },
+	{ SQFS_FLAG_UNCOMPRESSED_IDS, "uncompressed ids" },
+};
+
+static void print_value_difference(const char *name, uint64_t a, uint64_t b)
+{
+	uint64_t diff;
+	char c;
+
+	if (a != b) {
+		if (a < b) {
+			c = '+';
+			diff = b - a;
+		} else {
+			c = '-';
+			diff = a - b;
+		}
+		fprintf(stdout, "%s: %c%lu\n", name, c, diff);
+	}
+}
+
+static void print_offset_diff(const char *name, uint64_t a, uint64_t b)
+{
+	if (a != b)
+		fprintf(stdout, "Location of %s differs\n", name);
+}
+
+static void print_flag_diff(uint16_t a, uint16_t b)
+{
+	uint16_t diff = a ^ b, mask;
+	size_t i;
+	char c;
+
+	if (diff == 0)
+		return;
+
+	fputs("flags:\n", stdout);
+
+	for (i = 0; i < sizeof(sqfs_flags) / sizeof(sqfs_flags[0]); ++i) {
+		if (diff & sqfs_flags[i].mask) {
+			c = a & sqfs_flags[i].mask ? '<' : '>';
+
+			fprintf(stdout, "\t%c%s\n", c, sqfs_flags[i].name);
+		}
+
+		a &= ~sqfs_flags[i].mask;
+		b &= ~sqfs_flags[i].mask;
+		diff &= ~sqfs_flags[i].mask;
+	}
+
+	for (i = 0, mask = 0x01; i < 16; ++i, mask <<= 1) {
+		if (diff & mask) {
+			fprintf(stdout, "\t%c additional unknown\n",
+				a & mask ? '<' : '>');
+		}
+	}
+}
+
+int compare_super_blocks(const sqfs_super_t *a, const sqfs_super_t *b)
+{
+	if (memcmp(a, b, sizeof(*a)) == 0)
+		return 0;
+
+	fputs("======== super blocks are different ========\n", stdout);
+
+	/* TODO: if a new magic number or squashfs version is introduced,
+	   compare them. */
+
+	print_value_difference("inode count", a->inode_count, b->inode_count);
+	print_value_difference("modification time", a->modification_time,
+			       b->modification_time);
+	print_value_difference("block size", a->block_size, b->block_size);
+	print_value_difference("block log", a->block_log, b->block_log);
+	print_value_difference("fragment table entries",
+			       a->fragment_entry_count,
+			       b->fragment_entry_count);
+	print_value_difference("ID table entries", a->id_count, b->id_count);
+
+	if (a->compression_id != b->compression_id) {
+		fprintf(stdout, "compressor: %s vs %s\n",
+			compressor_name_from_id(a->compression_id),
+			compressor_name_from_id(b->compression_id));
+	}
+
+	print_flag_diff(a->flags, b->flags);
+
+	print_value_difference("total bytes used", a->bytes_used,
+			       b->bytes_used);
+
+	print_offset_diff("root inode", a->root_inode_ref, b->root_inode_ref);
+	print_offset_diff("ID table", a->id_table_start, b->id_table_start);
+	print_offset_diff("xattr ID table", a->xattr_id_table_start,
+			  b->xattr_id_table_start);
+	print_offset_diff("inode table", a->inode_table_start,
+			  b->inode_table_start);
+	print_offset_diff("directory table", a->directory_table_start,
+			  b->directory_table_start);
+	print_offset_diff("fragment table", a->fragment_table_start,
+			  b->fragment_table_start);
+	print_offset_diff("export table", a->export_table_start,
+			  b->export_table_start);
+	return 1;
+}