[s3] Fix newline handling for text-mode files

storages/backends/s3.py

@@ -123,7 +123,6 @@ def __init__(self, name, mode, storage, buffer_size=None):
         self._storage = storage
         self.name = name[len(self._storage.location) :].lstrip("/")
         self._mode = mode
-        self._force_mode = (lambda b: b) if "b" in mode else (lambda b: b.decode())
         self.obj = storage.bucket.Object(name)
         if "w" not in mode:
             # Force early RAII-style exception if object does not exist
@@ -172,6 +171,7 @@ def _get_file(self):
                 max_size=self._storage.max_memory_size,
                 suffix=".S3File",
                 dir=setting("FILE_UPLOAD_TEMP_DIR"),
+                mode=self._mode,
             )
             if "r" in self._mode:
                 self._is_dirty = False
@@ -195,12 +195,12 @@ def _set_file(self, value):
     def read(self, *args, **kwargs):
         if "r" not in self._mode:
             raise AttributeError("File was not opened in read mode.")
-        return self._force_mode(super().read(*args, **kwargs))
+        return super().read(*args, **kwargs)
 
     def readline(self, *args, **kwargs):
         if "r" not in self._mode:
             raise AttributeError("File was not opened in read mode.")
-        return self._force_mode(super().readline(*args, **kwargs))
+        return super().readline(*args, **kwargs)
 
     def readlines(self):
         return list(self)

tests/test_s3.py

@@ -305,25 +305,6 @@ def test_storage_open_read_string(self):
         self.assertEqual(content_str, "")
         file.close()
 
-    def test_storage_open_readlines(self):
-        """
-        Test readlines with file opened in "r" and "rb" modes
-        """
-        name = "test_open_readlines_string.txt"
-        with io.BytesIO() as temp_file:
-            temp_file.write(b"line1\nline2")
-            file = self.storage.open(name, "r")
-            file._file = temp_file
-
-            content_lines = file.readlines()
-            self.assertEqual(content_lines, ["line1\n", "line2"])
-
-            temp_file.seek(0)
-            file = self.storage.open(name, "rb")
-            file._file = temp_file
-            content_lines = file.readlines()
-            self.assertEqual(content_lines, [b"line1\n", b"line2"])
-
     def test_storage_open_write(self):
         """
         Test opening a file in write mode
@@ -338,7 +319,7 @@ def test_storage_open_write(self):
             "ACL": "public-read",
         }
 
-        file = self.storage.open(name, "w")
+        file = self.storage.open(name, "wb")
         self.storage.bucket.Object.assert_called_with(name)
         obj = self.storage.bucket.Object.return_value
         # Set the name of the mock object
@@ -449,7 +430,7 @@ def test_storage_write_beyond_buffer_size(self):
             "StorageClass": "REDUCED_REDUNDANCY",
         }
 
-        file = self.storage.open(name, "w")
+        file = self.storage.open(name, "wb")
         self.storage.bucket.Object.assert_called_with(name)
         obj = self.storage.bucket.Object.return_value
         # Set the name of the mock object
@@ -1145,6 +1126,48 @@ def test_content_type_not_detectable(self):
             s3.S3Storage.default_content_type,
         )
 
+    def test_storage_open_read_with_newlines(self):
+        """
+        Test opening a file in "r" and "rb" mode with various newline characters
+        """
+        name = "test_storage_open_read_with_newlines.txt"
+        with io.BytesIO() as temp_file:
+            temp_file.write(b"line1\nline2\r\nmore\rtext\n")
+            self.storage.save(name, temp_file)
+            file = self.storage.open(name, "r")
+            content_str = file.read()
+            file.close()
+        self.assertEqual(content_str, "line1\nline2\nmore\ntext\n")
+
+        with io.BytesIO() as temp_file:
+            temp_file.write(b"line1\nline2\r\nmore\rtext\n")
+            self.storage.save(name, temp_file)
+            file = self.storage.open(name, "rb")
+            content_str = file.read()
+            file.close()
+        self.assertEqual(content_str, b"line1\nline2\r\nmore\rtext\n")
+
+    def test_storage_open_readlines_with_newlines(self):
+        """
+        Test readlines with file opened in "r" and "rb" mode with various newline chars
+        """
+        name = "test_storage_open_readlines_with_newlines.txt"
+        with io.BytesIO() as temp_file:
+            temp_file.write(b"line1\nline2\r\nmore\rtext")
+            self.storage.save(name, temp_file)
+            file = self.storage.open(name, "r")
+            content_lines = file.readlines()
+            file.close()
+        self.assertEqual(content_lines, ["line1\n", "line2\n", "more\n", "text"])
+
+        with io.BytesIO() as temp_file:
+            temp_file.write(b"line1\nline2\r\nmore\rtext")
+            self.storage.save(name, temp_file)
+            file = self.storage.open(name, "rb")
+            content_lines = file.readlines()
+            file.close()
+        self.assertEqual(content_lines, [b"line1\n", b"line2\r\n", b"more\r", b"text"])
+
 
 class TestBackwardsNames(TestCase):
     def test_importing(self):