"""
Helpers for downloading data
The :func:`download` function access the network and requests the content at a
specific url using :mod:`urllib` or :mod:`urllib2`. You can either specify
where the data goes or download it to the default location in ubelt cache.
Either way this function returns the location of the downloaded data. You can
also specify the expected hash in order to check the validity of the data. By
default downloading is verbose.
The :func:`grabdata` function is almost identitcal to :func:`download`, but it
checks if the data already exists in the download location, and only downloads
if it needs to.
"""
from ubelt.util_const import NoParam
from os.path import basename, join, exists, dirname
import os
__all__ = ['download', 'grabdata']
[docs]def download(url, fpath=None, dpath=None, fname=None, hash_prefix=None,
hasher='sha512', chunksize=8192, verbose=1, timeout=NoParam,
progkw=None):
"""
Downloads a url to a file on disk.
If unspecified the location and name of the file is chosen automatically.
A hash_prefix can be specified to verify the integrity of the downloaded
data. This function will download the data every time its called. For
cached downloading see `grabdata`.
Args:
url (str):
The url to download.
fpath (Optional[str | PathLike | io.BytesIO]):
The path to download to. Defaults to basename of url and ubelt's
application cache. If this is a io.BytesIO object then information
is directly written to this object (note this prevents the use of
temporary files).
dpath (Optional[PathLike]):
where to download the file. If unspecified `appname` is used to
determine this. Mutually exclusive with fpath.
fname (Optional[str]):
What to name the downloaded file. Defaults to the url basename.
Mutually exclusive with fpath.
hash_prefix (None | str):
If specified, download will retry / error if the file hash
does not match this value. Defaults to None.
hasher (str | Hasher):
If hash_prefix is specified, this indicates the hashing
algorithm to apply to the file. Defaults to sha512.
chunksize (int, default=2 ** 13):
Download chunksize.
verbose (int, default=1):
Verbosity level 0 or 1.
timeout (float, default=NoParam):
Specify timeout in seconds for :func:`urllib.request.urlopen`. (if
not specified, the global default timeout setting will be used)
This only works for HTTP, HTTPS and FTP connections for blocking
operations like the connection attempt.
progkw (Dict | None):
if specified provides extra arguments to the progress iterator
Returns:
str | PathLike: fpath - path to the downloaded file.
Raises:
URLError - if there is problem downloading the url
RuntimeError - if the hash does not match the hash_prefix
Note:
Based largely on code in pytorch [TorchDL]_ with modifications
influenced by other resources [Shichao_2012]_ [SO_15644964]_
[SO_16694907]_.
References:
.. [Shichao_2012] https://blog.shichao.io/2012/10/04/progress_speed_indicator_for_urlretrieve_in_python.html
.. [SO_15644964] http://stackoverflow.com/questions/15644964/python-progress-bar-and-downloads
.. [SO_16694907] http://stackoverflow.com/questions/16694907/how-to-download-large-file-in-python-with-requests-py
.. [TorchDL] https://github.com/pytorch/pytorch/blob/2787f1d8edbd4aadd4a8680d204341a1d7112e2d/torch/hub.py#L347
Example:
>>> # xdoctest: +REQUIRES(--network)
>>> from ubelt.util_download import * # NOQA
>>> url = 'http://i.imgur.com/rqwaDag.png'
>>> fpath = download(url)
>>> print(basename(fpath))
rqwaDag.png
Example:
>>> # xdoctest: +REQUIRES(--network)
>>> import ubelt as ub
>>> import io
>>> url = 'http://i.imgur.com/rqwaDag.png'
>>> file = io.BytesIO()
>>> fpath = ub.download(url, file)
>>> file.seek(0)
>>> data = file.read()
>>> assert ub.hash_data(data, hasher='sha1').startswith('f79ea24571')
Example:
>>> # xdoctest: +REQUIRES(--network)
>>> url = 'http://i.imgur.com/rqwaDag.png'
>>> fpath = download(url, hasher='sha1', hash_prefix='f79ea24571da6ddd2ba12e3d57b515249ecb8a35')
Downloading url='http://i.imgur.com/rqwaDag.png' to fpath=...rqwaDag.png
...
...1233/1233... rate=... Hz, eta=..., total=...
Example:
>>> # xdoctest: +REQUIRES(--network)
>>> import pytest
>>> import ubelt as ub
>>> url = 'http://i.imgur.com/rqwaDag.png'
>>> #fpath = download(url, hasher='sha1', hash_prefix='f79ea24571da6ddd2ba12e3d57b515249ecb8a35')
>>> # test download from girder
>>> #url = 'https://data.kitware.com/api/v1/item/5b4039308d777f2e6225994c/download'
>>> #ub.download(url, hasher='sha512', hash_prefix='c98a46cb31205cf')
>>> with pytest.raises(RuntimeError):
>>> ub.download(url, hasher='sha512', hash_prefix='BAD_HASH')
"""
from ubelt import ProgIter as Progress
from ubelt import ensure_app_cache_dir
import shutil
import tempfile
import hashlib
if timeout is NoParam:
import socket
timeout = socket._GLOBAL_DEFAULT_TIMEOUT
from urllib.request import urlopen # NOQA
if fpath and (dpath or fname):
raise ValueError('Cannot specify fpath with dpath or fname')
if fpath is None:
if dpath is None:
dpath = ensure_app_cache_dir('ubelt')
if fname is None:
fname = basename(url)
fpath = join(dpath, fname)
# Check if fpath was given as an BytesIO object
_dst_is_io_object = hasattr(fpath, 'write')
if not _dst_is_io_object and not exists(dirname(fpath)):
raise Exception('parent of {} does not exist'.format(fpath))
if verbose:
if _dst_is_io_object:
print('Downloading url={!r} to IO object'.format(url))
else:
print('Downloading url={!r} to fpath={!r}'.format(
url, fpath))
# TODO: might want to open the url with different args
urldata = urlopen(url, timeout=timeout)
meta = urldata.info()
try:
if hasattr(meta, 'getheaders'): # nocover
file_size = int(meta.getheaders("Content-Length")[0])
else:
file_size = int(meta.get_all("Content-Length")[0])
except Exception: # nocover
# sometimes the url does not contain content length metadata
# TODO: find a public URL that exemplifies this or figure out how to
# mock it locally.
file_size = None
if hash_prefix:
if isinstance(hasher, str):
if hasher == 'sha1':
hasher = hashlib.sha1()
elif hasher == 'md5':
hasher = hashlib.md5()
elif hasher == 'sha256':
hasher = hashlib.sha256()
elif hasher == 'sha512':
hasher = hashlib.sha512()
else:
raise KeyError(hasher)
if _dst_is_io_object:
_file_write = fpath.write
else:
tmp = tempfile.NamedTemporaryFile(delete=False)
_file_write = tmp.write
# possible optimization (have not tested or timed)
_urldata_read = urldata.read
try:
_progkw = {
'total': file_size,
'freq': chunksize,
'time_thresh': 1,
}
if progkw is not None:
_progkw.update(progkw)
_progkw['disable'] = not verbose
pbar = Progress(**_progkw)
with pbar:
_pbar_update = pbar.update
def _critical_loop():
# Initialize the buffer to a non-empty object
buffer = ' '
if hash_prefix:
_hasher_update = hasher.update
while buffer:
buffer = _urldata_read(chunksize)
_file_write(buffer)
_hasher_update(buffer)
_pbar_update(len(buffer))
else:
# Same code as above, just without the hasher update.
# (tight loop optimization: remove in-loop conditional)
while buffer:
buffer = _urldata_read(chunksize)
_file_write(buffer)
_pbar_update(len(buffer))
_critical_loop()
if not _dst_is_io_object:
tmp.close()
# We keep a potentially corrupted file if the hash doesn't match.
# It could be the case that the user simply specified the wrong
# hash_prefix.
shutil.move(tmp.name, fpath)
if hash_prefix:
got = hasher.hexdigest()
if got[:len(hash_prefix)] != hash_prefix:
print('hash_prefix = {!r}'.format(hash_prefix))
print('got = {!r}'.format(got))
if _dst_is_io_object:
raise RuntimeError(
'invalid hash value '
'(expected "{}", got "{}")'.format(hash_prefix, got))
else:
raise RuntimeError(
'invalid hash value for fpath={!r} '
'(expected "{}", got "{}")'.format(
fpath, hash_prefix, got))
finally:
if not _dst_is_io_object: # nocover
tmp.close()
# If for some reason the move failed, delete the temporary file
if exists(tmp.name):
os.remove(tmp.name)
return fpath
[docs]def grabdata(url, fpath=None, dpath=None, fname=None, redo=False,
verbose=1, appname=None, hash_prefix=None, hasher='sha512',
**download_kw):
"""
Downloads a file, caches it, and returns its local path.
If unspecified the location and name of the file is chosen automatically.
A hash_prefix can be specified to verify the integrity of the downloaded
data.
Args:
url (str): url to the file to download
fpath (Optional[str | PathLike]):
The full path to download the file to. If unspecified, the
arguments `dpath` and `fname` are used to determine this.
dpath (Optional[str | PathLike]):
where to download the file. If unspecified `appname` is used to
determine this. Mutually exclusive with fpath.
fname (Optional[str]):
What to name the downloaded file. Defaults to the url basename.
Mutually exclusive with fpath.
redo (bool, default=False): if True forces redownload of the file
verbose (bool, default=True): verbosity flag
appname (str): set dpath to `ub.get_app_cache_dir(appname)`.
Mutually exclusive with dpath and fpath.
hash_prefix (None | str):
If specified, grabdata verifies that this matches the hash of the
file, and then saves the hash in a adjacent file to certify that
the download was successful. Defaults to None.
hasher (str | Hasher):
If hash_prefix is specified, this indicates the hashing
algorithm to apply to the file. Defaults to sha512.
**download_kw: additional kwargs to pass to
:func:`ubelt.util_download.download`
Returns:
str | PathLike: fpath - path to downloaded or cached file.
CommandLine:
xdoctest -m ubelt.util_download grabdata --network
Example:
>>> # xdoctest: +REQUIRES(--network)
>>> import ubelt as ub
>>> url = 'http://i.imgur.com/rqwaDag.png'
>>> fpath = ub.grabdata(url, fname='mario.png')
>>> result = basename(fpath)
>>> print(result)
mario.png
Example:
>>> # xdoctest: +REQUIRES(--network)
>>> import ubelt as ub
>>> fname = 'foo.bar'
>>> url = 'http://i.imgur.com/rqwaDag.png'
>>> prefix1 = '944389a39dfb8fa9'
>>> fpath = ub.grabdata(url, fname=fname, hash_prefix=prefix1)
>>> stamp_fpath = fpath + '.sha512.hash'
>>> assert ub.readfrom(stamp_fpath) == prefix1
>>> # Check that the download doesn't happen again
>>> fpath = ub.grabdata(url, fname=fname, hash_prefix=prefix1)
>>> # todo: check file timestamps have not changed
>>> #
>>> # Check redo works with hash
>>> fpath = ub.grabdata(url, fname=fname, hash_prefix=prefix1, redo=True)
>>> # todo: check file timestamps have changed
>>> #
>>> # Check that a redownload occurs when the stamp is changed
>>> with open(stamp_fpath, 'w') as file:
>>> file.write('corrupt-stamp')
>>> fpath = ub.grabdata(url, fname=fname, hash_prefix=prefix1)
>>> assert ub.readfrom(stamp_fpath) == prefix1
>>> #
>>> # Check that a redownload occurs when the stamp is removed
>>> ub.delete(stamp_fpath)
>>> with open(fpath, 'w') as file:
>>> file.write('corrupt-data')
>>> assert not ub.hash_file(fpath, base='hex', hasher='sha512').startswith(prefix1)
>>> fpath = ub.grabdata(url, fname=fname, hash_prefix=prefix1)
>>> assert ub.hash_file(fpath, base='hex', hasher='sha512').startswith(prefix1)
>>> #
>>> # Check that requesting new data causes redownload
>>> #url2 = 'https://data.kitware.com/api/v1/item/5b4039308d777f2e6225994c/download'
>>> #prefix2 = 'c98a46cb31205cf' # hack SSL
>>> url2 = 'http://i.imgur.com/rqwaDag.png'
>>> prefix2 = '944389a39dfb8fa9'
>>> fpath = ub.grabdata(url2, fname=fname, hash_prefix=prefix2)
>>> assert ub.readfrom(stamp_fpath) == prefix2
"""
from ubelt.util_platform import ensure_app_cache_dir
if appname and dpath:
raise ValueError('Cannot specify appname with dpath')
if fpath and (dpath or fname or appname):
raise ValueError('Cannot specify fpath with dpath or fname')
if fpath is None:
if dpath is None:
appname = appname or 'ubelt'
dpath = ensure_app_cache_dir(appname)
if fname is None:
fname = basename(url)
fpath = join(dpath, fname)
# note that needs_download is never set to false after it becomes true
# this is the key to working through the logic of the following checks
needs_download = redo
if not exists(fpath):
# always download if we are missing the file
needs_download = True
if hash_prefix:
stamp_fpath, needs_download = _check_hash_stamp(
fpath, hash_prefix, hasher, verbose, needs_download)
if needs_download:
fpath = download(url, fpath, verbose=verbose,
hash_prefix=hash_prefix, hasher=hasher,
**download_kw)
if hash_prefix:
# If the file successfully downloaded then the hashes match.
# write out the expected prefix so we can check it later
with open(stamp_fpath, 'w') as file:
file.write(hash_prefix)
else:
if verbose >= 2:
print('Already have file %s' % fpath)
return fpath
def _check_hash_stamp(fpath, hash_prefix, hasher, verbose, needs_download=False):
if isinstance(hasher, str):
hasher_name = hasher
else:
hasher_name = hasher.name
stamp_fpath = '{}.{}.hash'.format(fpath, hasher_name)
# Force a re-download if the hash file does not exist or it does
# not match the expected hash
if exists(stamp_fpath):
with open(stamp_fpath, 'r') as file:
hashstr = file.read()
if not hashstr.startswith(hash_prefix):
if verbose: # pragma: nobranch
print('invalid hash value (expected "{}", got "{}")'.format(
hash_prefix, hashstr))
needs_download = True
elif exists(fpath):
# If the file exists, but the hash does not exist, simply compute the
# hash of the existing file instead of redownloading it.
# Redownload if this fails.
from ubelt import util_hash
hashstr = util_hash.hash_file(fpath, hasher=hasher)
if hashstr.startswith(hash_prefix):
# Write the missing stamp file if it matches
with open(stamp_fpath, 'w') as file:
file.write(hash_prefix)
else:
if verbose: # pragma: nobranch
print('invalid hash value (expected "{}", got "{}")'.format(
hash_prefix, hashstr))
needs_download = True
else:
needs_download = True
return stamp_fpath, needs_download