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iotests: Add vvfat tests

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Added several tests to verify the implementation of the vvfat driver.

We needed a way to interact with it, so created a basic `fat16.py` driver
that handled writing correct sectors for us.

Added `vvfat` to the non-generic formats, as its not a normal image format.

Signed-off-by: Amjad Alsharafi <amjadsharafi10@gmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Tested-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <bb8149c945301aefbdf470a0924c07f69f9c087d.1721470238.git.amjadsharafi10@gmail.com>
[kwolf: Made mypy and pylint happy to unbreak 297]
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit c8f60bfb43)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This commit is contained in:
Amjad Alsharafi 2024-07-20 18:13:34 +08:00 committed by Michael Tokarev
parent 3f27fd9536
commit c179754c3c
5 changed files with 1182 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
tests/qemu-iotests/check
View File

@ -70,7 +70,7 @@ def make_argparser() -> argparse.ArgumentParser:
p.set_defaults(imgfmt='raw', imgproto='file')
format_list = ['raw', 'bochs', 'cloop', 'parallels', 'qcow', 'qcow2',
'qed', 'vdi', 'vpc', 'vhdx', 'vmdk', 'luks', 'dmg']
'qed', 'vdi', 'vpc', 'vhdx', 'vmdk', 'luks', 'dmg', 'vvfat']
g_fmt = p.add_argument_group(
' image format options',
'The following options set the IMGFMT environment variable. '

690
tests/qemu-iotests/fat16.py Normal file
View File

@ -0,0 +1,690 @@
# A simple FAT16 driver that is used to test the `vvfat` driver in QEMU.
#
# Copyright (C) 2024 Amjad Alsharafi <amjadsharafi10@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from typing import Callable, List, Optional, Protocol, Set
import string
SECTOR_SIZE = 512
DIRENTRY_SIZE = 32
ALLOWED_FILE_CHARS = set(
"!#$%&'()-@^_`{}~" + string.digits + string.ascii_uppercase
)
class MBR:
def __init__(self, data: bytes):
assert len(data) == 512
self.partition_table = []
for i in range(4):
partition = data[446 + i * 16 : 446 + (i + 1) * 16]
self.partition_table.append(
{
"status": partition[0],
"start_head": partition[1],
"start_sector": partition[2] & 0x3F,
"start_cylinder": ((partition[2] & 0xC0) << 2)
| partition[3],
"type": partition[4],
"end_head": partition[5],
"end_sector": partition[6] & 0x3F,
"end_cylinder": ((partition[6] & 0xC0) << 2)
| partition[7],
"start_lba": int.from_bytes(partition[8:12], "little"),
"size": int.from_bytes(partition[12:16], "little"),
}
)
def __str__(self):
return "\n".join(
[
f"{i}: {partition}"
for i, partition in enumerate(self.partition_table)
]
)
class FatBootSector:
# pylint: disable=too-many-instance-attributes
def __init__(self, data: bytes):
assert len(data) == 512
self.bytes_per_sector = int.from_bytes(data[11:13], "little")
self.sectors_per_cluster = data[13]
self.reserved_sectors = int.from_bytes(data[14:16], "little")
self.fat_count = data[16]
self.root_entries = int.from_bytes(data[17:19], "little")
total_sectors_16 = int.from_bytes(data[19:21], "little")
self.media_descriptor = data[21]
self.sectors_per_fat = int.from_bytes(data[22:24], "little")
self.sectors_per_track = int.from_bytes(data[24:26], "little")
self.heads = int.from_bytes(data[26:28], "little")
self.hidden_sectors = int.from_bytes(data[28:32], "little")
total_sectors_32 = int.from_bytes(data[32:36], "little")
assert (
total_sectors_16 == 0 or total_sectors_32 == 0
), "Both total sectors (16 and 32) fields are non-zero"
self.total_sectors = total_sectors_16 or total_sectors_32
self.drive_number = data[36]
self.volume_id = int.from_bytes(data[39:43], "little")
self.volume_label = data[43:54].decode("ascii").strip()
self.fs_type = data[54:62].decode("ascii").strip()
def root_dir_start(self):
"""
Calculate the start sector of the root directory.
"""
return self.reserved_sectors + self.fat_count * self.sectors_per_fat
def root_dir_size(self):
"""
Calculate the size of the root directory in sectors.
"""
return (
self.root_entries * DIRENTRY_SIZE + self.bytes_per_sector - 1
) // self.bytes_per_sector
def data_sector_start(self):
"""
Calculate the start sector of the data region.
"""
return self.root_dir_start() + self.root_dir_size()
def first_sector_of_cluster(self, cluster: int) -> int:
"""
Calculate the first sector of the given cluster.
"""
return (
self.data_sector_start() + (cluster - 2) * self.sectors_per_cluster
)
def cluster_bytes(self):
"""
Calculate the number of bytes in a cluster.
"""
return self.bytes_per_sector * self.sectors_per_cluster
def __str__(self):
return (
f"Bytes per sector: {self.bytes_per_sector}\n"
f"Sectors per cluster: {self.sectors_per_cluster}\n"
f"Reserved sectors: {self.reserved_sectors}\n"
f"FAT count: {self.fat_count}\n"
f"Root entries: {self.root_entries}\n"
f"Total sectors: {self.total_sectors}\n"
f"Media descriptor: {self.media_descriptor}\n"
f"Sectors per FAT: {self.sectors_per_fat}\n"
f"Sectors per track: {self.sectors_per_track}\n"
f"Heads: {self.heads}\n"
f"Hidden sectors: {self.hidden_sectors}\n"
f"Drive number: {self.drive_number}\n"
f"Volume ID: {self.volume_id}\n"
f"Volume label: {self.volume_label}\n"
f"FS type: {self.fs_type}\n"
)
class FatDirectoryEntry:
# pylint: disable=too-many-instance-attributes
def __init__(self, data: bytes, sector: int, offset: int):
self.name = data[0:8].decode("ascii").strip()
self.ext = data[8:11].decode("ascii").strip()
self.attributes = data[11]
self.reserved = data[12]
self.create_time_tenth = data[13]
self.create_time = int.from_bytes(data[14:16], "little")
self.create_date = int.from_bytes(data[16:18], "little")
self.last_access_date = int.from_bytes(data[18:20], "little")
high_cluster = int.from_bytes(data[20:22], "little")
self.last_mod_time = int.from_bytes(data[22:24], "little")
self.last_mod_date = int.from_bytes(data[24:26], "little")
low_cluster = int.from_bytes(data[26:28], "little")
self.cluster = (high_cluster << 16) | low_cluster
self.size_bytes = int.from_bytes(data[28:32], "little")
# extra (to help write back to disk)
self.sector = sector
self.offset = offset
def as_bytes(self) -> bytes:
return (
self.name.ljust(8, " ").encode("ascii")
+ self.ext.ljust(3, " ").encode("ascii")
+ self.attributes.to_bytes(1, "little")
+ self.reserved.to_bytes(1, "little")
+ self.create_time_tenth.to_bytes(1, "little")
+ self.create_time.to_bytes(2, "little")
+ self.create_date.to_bytes(2, "little")
+ self.last_access_date.to_bytes(2, "little")
+ (self.cluster >> 16).to_bytes(2, "little")
+ self.last_mod_time.to_bytes(2, "little")
+ self.last_mod_date.to_bytes(2, "little")
+ (self.cluster & 0xFFFF).to_bytes(2, "little")
+ self.size_bytes.to_bytes(4, "little")
)
def whole_name(self):
if self.ext:
return f"{self.name}.{self.ext}"
else:
return self.name
def __str__(self):
return (
f"Name: {self.name}\n"
f"Ext: {self.ext}\n"
f"Attributes: {self.attributes}\n"
f"Reserved: {self.reserved}\n"
f"Create time tenth: {self.create_time_tenth}\n"
f"Create time: {self.create_time}\n"
f"Create date: {self.create_date}\n"
f"Last access date: {self.last_access_date}\n"
f"Last mod time: {self.last_mod_time}\n"
f"Last mod date: {self.last_mod_date}\n"
f"Cluster: {self.cluster}\n"
f"Size: {self.size_bytes}\n"
)
def __repr__(self):
# convert to dict
return str(vars(self))
class SectorReader(Protocol):
def __call__(self, start_sector: int, num_sectors: int = 1) -> bytes: ...
# pylint: disable=broad-exception-raised
class Fat16:
def __init__(
self,
start_sector: int,
size: int,
sector_reader: SectorReader,
sector_writer: Callable[[int, bytes], None]
):
self.start_sector = start_sector
self.size_in_sectors = size
self.sector_reader = sector_reader
self.sector_writer = sector_writer
self.boot_sector = FatBootSector(self.sector_reader(start_sector, 1))
fat_size_in_sectors = (
self.boot_sector.sectors_per_fat * self.boot_sector.fat_count
)
self.fats = self.read_sectors(
self.boot_sector.reserved_sectors, fat_size_in_sectors
)
self.fats_dirty_sectors: Set[int] = set()
def read_sectors(self, start_sector: int, num_sectors: int) -> bytes:
return self.sector_reader(start_sector + self.start_sector,
num_sectors)
def write_sectors(self, start_sector: int, data: bytes) -> None:
return self.sector_writer(start_sector + self.start_sector, data)
def directory_from_bytes(
self, data: bytes, start_sector: int
) -> List[FatDirectoryEntry]:
"""
Convert `bytes` into a list of `FatDirectoryEntry` objects.
Will ignore long file names.
Will stop when it encounters a 0x00 byte.
"""
entries = []
for i in range(0, len(data), DIRENTRY_SIZE):
entry = data[i : i + DIRENTRY_SIZE]
current_sector = start_sector + (i // SECTOR_SIZE)
current_offset = i % SECTOR_SIZE
if entry[0] == 0:
break
if entry[0] == 0xE5:
# Deleted file
continue
if entry[11] & 0xF == 0xF:
# Long file name
continue
entries.append(
FatDirectoryEntry(entry, current_sector, current_offset)
)
return entries
def read_root_directory(self) -> List[FatDirectoryEntry]:
root_dir = self.read_sectors(
self.boot_sector.root_dir_start(), self.boot_sector.root_dir_size()
)
return self.directory_from_bytes(
root_dir, self.boot_sector.root_dir_start()
)
def read_fat_entry(self, cluster: int) -> int:
"""
Read the FAT entry for the given cluster.
"""
fat_offset = cluster * 2 # FAT16
return int.from_bytes(self.fats[fat_offset : fat_offset + 2], "little")
def write_fat_entry(self, cluster: int, value: int) -> None:
"""
Write the FAT entry for the given cluster.
"""
fat_offset = cluster * 2
self.fats = (
self.fats[:fat_offset]
+ value.to_bytes(2, "little")
+ self.fats[fat_offset + 2 :]
)
self.fats_dirty_sectors.add(fat_offset // SECTOR_SIZE)
def flush_fats(self) -> None:
"""
Write the FATs back to the disk.
"""
for sector in self.fats_dirty_sectors:
data = self.fats[sector * SECTOR_SIZE : (sector + 1) * SECTOR_SIZE]
sector = self.boot_sector.reserved_sectors + sector
self.write_sectors(sector, data)
self.fats_dirty_sectors = set()
def next_cluster(self, cluster: int) -> Optional[int]:
"""
Get the next cluster in the chain.
If its `None`, then its the last cluster.
The function will crash if the next cluster
is `FREE` (unexpected) or invalid entry.
"""
fat_entry = self.read_fat_entry(cluster)
if fat_entry == 0:
raise Exception("Unexpected: FREE cluster")
if fat_entry == 1:
raise Exception("Unexpected: RESERVED cluster")
if fat_entry >= 0xFFF8:
return None
if fat_entry >= 0xFFF7:
raise Exception("Invalid FAT entry")
return fat_entry
def next_free_cluster(self) -> int:
"""
Find the next free cluster.
"""
# simple linear search
for i in range(2, 0xFFFF):
if self.read_fat_entry(i) == 0:
return i
raise Exception("No free clusters")
def next_free_cluster_non_continuous(self) -> int:
"""
Find the next free cluster, but makes sure
that the cluster before and after it are not allocated.
"""
# simple linear search
before = False
for i in range(2, 0xFFFF):
if self.read_fat_entry(i) == 0:
if before and self.read_fat_entry(i + 1) == 0:
return i
else:
before = True
else:
before = False
raise Exception("No free clusters")
def read_cluster(self, cluster: int) -> bytes:
"""
Read the cluster at the given cluster.
"""
return self.read_sectors(
self.boot_sector.first_sector_of_cluster(cluster),
self.boot_sector.sectors_per_cluster,
)
def write_cluster(self, cluster: int, data: bytes) -> None:
"""
Write the cluster at the given cluster.
"""
assert len(data) == self.boot_sector.cluster_bytes()
self.write_sectors(
self.boot_sector.first_sector_of_cluster(cluster),
data,
)
def read_directory(
self, cluster: Optional[int]
) -> List[FatDirectoryEntry]:
"""
Read the directory at the given cluster.
"""
entries = []
while cluster is not None:
data = self.read_cluster(cluster)
entries.extend(
self.directory_from_bytes(
data, self.boot_sector.first_sector_of_cluster(cluster)
)
)
cluster = self.next_cluster(cluster)
return entries
def add_direntry(
self, cluster: Optional[int], name: str, ext: str, attributes: int
) -> FatDirectoryEntry:
"""
Add a new directory entry to the given cluster.
If the cluster is `None`, then it will be added to the root directory.
"""
def find_free_entry(data: bytes) -> Optional[int]:
for i in range(0, len(data), DIRENTRY_SIZE):
entry = data[i : i + DIRENTRY_SIZE]
if entry[0] == 0 or entry[0] == 0xE5:
return i
return None
assert len(name) <= 8, "Name must be 8 characters or less"
assert len(ext) <= 3, "Ext must be 3 characters or less"
assert attributes % 0x15 != 0x15, "Invalid attributes"
# initial dummy data
new_entry = FatDirectoryEntry(b"\0" * 32, 0, 0)
new_entry.name = name.ljust(8, " ")
new_entry.ext = ext.ljust(3, " ")
new_entry.attributes = attributes
new_entry.reserved = 0
new_entry.create_time_tenth = 0
new_entry.create_time = 0
new_entry.create_date = 0
new_entry.last_access_date = 0
new_entry.last_mod_time = 0
new_entry.last_mod_date = 0
new_entry.cluster = self.next_free_cluster()
new_entry.size_bytes = 0
# mark as EOF
self.write_fat_entry(new_entry.cluster, 0xFFFF)
if cluster is None:
for i in range(self.boot_sector.root_dir_size()):
sector_data = self.read_sectors(
self.boot_sector.root_dir_start() + i, 1
)
offset = find_free_entry(sector_data)
if offset is not None:
new_entry.sector = self.boot_sector.root_dir_start() + i
new_entry.offset = offset
self.update_direntry(new_entry)
return new_entry
else:
while cluster is not None:
data = self.read_cluster(cluster)
offset = find_free_entry(data)
if offset is not None:
new_entry.sector = (
self.boot_sector.first_sector_of_cluster(cluster)
+ (offset // SECTOR_SIZE))
new_entry.offset = offset % SECTOR_SIZE
self.update_direntry(new_entry)
return new_entry
cluster = self.next_cluster(cluster)
raise Exception("No free directory entries")
def update_direntry(self, entry: FatDirectoryEntry) -> None:
"""
Write the directory entry back to the disk.
"""
sector = self.read_sectors(entry.sector, 1)
sector = (
sector[: entry.offset]
+ entry.as_bytes()
+ sector[entry.offset + DIRENTRY_SIZE :]
)
self.write_sectors(entry.sector, sector)
def find_direntry(self, path: str) -> Optional[FatDirectoryEntry]:
"""
Find the directory entry for the given path.
"""
assert path[0] == "/", "Path must start with /"
path = path[1:] # remove the leading /
parts = path.split("/")
directory = self.read_root_directory()
current_entry = None
for i, part in enumerate(parts):
is_last = i == len(parts) - 1
for entry in directory:
if entry.whole_name() == part:
current_entry = entry
break
if current_entry is None:
return None
if is_last:
return current_entry
if current_entry.attributes & 0x10 == 0:
raise Exception(
f"{current_entry.whole_name()} is not a directory"
)
directory = self.read_directory(current_entry.cluster)
assert False, "Exited loop with is_last == False"
def read_file(self, entry: Optional[FatDirectoryEntry]) -> Optional[bytes]:
"""
Read the content of the file at the given path.
"""
if entry is None:
return None
if entry.attributes & 0x10 != 0:
raise Exception(f"{entry.whole_name()} is a directory")
data = b""
cluster: Optional[int] = entry.cluster
while cluster is not None and len(data) <= entry.size_bytes:
data += self.read_cluster(cluster)
cluster = self.next_cluster(cluster)
return data[: entry.size_bytes]
def truncate_file(
self,
entry: FatDirectoryEntry,
new_size: int,
allocate_non_continuous: bool = False,
) -> None:
"""
Truncate the file at the given path to the new size.
"""
if entry is None:
raise Exception("entry is None")
if entry.attributes & 0x10 != 0:
raise Exception(f"{entry.whole_name()} is a directory")
def clusters_from_size(size: int) -> int:
return (
size + self.boot_sector.cluster_bytes() - 1
) // self.boot_sector.cluster_bytes()
# First, allocate new FATs if we need to
required_clusters = clusters_from_size(new_size)
current_clusters = clusters_from_size(entry.size_bytes)
affected_clusters = set()
# Keep at least one cluster, easier to manage this way
if required_clusters == 0:
required_clusters = 1
if current_clusters == 0:
current_clusters = 1
cluster: Optional[int]
if required_clusters > current_clusters:
# Allocate new clusters
cluster = entry.cluster
to_add = required_clusters
for _ in range(current_clusters - 1):
to_add -= 1
assert cluster is not None, "Cluster is None"
affected_clusters.add(cluster)
cluster = self.next_cluster(cluster)
assert required_clusters > 0, "No new clusters to allocate"
assert cluster is not None, "Cluster is None"
assert (
self.next_cluster(cluster) is None
), "Cluster is not the last cluster"
# Allocate new clusters
for _ in range(to_add - 1):
if allocate_non_continuous:
new_cluster = self.next_free_cluster_non_continuous()
else:
new_cluster = self.next_free_cluster()
self.write_fat_entry(cluster, new_cluster)
self.write_fat_entry(new_cluster, 0xFFFF)
cluster = new_cluster
elif required_clusters < current_clusters:
# Truncate the file
cluster = entry.cluster
for _ in range(required_clusters - 1):
assert cluster is not None, "Cluster is None"
cluster = self.next_cluster(cluster)
assert cluster is not None, "Cluster is None"
next_cluster = self.next_cluster(cluster)
# mark last as EOF
self.write_fat_entry(cluster, 0xFFFF)
# free the rest
while next_cluster is not None:
cluster = next_cluster
next_cluster = self.next_cluster(next_cluster)
self.write_fat_entry(cluster, 0)
self.flush_fats()
# verify number of clusters
cluster = entry.cluster
count = 0
while cluster is not None:
count += 1
affected_clusters.add(cluster)
cluster = self.next_cluster(cluster)
assert (
count == required_clusters
), f"Expected {required_clusters} clusters, got {count}"
# update the size
entry.size_bytes = new_size
self.update_direntry(entry)
# trigger every affected cluster
for cluster in affected_clusters:
first_sector = self.boot_sector.first_sector_of_cluster(cluster)
first_sector_data = self.read_sectors(first_sector, 1)
self.write_sectors(first_sector, first_sector_data)
def write_file(self, entry: FatDirectoryEntry, data: bytes) -> None:
"""
Write the content of the file at the given path.
"""
if entry is None:
raise Exception("entry is None")
if entry.attributes & 0x10 != 0:
raise Exception(f"{entry.whole_name()} is a directory")
data_len = len(data)
self.truncate_file(entry, data_len)
cluster: Optional[int] = entry.cluster
while cluster is not None:
data_to_write = data[: self.boot_sector.cluster_bytes()]
if len(data_to_write) < self.boot_sector.cluster_bytes():
old_data = self.read_cluster(cluster)
data_to_write += old_data[len(data_to_write) :]
self.write_cluster(cluster, data_to_write)
data = data[self.boot_sector.cluster_bytes() :]
if len(data) == 0:
break
cluster = self.next_cluster(cluster)
assert (
len(data) == 0
), "Data was not written completely, clusters missing"
def create_file(self, path: str) -> Optional[FatDirectoryEntry]:
"""
Create a new file at the given path.
"""
assert path[0] == "/", "Path must start with /"
path = path[1:] # remove the leading /
parts = path.split("/")
directory_cluster = None
directory = self.read_root_directory()
parts, filename = parts[:-1], parts[-1]
for _, part in enumerate(parts):
current_entry = None
for entry in directory:
if entry.whole_name() == part:
current_entry = entry
break
if current_entry is None:
return None
if current_entry.attributes & 0x10 == 0:
raise Exception(
f"{current_entry.whole_name()} is not a directory"
)
directory = self.read_directory(current_entry.cluster)
directory_cluster = current_entry.cluster
# add new entry to the directory
filename, ext = filename.split(".")
if len(ext) > 3:
raise Exception("Ext must be 3 characters or less")
if len(filename) > 8:
raise Exception("Name must be 8 characters or less")
for c in filename + ext:
if c not in ALLOWED_FILE_CHARS:
raise Exception("Invalid character in filename")
return self.add_direntry(directory_cluster, filename, ext, 0)

2
tests/qemu-iotests/testenv.py
View File

@ -250,7 +250,7 @@ class TestEnv(ContextManager['TestEnv']):
self.qemu_img_options = os.getenv('QEMU_IMG_OPTIONS')
self.qemu_nbd_options = os.getenv('QEMU_NBD_OPTIONS')
is_generic = self.imgfmt not in ['bochs', 'cloop', 'dmg']
is_generic = self.imgfmt not in ['bochs', 'cloop', 'dmg', 'vvfat']
self.imgfmt_generic = 'true' if is_generic else 'false'
self.qemu_io_options = f'--cache {self.cachemode} --aio {self.aiomode}'

485
tests/qemu-iotests/tests/vvfat Executable file
View File

@ -0,0 +1,485 @@
#!/usr/bin/env python3
# group: rw vvfat
#
# Test vvfat driver implementation
# Here, we use a simple FAT16 implementation and check the behavior of
# the vvfat driver.
#
# Copyright (C) 2024 Amjad Alsharafi <amjadsharafi10@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import os
import shutil
import iotests
from iotests import imgfmt, QMPTestCase
from fat16 import MBR, Fat16, DIRENTRY_SIZE
filesystem = os.path.join(iotests.test_dir, "filesystem")
nbd_sock = iotests.file_path("nbd.sock", base_dir=iotests.sock_dir)
nbd_uri = "nbd+unix:///disk?socket=" + nbd_sock
SECTOR_SIZE = 512
class TestVVFatDriver(QMPTestCase):
# pylint: disable=broad-exception-raised
def setUp(self) -> None:
if os.path.exists(filesystem):
if os.path.isdir(filesystem):
shutil.rmtree(filesystem)
else:
raise Exception(f"{filesystem} exists and is not a directory")
os.mkdir(filesystem)
# Add some text files to the filesystem
for i in range(10):
with open(os.path.join(filesystem, f"file{i}.txt"),
"w", encoding="ascii") as f:
f.write(f"Hello, world! {i}\n")
# Add 2 large files, above the cluster size (8KB)
with open(os.path.join(filesystem, "large1.txt"), "wb") as f:
# write 'A' * 1KB, 'B' * 1KB, 'C' * 1KB, ...
for i in range(8 * 2): # two clusters
f.write(bytes([0x41 + i] * 1024))
with open(os.path.join(filesystem, "large2.txt"), "wb") as f:
# write 'A' * 1KB, 'B' * 1KB, 'C' * 1KB, ...
for i in range(8 * 3): # 3 clusters
f.write(bytes([0x41 + i] * 1024))
self.vm = iotests.VM()
self.vm.add_blockdev(
self.vm.qmp_to_opts(
{
"driver": imgfmt,
"node-name": "disk",
"rw": "true",
"fat-type": "16",
"dir": filesystem,
}
)
)
self.vm.launch()
self.vm.qmp_log("block-dirty-bitmap-add", **{
"node": "disk",
"name": "bitmap0",
})
# attach nbd server
self.vm.qmp_log(
"nbd-server-start",
**{"addr": {"type": "unix", "data": {"path": nbd_sock}}},
filters=[],
)
self.vm.qmp_log(
"nbd-server-add",
**{"device": "disk", "writable": True, "bitmap": "bitmap0"},
)
self.qio = iotests.QemuIoInteractive("-f", "raw", nbd_uri)
def tearDown(self) -> None:
self.qio.close()
self.vm.shutdown()
# print(self.vm.get_log())
shutil.rmtree(filesystem)
def read_sectors(self, sector: int, num: int = 1) -> bytes:
"""
Read `num` sectors starting from `sector` from the `disk`.
This uses `QemuIoInteractive` to read the sectors into `stdout` and
then parse the output.
"""
self.assertGreater(num, 0)
# The output contains the content of the sector in hex dump format
# We need to extract the content from it
output = self.qio.cmd(
f"read -v {sector * SECTOR_SIZE} {num * SECTOR_SIZE}")
# Each row is 16 bytes long, and we are writing `num` sectors
rows = num * SECTOR_SIZE // 16
output_rows = output.split("\n")[:rows]
hex_content = "".join(
[(row.split(": ")[1]).split(" ")[0] for row in output_rows]
)
bytes_content = bytes.fromhex(hex_content)
self.assertEqual(len(bytes_content), num * SECTOR_SIZE)
return bytes_content
def write_sectors(self, sector: int, data: bytes) -> None:
"""
Write `data` to the `disk` starting from `sector`.
This uses `QemuIoInteractive` to write the data into the disk.
"""
self.assertGreater(len(data), 0)
self.assertEqual(len(data) % SECTOR_SIZE, 0)
temp_file = os.path.join(iotests.test_dir, "temp.bin")
with open(temp_file, "wb") as f:
f.write(data)
self.qio.cmd(
f"write -s {temp_file} {sector * SECTOR_SIZE} {len(data)}"
)
os.remove(temp_file)
def init_fat16(self):
mbr = MBR(self.read_sectors(0))
return Fat16(
mbr.partition_table[0]["start_lba"],
mbr.partition_table[0]["size"],
self.read_sectors,
self.write_sectors,
)
# Tests
def test_fat_filesystem(self):
"""
Test that vvfat produce a valid FAT16 and MBR sectors
"""
mbr = MBR(self.read_sectors(0))
self.assertEqual(mbr.partition_table[0]["status"], 0x80)
self.assertEqual(mbr.partition_table[0]["type"], 6)
fat16 = Fat16(
mbr.partition_table[0]["start_lba"],
mbr.partition_table[0]["size"],
self.read_sectors,
self.write_sectors,
)
self.assertEqual(fat16.boot_sector.bytes_per_sector, 512)
self.assertEqual(fat16.boot_sector.volume_label, "QEMU VVFAT")
def test_read_root_directory(self):
"""
Test the content of the root directory
"""
fat16 = self.init_fat16()
root_dir = fat16.read_root_directory()
self.assertEqual(len(root_dir), 13) # 12 + 1 special file
files = {
"QEMU VVF.AT": 0, # special empty file
"FILE0.TXT": 16,
"FILE1.TXT": 16,
"FILE2.TXT": 16,
"FILE3.TXT": 16,
"FILE4.TXT": 16,
"FILE5.TXT": 16,
"FILE6.TXT": 16,
"FILE7.TXT": 16,
"FILE8.TXT": 16,
"FILE9.TXT": 16,
"LARGE1.TXT": 0x2000 * 2,
"LARGE2.TXT": 0x2000 * 3,
}
for entry in root_dir:
self.assertIn(entry.whole_name(), files)
self.assertEqual(entry.size_bytes, files[entry.whole_name()])
def test_direntry_as_bytes(self):
"""
Test if we can convert Direntry back to bytes, so that we can write it
back to the disk safely.
"""
fat16 = self.init_fat16()
root_dir = fat16.read_root_directory()
first_entry_bytes = fat16.read_sectors(
fat16.boot_sector.root_dir_start(), 1)
# The first entry won't be deleted, so we can compare it with the first
# entry in the root directory
self.assertEqual(root_dir[0].as_bytes(),
first_entry_bytes[:DIRENTRY_SIZE])
def test_read_files(self):
"""
Test reading the content of the files
"""
fat16 = self.init_fat16()
for i in range(10):
file = fat16.find_direntry(f"/FILE{i}.TXT")
self.assertIsNotNone(file)
self.assertEqual(
fat16.read_file(file), f"Hello, world! {i}\n".encode("ascii")
)
# test large files
large1 = fat16.find_direntry("/LARGE1.TXT")
with open(os.path.join(filesystem, "large1.txt"), "rb") as f:
self.assertEqual(fat16.read_file(large1), f.read())
large2 = fat16.find_direntry("/LARGE2.TXT")
self.assertIsNotNone(large2)
with open(os.path.join(filesystem, "large2.txt"), "rb") as f:
self.assertEqual(fat16.read_file(large2), f.read())
def test_write_file_same_content_direct(self):
"""
Similar to `test_write_file_in_same_content`, but we write the file
directly clusters and thus we don't go through the modification of
direntry.
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/FILE0.TXT")
self.assertIsNotNone(file)
data = fat16.read_cluster(file.cluster)
fat16.write_cluster(file.cluster, data)
with open(os.path.join(filesystem, "file0.txt"), "rb") as f:
self.assertEqual(fat16.read_file(file), f.read())
def test_write_file_in_same_content(self):
"""
Test writing the same content to the file back to it
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/FILE0.TXT")
self.assertIsNotNone(file)
self.assertEqual(fat16.read_file(file), b"Hello, world! 0\n")
fat16.write_file(file, b"Hello, world! 0\n")
self.assertEqual(fat16.read_file(file), b"Hello, world! 0\n")
with open(os.path.join(filesystem, "file0.txt"), "rb") as f:
self.assertEqual(f.read(), b"Hello, world! 0\n")
def test_modify_content_same_clusters(self):
"""
Test modifying the content of the file without changing the number of
clusters
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/FILE0.TXT")
self.assertIsNotNone(file)
new_content = b"Hello, world! Modified\n"
self.assertEqual(fat16.read_file(file), b"Hello, world! 0\n")
fat16.write_file(file, new_content)
self.assertEqual(fat16.read_file(file), new_content)
with open(os.path.join(filesystem, "file0.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
def test_truncate_file_same_clusters_less(self):
"""
Test truncating the file without changing number of clusters
Test decreasing the file size
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/FILE0.TXT")
self.assertIsNotNone(file)
self.assertEqual(fat16.read_file(file), b"Hello, world! 0\n")
fat16.truncate_file(file, 5)
new_content = fat16.read_file(file)
self.assertEqual(new_content, b"Hello")
with open(os.path.join(filesystem, "file0.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
def test_truncate_file_same_clusters_more(self):
"""
Test truncating the file without changing number of clusters
Test increase the file size
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/FILE0.TXT")
self.assertIsNotNone(file)
self.assertEqual(fat16.read_file(file), b"Hello, world! 0\n")
fat16.truncate_file(file, 20)
new_content = fat16.read_file(file)
self.assertIsNotNone(new_content)
# random pattern will be appended to the file, and its not always the
# same
self.assertEqual(new_content[:16], b"Hello, world! 0\n")
self.assertEqual(len(new_content), 20)
with open(os.path.join(filesystem, "file0.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
def test_write_large_file(self):
"""
Test writing a large file
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/LARGE1.TXT")
self.assertIsNotNone(file)
# The content of LARGE1 is A * 1KB, B * 1KB, C * 1KB, ..., P * 1KB
# Lets change it to be Z * 1KB, Y * 1KB, X * 1KB, ..., K * 1KB
# without changing the number of clusters or filesize
new_content = b"".join([bytes([0x5A - i] * 1024) for i in range(16)])
fat16.write_file(file, new_content)
self.assertEqual(fat16.read_file(file), new_content)
with open(os.path.join(filesystem, "large1.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
def test_truncate_file_change_clusters_less(self):
"""
Test truncating a file by reducing the number of clusters
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/LARGE1.TXT")
self.assertIsNotNone(file)
fat16.truncate_file(file, 1)
self.assertEqual(fat16.read_file(file), b"A")
with open(os.path.join(filesystem, "large1.txt"), "rb") as f:
self.assertEqual(f.read(), b"A")
def test_write_file_change_clusters_less(self):
"""
Test truncating a file by reducing the number of clusters
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/LARGE2.TXT")
self.assertIsNotNone(file)
new_content = b"X" * 8 * 1024 + b"Y" * 8 * 1024
fat16.write_file(file, new_content)
self.assertEqual(fat16.read_file(file), new_content)
with open(os.path.join(filesystem, "large2.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
def test_write_file_change_clusters_more(self):
"""
Test truncating a file by increasing the number of clusters
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/LARGE2.TXT")
self.assertIsNotNone(file)
# from 3 clusters to 4 clusters
new_content = (
b"W" * 8 * 1024 +
b"X" * 8 * 1024 +
b"Y" * 8 * 1024 +
b"Z" * 8 * 1024
)
fat16.write_file(file, new_content)
self.assertEqual(fat16.read_file(file), new_content)
with open(os.path.join(filesystem, "large2.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
def test_write_file_change_clusters_more_non_contiguous_2_mappings(self):
"""
Test truncating a file by increasing the number of clusters Here we
allocate the new clusters in a way that makes them non-contiguous so
that we will get 2 cluster mappings for the file
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/LARGE1.TXT")
self.assertIsNotNone(file)
# from 2 clusters to 3 clusters with non-contiguous allocation
fat16.truncate_file(file, 3 * 0x2000, allocate_non_continuous=True)
new_content = b"X" * 8 * 1024 + b"Y" * 8 * 1024 + b"Z" * 8 * 1024
fat16.write_file(file, new_content)
self.assertEqual(fat16.read_file(file), new_content)
with open(os.path.join(filesystem, "large1.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
def test_write_file_change_clusters_more_non_contiguous_3_mappings(self):
"""
Test truncating a file by increasing the number of clusters Here we
allocate the new clusters in a way that makes them non-contiguous so
that we will get 3 cluster mappings for the file
"""
fat16 = self.init_fat16()
file = fat16.find_direntry("/LARGE1.TXT")
self.assertIsNotNone(file)
# from 2 clusters to 4 clusters with non-contiguous allocation
fat16.truncate_file(file, 4 * 0x2000, allocate_non_continuous=True)
new_content = (
b"W" * 8 * 1024 +
b"X" * 8 * 1024 +
b"Y" * 8 * 1024 +
b"Z" * 8 * 1024
)
fat16.write_file(file, new_content)
self.assertEqual(fat16.read_file(file), new_content)
with open(os.path.join(filesystem, "large1.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
def test_create_file(self):
"""
Test creating a new file
"""
fat16 = self.init_fat16()
new_file = fat16.create_file("/NEWFILE.TXT")
self.assertIsNotNone(new_file)
self.assertEqual(new_file.size_bytes, 0)
new_content = b"Hello, world! New file\n"
fat16.write_file(new_file, new_content)
self.assertEqual(fat16.read_file(new_file), new_content)
with open(os.path.join(filesystem, "newfile.txt"), "rb") as f:
self.assertEqual(f.read(), new_content)
# TODO: support deleting files
if __name__ == "__main__":
# This is a specific test for vvfat driver
iotests.main(supported_fmts=["vvfat"], supported_protocols=["file"])

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