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Fix ext2 driver

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This commit is contained in:
mintsuki 2020-04-16 14:41:28 +02:00
parent 9038e3b8fe
commit 0a3f00f6e2
2 changed files with 45 additions and 13 deletions
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57
src/fs/ext2fs.c
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@ -68,8 +68,8 @@ struct ext2fs_superblock {
uint32_t s_checkinterval; // amount of time between required consistency checks
uint32_t s_creator_os; // operating system ID
uint32_t s_rev_level; // combine with minor portion to get full version
uint32_t s_def_resuid; // User ID that can use reserved blocks
uint32_t s_def_gid; // Group ID that can use reserved blocks
uint16_t s_def_resuid; // User ID that can use reserved blocks
uint16_t s_def_gid; // Group ID that can use reserved blocks
// if version number >= 1, we have to use the ext2 extended superblock as well
@ -95,7 +95,7 @@ struct ext2fs_superblock {
uint16_t unused; // Unused
uint64_t s_journal_uuid; // Journal ID
uint64_t s_journal_uuid[2]; // Journal ID
uint32_t s_journal_inum; // Journal Inode number
uint32_t s_journal_dev; // Journal device
@ -104,6 +104,8 @@ struct ext2fs_superblock {
uint8_t s_def_hash_version; // Default hash versrion used for dir indexing
uint8_t padding[3];
uint32_t s_default_mnt_opts; // Default mount options
uint32_t s_first_meta_bg; // Block group ID for first meta group
@ -193,7 +195,7 @@ static int ext2fs_get_inode(struct ext2fs_inode *ret, uint64_t drive, struct par
read_partition(drive, part, &target_descriptor, bgd_start_offset + (sizeof(struct ext2fs_bgd) * ino_blk_grp), sizeof(struct ext2fs_bgd));
read_partition(drive, part, ret, (target_descriptor.bg_inode_table * block_size) + (sizeof(struct ext2fs_inode) * ino_tbl_idx), sizeof(struct ext2fs_inode));
read_partition(drive, part, ret, (target_descriptor.bg_inode_table * block_size) + (sb->s_inode_size * ino_tbl_idx), sizeof(struct ext2fs_inode));
return 0;
}
@ -201,7 +203,7 @@ static int ext2fs_get_inode(struct ext2fs_inode *ret, uint64_t drive, struct par
static int ext2fs_parse_dirent(struct ext2fs_dir_entry *dir, struct ext2fs_file_handle *fd, const char *filename) {
uint64_t offset = fd->root_inode.i_blocks[0] * fd->block_size;
for (uint32_t i = 0; i < fd->num_entries; i++) {
while (offset < fd->root_inode.i_size + offset) {
// preliminary read
read_partition(fd->drive, &fd->part, dir, offset, sizeof(struct ext2fs_dir_entry));
@ -234,11 +236,9 @@ int ext2fs_open(struct ext2fs_file_handle *ret, int drive, int partition, const
ret->block_size = ((uint64_t)1024 << sb.s_log_block_size);
ext2fs_get_inode(&ret->root_inode, drive, &ret->part, 2, &sb);
ret->num_entries = ret->root_inode.i_links_count + 2;
struct ext2fs_dir_entry entry;
ext2fs_parse_dirent(&entry, ret, filename);
ext2fs_get_inode(&ret->inode, drive, &ret->part, entry.inode, &sb);
ret->size = ret->inode.i_size;
@ -246,11 +246,7 @@ int ext2fs_open(struct ext2fs_file_handle *ret, int drive, int partition, const
}
int ext2fs_read(struct ext2fs_file_handle *file, void* buf, uint64_t loc, uint64_t count) {
// read the contents of the inode
// it is assumed that bfread has already done the directory check
// TODO: add support for the indirect block pointers
// TODO: add support for reading multiple blocks
for (uint64_t progress = 0; progress < count;) {
uint64_t block = (loc + progress) / file->block_size;
@ -260,7 +256,44 @@ int ext2fs_read(struct ext2fs_file_handle *file, void* buf, uint64_t loc, uint64
if (chunk > file->block_size - offset)
chunk = file->block_size - offset;
read_partition(file->drive, &file->part, buf + progress, (file->inode.i_blocks[block] * file->block_size) + offset, chunk);
uint64_t block_index;
if (block < 12) {
// Direct block
block_index = file->inode.i_blocks[block];
} else {
// Indirect block
block -= 12;
if (block * sizeof(uint32_t) >= file->block_size) {
// Double indirect block
block -= file->block_size / sizeof(uint32_t);
uint32_t index = block / (file->block_size / sizeof(uint32_t));
if (index * sizeof(uint32_t) >= file->block_size) {
// Triple indirect block
panic("ext2fs: triply indirect blocks unsupported");
}
uint32_t offset = block % (file->block_size / sizeof(uint32_t));
uint32_t indirect_block;
read_partition(
file->drive, &file->part, &indirect_block,
file->inode.i_blocks[13] * file->block_size + index * sizeof(uint32_t),
sizeof(uint32_t)
);
read_partition(
file->drive, &file->part, &block_index,
indirect_block * file->block_size + offset * sizeof(uint32_t),
sizeof(uint32_t)
);
} else {
read_partition(
file->drive, &file->part, &block_index,
file->inode.i_blocks[12] * file->block_size + block * sizeof(uint32_t),
sizeof(uint32_t)
);
}
}
read_partition(file->drive, &file->part, buf + progress, (block_index * file->block_size) + offset, chunk);
progress += chunk;
}

1
src/fs/ext2fs.h
View File

@ -56,7 +56,6 @@ struct ext2fs_file_handle {
int size;
struct ext2fs_inode root_inode;
struct ext2fs_inode inode;
int num_entries;
uint64_t block_size;
};