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#include <mercury/kernel/fs/tarfs.hpp>
//in fs::tarfs_instance, storage::node_id_t refers to the number
//of bytes into the block device that the info sector is located
namespace mercury::kernel::fs {
storage::io_result tarfs_mounter(
storage::block_device *bd, storage::file_system_instance *&fs_out
) {
fs_out = new tarfs_instance(bd);
return storage::io_result::success;
}
tarfs_instance::tarfs_instance(storage::block_device *bd) : bd(bd) {}
storage::io_result tarfs_instance::next_node(storage::node_id_t &node) {
uint64_t file_length;
storage::io_result result = read_num(node + 124, 12, file_length);
if (result != storage::io_result::success)
return result;
node += ((file_length - 1) / 512 + 2) * 512;
uint8_t sector[512];
result = bd->read_bytes(node, 512, sector);
if (result != storage::io_result::success)
return result;
for (unsigned i = 0; i < 512; ++i)
if (sector[i] != 0)
return storage::io_result::success;
return storage::io_result::out_of_bounds;
}
storage::io_result tarfs_instance::read_name(
storage::node_id_t node, char *name_buf, unsigned &name_len_out
) {
name_len_out = 0;
storage::io_result result = bd->read_bytes(node + 345, 155, name_buf);
if (result != storage::io_result::success)
return result;
while (name_buf[name_len_out] && name_len_out < 155)
++name_len_out;
result = bd->read_bytes(node, 100, name_buf + name_len_out);
if (result != storage::io_result::success)
return result;
unsigned new_limit = name_len_out + 100;
while (name_buf[name_len_out] && name_len_out < new_limit)
++name_len_out;
return storage::io_result::success;
}
storage::io_result tarfs_instance::read_num(
uint64_t offset, unsigned len, uint64_t &out
) {
//len <= 12
char buffer[12];
storage::io_result result = bd->read_bytes(offset, len, buffer);
if (result != storage::io_result::success)
return result;
out = 0;
for (unsigned i = 0; i < len; ++i) {
if (!buffer[i])
return i == 0 ? storage::io_result::fs_corrupt
: storage::io_result::success;
if (buffer[i] < '0' || buffer[i] > '7')
return storage::io_result::fs_corrupt;
out = out * 8 + buffer[i] - '0';
}
return storage::io_result::success;
}
#define RETURN_MAYBE_NOT_FOUND(expr) \
{ \
storage::io_result _result = expr; \
if (_result == storage::io_result::out_of_bounds) \
return storage::io_result::not_found; \
if (_result != storage::io_result::success) \
return _result; \
}
#define RETURN_NOT_SUCCESS(expr) \
{ \
storage::io_result _result = expr; \
if (_result != storage::io_result::success) \
return _result; \
}
storage::io_result tarfs_instance::get_root_node(storage::node_id_t &out) {
out = 0;
while (true) {
char name_buf[255];
unsigned name_len;
RETURN_MAYBE_NOT_FOUND(read_name(out, name_buf, name_len))
if (name_len == 2 && name_buf[0] == '.' && name_buf[1] == '/')
return storage::io_result::success;
RETURN_MAYBE_NOT_FOUND(next_node(out))
}
}
storage::io_result tarfs_instance::get_first_child(storage::node_id_t node,
storage::node_id_t &out, storage::directory_iter_t &iter_out
) {
char name_buf[255];
unsigned name_len;
RETURN_NOT_SUCCESS(read_name(node, name_buf, name_len))
out = 0;
while (true) {
char cand_name_buf[255];
unsigned cand_name_len;
RETURN_MAYBE_NOT_FOUND(read_name(out, cand_name_buf, cand_name_len))
if (cand_name_len > name_len && utility::starts_with(
cand_name_buf, cand_name_len, name_buf, name_len
)) {
const char *rem = cand_name_buf + name_len;
unsigned rem_len = cand_name_len - name_len;
unsigned slash = utility::find(rem, rem_len, '/');
if (slash == rem_len - 1 || slash == rem_len) {
iter_out = out;
return storage::io_result::success;
}
}
RETURN_MAYBE_NOT_FOUND(next_node(out))
}
}
storage::io_result tarfs_instance::get_next_child(storage::node_id_t node,
storage::node_id_t &out, storage::directory_iter_t &iter
) {
char name_buf[255];
unsigned name_len;
RETURN_NOT_SUCCESS(read_name(node, name_buf, name_len))
out = iter;
RETURN_MAYBE_NOT_FOUND(next_node(out))
while (true) {
char cand_name_buf[255];
unsigned cand_name_len;
RETURN_MAYBE_NOT_FOUND(read_name(out, cand_name_buf, cand_name_len))
if (cand_name_len > name_len && utility::starts_with(
cand_name_buf, cand_name_len, name_buf, name_len
)) {
const char *rem = cand_name_buf + name_len;
unsigned rem_len = cand_name_len - name_len;
unsigned slash = utility::find(rem, rem_len, '/');
if (slash == rem_len - 1 || slash == rem_len) {
iter = out;
return storage::io_result::success;
}
}
RETURN_MAYBE_NOT_FOUND(next_node(out))
}
}
storage::io_result tarfs_instance::get_child(storage::node_id_t node,
storage::node_id_t &out, const char *name, unsigned name_len
) {
char full_name[255];
unsigned full_name_len;
RETURN_MAYBE_NOT_FOUND(read_name(node, full_name, full_name_len))
if (full_name_len + name_len > 255)
return storage::io_result::not_supported;
for (unsigned i = 0; i < name_len; ++i)
full_name[full_name_len + i] = name[i];
full_name_len += name_len;
out = 0;
while (true) {
char cand_name[255];
unsigned cand_name_len;
RETURN_MAYBE_NOT_FOUND(read_name(out, cand_name, cand_name_len))
if (cand_name_len != full_name_len && cand_name_len != full_name_len + 1)
goto next_iter;
for (unsigned i = 0; i < full_name_len; ++i)
if (cand_name[i] != full_name[i])
goto next_iter;
if (cand_name_len == full_name_len + 1 &&
cand_name[full_name_len] != '/')
goto next_iter;
return storage::io_result::success;
next_iter:
RETURN_MAYBE_NOT_FOUND(next_node(out))
}
}
storage::io_result tarfs_instance::get_name_length(
storage::node_id_t node, unsigned &length_out
) {
char name_buf[255];
return get_name(node, name_buf, length_out);
}
storage::io_result tarfs_instance::get_name(
storage::node_id_t node, char *buffer, unsigned &length_out
) {
unsigned full_length;
char full_buffer[255];
RETURN_NOT_SUCCESS(read_name(node, full_buffer, full_length))
if (full_length == 2) {
//full buffer must be ./
length_out = 0;
return storage::io_result::success;
}
if (full_buffer[full_length - 1] == '/')
--full_length;
unsigned start = utility::find_last(full_buffer, full_length, '/') + 1;
length_out = full_length - start;
for (unsigned i = 0; i < length_out; ++i)
buffer[i] = full_buffer[start + i];
return storage::io_result::success;
}
storage::io_result tarfs_instance::get_file_length(
storage::node_id_t node, uint64_t &length_out
) {
return read_num(node + 124, 12, length_out);
}
storage::io_result tarfs_instance::get_file_type(
storage::node_id_t node, storage::file_type &out
) {
uint64_t ft;
storage::io_result result = read_num(node + 156, 1, ft);
if (result != storage::io_result::success)
return result;
switch (ft) {
case 0:
out = storage::file_type::regular_file;
return storage::io_result::success;
case 2:
out = storage::file_type::symlink;
return storage::io_result::success;
case 5:
out = storage::file_type::directory;
return storage::io_result::success;
default:
return storage::io_result::not_supported;
}
}
storage::io_result tarfs_instance::resize_file(
storage::node_id_t, uint64_t
) {
//TODO: support resize if sector count isn't changed?
return storage::io_result::not_supported;
}
storage::io_result tarfs_instance::read_bytes_from_file(
storage::node_id_t node, uint64_t start, uint64_t count, void *into
) {
return bd->read_bytes(node + 512 + start, count, into);
}
storage::io_result tarfs_instance::write_bytes_into_file(
storage::node_id_t, uint64_t, uint64_t, const void *
) {
//TODO: support this.
return storage::io_result::not_supported;
}
}
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