Use resumable-urlretrieve to resume interrupted downloads

it's a dependency selected with extras_require for compatible Python versions, so it'll degrade gracefully on older Pythons
to the normal code that will restart the download every time

pythonz/downloader.py

@@ -1,19 +1,55 @@
 import sys
-from mmap import mmap as _mmap, ACCESS_READ
-from hashlib import sha256
+import os
 
 from pythonz.util import PY3K
 from pythonz.log import logger
 
 if PY3K:
-    mmap = _mmap
-    from urllib.request import Request, urlopen, urlretrieve
+    from urllib.request import Request, urlopen
 else:
-    from contextlib import closing
-    mmap = lambda *args, **kwargs: closing(_mmap(*args, **kwargs))
-    from urllib import urlretrieve
     from urllib2 import urlopen, Request
 
+try:
+    from resumable import urlretrieve, DownloadError, sha256
+except ImportError:
+    from mmap import mmap as _mmap, ACCESS_READ
+    import hashlib
+    if PY3K:
+        from urllib.request import urlretrieve as _urlretrieve
+        mmap = _mmap
+    else:
+        from contextlib import closing
+        mmap = lambda *args, **kwargs: closing(_mmap(*args, **kwargs))
+        from urllib import urlretrieve as _urlretrieve
+
+    class DownloadError(Exception):
+        """Exception during download"""
+
+    def sha256(filename):
+        with open(filename, 'rb') as f:
+            with mmap(f.fileno(), 0, access=ACCESS_READ) as m:
+                return hashlib.sha256(m).hexdigest()
+
+
+    def validate_sha256(filename, sha256sum):
+        if sha256sum is not None:
+            return sha256(filename) == sha256sum
+        else:
+            logger.warning("sha256sum unavailable, skipping verification.\nMake "
+                           "sure that the server you're downloading from is trusted")
+            return True
+
+
+    def urlretrieve(url, filename, reporthook, sha256sum):
+        try:
+            _urlretrieve(url, filename, reporthook)
+            if not validate_sha256(filename, sha256sum):
+                raise DownloadError("Corrupted download, the sha256 doesn't match")
+        except BaseException:
+            os.unlink(filename)
+            raise
+
+
 
 class ProgressBar(object):
     def __init__(self, out=sys.stdout):
@@ -48,10 +84,6 @@ def get_method(self):
         return "HEAD"
 
 
-class DownloadError(Exception):
-    """Exception during download"""
-
-
 class Downloader(object):
 
     @classmethod
@@ -76,22 +108,15 @@ def read_head_info(cls, url):
             return res.info()
 
     @classmethod
-    def fetch(cls, url, filename):
+    def fetch(cls, url, filename, expected_sha256):
         b = ProgressBar()
         try:
-            urlretrieve(url, filename, b.reporthook)
+            urlretrieve(url, filename, b.reporthook, sha256sum=expected_sha256)
             sys.stdout.write('\n')
+        except DownloadError:
+            if os.path.exists(filename):
+                os.unlink(filename)
+            raise
         except IOError:
             sys.stdout.write('\n')
             raise DownloadError('Failed to fetch %s from %s' % (filename, url))
-
-
-def validate_sha256(filename, sha256sum):
-    if sha256sum is not None:
-        with open(filename, 'rb') as f:
-            with mmap(f.fileno(), 0, access=ACCESS_READ) as m:
-                return sha256(m).hexdigest() == sha256sum
-    else:
-        logger.warning("sha256sum unavailable, skipping verification.\nMake "
-                       "sure that the server you're downloading from is trusted")
-        return True

pythonz/installer/pythoninstaller.py

@@ -16,7 +16,7 @@
     get_macosx_deployment_target, Version, is_python25, is_python24, is_python33
 from pythonz.define import PATH_BUILD, PATH_DISTS, PATH_PYTHONS, PATH_LOG, \
     PATH_PATCHES_ALL, PATH_PATCHES_OSX
-from pythonz.downloader import Downloader, DownloadError, validate_sha256
+from pythonz.downloader import Downloader, DownloadError, sha256
 from pythonz.log import logger
 
 
@@ -100,22 +100,17 @@ def expected_sha256(self):
         return self.supported_versions.get(self.pkg.version)
 
     def download(self):
-        if os.path.isfile(self.download_file):
+        if os.path.isfile(self.download_file) and sha256(self.download_file) == self.expected_sha256:
             logger.info("Use the previously fetched %s" % (self.download_file))
         else:
             base_url = Link(self.download_url).base_url
             logger.info("Downloading %s as %s" % (base_url, self.download_file))
             try:
-                Downloader.fetch(self.download_url, self.download_file)
+                Downloader.fetch(self.download_url, self.download_file, self.expected_sha256)
             except DownloadError:
-                unlink(self.download_file)
                 logger.error("Failed to download.\n%s" % (sys.exc_info()[1]))
                 sys.exit(1)
-            except:
-                unlink(self.download_file)
-                raise
-        if not validate_sha256(self.download_file, self.expected_sha256):
-            raise DownloadError("Corrupted download, the sha256 doesn't match")
+
 
     def install(self):
         raise NotImplementedError

setup.py

@@ -24,6 +24,7 @@ def get_version():
       url                  = 'https://github.com/saghul/pythonz',
       license              = 'MIT',
       packages             = find_packages('pythonz'),
+      extras_require       = {':python_version>="3.5"': ['resumable-urlretrieve']},
       include_package_data = True,
       entry_points         = dict(console_scripts=['pythonz=pythonz:main',
                                                    'pythonz_install=pythonz.installer:install_pythonz']),
@@ -40,4 +41,3 @@ def get_version():
         'Programming Language :: Python :: 3.2',
         'Programming Language :: Python :: 3.3',
       ])
-