gh-99987: fcntl add the F_KINFO constant for FreeBSD 13.1 and onwards.

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 +193,15 @@ 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')
+        buffer = fcntl.kinfoalloc()
+        expected = os.path.abspath(TESTFN).encode('utf-8')
+        res = fcntl.fcntl(self.f.fileno(), fcntl.F_KINFO, buffer)
+        path = fcntl.kinfodict(res)["path"]
+        self.assertEqual(expected, path)
+
     @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.")

Misc/NEWS.d/next/Library/2022-12-04-12-39-46.gh-issue-99987.RYtvKZ.rst

@@ -0,0 +1 @@
+Expose ``F_KINFO`` constant in :mod:`fcntl`. Patch by David Carlier.

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]*/
@@ -55,7 +59,6 @@ fcntl_fcntl_impl(PyObject *module, int fd, int code, PyObject *arg)
     int ret;
     char *str;
     Py_ssize_t len;
-    char buf[1024];
     int async_err = 0;
 
     if (PySys_Audit("fcntl.fcntl", "iiO", fd, code, arg ? arg : Py_None) < 0) {
@@ -66,6 +69,7 @@ fcntl_fcntl_impl(PyObject *module, int fd, int code, PyObject *arg)
         int parse_result;
 
         if (PyArg_Parse(arg, "s#", &str, &len)) {
+            char buf[4096];
             if ((size_t)len > sizeof buf) {
                 PyErr_SetString(PyExc_ValueError,
                                 "fcntl string arg too long");
@@ -438,13 +442,70 @@ fcntl_lockf_impl(PyObject *module, int fd, int code, PyObject *lenobj,
     Py_RETURN_NONE;
 }
 
+#ifdef F_KINFO
+/*[clinic input]
+fcntl.kinfoalloc
+
+Return a FreeBSD's kinfo_file buffer with the `kf_structsize` field pre-initialised.
+
+[clinic start generated code]*/
+
+static PyObject *
+fcntl_kinfoalloc_impl(PyObject *module)
+/*[clinic end generated code: output=c61603aeb3d91a0e input=28e2e82cc296f82c]*/
+{
+    char buf[KINFO_FILE_SIZE+1];
+    ((struct kinfo_file *)buf)->kf_structsize = KINFO_FILE_SIZE;
+    return PyBytes_FromStringAndSize(buf, KINFO_FILE_SIZE);
+}
+
+/*[clinic input]
+fcntl.kinfodict
+
+    arg: object(c_default='NULL') = 0
+    /
+
+Return a FreeBSD's kinfo_file as dictionary.
+
+[clinic start generated code]*/
+
+static PyObject *
+fcntl_kinfodict_impl(PyObject *module, PyObject *arg)
+/*[clinic end generated code: output=3873ae40aeac8e7f input=faba1f2ce099752f]*/
+{
+        PyObject *dict;
+
+        if (PySys_Audit("fcntl.kinfodict", "O", arg) < 0 || arg == NULL) {
+                return NULL;
+        }
+
+        dict = PyDict_New();
+        if (dict) {
+                struct kinfo_file *kf;
+                kf = (struct kinfo_file *)PyBytes_AsString(arg);
+
+                PyDict_SetItemString(dict, "status", PyLong_FromLong(kf->kf_status));
+                PyDict_SetItemString(dict, "type", PyLong_FromLong(kf->kf_type));
+                PyDict_SetItemString(dict, "offset", PyLong_FromLongLong(kf->kf_offset));
+                PyDict_SetItemString(dict, "path", PyBytes_FromString(kf->kf_path));
+                return dict;
+        }
+
+        PyErr_SetString(PyExc_ValueError, "fcntl.kinfodict could not create its dictionary");
+        return NULL;
+}
+
+#endif
+
 /* List of functions */
 
 static PyMethodDef fcntl_methods[] = {
     FCNTL_FCNTL_METHODDEF
     FCNTL_IOCTL_METHODDEF
     FCNTL_FLOCK_METHODDEF
     FCNTL_LOCKF_METHODDEF
+    FCNTL_KINFOALLOC_METHODDEF
+    FCNTL_KINFODICT_METHODDEF
     {NULL, NULL}  /* sentinel */
 };
 
@@ -485,6 +546,9 @@ 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

@@ -2702,7 +2702,7 @@ AC_CHECK_HEADERS([ \
   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/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