GeezerVison is showing github.com — bpython/bpython/filelock.py at main · dsfb/bpython

Expand file tree

filelock.py

Copy path

More file actions

Latest commit

History

134 lines (106 loc) · 3.61 KB

filelock.py

Copy path

File metadata and controls

134 lines (106 loc) · 3.61 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

# The MIT License

# Permission is hereby granted, free of charge, to any person obtaining a copy

# of this software and associated documentation files (the "Software"), to deal

# in the Software without restriction, including without limitation the rights

# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

# copies of the Software, and to permit persons to whom the Software is

# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in

# all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

# THE SOFTWARE.

from typing import Optional, Type, IO, Literal

from types import TracebackType

has_fcntl = True

try:

import fcntl

import errno

except ImportError:

has_fcntl = False

has_msvcrt = True

try:

import msvcrt

import os

except ImportError:

has_msvcrt = False

class BaseLock:

"""Base class for file locking"""

def __init__(self) -> None:

self.locked = False

def acquire(self) -> None:

pass

def release(self) -> None:

pass

def __enter__(self) -> "BaseLock":

self.acquire()

return self

def __exit__(

self,

exc_type: Optional[Type[BaseException]],

exc: Optional[BaseException],

exc_tb: Optional[TracebackType],

) -> Literal[False]:

if self.locked:

self.release()

return False

def __del__(self) -> None:

if self.locked:

self.release()

class UnixFileLock(BaseLock):

"""Simple file locking for Unix using fcntl"""

def __init__(self, fileobj, mode: int = 0) -> None:

super().__init__()

self.fileobj = fileobj

self.mode = mode | fcntl.LOCK_EX

def acquire(self) -> None:

try:

fcntl.flock(self.fileobj, self.mode)

self.locked = True

except OSError as e:

if e.errno != errno.ENOLCK:

raise e

def release(self) -> None:

self.locked = False

fcntl.flock(self.fileobj, fcntl.LOCK_UN)

class WindowsFileLock(BaseLock):

"""Simple file locking for Windows using msvcrt"""

def __init__(self, filename: str) -> None:

super().__init__()

self.filename = f"{filename}.lock"

self.fileobj = -1

def acquire(self) -> None:

# create a lock file and lock it

self.fileobj = os.open(

self.filename, os.O_RDWR | os.O_CREAT | os.O_TRUNC

)

msvcrt.locking(self.fileobj, msvcrt.LK_NBLCK, 1)

self.locked = True

def release(self) -> None:

self.locked = False

# unlock lock file and remove it

msvcrt.locking(self.fileobj, msvcrt.LK_UNLCK, 1)

os.close(self.fileobj)

self.fileobj = -1

try:

os.remove(self.filename)

except OSError:

pass

def FileLock(

fileobj: IO, mode: int = 0, filename: Optional[str] = None

) -> BaseLock:

if has_fcntl:

return UnixFileLock(fileobj, mode)

elif has_msvcrt and filename is not None:

return WindowsFileLock(filename)

return BaseLock()

# vim: sw=4 ts=4 sts=4 ai et