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| Dir : //proc/self/root/opt/saltstack/salt/lib/python3.10/site-packages/salt/utils/filebuffer.py |
"""
:codeauthor: Pedro Algarvio (pedro@algarvio.me)
salt.utils.filebuffer
~~~~~~~~~~~~~~~~~~~~~
This utility allows parsing a file in chunks.
"""
import salt.utils.files
import salt.utils.stringutils
from salt.exceptions import SaltException
class InvalidFileMode(SaltException):
"""
An invalid file mode was used to open the file passed to the buffer
"""
class BufferedReader:
"""
This object allows iterating through the contents of a file keeping
X configurable bytes in memory which can be used to, for example,
do regex search/matching on more than a single line.
So, **an imaginary, non accurate**, example could be:
1 - Initiate the BufferedReader filling it to max_in_men:
br = [1, 2, 3]
2 - next chunk(pop chunk_size from the left, append chunk_size to the
right):
br = [2, 3, 4]
:type path: str
:param path: The file path to be read
:type max_in_mem: int
:param max_in_mem: The maximum bytes kept in memory while iterating through
the file. Default 256KB.
:type chunk_size: int
:param chunk_size: The size of each consequent read chunk. Default 32KB.
:type mode: str
:param mode: The mode the file should be opened. **Only read modes**.
"""
def __init__(self, path, max_in_mem=256 * 1024, chunk_size=32 * 1024, mode="r"):
if "a" in mode or "w" in mode:
raise InvalidFileMode("Cannot open file in write or append mode")
self.__path = path
# pylint: disable=resource-leakage
self.__file = salt.utils.files.fopen(self.__path, mode)
# pylint: enable=resource-leakage
self.__max_in_mem = max_in_mem
self.__chunk_size = chunk_size
self.__buffered = None
# Public attributes
@property
def buffered(self):
return self.__buffered
# Support iteration
def __iter__(self):
return self
def next(self):
"""
Return the next iteration by popping `chunk_size` from the left and
appending `chunk_size` to the right if there's info on the file left
to be read.
"""
if self.__buffered is None:
# Use floor division to force multiplier to an integer
multiplier = self.__max_in_mem // self.__chunk_size
self.__buffered = ""
else:
multiplier = 1
self.__buffered = self.__buffered[self.__chunk_size :]
data = self.__file.read(self.__chunk_size * multiplier)
# Data is a byte object in Python 3
# Decode it in order to append to self.__buffered str later
# Use the salt util in case it's already a string (Windows)
data = salt.utils.stringutils.to_str(data)
if not data:
self.__file.close()
raise StopIteration
self.__buffered += data
return self.__buffered
# Alias next to __next__ for Py3 compatibility
__next__ = next
# Support with statements
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
if self.__file.closed is False:
self.__file.close()