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from contextlib import contextmanager
from ctypes import cast, c_void_p, POINTER, create_string_buffer
from os import fstat, stat
from . import ffi
from .ffi import (
ARCHIVE_EOF, OPEN_CALLBACK, READ_CALLBACK, CLOSE_CALLBACK, SEEK_CALLBACK,
NO_OPEN_CB, NO_CLOSE_CB, page_size,
)
from .entry import ArchiveEntry, PassedArchiveEntry
class ArchiveRead:
def __init__(self, archive_p, header_codec='utf-8'):
self._pointer = archive_p
self.header_codec = header_codec
def __iter__(self):
"""Iterates through an archive's entries.
"""
archive_p = self._pointer
header_codec = self.header_codec
read_next_header2 = ffi.read_next_header2
while 1:
entry = ArchiveEntry(archive_p, header_codec)
r = read_next_header2(archive_p, entry._entry_p)
if r == ARCHIVE_EOF:
return
yield entry
entry.__class__ = PassedArchiveEntry
@property
def bytes_read(self):
return ffi.filter_bytes(self._pointer, -1)
@property
def filter_names(self):
count = ffi.filter_count(self._pointer)
return [ffi.filter_name(self._pointer, i) for i in range(count - 1)]
@property
def format_name(self):
return ffi.format_name(self._pointer)
@contextmanager
def new_archive_read(format_name='all', filter_name='all', passphrase=None):
"""Creates an archive struct suitable for reading from an archive.
Returns a pointer if successful. Raises ArchiveError on error.
"""
archive_p = ffi.read_new()
try:
if passphrase:
if not isinstance(passphrase, bytes):
passphrase = passphrase.encode('utf-8')
try:
ffi.read_add_passphrase(archive_p, passphrase)
except AttributeError:
raise NotImplementedError(
f"the libarchive being used (version {ffi.version_number()}, "
f"path {ffi.libarchive_path}) doesn't support encryption"
)
ffi.get_read_filter_function(filter_name)(archive_p)
ffi.get_read_format_function(format_name)(archive_p)
yield archive_p
finally:
ffi.read_free(archive_p)
@contextmanager
def custom_reader(
read_func, format_name='all', filter_name='all',
open_func=None, seek_func=None, close_func=None,
block_size=page_size, archive_read_class=ArchiveRead, passphrase=None,
header_codec='utf-8',
):
"""Read an archive using a custom function.
"""
open_cb = OPEN_CALLBACK(open_func) if open_func else NO_OPEN_CB
read_cb = READ_CALLBACK(read_func)
close_cb = CLOSE_CALLBACK(close_func) if close_func else NO_CLOSE_CB
seek_cb = SEEK_CALLBACK(seek_func)
with new_archive_read(format_name, filter_name, passphrase) as archive_p:
if seek_func:
ffi.read_set_seek_callback(archive_p, seek_cb)
ffi.read_open(archive_p, None, open_cb, read_cb, close_cb)
yield archive_read_class(archive_p, header_codec)
@contextmanager
def fd_reader(
fd, format_name='all', filter_name='all', block_size=4096, passphrase=None,
header_codec='utf-8',
):
"""Read an archive from a file descriptor.
"""
with new_archive_read(format_name, filter_name, passphrase) as archive_p:
try:
block_size = fstat(fd).st_blksize
except (OSError, AttributeError): # pragma: no cover
pass
ffi.read_open_fd(archive_p, fd, block_size)
yield ArchiveRead(archive_p, header_codec)
@contextmanager
def file_reader(
path, format_name='all', filter_name='all', block_size=4096, passphrase=None,
header_codec='utf-8',
):
"""Read an archive from a file.
"""
with new_archive_read(format_name, filter_name, passphrase) as archive_p:
try:
block_size = stat(path).st_blksize
except (OSError, AttributeError): # pragma: no cover
pass
ffi.read_open_filename_w(archive_p, path, block_size)
yield ArchiveRead(archive_p, header_codec)
@contextmanager
def memory_reader(
buf, format_name='all', filter_name='all', passphrase=None,
header_codec='utf-8',
):
"""Read an archive from memory.
"""
with new_archive_read(format_name, filter_name, passphrase) as archive_p:
ffi.read_open_memory(archive_p, cast(buf, c_void_p), len(buf))
yield ArchiveRead(archive_p, header_codec)
@contextmanager
def stream_reader(
stream, format_name='all', filter_name='all', block_size=page_size,
passphrase=None, header_codec='utf-8',
):
"""Read an archive from a stream.
The `stream` object must support the standard `readinto` method.
If `stream.seekable()` returns `True`, then an appropriate seek callback is
passed to libarchive.
"""
buf = create_string_buffer(block_size)
buf_p = cast(buf, c_void_p)
def read_func(archive_p, context, ptrptr):
# readinto the buffer, returns number of bytes read
length = stream.readinto(buf)
# write the address of the buffer into the pointer
ptrptr = cast(ptrptr, POINTER(c_void_p))
ptrptr[0] = buf_p
# tell libarchive how much data was written into the buffer
return length
def seek_func(archive_p, context, offset, whence):
stream.seek(offset, whence)
# tell libarchive the current position
return stream.tell()
open_cb = NO_OPEN_CB
read_cb = READ_CALLBACK(read_func)
close_cb = NO_CLOSE_CB
seek_cb = SEEK_CALLBACK(seek_func)
with new_archive_read(format_name, filter_name, passphrase) as archive_p:
if stream.seekable():
ffi.read_set_seek_callback(archive_p, seek_cb)
ffi.read_open(archive_p, None, open_cb, read_cb, close_cb)
yield ArchiveRead(archive_p, header_codec)
seekable_stream_reader = stream_reader
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