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[wolnelektury.git] / apps / catalogue / utils.py

diff --git a/apps/catalogue/utils.py b/apps/catalogue/utils.py
index d1cee50..29a1857 100644 (file)
--- a/apps/catalogue/utils.py
+++ b/apps/catalogue/utils.py
@@ -1,4 +1,38 @@
 # -*- coding: utf-8 -*-
+# This file is part of Wolnelektury, licensed under GNU Affero GPLv3 or later.
+# Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
+#
+from __future__ import with_statement
+
+import random
+import time
+from base64 import urlsafe_b64encode
+
+from django.core.files.uploadedfile import UploadedFile
+from django.utils.hashcompat import sha_constructor
+from django.conf import settings
+from celery.task import task
+from os import mkdir, path, unlink
+from errno import EEXIST, ENOENT
+from fcntl import flock, LOCK_EX
+from zipfile import ZipFile
+
+from librarian import DocProvider
+
+
+# Use the system (hardware-based) random number generator if it exists.
+if hasattr(random, 'SystemRandom'):
+    randrange = random.SystemRandom().randrange
+else:
+    randrange = random.randrange
+MAX_SESSION_KEY = 18446744073709551616L     # 2 << 63
+
+
+def get_random_hash(seed):
+    sha_digest = sha_constructor('%s%s%s%s' %
+        (randrange(0, MAX_SESSION_KEY), time.time(), unicode(seed).encode('utf-8', 'replace'),
+        settings.SECRET_KEY)).digest()
+    return urlsafe_b64encode(sha_digest).replace('=', '').replace('_', '-').lower()
 
 
 def split_tags(tags):
@@ -7,3 +41,91 @@ def split_tags(tags):
         result.setdefault(tag.category, []).append(tag)
     return result
 
+
+class ExistingFile(UploadedFile):
+
+    def __init__(self, path, *args, **kwargs):
+        self.path = path
+        return super(ExistingFile, self).__init__(*args, **kwargs)
+
+    def temporary_file_path(self):
+        return self.path
+
+    def close(self):
+        pass
+
+
+class ORMDocProvider(DocProvider):
+    """Used for getting books' children."""
+
+    def __init__(self, book):
+        self.book = book
+
+    def by_slug(self, slug):
+        if slug == self.book.slug:
+            return self.book.xml_file
+        else:
+            return type(self.book).objects.get(slug=slug).xml_file
+
+
+class LockFile(object):
+    """
+    A file lock monitor class; createas an ${objname}.lock
+    file in directory dir, and locks it exclusively.
+    To be used in 'with' construct.
+    """
+    def __init__(self, dir, objname):
+        self.lockname = path.join(dir, objname + ".lock")
+
+    def __enter__(self):
+        self.lock = open(self.lockname, 'w')
+        flock(self.lock, LOCK_EX)
+
+    def __exit__(self, *err):
+        try:
+            unlink(self.lockname)
+        except OSError as oe:
+            if oe.errno != oe.EEXIST:
+                raise oe
+        self.lock.close()
+
+
+@task
+def create_zip(paths, zip_slug):
+    """
+    Creates a zip in MEDIA_ROOT/zip directory containing files from path.
+    Resulting archive filename is ${zip_slug}.zip
+    Returns it's path relative to MEDIA_ROOT (no initial slash)
+    """
+    # directory to store zip files
+    zip_path = path.join(settings.MEDIA_ROOT, 'zip')
+
+    try:
+        mkdir(zip_path)
+    except OSError as oe:
+        if oe.errno != EEXIST:
+            raise oe
+    zip_filename = zip_slug + ".zip"
+
+    with LockFile(zip_path, zip_slug):
+        if not path.exists(path.join(zip_path, zip_filename)):
+            zipf = ZipFile(path.join(zip_path, zip_filename), 'w')
+            try:
+                for p in paths:
+                    zipf.write(p, path.basename(p))
+            finally:
+                zipf.close()
+
+        return 'zip/' + zip_filename
+
+
+def remove_zip(zip_slug):
+    """
+    removes the ${zip_slug}.zip file from zip store.
+    """
+    zip_file = path.join(settings.MEDIA_ROOT, 'zip', zip_slug + '.zip')
+    try:
+        unlink(zip_file)
+    except OSError as oe:
+        if oe.errno != ENOENT:
+            raise oe