fcntl add the F_KINFO constant for FreeBSD 13.1 and onwards.

Author: devnexen

Doc/library/fcntl.rst

@@ -57,6 +57,8 @@ descriptor.
    ``FICLONERANGE`` constants, which allow to share some data of one file with
    another file by reflinking on some filesystems (e.g., btrfs, OCFS2, and
    XFS). This behavior is commonly referred to as "copy-on-write".
+   On FreeBSD >= 13.1, the :mod:`fcntl` module exposes the ``F_KINFO``
+   constant which allow to get the path of the file descriptor.
 
 The module defines the following functions:
 

Lib/test/test_fcntl.py

@@ -193,6 +193,13 @@ def test_fcntl_f_getpath(self):
         res = fcntl.fcntl(self.f.fileno(), fcntl.F_GETPATH, bytes(len(expected)))
         self.assertEqual(expected, res)
 
+    @unittest.skipUnless(sys.platform.startswith("freebsd") and hasattr(fcntl, "F_KINFO"), "F_KINFO is only available on freebsd")
+    def test_fcntl_f_kinfo(self):
+        self.f = open(TESTFN, 'wb')
+        expected = os.path.abspath(TESTFN).encode('utf-8')
+        res = fcntl.fcntl(self.f.fileno(), fcntl.F_KINFO)
+        self.assertEqual(expected, res)
+
     @unittest.skipUnless(
         hasattr(fcntl, "F_SETPIPE_SZ") and hasattr(fcntl, "F_GETPIPE_SZ"),
         "F_SETPIPE_SZ and F_GETPIPE_SZ are not available on all platforms.")

Modules/fcntlmodule.c

@@ -19,6 +19,10 @@
 #include <stropts.h>
 #endif
 
+#ifdef HAVE_SYS_USER_H
+#include <sys/user.h>
+#endif
+
 /*[clinic input]
 module fcntl
 [clinic start generated code]*/
@@ -64,6 +68,12 @@ fcntl_fcntl_impl(PyObject *module, int fd, int code, PyObject *arg)
 
     if (arg != NULL) {
         int parse_result;
+#ifdef F_KINFO
+	if (code == F_KINFO) {
+		PyErr_SetString(PyExc_ValueError,
+				"fcntl arg not permitted with F_KINFO");
+	}
+#endif
 
         if (PyArg_Parse(arg, "s#", &str, &len)) {
             if ((size_t)len > sizeof buf) {
@@ -93,6 +103,21 @@ fcntl_fcntl_impl(PyObject *module, int fd, int code, PyObject *arg)
         }
     }
 
+#ifdef F_KINFO
+    if (code == F_KINFO) {
+        struct kinfo_file f = {.kf_structsize = KINFO_FILE_SIZE};
+        do {
+            Py_BEGIN_ALLOW_THREADS
+            ret = fcntl(fd, code, &f);
+            Py_END_ALLOW_THREADS
+        } while (ret == -1 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
+        if (ret < 0) {
+            return !async_err ? PyErr_SetFromErrno(PyExc_OSError) : NULL;
+        }
+	return PyBytes_FromString(f.kf_path);
+    }
+#endif
+
     do {
         Py_BEGIN_ALLOW_THREADS
         ret = fcntl(fd, code, (int)int_arg);
@@ -485,6 +510,9 @@ all_ins(PyObject* m)
 #ifdef F_DUPFD_CLOEXEC
     if (PyModule_AddIntMacro(m, F_DUPFD_CLOEXEC)) return -1;
 #endif
+#ifdef F_KINFO
+    if (PyModule_AddIntMacro(m, F_KINFO)) return -1;
+#endif
 #ifdef F_GETFD
     if (PyModule_AddIntMacro(m, F_GETFD)) return -1;
 #endif

configure.ac

@@ -2701,8 +2701,8 @@ AC_CHECK_HEADERS([ \
   sys/endian.h sys/epoll.h sys/event.h sys/eventfd.h sys/file.h sys/ioctl.h sys/kern_control.h \
   sys/loadavg.h sys/lock.h sys/memfd.h sys/mkdev.h sys/mman.h sys/modem.h sys/param.h sys/poll.h \
   sys/random.h sys/resource.h sys/select.h sys/sendfile.h sys/socket.h sys/soundcard.h sys/stat.h \
-  sys/statvfs.h sys/sys_domain.h sys/syscall.h sys/sysmacros.h sys/termio.h sys/time.h sys/times.h sys/timerfd.h \
-  sys/types.h sys/uio.h sys/un.h sys/utsname.h sys/wait.h sys/xattr.h sysexits.h syslog.h \
+  sys/statvfs.h sys/sys_domain.h sys/syscall.h sys/sysmacros.h sys/termio.h sys/time.h sys/times.h \
+  sys/types.h sys/uio.h sys/un.h sys/user.h sys/utsname.h sys/wait.h sys/xattr.h sysexits.h syslog.h \
   termios.h util.h utime.h utmp.h \
 ])
 AC_HEADER_DIRENT

pyconfig.h.in

@@ -1391,6 +1391,9 @@
 /* Define to 1 if you have the <sys/un.h> header file. */
 #undef HAVE_SYS_UN_H
 
+/* Define to 1 if you have the <sys/user.h> header file. */
+#undef HAVE_SYS_USER_H
+
 /* Define to 1 if you have the <sys/utsname.h> header file. */
 #undef HAVE_SYS_UTSNAME_H