[utils] locked_file: Do not truncate files before locking (#2994)

Authored by: jakeogh, pukkandan
This commit is contained in:
Justin Keogh 2022-04-07 05:58:56 +00:00 committed by GitHub
parent 06b1628d3e
commit fcfa8853e4
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23

View file

@ -2222,10 +2222,23 @@ class locked_file(object):
locked = False locked = False
def __init__(self, filename, mode, block=True, encoding=None): def __init__(self, filename, mode, block=True, encoding=None):
assert mode in {'r', 'rb', 'a', 'ab', 'w', 'wb'} if mode not in {'r', 'rb', 'a', 'ab', 'w', 'wb'}:
self.f = open(filename, mode, encoding=encoding) raise NotImplementedError(mode)
self.mode = mode self.mode, self.block = mode, block
self.block = block
writable = any(f in mode for f in 'wax+')
readable = any(f in mode for f in 'r+')
flags = functools.reduce(operator.ior, (
getattr(os, 'O_CLOEXEC', 0), # UNIX only
getattr(os, 'O_BINARY', 0), # Windows only
getattr(os, 'O_NOINHERIT', 0), # Windows only
os.O_CREAT if writable else 0, # O_TRUNC only after locking
os.O_APPEND if 'a' in mode else 0,
os.O_EXCL if 'x' in mode else 0,
os.O_RDONLY if not writable else os.O_RDWR if readable else os.O_WRONLY,
))
self.f = os.fdopen(os.open(filename, flags), mode, encoding=encoding)
def __enter__(self): def __enter__(self):
exclusive = 'r' not in self.mode exclusive = 'r' not in self.mode
@ -2235,6 +2248,8 @@ def __enter__(self):
except IOError: except IOError:
self.f.close() self.f.close()
raise raise
if 'w' in self.mode:
self.f.truncate()
return self return self
def unlock(self): def unlock(self):