partially fixed #2805 (multiple http byte ranges are not yet supported)

CHANGES/2805.bugfix

@@ -0,0 +1,2 @@
+Property `BaseRequest.http_range` now returns a python-like slice when requesting the tail of the range. 
+It's now indicated by a negative value in `range.start` rather then in `range.stop`

aiohttp/web_fileresponse.py

@@ -193,9 +193,9 @@ async def prepare(self, request):
         # If a range request has been made, convert start, end slice notation
         # into file pointer offset and count
         if start is not None or end is not None:
-            if start is None and end < 0:  # return tail of file
-                start = file_size + end
-                count = -end
+            if start < 0 and end is None:  # return tail of file
+                start = file_size + start
+                count = file_size - start
             else:
                 count = (end or file_size) - start
 

aiohttp/web_request.py

@@ -439,7 +439,8 @@ def http_range(self, *, _RANGE=hdrs.RANGE):
 
             if start is None and end is not None:
                 # end with no start is to return tail of content
-                end = -end
+                start = -end
+                end = None
 
             if start is not None and end is not None:
                 # end is inclusive in range header, exclusive for slice
@@ -450,6 +451,7 @@ def http_range(self, *, _RANGE=hdrs.RANGE):
 
             if start is end is None:  # No valid range supplied
                 raise ValueError('No start or end of range specified')
+
         return slice(start, end, 1)
 
     @property

tests/test_web_request.py

@@ -110,6 +110,58 @@ def test_content_length():
     assert 123 == req.content_length
 
 
+def test_range_to_slice_head():
+    def bytes_gen(size):
+        for i in range(size):
+            yield i % 256
+    payload = bytearray(bytes_gen(10000))
+    req = make_mocked_request(
+        'GET', '/',
+        headers=CIMultiDict([('RANGE', 'bytes=0-499')]),
+        payload=payload)
+    assert isinstance(req.http_range, slice)
+    assert req.content[req.http_range] == payload[:500]
+
+
+def test_range_to_slice_mid():
+    def bytes_gen(size):
+        for i in range(size):
+            yield i % 256
+    payload = bytearray(bytes_gen(10000))
+    req = make_mocked_request(
+        'GET', '/',
+        headers=CIMultiDict([('RANGE', 'bytes=500-999')]),
+        payload=payload)
+    assert isinstance(req.http_range, slice)
+    assert req.content[req.http_range] == payload[500:1000]
+
+
+def test_range_to_slice_tail_start():
+    def bytes_gen(size):
+        for i in range(size):
+            yield i % 256
+    payload = bytearray(bytes_gen(10000))
+    req = make_mocked_request(
+        'GET', '/',
+        headers=CIMultiDict([('RANGE', 'bytes=9500-')]),
+        payload=payload)
+    assert isinstance(req.http_range, slice)
+    assert req.content[req.http_range] == payload[-500:]
+
+
+def test_range_to_slice_tail_stop():
+    def bytes_gen(size):
+        for i in range(size):
+            yield i % 256
+    payload = bytearray(bytes_gen(10000))
+    req = make_mocked_request(
+        'GET', '/',
+        headers=CIMultiDict([('RANGE', 'bytes=-500')]),
+        payload=payload)
+    assert isinstance(req.http_range, slice)
+    assert req.content[req.http_range] == payload[-500:]
+
+
 def test_non_keepalive_on_http10():
     req = make_mocked_request('GET', '/', version=HttpVersion(1, 0))
     assert not req.keep_alive