Issue #12196: Add pipe2() to the os module.

Doc/library/os.rst

@@ -1019,6 +1019,19 @@ as internal buffering of data.
    Availability: Unix, Windows.
 
 
+.. function:: pipe2(flags=0)
+
+   Create a pipe with *flags* set atomically.
+   *flags* is optional and can be constructed by ORing together zero or more of
+   these values: :data:`O_NONBLOCK`, :data:`O_CLOEXEC`.
+   Return a pair of file descriptors ``(r, w)`` usable for reading and writing,
+   respectively.
+
+   Availability: some flavors of Unix.
+
+   .. versionadded:: 3.3
+
+
 .. function:: posix_fallocate(fd, offset, len)
 
    Ensures that enough disk space is allocated for the file specified by *fd*

Lib/test/test_posix.py

@@ -478,6 +478,31 @@ class PosixTester(unittest.TestCase):
             os.close(reader)
             os.close(writer)
 
+    @unittest.skipUnless(hasattr(os, 'pipe2'), "test needs os.pipe2()")
+    def test_pipe2(self):
+        self.assertRaises(TypeError, os.pipe2, 'DEADBEEF')
+        self.assertRaises(TypeError, os.pipe2, 0, 0)
+
+        # try calling without flag, like os.pipe()
+        r, w = os.pipe2()
+        os.close(r)
+        os.close(w)
+
+        # test flags
+        r, w = os.pipe2(os.O_CLOEXEC|os.O_NONBLOCK)
+        self.addCleanup(os.close, r)
+        self.addCleanup(os.close, w)
+        self.assertTrue(fcntl.fcntl(r, fcntl.F_GETFD) & fcntl.FD_CLOEXEC)
+        self.assertTrue(fcntl.fcntl(w, fcntl.F_GETFD) & fcntl.FD_CLOEXEC)
+        # try reading from an empty pipe: this should fail, not block
+        self.assertRaises(OSError, os.read, r, 1)
+        # try a write big enough to fill-up the pipe: this should either
+        # fail or perform a partial write, not block
+        try:
+            os.write(w, b'x' * support.PIPE_MAX_SIZE)
+        except OSError:
+            pass
+
     def test_utime(self):
         if hasattr(posix, 'utime'):
             now = time.time()

Misc/NEWS

@@ -175,6 +175,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #12196: Add pipe2() to the os module. 
+
 - Issue #985064: Make plistlib more resilient to faulty input plists.
   Patch by Mher Movsisyan.
 

Modules/posixmodule.c

@@ -6547,6 +6547,31 @@ posix_pipe(PyObject *self, PyObject *noargs)
 }
 #endif  /* HAVE_PIPE */
 
+#ifdef HAVE_PIPE2
+PyDoc_STRVAR(posix_pipe2__doc__,
+"pipe2(flags=0) -> (read_end, write_end)\n\n\
+Create a pipe with flags set atomically.\
+flags is optional and can be constructed by ORing together zero or more\n\
+of these values: O_NONBLOCK, O_CLOEXEC.\n\
+");
+
+static PyObject *
+posix_pipe2(PyObject *self, PyObject *args)
+{
+    int flags = 0;
+    int fds[2];
+    int res;
+
+    if (!PyArg_ParseTuple(args, "|i:pipe2", &flags))
+        return NULL;
+
+    res = pipe2(fds, flags);
+    if (res != 0)
+        return posix_error();
+    return Py_BuildValue("(ii)", fds[0], fds[1]);
+}
+#endif /* HAVE_PIPE2 */
+
 #ifdef HAVE_WRITEV
 PyDoc_STRVAR(posix_writev__doc__,
 "writev(fd, buffers) -> byteswritten\n\n\
@@ -9441,6 +9466,9 @@ static PyMethodDef posix_methods[] = {
 #ifdef HAVE_PIPE
     {"pipe",            posix_pipe, METH_NOARGS, posix_pipe__doc__},
 #endif
+#ifdef HAVE_PIPE2
+    {"pipe2",           posix_pipe2, METH_VARARGS, posix_pipe2__doc__},
+#endif
 #ifdef HAVE_MKFIFO
     {"mkfifo",          posix_mkfifo, METH_VARARGS, posix_mkfifo__doc__},
 #endif

configure

@@ -9307,7 +9307,7 @@ for ac_func in alarm accept4 setitimer getitimer bind_textdomain_codeset chown \
  getpriority getresuid getresgid getpwent getspnam getspent getsid getwd \
  if_nameindex \
  initgroups kill killpg lchmod lchown lockf linkat lstat lutimes mbrtowc mkdirat mkfifo \
- mkfifoat mknod mknodat mktime mremap nice openat pathconf pause plock poll \
+ mkfifoat mknod mknodat mktime mremap nice openat pathconf pause pipe2 plock poll \
  posix_fallocate posix_fadvise pread \
  pthread_init pthread_kill putenv pwrite readlink readlinkat readv realpath renameat \
  select sem_open sem_timedwait sem_getvalue sem_unlink sendfile setegid seteuid \
@@ -13824,14 +13824,6 @@ $as_echo "#define HAVE_BROKEN_PIPE_BUF 1" >>confdefs.h
 esac
 
 
-ac_fn_c_check_func "$LINENO" "pipe2" "ac_cv_func_pipe2"
-if test "x$ac_cv_func_pipe2" = x""yes; then :
-
-$as_echo "#define HAVE_PIPE2 1" >>confdefs.h
-
-fi
-
-
 
 
 for h in `(cd $srcdir;echo Python/thread_*.h)`

configure.in

@@ -2531,7 +2531,7 @@ AC_CHECK_FUNCS(alarm accept4 setitimer getitimer bind_textdomain_codeset chown \
  getpriority getresuid getresgid getpwent getspnam getspent getsid getwd \
  if_nameindex \
  initgroups kill killpg lchmod lchown lockf linkat lstat lutimes mbrtowc mkdirat mkfifo \
- mkfifoat mknod mknodat mktime mremap nice openat pathconf pause plock poll \
+ mkfifoat mknod mknodat mktime mremap nice openat pathconf pause pipe2 plock poll \
  posix_fallocate posix_fadvise pread \
  pthread_init pthread_kill putenv pwrite readlink readlinkat readv realpath renameat \
  select sem_open sem_timedwait sem_getvalue sem_unlink sendfile setegid seteuid \
@@ -4244,8 +4244,6 @@ AIX*)
 esac
 
 
-AC_CHECK_FUNC(pipe2, AC_DEFINE(HAVE_PIPE2, 1, [Define if the OS supports pipe2()]), )
-
 AC_SUBST(THREADHEADERS)
 
 for h in `(cd $srcdir;echo Python/thread_*.h)`

pyconfig.h.in

@@ -560,7 +560,7 @@
 /* Define to 1 if you have the `pause' function. */
 #undef HAVE_PAUSE
 
-/* Define if the OS supports pipe2() */
+/* Define to 1 if you have the `pipe2' function. */
 #undef HAVE_PIPE2
 
 /* Define to 1 if you have the `plock' function. */