464 lines
14 KiB
C
464 lines
14 KiB
C
#include <stdint.h>
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#include <stddef.h>
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#include <stdbool.h>
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#include <fs/ext2.h>
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#include <drivers/disk.h>
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#include <lib/libc.h>
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#include <lib/blib.h>
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#include <lib/print.h>
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#include <mm/pmm.h>
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/* Inode types */
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#define S_IFIFO 0x1000
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#define S_IFCHR 0x2000
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#define S_IFDIR 0x4000
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#define S_IFBLK 0x6000
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#define S_IFREG 0x8000
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#define S_IFLNK 0xa000
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#define S_IFSOCK 0xc000
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#define FMT_MASK 0xf000
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/* EXT2 Filesystem States */
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#define EXT2_FS_UNRECOVERABLE_ERRORS 3
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/* Ext2 incompatible features */
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#define EXT2_IF_COMPRESSION 0x01
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#define EXT2_IF_EXTENTS 0x40
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#define EXT2_IF_64BIT 0x80
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#define EXT2_IF_INLINE_DATA 0x8000
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#define EXT2_IF_ENCRYPT 0x10000
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#define EXT2_FEATURE_INCOMPAT_META_BG 0x0010
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/* Ext4 flags */
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#define EXT4_EXTENTS_FLAG 0x80000
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#define EXT2_S_MAGIC 0xEF53
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/* EXT2 Block Group Descriptor */
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struct ext2_bgd {
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uint32_t bg_block_bitmap;
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uint32_t bg_inode_bitmap;
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uint32_t bg_inode_table;
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uint16_t bg_free_blocks_count;
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uint16_t bg_free_inodes_count;
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uint16_t bg_dirs_count;
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uint16_t reserved[7];
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} __attribute__((packed));
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struct ext4_bgd {
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uint32_t bg_block_bitmap;
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uint32_t bg_inode_bitmap;
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uint32_t bg_inode_table;
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uint16_t bg_free_blocks_count;
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uint16_t bg_free_inodes_count;
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uint16_t bg_dirs_count;
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uint16_t pad;
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uint32_t reserved[3];
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uint32_t block_id_hi;
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uint32_t inode_id_hi;
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uint32_t inode_table_id_hi;
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uint16_t free_blocks_hi;
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uint16_t free_inodes_hi;
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uint16_t used_dirs_hi;
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uint16_t pad2;
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uint32_t reserved2[3];
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} __attribute__((packed));
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/* EXT2 Inode Types */
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#define EXT2_INO_DIRECTORY 0x4000
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/* EXT2 Directory Entry */
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struct ext2_dir_entry {
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uint32_t inode;
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uint16_t rec_len;
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uint8_t name_len;
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uint8_t type;
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} __attribute__((packed));
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struct ext4_extent_header {
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uint16_t magic;
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uint16_t entries;
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uint16_t max;
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uint16_t depth;
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uint16_t generation;
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} __attribute__((packed));
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struct ext4_extent {
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uint32_t block;
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uint16_t len;
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uint16_t start_hi;
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uint32_t start;
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} __attribute__((packed));
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struct ext4_extent_idx {
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uint32_t block;
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uint32_t leaf;
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uint16_t leaf_hi;
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uint16_t empty;
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} __attribute__((packed));
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static int inode_read(void *buf, uint64_t loc, uint64_t count,
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struct ext2_inode *inode, struct ext2_file_handle *fd,
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uint32_t *alloc_map);
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static bool ext2_parse_dirent(struct ext2_dir_entry *dir, struct ext2_file_handle *fd, const char *path);
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// parse an inode given the partition base and inode number
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static bool ext2_get_inode(struct ext2_inode *ret,
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struct ext2_file_handle *fd, uint64_t inode) {
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if (inode == 0)
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return false;
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struct ext2_superblock *sb = &fd->sb;
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//determine if we need to use 64 bit inode ids
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bool bit64 = false;
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if (sb->s_rev_level != 0
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&& (sb->s_feature_incompat & (EXT2_IF_64BIT))
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&& sb->group_desc_size != 0
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&& ((sb->group_desc_size & (sb->group_desc_size - 1)) == 0)) {
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if(sb->group_desc_size > 32) {
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bit64 = true;
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}
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}
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const uint64_t ino_blk_grp = (inode - 1) / sb->s_inodes_per_group;
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const uint64_t ino_tbl_idx = (inode - 1) % sb->s_inodes_per_group;
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const uint64_t block_size = ((uint64_t)1024 << sb->s_log_block_size);
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uint64_t ino_offset;
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const uint64_t bgd_start_offset = block_size >= 2048 ? block_size : block_size * 2;
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const uint64_t ino_size = sb->s_rev_level == 0 ? sizeof(struct ext2_inode) : sb->s_inode_size;
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if (!bit64) {
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struct ext2_bgd target_descriptor;
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const uint64_t bgd_offset = bgd_start_offset + (sizeof(struct ext2_bgd) * ino_blk_grp);
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volume_read(fd->part, &target_descriptor, bgd_offset, sizeof(struct ext2_bgd));
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ino_offset = ((target_descriptor.bg_inode_table) * block_size) +
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(ino_size * ino_tbl_idx);
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} else {
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struct ext4_bgd target_descriptor;
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const uint64_t bgd_offset = bgd_start_offset + (sizeof(struct ext4_bgd) * ino_blk_grp);
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volume_read(fd->part, &target_descriptor, bgd_offset, sizeof(struct ext4_bgd));
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ino_offset = ((target_descriptor.bg_inode_table | (bit64 ? ((uint64_t)target_descriptor.inode_id_hi << 32) : 0)) * block_size) +
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(ino_size * ino_tbl_idx);
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}
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volume_read(fd->part, ret, ino_offset, sizeof(struct ext2_inode));
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return true;
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}
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static uint32_t *create_alloc_map(struct ext2_file_handle *fd,
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struct ext2_inode *inode) {
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if (inode->i_flags & EXT4_EXTENTS_FLAG)
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return NULL;
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size_t entries_per_block = fd->block_size / sizeof(uint32_t);
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// Cache the map of blocks
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uint32_t *alloc_map = ext_mem_alloc(inode->i_blocks_count * sizeof(uint32_t));
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for (uint32_t i = 0; i < inode->i_blocks_count; i++) {
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uint32_t block = i;
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if (block < 12) {
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// Direct block
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alloc_map[i] = inode->i_blocks[block];
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} else {
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// Indirect block
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block -= 12;
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if (block >= entries_per_block) {
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// Double indirect block
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block -= entries_per_block;
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uint32_t index = block / entries_per_block;
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uint32_t indirect_block;
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if (index >= entries_per_block) {
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uint32_t first_index = index / entries_per_block;
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uint32_t first_indirect_block;
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volume_read(
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fd->part, &first_indirect_block,
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inode->i_blocks[14] * fd->block_size + first_index * sizeof(uint32_t),
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sizeof(uint32_t)
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);
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uint32_t second_index = index % entries_per_block;
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volume_read(
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fd->part, &indirect_block,
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first_indirect_block * fd->block_size + second_index * sizeof(uint32_t),
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sizeof(uint32_t)
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);
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} else {
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volume_read(
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fd->part, &indirect_block,
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inode->i_blocks[13] * fd->block_size + index * sizeof(uint32_t),
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sizeof(uint32_t)
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);
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}
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for (uint32_t j = 0; j < entries_per_block; j++) {
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if (i + j >= inode->i_blocks_count)
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return alloc_map;
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volume_read(
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fd->part, &alloc_map[i + j],
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indirect_block * fd->block_size + j * sizeof(uint32_t),
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sizeof(uint32_t)
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);
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}
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i += entries_per_block - 1;
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} else {
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// Single indirect block
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volume_read(
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fd->part, &alloc_map[i],
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inode->i_blocks[12] * fd->block_size + block * sizeof(uint32_t),
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sizeof(uint32_t)
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);
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}
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}
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}
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return alloc_map;
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}
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static bool symlink_to_inode(struct ext2_inode *inode, struct ext2_file_handle *fd) {
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// I cannot find whether this is 0-terminated or not, so I'm gonna take the
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// safe route here and assume it is not.
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if (inode->i_size < 59) {
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struct ext2_dir_entry dir;
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char *symlink = (char *)inode->i_blocks;
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symlink[59] = 0;
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if (!ext2_parse_dirent(&dir, fd, symlink))
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return false;
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ext2_get_inode(inode, fd, dir.inode);
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return true;
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} else {
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print("ext2: Symlinks with destination paths longer than 60 chars unsupported\n");
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return false;
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}
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}
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static bool ext2_parse_dirent(struct ext2_dir_entry *dir, struct ext2_file_handle *fd, const char *path) {
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if (*path == '/')
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path++;
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struct ext2_inode current_inode = fd->root_inode;
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bool escape = false;
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static char token[256];
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next:
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memset(token, 0, 256);
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for (size_t i = 0; i < 255 && *path != '/' && *path != '\0'; i++, path++)
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token[i] = *path;
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if (*path == '\0')
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escape = true;
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else
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path++;
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uint32_t *alloc_map = create_alloc_map(fd, ¤t_inode);
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for (uint32_t i = 0; i < current_inode.i_size; ) {
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// preliminary read
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inode_read(dir, i, sizeof(struct ext2_dir_entry),
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¤t_inode, fd, alloc_map);
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// name read
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char name[dir->name_len + 1];
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memset(name, 0, dir->name_len + 1);
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inode_read(name, i + sizeof(struct ext2_dir_entry), dir->name_len,
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¤t_inode, fd, alloc_map);
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if (!strcmp(token, name)) {
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if (escape) {
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return true;
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} else {
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// update the current inode
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ext2_get_inode(¤t_inode, fd, dir->inode);
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while ((current_inode.i_mode & FMT_MASK) != S_IFDIR) {
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if ((current_inode.i_mode & FMT_MASK) == S_IFLNK) {
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if (!symlink_to_inode(¤t_inode, fd))
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return false;
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} else {
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print("ext2: Part of path is not directory nor symlink\n");
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return false;
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}
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}
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goto next;
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}
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}
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i += dir->rec_len;
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}
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return false;
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}
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int ext2_open(struct ext2_file_handle *ret, struct volume *part, const char *path) {
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ret->part = part;
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volume_read(ret->part, &ret->sb, 1024, sizeof(struct ext2_superblock));
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struct ext2_superblock *sb = &ret->sb;
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if (sb->s_state == EXT2_FS_UNRECOVERABLE_ERRORS)
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panic("ext2: unrecoverable errors found");
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ret->block_size = ((uint64_t)1024 << ret->sb.s_log_block_size);
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ext2_get_inode(&ret->root_inode, ret, 2);
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struct ext2_dir_entry entry;
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if (!ext2_parse_dirent(&entry, ret, path))
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return -1;
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ext2_get_inode(&ret->inode, ret, entry.inode);
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while ((ret->inode.i_mode & FMT_MASK) != S_IFREG) {
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if ((ret->inode.i_mode & FMT_MASK) == S_IFLNK) {
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if (!symlink_to_inode(&ret->inode, ret))
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return -1;
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} else {
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print("ext2: Entity is not regular file nor symlink\n");
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return -1;
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}
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}
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ret->size = ret->inode.i_size;
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ret->alloc_map = create_alloc_map(ret, &ret->inode);
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return 0;
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}
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int ext2_read(struct ext2_file_handle *file, void *buf, uint64_t loc, uint64_t count) {
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return inode_read(buf, loc, count, &file->inode, file, file->alloc_map);
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}
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static struct ext4_extent_header* ext4_find_leaf(struct ext4_extent_header* ext_block, uint32_t read_block, uint64_t block_size, struct volume *part) {
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struct ext4_extent_idx* index;
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void* buf = NULL;
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while (1) {
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index = (struct ext4_extent_idx*)((size_t)ext_block + 12);
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#define EXT4_EXT_MAGIC 0xf30a
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if (ext_block->magic != EXT4_EXT_MAGIC)
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panic("invalid extent magic");
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if (ext_block->depth == 0) {
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return ext_block;
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}
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int i;
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for (i = 0; i < ext_block->entries; i++) {
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if(read_block < index[i].block)
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break;
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}
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if (--i < 0)
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panic("extent not found");
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uint64_t block = ((uint64_t)index[i].leaf_hi << 32) | index[i].leaf;
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if(!buf)
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buf = ext_mem_alloc(block_size);
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volume_read(part, buf, (block * block_size), block_size);
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ext_block = buf;
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}
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}
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static int inode_read(void *buf, uint64_t loc, uint64_t count,
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struct ext2_inode *inode, struct ext2_file_handle *fd,
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uint32_t *alloc_map) {
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for (uint64_t progress = 0; progress < count;) {
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uint64_t block = (loc + progress) / fd->block_size;
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uint64_t chunk = count - progress;
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uint64_t offset = (loc + progress) % fd->block_size;
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if (chunk > fd->block_size - offset)
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chunk = fd->block_size - offset;
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uint32_t block_index;
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if (inode->i_flags & EXT4_EXTENTS_FLAG) {
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struct ext4_extent_header *leaf;
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struct ext4_extent *ext;
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int i;
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leaf = ext4_find_leaf((struct ext4_extent_header*)inode->i_blocks, block, fd->block_size, fd->part);
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if (!leaf)
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panic("invalid extent");
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ext = (struct ext4_extent*)((size_t)leaf + 12);
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for (i = 0; i < leaf->entries; i++) {
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if (block < ext[i].block) {
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break;
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}
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}
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if (--i >= 0) {
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block -= ext[i].block;
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if (block >= ext[i].len) {
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panic("block longer than extent");
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} else {
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uint64_t start = ((uint64_t)ext[i].start_hi << 32) + ext[i].start;
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block_index = start + block;
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}
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} else {
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panic("extent for block not found");
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}
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} else {
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block_index = alloc_map[block];
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}
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volume_read(fd->part, buf + progress, (block_index * fd->block_size) + offset, chunk);
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progress += chunk;
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}
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return 0;
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}
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// attempts to initialize the ext2 filesystem
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// and checks if all features are supported
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int ext2_check_signature(struct volume *part) {
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struct ext2_superblock sb;
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volume_read(part, &sb, 1024, sizeof(struct ext2_superblock));
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if (sb.s_magic != EXT2_S_MAGIC)
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return 0;
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// If the revision level is 0, we can't test for features.
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if (sb.s_rev_level == 0)
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return 1;
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if (sb.s_feature_incompat & EXT2_IF_COMPRESSION ||
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sb.s_feature_incompat & EXT2_IF_INLINE_DATA ||
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sb.s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG ||
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sb.s_feature_incompat & EXT2_IF_ENCRYPT)
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panic("EXT2: filesystem has unsupported features %x", sb.s_feature_incompat);
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return 1;
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}
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bool ext2_get_guid(struct guid *guid, struct volume *part) {
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struct ext2_superblock sb;
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volume_read(part, &sb, 1024, sizeof(struct ext2_superblock));
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if (sb.s_magic != EXT2_S_MAGIC)
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return false;
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((uint64_t *)guid)[0] = sb.s_uuid[0];
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((uint64_t *)guid)[1] = sb.s_uuid[1];
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return true;
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}
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