Scripts to download files from google storage based on sha1 sums

third_party/gsutil/boto/glacier/job.py

+# -*- coding: utf-8 -*-
+# Copyright (c) 2012 Thomas Parslow http://almostobsolete.net/
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish, dis-
+# tribute, sublicense, and/or sell copies of the Software, and to permit
+# persons to whom the Software is furnished to do so, subject to the fol-
+# lowing conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
+# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+# IN THE SOFTWARE.
+#
+from __future__ import with_statement
+import math
+import socket
+
+from .exceptions import TreeHashDoesNotMatchError, DownloadArchiveError
+from .utils import bytes_to_hex, chunk_hashes, tree_hash
+
+
+class Job(object):
+
+    DefaultPartSize = 4 * 1024 * 1024
+
+    ResponseDataElements = (('Action', 'action', None),
+                            ('ArchiveId', 'archive_id', None),
+                            ('ArchiveSizeInBytes', 'archive_size', 0),
+                            ('Completed', 'completed', False),
+                            ('CompletionDate', 'completion_date', None),
+                            ('CreationDate', 'creation_date', None),
+                            ('InventorySizeInBytes', 'inventory_size', 0),
+                            ('JobDescription', 'description', None),
+                            ('JobId', 'id', None),
+                            ('SHA256TreeHash', 'sha256_treehash', None),
+                            ('SNSTopic', 'sns_topic', None),
+                            ('StatusCode', 'status_code', None),
+                            ('StatusMessage', 'status_message', None),
+                            ('VaultARN', 'arn', None))
+
+    def __init__(self, vault, response_data=None):
+        self.vault = vault
+        if response_data:
+            for response_name, attr_name, default in self.ResponseDataElements:
+                setattr(self, attr_name, response_data[response_name])
+        else:
+            for response_name, attr_name, default in self.ResponseDataElements:
+                setattr(self, attr_name, default)
+
+    def __repr__(self):
+        return 'Job(%s)' % self.arn
+
+    def get_output(self, byte_range=None):
+        """
+        This operation downloads the output of the job.  Depending on
+        the job type you specified when you initiated the job, the
+        output will be either the content of an archive or a vault
+        inventory.
+
+        You can download all the job output or download a portion of
+        the output by specifying a byte range. In the case of an
+        archive retrieval job, depending on the byte range you
+        specify, Amazon Glacier returns the checksum for the portion
+        of the data. You can compute the checksum on the client and
+        verify that the values match to ensure the portion you
+        downloaded is the correct data.
+
+        :type byte_range: tuple
+        :param range: A tuple of integer specifying the slice (in bytes)
+            of the archive you want to receive
+        """
+        return self.vault.layer1.get_job_output(self.vault.name,
+                                                self.id,
+                                                byte_range)
+
+    def download_to_file(self, filename, chunk_size=DefaultPartSize,
+                         verify_hashes=True, retry_exceptions=(socket.error,)):
+        """Download an archive to a file.
+
+        :type filename: str
+        :param filename: The name of the file where the archive
+            contents will be saved.
+
+        :type chunk_size: int
+        :param chunk_size: The chunk size to use when downloading
+            the archive.
+
+        :type verify_hashes: bool
+        :param verify_hashes: Indicates whether or not to verify
+            the tree hashes for each downloaded chunk.
+
+        """
+        num_chunks = int(math.ceil(self.archive_size / float(chunk_size)))
+        with open(filename, 'wb') as output_file:
+            self._download_to_fileob(output_file, num_chunks, chunk_size,
+                                     verify_hashes, retry_exceptions)
+
+    def _download_to_fileob(self, fileobj, num_chunks, chunk_size, verify_hashes,
+                            retry_exceptions):
+        for i in xrange(num_chunks):
+            byte_range = ((i * chunk_size), ((i + 1) * chunk_size) - 1)
+            data, expected_tree_hash = self._download_byte_range(
+                byte_range, retry_exceptions)
+            if verify_hashes:
+                actual_tree_hash = bytes_to_hex(tree_hash(chunk_hashes(data)))
+                if expected_tree_hash != actual_tree_hash:
+                    raise TreeHashDoesNotMatchError(
+                        "The calculated tree hash %s does not match the "
+                        "expected tree hash %s for the byte range %s" % (
+                            actual_tree_hash, expected_tree_hash, byte_range))
+            fileobj.write(data)
+
+    def _download_byte_range(self, byte_range, retry_exceptions):
+        # You can occasionally get socket.errors when downloading
+        # chunks from Glacier, so each chunk can be retried up
+        # to 5 times.
+        for _ in xrange(5):
+            try:
+                response = self.get_output(byte_range)
+                data = response.read()
+                expected_tree_hash = response['TreeHash']
+                return data, expected_tree_hash
+            except retry_exceptions, e:
+                continue
+        else:
+            raise DownloadArchiveError("There was an error downloading"
+                                       "byte range %s: %s" % (byte_range,
+                                                              e))