def unmap_url_cache(cachedir, url, expected_md5):
"""
Downloads a file from a URL to a cache directory. If the file is already
at the expected position and has the expected md5 number, let's not
download it again.
"""
# Let's convert cachedir to a canonical path, if it's not already
cachedir = os.path.realpath(cachedir)
if not os.path.isdir(cachedir):
try:
utils.system("mkdir -p " + cachedir)
except:
raise ValueError("Could not create cache directory %s" % cachedir)
file_from_url = os.path.basename(url)
file_local_path = os.path.join(cachedir, file_from_url)
if os.path.isfile(file_local_path):
file_md5 = get_md5sum(file_local_path)
if file_md5 == expected_md5:
# File is already at the expected position and ready to go
src = file_from_url
else:
# Let's download the package again, it's corrupted...
src = url
else:
# File is not there, let's download it
src = url
return utils.unmap_url(cachedir, src, cachedir)
def unmap_url_cache(cachedir, url, expected_hash, method="md5"):
"""
Downloads a file from a URL to a cache directory. If the file is already
at the expected position and has the expected hash, let's not download it
again.
@param cachedir: Directory that might hold a copy of the file we want to
download.
@param url: URL for the file we want to download.
@param expected_hash: Hash string that we expect the file downloaded to
have.
@param method: Method used to calculate the hash string (md5, sha1).
"""
# Let's convert cachedir to a canonical path, if it's not already
cachedir = os.path.realpath(cachedir)
if not os.path.isdir(cachedir):
try:
os.makedirs(cachedir)
except:
raise ValueError('Could not create cache directory %s' % cachedir)
file_from_url = os.path.basename(url)
file_local_path = os.path.join(cachedir, file_from_url)
file_hash = None
failure_counter = 0
while not file_hash == expected_hash:
if os.path.isfile(file_local_path):
file_hash = hash_file(file_local_path, method)
if file_hash == expected_hash:
# File is already at the expected position and ready to go
src = file_from_url
else:
# Let's download the package again, it's corrupted...
logging.error(
"Seems that file %s is corrupted, trying to "
"download it again", file_from_url)
src = url
failure_counter += 1
else:
# File is not there, let's download it
src = url
if failure_counter > 1:
raise EnvironmentError(
"Consistently failed to download the "
"package %s. Aborting further download "
"attempts. This might mean either the "
"network connection has problems or the "
"expected hash string that was determined "
"for this file is wrong", file_from_url)
file_path = utils.unmap_url(cachedir, src, cachedir)
return file_path
def unmap_url_cache(cachedir, url, expected_hash, method="md5"):
"""
Downloads a file from a URL to a cache directory. If the file is already
at the expected position and has the expected hash, let's not download it
again.
@param cachedir: Directory that might hold a copy of the file we want to
download.
@param url: URL for the file we want to download.
@param expected_hash: Hash string that we expect the file downloaded to
have.
@param method: Method used to calculate the hash string (md5, sha1).
"""
# Let's convert cachedir to a canonical path, if it's not already
cachedir = os.path.realpath(cachedir)
if not os.path.isdir(cachedir):
try:
os.makedirs(cachedir)
except:
raise ValueError("Could not create cache directory %s" % cachedir)
file_from_url = os.path.basename(url)
file_local_path = os.path.join(cachedir, file_from_url)
file_hash = None
failure_counter = 0
while not file_hash == expected_hash:
if os.path.isfile(file_local_path):
file_hash = hash_file(file_local_path, method)
if file_hash == expected_hash:
# File is already at the expected position and ready to go
src = file_from_url
else:
# Let's download the package again, it's corrupted...
logging.error("Seems that file %s is corrupted, trying to " "download it again" % file_from_url)
src = url
failure_counter += 1
else:
# File is not there, let's download it
src = url
if failure_counter > 1:
raise EnvironmentError(
"Consistently failed to download the "
"package %s. Aborting further download "
"attempts. This might mean either the "
"network connection has problems or the "
"expected hash string that was determined "
"for this file is wrong" % file_from_url
)
file_path = utils.unmap_url(cachedir, src, cachedir)
return file_path
