diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makemodule.am | 1 | ||||
| -rw-r--r-- | lib/sqfs/read_super.c | 84 |
2 files changed, 85 insertions, 0 deletions
diff --git a/lib/Makemodule.am b/lib/Makemodule.am index c2d7dab..026e3f1 100644 --- a/lib/Makemodule.am +++ b/lib/Makemodule.am @@ -11,6 +11,7 @@ libsquashfs_a_SOURCES = include/meta_writer.h include/squashfs.h libsquashfs_a_SOURCES += lib/sqfs/meta_writer.c lib/sqfs/super.c libsquashfs_a_SOURCES += lib/sqfs/id_table.c include/id_table.h libsquashfs_a_SOURCES += lib/sqfs/table.c include/table.h +libsquashfs_a_SOURCES += lib/sqfs/read_super.c libutil_a_SOURCES = lib/util/canonicalize_name.c lib/util/write_retry.c libutil_a_SOURCES += lib/util/read_retry.c include/util.h diff --git a/lib/sqfs/read_super.c b/lib/sqfs/read_super.c new file mode 100644 index 0000000..22dd822 --- /dev/null +++ b/lib/sqfs/read_super.c @@ -0,0 +1,84 @@ +/* SPDX-License-Identifier: GPL-3.0-or-later */ +#include "squashfs.h" +#include "util.h" + +#include <endian.h> +#include <string.h> +#include <unistd.h> +#include <stdio.h> + +int sqfs_super_read(sqfs_super_t *super, int fd) +{ + sqfs_super_t temp; + size_t block_size; + ssize_t ret; + int i; + + if (lseek(fd, 0, SEEK_SET) == (off_t)-1) + goto fail_seek; + + ret = read_retry(fd, &temp, sizeof(temp)); + + if (ret < 0) { + perror("reading super block"); + return -1; + } + + if ((size_t)ret < sizeof(temp)) { + fputs("reading super block: unexpected end of file\n", stderr); + return -1; + } + + temp.magic = le32toh(temp.magic); + temp.inode_count = le32toh(temp.inode_count); + temp.modification_time = le32toh(temp.modification_time); + temp.block_size = le32toh(temp.block_size); + temp.fragment_entry_count = le32toh(temp.fragment_entry_count); + temp.compression_id = le16toh(temp.compression_id); + temp.block_log = le16toh(temp.block_log); + temp.flags = le16toh(temp.flags); + temp.id_count = le16toh(temp.id_count); + temp.version_major = le16toh(temp.version_major); + temp.version_minor = le16toh(temp.version_minor); + temp.root_inode_ref = le64toh(temp.root_inode_ref); + temp.bytes_used = le64toh(temp.bytes_used); + temp.id_table_start = le64toh(temp.id_table_start); + temp.xattr_id_table_start = le64toh(temp.xattr_id_table_start); + temp.inode_table_start = le64toh(temp.inode_table_start); + temp.directory_table_start = le64toh(temp.directory_table_start); + temp.fragment_table_start = le64toh(temp.fragment_table_start); + temp.export_table_start = le64toh(temp.export_table_start); + + if (temp.magic != SQFS_MAGIC) { + fputs("Magic number missing. Not a squashfs image.\n", stderr); + return -1; + } + + if ((temp.block_size - 1) & temp.block_size) { + fputs("Block size in image is not a power of 2!\n", stderr); + return -1; + } + + block_size = 1; + + for (i = 0; i < temp.block_log; ++i) + block_size <<= 1; + + if (temp.block_size != block_size) { + fputs("Mismatch between block size and block log\n", stderr); + fputs("Filesystem probably currupted.\n", stderr); + return -1; + } + + if (temp.compression_id < SQFS_COMP_MIN || + temp.compression_id > SQFS_COMP_MAX) { + fputs("Image uses an unsupported compressor\n", stderr); + return -1; + } + + memcpy(super, &temp, sizeof(temp)); + return 0; +fail_seek: + perror("squashfs writing super block: seek on output file"); + return -1; +} |