Fixed #9893 -- Allowed using a field's max_length in the Storage.

2 files changed, 53 insertions, 8 deletions

diff --git a/django/core/files/storage.py b/django/core/files/storage.py
index 2d7c0c78e9..90ab1be27a 100644
--- a/django/core/files/storage.py
+++ b/django/core/files/storage.py
@@ -1,8 +1,11 @@
-import os
-import errno
 from datetime import datetime
+import errno
+from inspect import getargspec
+import os
+import warnings
 
 from django.conf import settings
+from django.core.exceptions import SuspiciousFileOperation
 from django.core.files import locks, File
 from django.core.files.move import file_move_safe
 from django.utils.crypto import get_random_string
@@ -13,6 +16,7 @@ from django.utils.six.moves.urllib.parse import urljoin
 from django.utils.text import get_valid_filename
 from django.utils._os import safe_join, abspathu
 from django.utils.deconstruct import deconstructible
+from django.utils.deprecation import RemovedInDjango20Warning
 
 
 __all__ = ('Storage', 'FileSystemStorage', 'DefaultStorage', 'default_storage')
@@ -33,7 +37,7 @@ class Storage(object):
         """
         return self._open(name, mode)
 
-    def save(self, name, content):
+    def save(self, name, content, max_length=None):
         """
         Saves new content to the file specified by name. The content should be
         a proper File object or any python file-like object, ready to be read
@@ -46,7 +50,18 @@ class Storage(object):
         if not hasattr(content, 'chunks'):
             content = File(content)
 
-        name = self.get_available_name(name)
+        args, varargs, varkw, defaults = getargspec(self.get_available_name)
+        if 'max_length' in args:
+            name = self.get_available_name(name, max_length=max_length)
+        else:
+            warnings.warn(
+                'Backwards compatibility for storage backends without '
+                'support for the `max_length` argument in '
+                'Storage.get_available_name() will be removed in Django 2.0.',
+                RemovedInDjango20Warning, stacklevel=2
+            )
+            name = self.get_available_name(name)
+
         name = self._save(name, content)
 
         # Store filenames with forward slashes, even on Windows
@@ -61,7 +76,7 @@ class Storage(object):
         """
         return get_valid_filename(name)
 
-    def get_available_name(self, name):
+    def get_available_name(self, name, max_length=None):
         """
         Returns a filename that's free on the target storage system, and
         available for new content to be written to.
@@ -71,10 +86,25 @@ class Storage(object):
         # If the filename already exists, add an underscore and a random 7
         # character alphanumeric string (before the file extension, if one
         # exists) to the filename until the generated filename doesn't exist.
-        while self.exists(name):
+        # Truncate original name if required, so the new filename does not
+        # exceed the max_length.
+        while self.exists(name) or (max_length and len(name) > max_length):
             # file_ext includes the dot.
             name = os.path.join(dir_name, "%s_%s%s" % (file_root, get_random_string(7), file_ext))
-
+            if max_length is None:
+                continue
+            # Truncate file_root if max_length exceeded.
+            truncation = len(name) - max_length
+            if truncation > 0:
+                file_root = file_root[:-truncation]
+                # Entire file_root was truncated in attempt to find an available filename.
+                if not file_root:
+                    raise SuspiciousFileOperation(
+                        'Storage can not find an available filename for "%s". '
+                        'Please make sure that the corresponding file field '
+                        'allows sufficient "max_length".' % name
+                    )
+                name = os.path.join(dir_name, "%s_%s%s" % (file_root, get_random_string(7), file_ext))
         return name
 
     def path(self, name):
diff --git a/django/db/models/fields/files.py b/django/db/models/fields/files.py
index 8ca8532113..301244bbef 100644
--- a/django/db/models/fields/files.py
+++ b/django/db/models/fields/files.py
@@ -1,5 +1,7 @@
 import datetime
+from inspect import getargspec
 import os
+import warnings
 
 from django import forms
 from django.db.models.fields import Field
@@ -11,6 +13,7 @@ from django.db.models import signals
 from django.utils.encoding import force_str, force_text
 from django.utils import six
 from django.utils.translation import ugettext_lazy as _
+from django.utils.deprecation import RemovedInDjango20Warning
 
 
 class FieldFile(File):
@@ -85,7 +88,19 @@ class FieldFile(File):
 
     def save(self, name, content, save=True):
         name = self.field.generate_filename(self.instance, name)
-        self.name = self.storage.save(name, content)
+
+        args, varargs, varkw, defaults = getargspec(self.storage.save)
+        if 'max_length' in args:
+            self.name = self.storage.save(name, content, max_length=self.field.max_length)
+        else:
+            warnings.warn(
+                'Backwards compatibility for storage backends without '
+                'support for the `max_length` argument in '
+                'Storage.save() will be removed in Django 2.0.',
+                RemovedInDjango20Warning, stacklevel=2
+            )
+            self.name = self.storage.save(name, content)
+
         setattr(self.instance, self.field.name, self.name)
 
         # Update the filesize cache