refactor sendfile and add an example.

examples/hello.txt

@@ -0,0 +1 @@
+Hello world!

examples/sendfile.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -
+#
+# This file is part of gunicorn released under the MIT license. 
+# See the NOTICE for more information.
+#
+# Example code from Eventlet sources
+
+import os
+from wsgiref.validate import validator
+
+#@validator
+def app(environ, start_response):
+    """Simplest possible application object"""
+    status = '200 OK'
+    fname = os.path.join(os.path.dirname(__file__), "hello.txt")
+    f = open(fname, 'rb')
+
+    response_headers = [
+        ('Content-type','text/plain'),
+    ]
+    start_response(status, response_headers)
+
+    return environ['wsgi.file_wrapper'](f)

gunicorn/http/_sendfile.py

@@ -0,0 +1,66 @@
+# -*- coding: utf-8 -
+#
+# This file is part of gunicorn released under the MIT license. 
+# See the NOTICE for more information.
+
+import errno
+import os
+import sys
+
+try:
+    import ctypes
+    import ctypes.util
+except MemoryError:
+    # selinux execmem denial
+    # https://bugzilla.redhat.com/show_bug.cgi?id=488396
+    raise ImportError
+
+SUPPORTED_PLATFORMS = (
+        'darwin',
+        'freebsd',
+        'dragonfly'
+        'linux2')
+
+if sys.version_info < (2, 6) or \
+        sys.platform not in SUPPORTED_PLATFORMS:
+    raise ImportError("sendfile isn't supported on this platform")
+
+_libc = ctypes.CDLL(ctypes.util.find_library("c"), use_errno=True)
+_sendfile = _libc.sendfile
+
+def sendfile(fdout, fdin, offset, nbytes):
+    if sys.platform == 'darwin':
+        _sendfile.argtypes = [ctypes.c_int, ctypes.c_int, ctypes.c_uint64,
+                              ctypes.POINTER(ctypes.c_uint64), ctypes.c_voidp,
+                              ctypes.c_int]
+        _nbytes = ctypes.c_uint64(nbytes)
+        result = _sendfile(fdin, fdout, offset, _nbytes, None, 0)
+        if result == -1:
+            e = ctypes.get_errno()
+            if e == errno.EAGAIN and _nbytes.value:
+                return nbytes.value
+            raise OSError(e, os.strerror(e))
+        return _nbytes.value
+    elif sys.platform in ('freebsd', 'dragonfly',):
+        _sendfile.argtypes = [ctypes.c_int, ctypes.c_int, ctypes.c_uint64,
+                              ctypes.c_uint64, ctypes.c_voidp,
+                              ctypes.POINTER(ctypes.c_uint64), ctypes.c_int]
+        _sbytes = ctypes.c_uint64(nbytes)
+        result = _sendfile(fdin, fdout, offset, nbytes, None, _sbytes, 0)
+        if result == -1:
+            e = ctypes.get_errno()
+            if e == errno.EAGAIN and _sbytes.value:
+                return _sbytes.value
+            raise OSError(e, os.strerror(e))
+        return _sbytes.value
+
+    else:
+        _sendfile.argtypes = [ctypes.c_int, ctypes.c_int,
+                ctypes.POINTER(ctypes.c_uint64), ctypes.c_size_t]
+
+        _offset = ctypes.c_uint64(offset)
+        sent = _sendfile(fdout, fdin, _offset, nbytes) 
+        if sent == -1:
+            e = ctypess.get_errno()
+            raise OSError(e, os.strerror(e))
+        return sent

gunicorn/http/wsgi.py

@@ -15,8 +15,11 @@
 try:
     # Python 3.3 has os.sendfile().
     from os import sendfile
-except:
-    from sendfile import sendfile
+except ImportError:
+    try:
+        from _senfile import sendfile
+    except ImportError:
+        sendfile = None
 
 NORMALIZE_SPACE = re.compile(r'(?:\r\n)?[ \t]+')
 
@@ -271,8 +274,9 @@ def sendfile_all(self, fileno, sockno, offset, nbytes):
                 sent += sendfile(fileno, sockno, offset+sent, nbytes-sent)
 
     def write_file(self, respiter):
-        if sendfile and hasattr(respiter.filelike, 'fileno') and \
-               hasattr(respiter.filelike, 'tell'):
+        if sendfile is not None and \
+                hasattr(respiter.filelike, 'fileno') and \
+                hasattr(respiter.filelike, 'tell'):
 
             fileno = respiter.filelike.fileno()
             fd_offset = os.lseek(fileno, 0, os.SEEK_CUR)