"""
Misc utilities
"""
import logging
import os
import tempfile
from pathlib import Path
import hashlib
from urllib.parse import urlsplit
from contextlib import contextmanager
import appdirs
from packaging.version import Version
LOGGER = logging.Logger("pooch")
LOGGER.addHandler(logging.StreamHandler())
[docs]def get_logger():
r"""
Get the default event logger.
The logger records events like downloading files, unzipping archives, etc.
Use the method :meth:`logging.Logger.setLevel` of this object to adjust the
verbosity level from Pooch.
Returns
-------
logger : :class:`logging.Logger`
The logger object for Pooch
"""
return LOGGER
[docs]def os_cache(project):
r"""
Default cache location based on the operating system.
The folder locations are defined by the ``appdirs`` package
using the ``user_cache_dir`` function.
Usually, the locations will be following (see the
`appdirs documentation <https://github.com/ActiveState/appdirs>`__):
* Mac: ``~/Library/Caches/<AppName>``
* Unix: ``~/.cache/<AppName>`` or the value of the ``XDG_CACHE_HOME``
environment variable, if defined.
* Windows: ``C:\Users\<user>\AppData\Local\<AppAuthor>\<AppName>\Cache``
Parameters
----------
project : str
The project name.
Returns
-------
cache_path : :class:`pathlib.Path`
The default location for the data cache. User directories (``'~'``) are
not expanded.
"""
return Path(appdirs.user_cache_dir(project))
[docs]def file_hash(fname, alg="sha256"):
"""
Calculate the hash of a given file.
Useful for checking if a file has changed or been corrupted.
Parameters
----------
fname : str
The name of the file.
alg : str
The type of the hashing algorithm
Returns
-------
hash : str
The hash of the file.
Examples
--------
>>> fname = "test-file-for-hash.txt"
>>> with open(fname, "w") as f:
... __ = f.write("content of the file")
>>> print(file_hash(fname))
0fc74468e6a9a829f103d069aeb2bb4f8646bad58bf146bb0e3379b759ec4a00
>>> import os
>>> os.remove(fname)
"""
if alg not in hashlib.algorithms_available:
raise ValueError("Algorithm '{}' not available in hashlib".format(alg))
# Calculate the hash in chunks to avoid overloading the memory
chunksize = 65536
hasher = hashlib.new(alg)
with open(fname, "rb") as fin:
buff = fin.read(chunksize)
while buff:
hasher.update(buff)
buff = fin.read(chunksize)
return hasher.hexdigest()
[docs]def check_version(version, fallback="master"):
"""
Check if a version is PEP440 compliant and there are no unreleased changes.
For example, ``version = "0.1"`` will be returned as is but ``version =
"0.1+10.8dl8dh9"`` will return the fallback. This is the convention used by
`versioneer <https://github.com/warner/python-versioneer>`__ to mark that
this version is 10 commits ahead of the last release.
Parameters
----------
version : str
A version string.
fallback : str
What to return if the version string has unreleased changes.
Returns
-------
version : str
If *version* is PEP440 compliant and there are unreleased changes, then
return *version*. Otherwise, return *fallback*.
Raises
------
InvalidVersion
If *version* is not PEP440 compliant.
Examples
--------
>>> check_version("0.1")
'0.1'
>>> check_version("0.1a10")
'0.1a10'
>>> check_version("0.1+111.9hdg36")
'master'
>>> check_version("0.1+111.9hdg36", fallback="dev")
'dev'
"""
parse = Version(version)
if parse.local is not None:
return fallback
return version
[docs]def make_registry(directory, output, recursive=True):
"""
Make a registry of files and hashes for the given directory.
This is helpful if you have many files in your test dataset as it keeps you
from needing to manually update the registry.
Parameters
----------
directory : str
Directory of the test data to put in the registry. All file names in
the registry will be relative to this directory.
output : str
Name of the output registry file.
recursive : bool
If True, will recursively look for files in subdirectories of
*directory*.
"""
directory = Path(directory)
if recursive:
pattern = "**/*"
else:
pattern = "*"
files = sorted(
[
str(path.relative_to(directory))
for path in directory.glob(pattern)
if path.is_file()
]
)
hashes = [file_hash(str(directory / fname)) for fname in files]
with open(output, "w") as outfile:
for fname, fhash in zip(files, hashes):
# Only use Unix separators for the registry so that we don't go
# insane dealing with file paths.
outfile.write("{} {}\n".format(fname.replace("\\", "/"), fhash))
def parse_url(url):
"""
Parse a URL into 3 components:
<protocol>://<netloc>/<path>
Parameters
----------
url : str
URL (e.g.: http://127.0.0.1:8080/test.nc, ftp://127.0.0.1:8080/test.nc)
Returns
-------
parsed_url : dict
Three components of a URL (e.g., {'protocol': 'http', 'netloc':
'127.0.0.1:8080', 'path': '/test.nc'})
"""
parsed_url = urlsplit(url)
protocol = parsed_url.scheme or "file"
return {"protocol": protocol, "netloc": parsed_url.netloc, "path": parsed_url.path}
def make_local_storage(path, env=None, version=None):
"""
Create the local cache directory and make sure it's writable.
If the directory doesn't exist, it will be created.
Parameters
----------
path : str, PathLike, list or tuple
The path to the local data storage folder. If this is a list or tuple,
we'll join the parts with the appropriate separator. Use
:func:`pooch.os_cache` for a sensible default.
version : str or None
The version string for your project. Will be appended to given path if
not None.
env : str or None
An environment variable that can be used to overwrite *path*. This
allows users to control where they want the data to be stored. We'll
append *version* to the end of this value as well.
Returns
-------
local_path : PathLike
The path to the local directory.
"""
if env is not None and env in os.environ and os.environ[env]:
path = os.environ[env]
if isinstance(path, (list, tuple)):
path = os.path.join(*path)
if version is not None:
path = os.path.join(str(path), version)
path = os.path.expanduser(str(path))
# Check that the data directory is writable
try:
if not os.path.exists(path):
action = "create"
os.makedirs(path)
else:
action = "write to"
with tempfile.NamedTemporaryFile(dir=path):
pass
except PermissionError:
message = (
"Cannot %s data cache folder '%s'. "
"Will not be able to download remote data files. "
)
args = [action, path]
if env is not None:
message += "Use environment variable '%s' to specify another directory."
args += [env]
get_logger().warning(message, *args)
return Path(path)
def hash_algorithm(hash_string):
"""
Parse the name of the hash method from the hash string.
The hash string should have the following form ``algorithm:hash``, where
algorithm can be the name of any algorithm known to :mod:`hashlib`.
If the algorithm is omitted or the hash string is None, will default to
``"sha256"``.
Parameters
----------
hash_string : str
The hash string with optional algorithm prepended.
Returns
-------
hash_algorithm : str
The name of the algorithm.
Examples
--------
>>> print(hash_algorithm("qouuwhwd2j192y1lb1iwgowdj2898wd2d9"))
sha256
>>> print(hash_algorithm("md5:qouuwhwd2j192y1lb1iwgowdj2898wd2d9"))
md5
>>> print(hash_algorithm("sha256:qouuwhwd2j192y1lb1iwgowdj2898wd2d9"))
sha256
>>> print(hash_algorithm(None))
sha256
"""
default = "sha256"
if hash_string is None:
algorithm = default
elif ":" not in hash_string:
algorithm = default
else:
algorithm = hash_string.split(":")[0]
return algorithm
def hash_matches(fname, known_hash, strict=False, source=None):
"""
Check if the hash of a file matches a known hash.
If the *known_hash* is None, will always return True.
Parameters
----------
fname : str or PathLike
The path to the file.
known_hash : str
The known hash. Optionally, prepend ``alg:`` to the hash to specify the
hashing algorithm. Default is SHA256.
strict : bool
If True, will raise a :class:`ValueError` if the hash does not match
informing the user that the file may be corrupted.
source : str
The source of the downloaded file (name or URL, for example). Will be
used in the error message if *strict* is True. Has no other use other
than reporting to the user where the file came from in case of hash
mismatch. If None, will default to *fname*.
Returns
-------
is_same : bool
True if the hash matches, False otherwise.
"""
if known_hash is None:
return True
algorithm = hash_algorithm(known_hash)
new_hash = file_hash(fname, alg=algorithm)
matches = new_hash == known_hash.split(":")[-1]
if strict and not matches:
if source is None:
source = str(fname)
raise ValueError(
"{} hash of downloaded file ({}) does not match the known hash:"
" expected {} but got {}. Deleted download for safety."
" The downloaded file may have been corrupted or"
" the known hash may be outdated.".format(
algorithm.upper(), source, known_hash, new_hash,
)
)
return matches
@contextmanager
def temporary_file(path=None):
"""
Create a closed and named temporary file and make sure it's cleaned up.
Using :class:`tempfile.NamedTemporaryFile` will fail on Windows if trying
to open the file a second time (when passing its name to Pooch function,
for example). This context manager creates the file, closes it, yields the
file path, and makes sure it's deleted in the end.
Parameters
----------
path : str or PathLike
The directory in which the temporary file will be created.
Yields
------
fname : str
The path to the temporary file.
"""
tmp = tempfile.NamedTemporaryFile(delete=False, dir=path)
# Close the temp file so that it can be opened elsewhere
tmp.close()
try:
yield tmp.name
finally:
if os.path.exists(tmp.name):
os.remove(tmp.name)
def unique_file_name(url):
"""
Create a unique file name based on the given URL.
The file name will be unique to the URL by prepending the name with the MD5
hash (hex digest) of the URL. The name will also include the last portion
of the URL.
The format will be: ``{md5}-{filename}.{ext}``
The file name will be cropped so that the entire name (including the hash)
is less than 255 characters long (the limit on most file systems).
Parameters
----------
url : str
The URL with a file name at the end.
Returns
-------
fname : str
The file name, unique to this URL.
Examples
--------
>>> print(unique_file_name("https://www.some-server.org/2020/data.txt"))
02ddee027ce5ebb3d7059fb23d210604-data.txt
>>> print(unique_file_name("https://www.some-server.org/2019/data.txt"))
9780092867b497fca6fc87d8308f1025-data.txt
>>> print(unique_file_name("https://www.some-server.org/2020/data.txt.gz"))
181a9d52e908219c2076f55145d6a344-data.txt.gz
"""
md5 = hashlib.md5(url.encode()).hexdigest()
fname = parse_url(url)["path"].split("/")[-1]
# Crop the start of the file name to fit 255 characters including the hash
# and the :
fname = fname[-(255 - len(md5) - 1) :]
unique_name = "{}-{}".format(md5, fname)
return unique_name