From c0f6149926119fdf300cd07863712146802fa22a Mon Sep 17 00:00:00 2001
From: Hristo Venev <hristo@venev.name>
Date: Mon, 7 Mar 2016 14:07:43 +0200
Subject: [PATCH 2/2] fcntl: Support Linux open file descriptor locks

- Add open_file_descriptor argument to lockf
- Add F_OFD_{GETLK,SETLK,SETLKW}
---
 Lib/test/test_fcntl.py | 19 +++++++++++++++++++
 Modules/fcntlmodule.c  | 27 +++++++++++++++++++++++----
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/Lib/test/test_fcntl.py b/Lib/test/test_fcntl.py
index e3b7ed2..c54b5cd 100644
--- a/Lib/test/test_fcntl.py
+++ b/Lib/test/test_fcntl.py
@@ -11,6 +11,11 @@ from test.support import (verbose, TESTFN, unlink, run_unittest, import_module,
 # Skip test if no fcntl module.
 fcntl = import_module('fcntl')
 
+class NotInt:
+    def __init__(self, a):
+        self.a=a
+    def __int__(self):
+        return self.a
 
 # TODO - Write tests for flock() and lockf().
 
@@ -134,6 +139,20 @@ class TestFcntl(unittest.TestCase):
         fcntl.flock(self.f, fcntl.LOCK_UN)
         fcntl.flock(fileno, fcntl.LOCK_EX)
         fcntl.flock(fileno, fcntl.LOCK_UN)
+        fcntl.lockf(fileno, fcntl.LOCK_EX, 2**31-1)
+        fcntl.lockf(fileno, fcntl.LOCK_EX, 2**31)
+        fcntl.lockf(fileno, fcntl.LOCK_EX, NotInt(2**31-1))
+        fcntl.lockf(fileno, fcntl.LOCK_EX, NotInt(2**31))
+        self.assertRaises(BlockingIOError, fcntl.lockf, fileno, fcntl.LOCK_EX | fcntl.LOCK_NB, open_file_descriptor=True)
+        fcntl.lockf(fileno, fcntl.LOCK_UN)
+        fcntl.lockf(fileno, fcntl.LOCK_SH)
+        fcntl.lockf(fileno, fcntl.LOCK_SH | fcntl.LOCK_NB)
+        fcntl.lockf(fileno, fcntl.LOCK_SH | fcntl.LOCK_NB, open_file_descriptor=True)
+        fcntl.lockf(fileno, fcntl.LOCK_SH | fcntl.LOCK_NB, open_file_descriptor=True)
+        self.assertRaises(BlockingIOError, fcntl.lockf, fileno, fcntl.LOCK_EX | fcntl.LOCK_NB, open_file_descriptor=True)
+        fcntl.lockf(fileno, fcntl.LOCK_UN)
+        fcntl.lockf(fileno, fcntl.LOCK_EX | fcntl.LOCK_NB, open_file_descriptor=True)
+        fcntl.lockf(fileno, fcntl.LOCK_UN, open_file_descriptor=True)
 
         self.assertRaises(ValueError, fcntl.flock, -1, fcntl.LOCK_SH)
         self.assertRaises(TypeError, fcntl.flock, 'spam', fcntl.LOCK_SH)
diff --git a/Modules/fcntlmodule.c b/Modules/fcntlmodule.c
index 1875326..b100498 100644
--- a/Modules/fcntlmodule.c
+++ b/Modules/fcntlmodule.c
@@ -331,7 +331,7 @@ fcntl.lockf
     len as lenobj: object(c_default='NULL') = 0
     start as startobj: object(c_default='NULL') = 0
     whence: int = 0
-    /
+    open_file_descriptor: bool = False
 
 A wrapper around the fcntl() locking calls.
 
@@ -359,8 +359,8 @@ starts.  `whence` is as with fileobj.seek(), specifically:
 
 static PyObject *
 fcntl_lockf_impl(PyModuleDef *module, int fd, int code, PyObject *lenobj,
-                 PyObject *startobj, int whence)
-/*[clinic end generated code: output=31af35eba08b9af7 input=9c594391de821f24]*/
+                 PyObject *startobj, int whence, int open_file_descriptor)
+/*[clinic end generated code: output=35b767f635507cd4 input=57433c68e144e94b]*/
 {
     int ret;
 
@@ -403,8 +403,18 @@ fcntl_lockf_impl(PyModuleDef *module, int fd, int code, PyObject *lenobj,
                 return NULL;
         }
         l.l_whence = whence;
+        l.l_pid = 0;
         Py_BEGIN_ALLOW_THREADS
-        ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
+        if (open_file_descriptor) {
+#ifdef F_OFD_SETLK
+            ret = fcntl(fd, (code & LOCK_NB) ? F_OFD_SETLK : F_OFD_SETLKW, &l);
+#else
+            PyErr_SetString(PyExc_NotImplementedError,
+                            "lockf: open_file_descriptor not supported on this platform");
+            return NULL;
+#endif
+        } else
+            ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
         Py_END_ALLOW_THREADS
     }
     if (ret < 0) {
@@ -482,6 +492,15 @@ all_ins(PyObject* m)
 #ifdef F_SETLKW
     if (PyModule_AddIntMacro(m, F_SETLKW)) return -1;
 #endif
+#ifdef F_OFD_GETLK
+    if (PyModule_AddIntMacro(m, F_OFD_GETLK)) return -1;
+#endif
+#ifdef F_OFD_SETLK
+    if (PyModule_AddIntMacro(m, F_OFD_SETLK)) return -1;
+#endif
+#ifdef F_OFD_SETLKW
+    if (PyModule_AddIntMacro(m, F_OFD_SETLKW)) return -1;
+#endif
 #ifdef F_GETOWN
     if (PyModule_AddIntMacro(m, F_GETOWN)) return -1;
 #endif
-- 
2.7.2