Move library source into src sub-directory

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

9 files changed, 953 insertions, 0 deletions

diff --git a/bin/sqfsdiff/src/compare_dir.c b/bin/sqfsdiff/src/compare_dir.c
new file mode 100644
index 0000000..1a4c800
--- /dev/null
+++ b/bin/sqfsdiff/src/compare_dir.c
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * compare_dir.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "sqfsdiff.h"
+
+static int print_omitted(sqfsdiff_t *sd, bool is_old, sqfs_tree_node_t *n)
+{
+	char *path = node_path(n);
+
+	if (path == NULL)
+		return -1;
+
+	fprintf(stdout, "%c %s\n", is_old ? '<' : '>', path);
+
+	if ((sd->compare_flags & COMPARE_EXTRACT_FILES) &&
+	    S_ISREG(n->inode->base.mode)) {
+		if (extract_files(sd, is_old ? n->inode : NULL,
+				  is_old ? NULL : n->inode, path)) {
+			free(path);
+			return -1;
+		}
+	}
+
+	free(path);
+
+	for (n = n->children; n != NULL; n = n->next) {
+		if (print_omitted(sd, is_old, n))
+			return -1;
+	}
+
+	return 0;
+}
+
+int compare_dir_entries(sqfsdiff_t *sd, sqfs_tree_node_t *old,
+			sqfs_tree_node_t *new)
+{
+	sqfs_tree_node_t *old_it = old->children, *old_prev = NULL;
+	sqfs_tree_node_t *new_it = new->children, *new_prev = NULL;
+	int ret, result = 0;
+
+	while (old_it != NULL || new_it != NULL) {
+		if (old_it != NULL && new_it != NULL) {
+			ret = strcmp((const char *)old_it->name,
+				     (const char *)new_it->name);
+		} else if (old_it == NULL) {
+			ret = 1;
+		} else {
+			ret = -1;
+		}
+
+		if (ret < 0) {
+			result = 1;
+
+			if (print_omitted(sd, true, old_it))
+				return -1;
+
+			if (old_prev == NULL) {
+				old->children = old_it->next;
+				sqfs_dir_tree_destroy(old_it);
+				old_it = old->children;
+			} else {
+				old_prev->next = old_it->next;
+				sqfs_dir_tree_destroy(old_it);
+				old_it = old_prev->next;
+			}
+		} else if (ret > 0) {
+			result = 1;
+
+			if (print_omitted(sd, false, new_it))
+				return -1;
+
+			if (new_prev == NULL) {
+				new->children = new_it->next;
+				sqfs_dir_tree_destroy(new_it);
+				new_it = new->children;
+			} else {
+				new_prev->next = new_it->next;
+				sqfs_dir_tree_destroy(new_it);
+				new_it = new_prev->next;
+			}
+		} else {
+			old_prev = old_it;
+			old_it = old_it->next;
+
+			new_prev = new_it;
+			new_it = new_it->next;
+		}
+	}
+
+	return result;
+}
diff --git a/bin/sqfsdiff/src/compare_files.c b/bin/sqfsdiff/src/compare_files.c
new file mode 100644
index 0000000..51b66bb
--- /dev/null
+++ b/bin/sqfsdiff/src/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;
+}
diff --git a/bin/sqfsdiff/src/extract.c b/bin/sqfsdiff/src/extract.c
new file mode 100644
index 0000000..f2072d4
--- /dev/null
+++ b/bin/sqfsdiff/src/extract.c
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * extract.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "sqfsdiff.h"
+
+static int extract(sqfs_data_reader_t *data, const sqfs_inode_generic_t *inode,
+		   const char *prefix, const char *path, size_t block_size)
+{
+	char *ptr, *temp;
+	ostream_t *fp;
+
+	temp = alloca(strlen(prefix) + strlen(path) + 2);
+	sprintf(temp, "%s/%s", prefix, path);
+
+	ptr = strrchr(temp, '/');
+	*ptr = '\0';
+	if (mkdir_p(temp))
+		return -1;
+	*ptr = '/';
+
+	fp = ostream_open_file(temp, OSTREAM_OPEN_OVERWRITE |
+			       OSTREAM_OPEN_SPARSE);
+	if (fp == NULL) {
+		perror(temp);
+		return -1;
+	}
+
+	if (sqfs_data_reader_dump(path, data, inode, fp, block_size)) {
+		sqfs_drop(fp);
+		return -1;
+	}
+
+	ostream_flush(fp);
+	sqfs_drop(fp);
+	return 0;
+}
+
+int extract_files(sqfsdiff_t *sd, const sqfs_inode_generic_t *old,
+		  const sqfs_inode_generic_t *new,
+		  const char *path)
+{
+	if (old != NULL) {
+		if (extract(sd->sqfs_old.data, old, "old",
+			    path, sd->sqfs_old.super.block_size))
+			return -1;
+	}
+
+	if (new != NULL) {
+		if (extract(sd->sqfs_new.data, new, "new",
+			    path, sd->sqfs_new.super.block_size))
+			return -1;
+	}
+
+	return 0;
+}
diff --git a/bin/sqfsdiff/src/node_compare.c b/bin/sqfsdiff/src/node_compare.c
new file mode 100644
index 0000000..a0c99c7
--- /dev/null
+++ b/bin/sqfsdiff/src/node_compare.c
@@ -0,0 +1,206 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * node_compare.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "sqfsdiff.h"
+
+int node_compare(sqfsdiff_t *sd, sqfs_tree_node_t *a, sqfs_tree_node_t *b)
+{
+	sqfs_tree_node_t *ait, *bit;
+	bool promoted, demoted;
+	int ret, status = 0;
+	char *path;
+
+	ret = sqfs_tree_node_get_path(a, &path);
+	if (ret != 0) {
+		sqfs_perror(NULL, "constructing absolute file path", ret);
+		return -1;
+	}
+
+	if (a->inode->base.type != b->inode->base.type) {
+		promoted = demoted = false;
+
+		switch (a->inode->base.type) {
+		case SQFS_INODE_DIR:
+			if (b->inode->base.type == SQFS_INODE_EXT_DIR)
+				promoted = true;
+			break;
+		case SQFS_INODE_FILE:
+			if (b->inode->base.type == SQFS_INODE_EXT_FILE)
+				promoted = true;
+			break;
+		case SQFS_INODE_SLINK:
+			if (b->inode->base.type == SQFS_INODE_EXT_SLINK)
+				promoted = true;
+			break;
+		case SQFS_INODE_BDEV:
+			if (b->inode->base.type == SQFS_INODE_EXT_BDEV)
+				promoted = true;
+			break;
+		case SQFS_INODE_CDEV:
+			if (b->inode->base.type == SQFS_INODE_EXT_CDEV)
+				promoted = true;
+			break;
+		case SQFS_INODE_FIFO:
+			if (b->inode->base.type == SQFS_INODE_EXT_FIFO)
+				promoted = true;
+			break;
+		case SQFS_INODE_SOCKET:
+			if (b->inode->base.type == SQFS_INODE_EXT_SOCKET)
+				promoted = true;
+			break;
+		case SQFS_INODE_EXT_DIR:
+			if (b->inode->base.type == SQFS_INODE_DIR)
+				demoted = true;
+			break;
+		case SQFS_INODE_EXT_FILE:
+			if (b->inode->base.type == SQFS_INODE_FILE)
+				demoted = true;
+			break;
+		case SQFS_INODE_EXT_SLINK:
+			if (b->inode->base.type == SQFS_INODE_SLINK)
+				demoted = true;
+			break;
+		case SQFS_INODE_EXT_BDEV:
+			if (b->inode->base.type == SQFS_INODE_BDEV)
+				demoted = true;
+			break;
+		case SQFS_INODE_EXT_CDEV:
+			if (b->inode->base.type == SQFS_INODE_CDEV)
+				demoted = true;
+			break;
+		case SQFS_INODE_EXT_FIFO:
+			if (b->inode->base.type == SQFS_INODE_FIFO)
+				demoted = true;
+			break;
+		case SQFS_INODE_EXT_SOCKET:
+			if (b->inode->base.type == SQFS_INODE_SOCKET)
+				demoted = true;
+			break;
+		default:
+			break;
+		}
+
+		if (promoted) {
+			fprintf(stdout, "%s has an extended type\n", path);
+			status = 1;
+		} else if (demoted) {
+			fprintf(stdout, "%s has a basic type\n", path);
+			status = 1;
+		} else {
+			fprintf(stdout, "%s has a different type\n", path);
+			sqfs_free(path);
+			return 1;
+		}
+	}
+
+	if (!(sd->compare_flags & COMPARE_NO_PERM)) {
+		if ((a->inode->base.mode & ~S_IFMT) !=
+		    (b->inode->base.mode & ~S_IFMT)) {
+			fprintf(stdout, "%s has different permissions\n",
+				path);
+			status = 1;
+		}
+	}
+
+	if (!(sd->compare_flags & COMPARE_NO_OWNER)) {
+		if (a->uid != b->uid || a->gid != b->gid) {
+			fprintf(stdout, "%s has different ownership\n", path);
+			status = 1;
+		}
+	}
+
+	if (sd->compare_flags & COMPARE_TIMESTAMP) {
+		if (a->inode->base.mod_time != b->inode->base.mod_time) {
+			fprintf(stdout, "%s has a different timestamp\n", path);
+			status = 1;
+		}
+	}
+
+	if (sd->compare_flags & COMPARE_INODE_NUM) {
+		if (a->inode->base.inode_number !=
+		    b->inode->base.inode_number) {
+			fprintf(stdout, "%s has a different inode number\n",
+				path);
+			status = 1;
+		}
+	}
+
+	switch (a->inode->base.type) {
+	case SQFS_INODE_SOCKET:
+	case SQFS_INODE_EXT_SOCKET:
+	case SQFS_INODE_FIFO:
+	case SQFS_INODE_EXT_FIFO:
+		break;
+	case SQFS_INODE_BDEV:
+	case SQFS_INODE_CDEV:
+		if (a->inode->data.dev.devno != b->inode->data.dev.devno) {
+			fprintf(stdout, "%s has different device number\n",
+				path);
+			status = 1;
+		}
+		break;
+	case SQFS_INODE_EXT_BDEV:
+	case SQFS_INODE_EXT_CDEV:
+		if (a->inode->data.dev_ext.devno !=
+		    b->inode->data.dev_ext.devno) {
+			fprintf(stdout, "%s has different device number\n",
+				path);
+			status = 1;
+		}
+		break;
+	case SQFS_INODE_SLINK:
+	case SQFS_INODE_EXT_SLINK:
+		if (strcmp((const char *)a->inode->extra,
+			   (const char *)b->inode->extra)) {
+			fprintf(stdout, "%s has a different link target\n",
+				path);
+		}
+		break;
+	case SQFS_INODE_DIR:
+	case SQFS_INODE_EXT_DIR:
+		ret = compare_dir_entries(sd, a, b);
+		if (ret < 0) {
+			status = -1;
+			break;
+		}
+		if (ret > 0)
+			status = 1;
+
+		sqfs_free(path);
+		path = NULL;
+
+		ait = a->children;
+		bit = b->children;
+
+		while (ait != NULL && bit != NULL) {
+			ret = node_compare(sd, ait, bit);
+			if (ret < 0)
+				return -1;
+			if (ret > 0)
+				status = 1;
+
+			ait = ait->next;
+			bit = bit->next;
+		}
+		break;
+	case SQFS_INODE_FILE:
+	case SQFS_INODE_EXT_FILE:
+		ret = compare_files(sd, a->inode, b->inode, path);
+		if (ret < 0) {
+			status = -1;
+		} else if (ret > 0) {
+			fprintf(stdout, "regular file %s differs\n", path);
+			status = 1;
+		}
+		break;
+	default:
+		fprintf(stdout, "%s has unknown type, ignoring\n", path);
+		break;
+	}
+
+	sqfs_free(path);
+	return status;
+}
diff --git a/bin/sqfsdiff/src/options.c b/bin/sqfsdiff/src/options.c
new file mode 100644
index 0000000..b8ce7f0
--- /dev/null
+++ b/bin/sqfsdiff/src/options.c
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * sqfsdiff.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "sqfsdiff.h"
+
+static struct option long_opts[] = {
+	{ "old", required_argument, NULL, 'a' },
+	{ "new", required_argument, NULL, 'b' },
+	{ "no-owner", no_argument, NULL, 'O' },
+	{ "no-permissions", no_argument, NULL, 'P' },
+	{ "no-contents", no_argument, NULL, 'C' },
+	{ "timestamps", no_argument, NULL, 'T' },
+	{ "inode-num", no_argument, NULL, 'I' },
+	{ "super", no_argument, NULL, 'S' },
+	{ "extract", required_argument, NULL, 'e' },
+	{ "help", no_argument, NULL, 'h' },
+	{ "version", no_argument, NULL, 'V' },
+	{ NULL, 0, NULL, 0 },
+};
+
+static const char *short_opts = "a:b:OPCTISe:hV";
+
+static const char *usagestr =
+"Usage: sqfsdiff [OPTIONS...] --old,-a <first> --new,-b <second>\n"
+"\n"
+"Compare two squashfs images. In contrast to doing a direct diff of the\n"
+"images, this actually parses the filesystems and generates a more\n"
+"meaningful difference report.\n"
+"\n"
+"If only contents are compared, any differences in packed file layout,\n"
+"ordering, compression, inode meta data and so on is ignored and the two\n"
+"images are considered equal if each directory contains the same entries,\n"
+"symlink with the same paths have the same targets, device nodes the same\n"
+"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"
+"  --old, -a <first>           The first of the two filesystems to compare.\n"
+"  --new, -b <second>          The second of the two filesystems to compare.\n"
+"\n"
+"  --no-contents, -C           Do not compare file contents.\n"
+"  --no-owner, -O              Do not compare file owners.\n"
+"  --no-permissions, -P        Do not compare permission bits.\n"
+"\n"
+"  --timestamps, -T            Compare file timestamps.\n"
+"  --inode-num, -I             Compare inode numbers of all files.\n"
+"  --super, -S                 Also compare meta data in super blocks.\n"
+"\n"
+"  --extract, -e <path>        Extract files that differ to the specified\n"
+"                              directory. Contents of the first filesystem\n"
+"                              end up in a subdirectory 'old' and of the\n"
+"                              second filesystem in a subdirectory 'new'.\n"
+"\n"
+"  --help, -h                  Print help text and exit.\n"
+"  --version, -V               Print version information and exit.\n"
+"\n";
+
+void process_options(sqfsdiff_t *sd, int argc, char **argv)
+{
+	int i;
+
+	for (;;) {
+		i = getopt_long(argc, argv, short_opts, long_opts, NULL);
+		if (i == -1)
+			break;
+
+		switch (i) {
+		case 'a':
+			sd->old_path = optarg;
+			break;
+		case 'b':
+			sd->new_path = optarg;
+			break;
+		case 'O':
+			sd->compare_flags |= COMPARE_NO_OWNER;
+			break;
+		case 'P':
+			sd->compare_flags |= COMPARE_NO_PERM;
+			break;
+		case 'C':
+			sd->compare_flags |= COMPARE_NO_CONTENTS;
+			break;
+		case 'T':
+			sd->compare_flags |= COMPARE_TIMESTAMP;
+			break;
+		case 'I':
+			sd->compare_flags |= COMPARE_INODE_NUM;
+			break;
+		case 'S':
+			sd->compare_super = true;
+			break;
+		case 'e':
+			sd->compare_flags |= COMPARE_EXTRACT_FILES;
+			sd->extract_dir = optarg;
+			break;
+		case 'h':
+			fputs(usagestr, stdout);
+			exit(0);
+		case 'V':
+			print_version("sqfsdiff");
+			exit(0);
+		default:
+			goto fail_arg;
+		}
+	}
+
+	if (sd->old_path == NULL) {
+		fputs("Missing arguments: first filesystem\n", stderr);
+		goto fail_arg;
+	}
+
+	if (sd->new_path == NULL) {
+		fputs("Missing arguments: second filesystem\n", stderr);
+		goto fail_arg;
+	}
+
+	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(2);
+}
diff --git a/bin/sqfsdiff/src/sqfsdiff.c b/bin/sqfsdiff/src/sqfsdiff.c
new file mode 100644
index 0000000..d789fe1
--- /dev/null
+++ b/bin/sqfsdiff/src/sqfsdiff.c
@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * sqfsdiff.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "sqfsdiff.h"
+
+static void close_sfqs(sqfs_state_t *state)
+{
+	sqfs_drop(state->data);
+	sqfs_dir_tree_destroy(state->root);
+	sqfs_drop(state->dr);
+	sqfs_drop(state->idtbl);
+	sqfs_drop(state->cmp);
+	sqfs_drop(state->file);
+}
+
+static int open_sfqs(sqfs_state_t *state, const char *path)
+{
+	int ret;
+
+	memset(state, 0, sizeof(*state));
+
+	state->file = sqfs_open_file(path, SQFS_FILE_OPEN_READ_ONLY);
+	if (state->file == NULL) {
+		perror(path);
+		return -1;
+	}
+
+	ret = sqfs_super_read(&state->super, state->file);
+	if (ret) {
+		sqfs_perror(path, "reading super block", ret);
+		goto fail;
+	}
+
+	sqfs_compressor_config_init(&state->cfg, state->super.compression_id,
+				    state->super.block_size,
+				    SQFS_COMP_FLAG_UNCOMPRESS);
+
+	ret = sqfs_compressor_create(&state->cfg, &state->cmp);
+
+#ifdef WITH_LZO
+	if (state->super.compression_id == SQFS_COMP_LZO && ret != 0)
+		ret = lzo_compressor_create(&state->cfg, &state->cmp);
+#endif
+
+	if (ret != 0) {
+		sqfs_perror(path, "creating compressor", ret);
+		goto fail;
+	}
+
+	if (state->super.flags & SQFS_FLAG_COMPRESSOR_OPTIONS) {
+		ret = state->cmp->read_options(state->cmp, state->file);
+
+		if (ret == 0) {
+			state->cmp->get_configuration(state->cmp,
+						      &state->options);
+			state->have_options = true;
+		} else {
+			sqfs_perror(path, "reading compressor options", ret);
+			state->have_options = false;
+		}
+	} else {
+		state->have_options = false;
+	}
+
+	state->idtbl = sqfs_id_table_create(0);
+	if (state->idtbl == NULL) {
+		sqfs_perror(path, "creating ID table", SQFS_ERROR_ALLOC);
+		goto fail;
+	}
+
+	ret = sqfs_id_table_read(state->idtbl, state->file,
+				 &state->super, state->cmp);
+	if (ret) {
+		sqfs_perror(path, "loading ID table", ret);
+		goto fail;
+	}
+
+	state->dr = sqfs_dir_reader_create(&state->super, state->cmp,
+					   state->file, 0);
+	if (state->dr == NULL) {
+		sqfs_perror(path, "creating directory reader",
+			    SQFS_ERROR_ALLOC);
+		goto fail;
+	}
+
+	ret = sqfs_dir_reader_get_full_hierarchy(state->dr, state->idtbl,
+						 NULL, 0, &state->root);
+	if (ret) {
+		sqfs_perror(path, "loading filesystem tree", ret);
+		goto fail;
+	}
+
+	state->data = sqfs_data_reader_create(state->file,
+					      state->super.block_size,
+					      state->cmp, 0);
+	if (state->data == NULL) {
+		sqfs_perror(path, "creating data reader", SQFS_ERROR_ALLOC);
+		goto fail;
+	}
+
+	ret = sqfs_data_reader_load_fragment_table(state->data, &state->super);
+	if (ret) {
+		sqfs_perror(path, "loading fragment table", ret);
+		goto fail;
+	}
+
+	return 0;
+fail:
+	close_sfqs(state);
+	return -1;
+}
+
+int main(int argc, char **argv)
+{
+	int status, ret = 0;
+	sqfsdiff_t sd;
+
+	memset(&sd, 0, sizeof(sd));
+	process_options(&sd, argc, argv);
+
+	if (sd.extract_dir != NULL) {
+		if (mkdir_p(sd.extract_dir))
+			return 2;
+	}
+
+	if (open_sfqs(&sd.sqfs_old, sd.old_path))
+		return 2;
+
+	if (open_sfqs(&sd.sqfs_new, sd.new_path)) {
+		status = 2;
+		goto out_sqfs_old;
+	}
+
+	if (sd.extract_dir != NULL) {
+		if (chdir(sd.extract_dir)) {
+			perror(sd.extract_dir);
+			ret = -1;
+			goto out;
+		}
+	}
+
+	ret = node_compare(&sd, sd.sqfs_old.root, sd.sqfs_new.root);
+	if (ret != 0)
+		goto out;
+
+	if (sd.compare_super) {
+		ret = compare_super_blocks(&sd.sqfs_old.super,
+					   &sd.sqfs_new.super);
+		if (ret != 0)
+			goto out;
+	}
+out:
+	if (ret < 0) {
+		status = 2;
+	} else if (ret > 0) {
+		status = 1;
+	} else {
+		status = 0;
+	}
+	close_sfqs(&sd.sqfs_new);
+out_sqfs_old:
+	close_sfqs(&sd.sqfs_old);
+	return status;
+}
diff --git a/bin/sqfsdiff/src/sqfsdiff.h b/bin/sqfsdiff/src/sqfsdiff.h
new file mode 100644
index 0000000..65e8120
--- /dev/null
+++ b/bin/sqfsdiff/src/sqfsdiff.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * sqfsdiff.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef DIFFTOOL_H
+#define DIFFTOOL_H
+
+#include "config.h"
+#include "common.h"
+#include "fstree.h"
+#include "util/util.h"
+
+#include <stdlib.h>
+#include <getopt.h>
+#include <string.h>
+#include <errno.h>
+
+#define MAX_WINDOW_SIZE (1024 * 1024 * 4)
+
+typedef struct {
+	sqfs_compressor_config_t cfg;
+	sqfs_compressor_t *cmp;
+	sqfs_super_t super;
+	sqfs_file_t *file;
+	sqfs_id_table_t *idtbl;
+	sqfs_dir_reader_t *dr;
+	sqfs_tree_node_t *root;
+	sqfs_data_reader_t *data;
+
+	sqfs_compressor_config_t options;
+	bool have_options;
+} sqfs_state_t;
+
+typedef struct {
+	const char *old_path;
+	const char *new_path;
+	int compare_flags;
+	sqfs_state_t sqfs_old;
+	sqfs_state_t sqfs_new;
+	bool compare_super;
+	const char *extract_dir;
+} sqfsdiff_t;
+
+enum {
+	COMPARE_NO_PERM = 0x01,
+	COMPARE_NO_OWNER = 0x02,
+	COMPARE_NO_CONTENTS = 0x04,
+	COMPARE_TIMESTAMP = 0x08,
+	COMPARE_INODE_NUM = 0x10,
+	COMPARE_EXTRACT_FILES = 0x20,
+};
+
+int compare_dir_entries(sqfsdiff_t *sd, sqfs_tree_node_t *old,
+			sqfs_tree_node_t *new);
+
+char *node_path(const sqfs_tree_node_t *n);
+
+int compare_files(sqfsdiff_t *sd, const sqfs_inode_generic_t *old,
+		  const sqfs_inode_generic_t *new, const char *path);
+
+int node_compare(sqfsdiff_t *sd, sqfs_tree_node_t *a, sqfs_tree_node_t *b);
+
+int compare_super_blocks(const sqfs_super_t *a, const sqfs_super_t *b);
+
+int extract_files(sqfsdiff_t *sd, const sqfs_inode_generic_t *old,
+		  const sqfs_inode_generic_t *new,
+		  const char *path);
+
+void process_options(sqfsdiff_t *sd, int argc, char **argv);
+
+#endif /* DIFFTOOL_H */
diff --git a/bin/sqfsdiff/src/super.c b/bin/sqfsdiff/src/super.c
new file mode 100644
index 0000000..0cf18e0
--- /dev/null
+++ b/bin/sqfsdiff/src/super.c
@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * super.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "sqfsdiff.h"
+
+static const struct {
+	sqfs_u16 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_NO_DUPLICATES, "no 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, sqfs_u64 a, sqfs_u64 b)
+{
+	sqfs_u64 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,
+			(unsigned long)diff);
+	}
+}
+
+static void print_offset_diff(const char *name, sqfs_u64 a, sqfs_u64 b)
+{
+	if (a != b)
+		fprintf(stdout, "Location of %s differs\n", name);
+}
+
+static void print_flag_diff(sqfs_u16 a, sqfs_u16 b)
+{
+	sqfs_u16 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",
+			sqfs_compressor_name_from_id(a->compression_id),
+			sqfs_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;
+}
diff --git a/bin/sqfsdiff/src/util.c b/bin/sqfsdiff/src/util.c
new file mode 100644
index 0000000..a11770f
--- /dev/null
+++ b/bin/sqfsdiff/src/util.c
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * util.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "sqfsdiff.h"
+
+char *node_path(const sqfs_tree_node_t *n)
+{
+	char *path;
+	int ret;
+
+	ret = sqfs_tree_node_get_path(n, &path);
+	if (ret != 0) {
+		sqfs_perror(NULL, "get path", ret);
+		return NULL;
+	}
+
+	if (canonicalize_name(path)) {
+		fprintf(stderr, "failed to canonicalization '%s'\n", path);
+		sqfs_free(path);
+		return NULL;
+	}
+
+	return path;
+}