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"""
file related operations, mainly reading
"""
import mmap
import os
from functools import partial
from . import _fileutils, data_source
from .compatibility import IGNORED_EXCEPTIONS
from .currying import pretty_docs
from .klass import GetAttrProxy
def touch(fname, mode=0o644, **kwargs):
"""touch(1) equivalent
:param fname: file path
:type fname: str
:param mode: file mode
:type mode: octal
See os.utime for other supported arguments.
"""
flags = os.O_CREAT | os.O_APPEND
dir_fd = kwargs.get("dir_fd", None)
os_open = partial(os.open, dir_fd=dir_fd)
with os.fdopen(os_open(fname, flags, mode)) as f:
os.utime(
f.fileno() if os.utime in os.supports_fd else fname,
dir_fd=None if os.supports_fd else dir_fd,
**kwargs
)
def mmap_or_open_for_read(path):
size = os.stat(path).st_size
if size == 0:
return (None, data_source.bytes_ro_StringIO(b""))
fd = None
try:
fd = os.open(path, os.O_RDONLY)
return (
_fileutils.mmap_and_close(fd, size, mmap.MAP_SHARED, mmap.PROT_READ),
None,
)
except IGNORED_EXCEPTIONS:
raise
except:
try:
os.close(fd)
except EnvironmentError:
pass
raise
class AtomicWriteFile_mixin:
"""File class that stores the changes in a tempfile.
Upon invocation of the close method, this class will use
:py:func:`os.rename` to atomically replace the destination.
Similar to file protocol behavior, except that close *must*
be called for the changes to be made live,
If along the way it's decided that these changes should be discarded,
invoke :py:func:`AtomicWriteFile.discard`; this will close the file
without updating the target.
If this object falls out of memory without ever being discarded nor
closed, the contents are discarded and a warning is issued.
"""
def __init__(self, fp, binary=False, perms=None, uid=-1, gid=-1):
"""
:param fp: filepath to write to upon close
:param binary: should we open the file in binary mode?
:param perms: if specified, permissions we should force for the file.
:param uid: if specified, the uid to force for the file.
:param gid: if specified, the uid to force for the file.
"""
self._is_finalized = True
if binary:
file_mode = "wb"
else:
file_mode = "w"
self._computed_mode = file_mode
fp = os.path.realpath(fp)
self._original_fp = fp
self._temp_fp = os.path.join(
os.path.dirname(fp), ".update." + os.path.basename(fp)
)
old_umask = None
if perms:
# give it just write perms
old_umask = os.umask(0o0200)
try:
self._actual_init()
finally:
if old_umask is not None:
os.umask(old_umask)
self._is_finalized = False
if perms:
os.chmod(self._temp_fp, perms)
if (gid, uid) != (-1, -1):
os.chown(self._temp_fp, uid, gid)
def discard(self):
"""If we've not already flushed our changes to the target, discard them
and close this file handle."""
if not self._is_finalized:
self._real_close()
os.unlink(self._temp_fp)
self._is_finalized = True
def __enter__(self):
return self
def __exit__(self, exc_type, exc, tb):
if exc is not None:
self.discard()
else:
self.close()
def close(self):
"""Close this file handle, atomically updating the target in the process.
Note that if we're already closed, this method does nothing
"""
if not self._is_finalized:
self._real_close()
os.rename(self._temp_fp, self._original_fp)
self._is_finalized = True
def __del__(self):
self.discard()
class AtomicWriteFile(AtomicWriteFile_mixin):
__doc__ = AtomicWriteFile_mixin.__doc__
def _actual_init(self):
self.raw = open(self._temp_fp, mode=self._computed_mode)
def _real_close(self):
if hasattr(self, "raw"):
return self.raw.close()
return None
__getattr__ = GetAttrProxy("raw")
def _mk_pretty_derived_func(func, name_base, name, *args, **kwds):
if name:
name = "_" + name
return pretty_docs(partial(func, *args, **kwds), name="%s%s" % (name_base, name))
_mk_readfile = partial(_mk_pretty_derived_func, _fileutils.native_readfile, "readfile")
readfile_ascii = _mk_readfile("ascii", "rt")
readfile_bytes = _mk_readfile("bytes", "rb")
readfile_utf8 = _mk_readfile("utf8", "r", encoding="utf8")
readfile = readfile_utf8
_mk_readlines = partial(
_mk_pretty_derived_func, _fileutils.native_readlines, "readlines"
)
readlines_ascii = _mk_readlines("ascii", "r", encoding="ascii")
readlines_bytes = _mk_readlines("bytes", "rb")
readlines_utf8 = _mk_readlines("utf8", "r", encoding="utf8")
readlines = readlines_utf8
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