Source code for fsspec.implementations.libarchive

from __future__ import absolute_import, division, print_function

from contextlib import contextmanager
from ctypes import (
    CFUNCTYPE,
    POINTER,
    c_int,
    c_longlong,
    c_void_p,
    cast,
    create_string_buffer,
)

import libarchive
import libarchive.ffi as ffi

from fsspec import open_files
from fsspec.archive import AbstractArchiveFileSystem
from fsspec.implementations.memory import MemoryFile
from fsspec.utils import DEFAULT_BLOCK_SIZE

# Libarchive requires seekable files or memory only for certain archive
# types. However, since we read the directory first to cache the contents
# and also allow random access to any file, the file-like object needs
# to be seekable no matter what.

# Seek call-backs (not provided in the libarchive python wrapper)
SEEK_CALLBACK = CFUNCTYPE(c_longlong, c_int, c_void_p, c_longlong, c_int)
read_set_seek_callback = ffi.ffi(
    "read_set_seek_callback", [ffi.c_archive_p, SEEK_CALLBACK], c_int, ffi.check_int
)
new_api = hasattr(ffi, "NO_OPEN_CB")


@contextmanager
def custom_reader(file, format_name="all", filter_name="all", block_size=ffi.page_size):
    """Read an archive from a seekable file-like object.

    The `file` object must support the standard `readinto` and 'seek' methods.
    """
    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 = file.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):
        file.seek(offset, whence)
        # tell libarchvie the current position
        return file.tell()

    read_cb = ffi.READ_CALLBACK(read_func)
    seek_cb = SEEK_CALLBACK(seek_func)

    if new_api:
        open_cb = ffi.NO_OPEN_CB
        close_cb = ffi.NO_CLOSE_CB
    else:
        open_cb = libarchive.read.OPEN_CALLBACK(ffi.VOID_CB)
        close_cb = libarchive.read.CLOSE_CALLBACK(ffi.VOID_CB)

    with libarchive.read.new_archive_read(format_name, filter_name) as archive_p:
        read_set_seek_callback(archive_p, seek_cb)
        ffi.read_open(archive_p, None, open_cb, read_cb, close_cb)
        yield libarchive.read.ArchiveRead(archive_p)


[docs]class LibArchiveFileSystem(AbstractArchiveFileSystem): """Compressed archives as a file-system (read-only) Supports the following formats: tar, pax , cpio, ISO9660, zip, mtree, shar, ar, raw, xar, lha/lzh, rar Microsoft CAB, 7-Zip, WARC See the libarchive documentation for further restrictions. https://www.libarchive.org/ Keeps file object open while instance lives. It only works in seekable file-like objects. In case the filesystem does not support this kind of file object, it is recommended to cache locally. This class is pickleable, but not necessarily thread-safe (depends on the platform). See libarchive documentation for details. """ root_marker = "" protocol = "libarchive"
[docs] def __init__( self, fo="", mode="r", target_protocol=None, target_options=None, block_size=DEFAULT_BLOCK_SIZE, **kwargs, ): """ Parameters ---------- fo: str or file-like Contains ZIP, and must exist. If a str, will fetch file using `open_files()`, which must return one file exactly. mode: str Currently, only 'r' accepted target_protocol: str (optional) If ``fo`` is a string, this value can be used to override the FS protocol inferred from a URL target_options: dict (optional) Kwargs passed when instantiating the target FS, if ``fo`` is a string. """ super().__init__(self, **kwargs) if mode != "r": raise ValueError("Only read from archive files accepted") if isinstance(fo, str): files = open_files(fo, protocol=target_protocol, **(target_options or {})) if len(files) != 1: raise ValueError( 'Path "{}" did not resolve to exactly' 'one file: "{}"'.format(fo, files) ) fo = files[0] self.fo = fo.__enter__() # the whole instance is a context self.block_size = block_size self.dir_cache = None
@contextmanager def _open_archive(self): self.fo.seek(0) with custom_reader(self.fo, block_size=self.block_size) as arc: yield arc @classmethod def _strip_protocol(cls, path): # file paths are always relative to the archive root return super()._strip_protocol(path).lstrip("/") def _get_dirs(self): fields = { "name": "pathname", "size": "size", "created": "ctime", "mode": "mode", "uid": "uid", "gid": "gid", "mtime": "mtime", } if self.dir_cache is not None: return self.dir_cache = {} list_names = [] with self._open_archive() as arc: for entry in arc: if not entry.isdir and not entry.isfile: # Skip symbolic links, fifo entries, etc. continue self.dir_cache.update( { dirname + "/": {"name": dirname + "/", "size": 0, "type": "directory"} for dirname in self._all_dirnames(set(entry.name)) } ) f = {key: getattr(entry, fields[key]) for key in fields} f["type"] = "directory" if entry.isdir else "file" list_names.append(entry.name) self.dir_cache[f["name"]] = f # libarchive does not seem to return an entry for the directories (at least # not in all formats), so get the directories names from the files names self.dir_cache.update( { dirname + "/": {"name": dirname + "/", "size": 0, "type": "directory"} for dirname in self._all_dirnames(list_names) } ) def _open( self, path, mode="rb", block_size=None, autocommit=True, cache_options=None, **kwargs, ): path = self._strip_protocol(path) if mode != "rb": raise NotImplementedError data = bytes() with self._open_archive() as arc: for entry in arc: if entry.pathname != path: continue for block in entry.get_blocks(entry.size): data = block break else: raise ValueError return MemoryFile(fs=self, path=path, data=data)