On Mon, Jun 10, 2024 at 02:01:24PM +0200, Kevin Wolf wrote:
> Am 05.06.2024 um 02:58 hat Amjad Alsharafi geschrieben:
> > 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 <amjadsharaf...@gmail.com>
> > ---
> > tests/qemu-iotests/check | 2 +-
> > tests/qemu-iotests/fat16.py | 635 +++++++++++++++++++++++++++++
> > tests/qemu-iotests/testenv.py | 2 +-
> > tests/qemu-iotests/tests/vvfat | 440 ++++++++++++++++++++
> > tests/qemu-iotests/tests/vvfat.out | 5 +
> > 5 files changed, 1082 insertions(+), 2 deletions(-)
> > create mode 100644 tests/qemu-iotests/fat16.py
> > create mode 100755 tests/qemu-iotests/tests/vvfat
> > create mode 100755 tests/qemu-iotests/tests/vvfat.out
> >
> > diff --git a/tests/qemu-iotests/check b/tests/qemu-iotests/check
> > index 56d88ca423..545f9ec7bd 100755
> > --- a/tests/qemu-iotests/check
> > +++ b/tests/qemu-iotests/check
> > @@ -84,7 +84,7 @@ 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. '
> > diff --git a/tests/qemu-iotests/fat16.py b/tests/qemu-iotests/fat16.py
> > new file mode 100644
> > index 0000000000..baf801b4d5
> > --- /dev/null
> > +++ b/tests/qemu-iotests/fat16.py
> > @@ -0,0 +1,635 @@
> > +# A simple FAT16 driver that is used to test the `vvfat` driver in QEMU.
> > +#
> > +# Copyright (C) 2024 Amjad Alsharafi <amjadsharaf...@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 List
> > +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:
> > + 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")
> > + self.media_descriptor = data[21]
> > + self.fat_size = int.from_bytes(data[22:24], "little")
> > + self.sectors_per_fat = int.from_bytes(data[22:24], "little")
>
> Why two different attributes self.fat_size and self.sectors_per_fat that
> contain the same value?
>
> > + 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")
> > + self.total_sectors = int.from_bytes(data[32:36], "little")
>
> This value should only be considered if the 16 bit value at byte 19
> (which you don't store at all) was 0.
>
> > + 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):
> > + """
> > + 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:
> > + 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 Fat16:
> > + def __init__(
> > + self,
> > + start_sector: int,
> > + size: int,
> > + sector_reader: callable,
> > + sector_writer: callable,
> > + ):
> > + 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))
> > +
> > + fat_size_in_sectors = \
> > + self.boot_sector.fat_size * self.boot_sector.fat_count
> > + self.fats = self.read_sectors(
> > + self.boot_sector.reserved_sectors, fat_size_in_sectors
> > + )
> > + self.fats_dirty_sectors = 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):
> > + 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
> > + elif 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):
> > + """
> > + 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):
> > + """
> > + 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) -> int | None:
> > + """
> > + 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")
> > + elif fat_entry == 1:
> > + raise Exception("Unexpected: RESERVED cluster")
> > + elif fat_entry >= 0xFFF8:
> > + return None
> > + elif fat_entry >= 0xFFF7:
> > + raise Exception("Invalid FAT entry")
> > + else:
> > + 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 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):
> > + """
> > + Write the cluster at the given cluster.
> > + """
> > + assert len(data) == self.boot_sector.cluster_bytes()
> > + return self.write_sectors(
> > + self.boot_sector.first_sector_of_cluster(cluster),
> > + data,
> > + )
> > +
> > + def read_directory(self, cluster: 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: int | None,
> > + name: str, ext: str,
> > + attributes: int):
> > + """
> > + 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):
> > + 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):
> > + """
> > + 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) -> FatDirectoryEntry | None:
> > + """
> > + 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
> > + else:
> > + if current_entry.attributes & 0x10 == 0:
> > + raise Exception(
> > + f"{current_entry.whole_name()} is not a directory")
> > + else:
> > + directory = self.read_directory(current_entry.cluster)
> > +
> > + def read_file(self, entry: FatDirectoryEntry) -> 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 = 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):
> > + """
> > + Truncate the file at the given path to the new size.
> > + """
> > + if entry is None:
> > + return Exception("entry is None")
> > + if entry.attributes & 0x10 != 0:
> > + raise Exception(f"{entry.whole_name()} is a directory")
> > +
> > + def clusters_from_size(size: 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
> > +
> > + if required_clusters > current_clusters:
> > + # Allocate new clusters
> > + cluster = entry.cluster
> > + to_add = required_clusters
> > + for _ in range(current_clusters - 1):
> > + to_add -= 1
> > + 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):
> > + 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):
> > + 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):
> > + """
> > + Write the content of the file at the given path.
> > + """
> > + if entry is None:
> > + return 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 = entry.cluster
> > + while cluster is not None:
> > + data_to_write = data[: self.boot_sector.cluster_bytes()]
> > + last_data = False
> > + if len(data_to_write) < self.boot_sector.cluster_bytes():
> > + last_data = True
> > + 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):
> > + """
> > + 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 i, 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")
> > + else:
> > + 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)
> > diff --git a/tests/qemu-iotests/testenv.py b/tests/qemu-iotests/testenv.py
> > index 588f30a4f1..4053d29de4 100644
> > --- a/tests/qemu-iotests/testenv.py
> > +++ b/tests/qemu-iotests/testenv.py
> > @@ -250,7 +250,7 @@ def __init__(self, source_dir: str, build_dir: str,
> > 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}'
> > diff --git a/tests/qemu-iotests/tests/vvfat b/tests/qemu-iotests/tests/vvfat
> > new file mode 100755
> > index 0000000000..113d7d3270
> > --- /dev/null
> > +++ b/tests/qemu-iotests/tests/vvfat
> > @@ -0,0 +1,440 @@
> > +#!/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 <amjadsharaf...@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, 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):
> > + def setUp(self) -> None:
> > + if os.path.exists(filesystem):
> > + if os.path.isdir(filesystem):
> > + shutil.rmtree(filesystem)
> > + else:
> > + print(f"Error: {filesystem} exists and is not a directory")
> > + exit(1)
> > + 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") 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):
> > + """
> > + 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)
> > +
> > + # 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)
> > +
> > + 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"Hello, world! This was a large file\n"
> > + new_content = b"X" * 8 * 1024 + b"Y" * 8 * 1024
>
> This sets and then immediately overwrites new_content. What was intended
> here?
>
> > +
> > + 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)
> > +
> > + new_content = b"X" * 8 * 1024 + b"Y" * 8 * 1024 + b"Z" * 8 * 1024
> > +
> > + fat16.write_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_last_file(self):
> > + """
> > + Test truncating a file by increasing the number of clusters
> > + This is a special variant of the above test, where we write to
> > + a file so that when allocating new clusters, it won't have
> > contiguous clusters
> > + """
> > + fat16 = self.init_fat16()
> > +
> > + file = fat16.find_direntry("/LARGE1.TXT")
> > + self.assertIsNotNone(file)
> > +
> > + new_content = b"X" * 8 * 1024 + b"Y" * 8 * 1024 + b"Z" * 8 * 1024
> > +
> > + fat16.write_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"])
> > diff --git a/tests/qemu-iotests/tests/vvfat.out
> > b/tests/qemu-iotests/tests/vvfat.out
> > new file mode 100755
> > index 0000000000..96961ed0b5
> > --- /dev/null
> > +++ b/tests/qemu-iotests/tests/vvfat.out
> > @@ -0,0 +1,5 @@
> > +...............
> > +----------------------------------------------------------------------
> > +Ran 15 tests
> > +
> > +OK
>
> With the updated test, I can catch the problems that are fixed by
> patches 1 and 2, but it still doesn't need patch 3 to pass.
>
> Kevin
>
Thanks for reviewing, those are all mistakes, and I fixed them (included
a small patch to fix these issues at the end...).
Regarding the failing test, I forgot to also read the files from the fat
driver, and instead I was just reading from the host filesystem.
I'm not sure exactly, why reading from the filesystem works, but reading
from the driver (i.e. guest) gives the weird buggy result.
I have updated the test in the patch below to reflect this.
I would love if you can test the patch below and let me know if the
issues are fixed, after that I can send the new series.
Thanks,
Amjad
--- PATCH ---
diff --git a/tests/qemu-iotests/fat16.py b/tests/qemu-iotests/fat16.py
index baf801b4d5..411a277906 100644
--- a/tests/qemu-iotests/fat16.py
+++ b/tests/qemu-iotests/fat16.py
@@ -62,13 +62,16 @@ def __init__(self, data: bytes):
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.fat_size = int.from_bytes(data[22:24], "little")
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")
- self.total_sectors = int.from_bytes(data[32:36], "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()
@@ -208,7 +211,7 @@ def __init__(
self.boot_sector = FatBootSector(self.sector_reader(start_sector))
fat_size_in_sectors = \
- self.boot_sector.fat_size * self.boot_sector.fat_count
+ 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
)
diff --git a/tests/qemu-iotests/tests/vvfat b/tests/qemu-iotests/tests/vvfat
index 113d7d3270..8d04f292e3 100755
--- a/tests/qemu-iotests/tests/vvfat
+++ b/tests/qemu-iotests/tests/vvfat
@@ -369,7 +369,6 @@ class TestVVFatDriver(QMPTestCase):
file = fat16.find_direntry("/LARGE2.TXT")
self.assertIsNotNone(file)
- new_content = b"Hello, world! This was a large file\n"
new_content = b"X" * 8 * 1024 + b"Y" * 8 * 1024
fat16.write_file(file, new_content)
@@ -388,10 +387,13 @@ class TestVVFatDriver(QMPTestCase):
file = fat16.find_direntry("/LARGE2.TXT")
self.assertIsNotNone(file)
- new_content = b"X" * 8 * 1024 + b"Y" * 8 * 1024 + b"Z" * 8 * 1024
+ # 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)
@@ -406,10 +408,13 @@ class TestVVFatDriver(QMPTestCase):
file = fat16.find_direntry("/LARGE1.TXT")
self.assertIsNotNone(file)
+ # from 2 clusters to 3 clusters
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)
