#1663329: add os.closerange() to close a range of fds,

ignoring errors, and use this in subprocess to speed up
subprocess creation in close_fds mode. Patch by Mike Klaas.

Doc/library/os.rst

@@ -481,6 +481,20 @@ by file descriptors.
       :func:`fdopen`, use its :meth:`close` method.
 
 
+.. function:: closerange(fd_low, fd_high)
+
+   Close all file descriptors from *fd_low* (inclusive) to *fd_high* (exclusive),
+   ignoring errors. Availability: Macintosh, Unix, Windows. Equivalent to::
+
+      for fd in xrange(fd_low, fd_high):
+          try:
+              os.close(fd)
+          except OSError:
+              pass
+
+   .. versionadded:: 2.6
+
+
 .. function:: dup(fd)
 
    Return a duplicate of file descriptor *fd*. Availability: Macintosh, Unix,

Lib/subprocess.py

@@ -965,13 +965,8 @@ class Popen(object):
 
 
         def _close_fds(self, but):
-            for i in xrange(3, MAXFD):
+            os.closerange(3, but)
-                if i == but:
+            os.closerange(but + 1, MAXFD)
-                    continue
-                try:
-                    os.close(i)
-                except:
-                    pass
 
 
         def _execute_child(self, args, executable, preexec_fn, close_fds,

Lib/test/test_os.py

@@ -23,6 +23,12 @@ class FileTests(unittest.TestCase):
         os.close(f)
         self.assert_(os.access(test_support.TESTFN, os.W_OK))
 
+    def test_closerange(self):
+        f = os.open(test_support.TESTFN, os.O_CREAT|os.O_RDWR)
+        # close a fd that is open, and one that isn't
+        os.closerange(f, f+2)
+        self.assertRaises(OSError, os.write, f, "a")
+
 
 class TemporaryFileTests(unittest.TestCase):
     def setUp(self):

Misc/NEWS

@@ -1019,6 +1019,9 @@ Library
 Extension Modules
 -----------------
 
+- Patch #1663329: added ``os.closerange()`` function to quickly close a range
+  of file descriptors without considering errors.
+
 - Patch 976880: ``mmap`` objects now have an ``rfind`` method that
   works as expected.  ``mmap.find`` also takes an optional ``end``
   parameter.

Modules/posixmodule.c

@@ -6156,6 +6156,24 @@ posix_close(PyObject *self, PyObject *args)
 }
 
 
+PyDoc_STRVAR(posix_closerange__doc__, 
+"closerange(fd_low, fd_high)\n\n\
+Closes all file descriptors in [fd_low, fd_high), ignoring errors.");
+
+static PyObject *
+posix_closerange(PyObject *self, PyObject *args)
+{
+	int fd_from, fd_to, i;
+	if (!PyArg_ParseTuple(args, "ii:closerange", &fd_from, &fd_to))
+		return NULL;
+	Py_BEGIN_ALLOW_THREADS
+	for (i = fd_from; i < fd_to; i++)
+		close(i);
+	Py_END_ALLOW_THREADS
+	Py_RETURN_NONE;
+}
+
+
 PyDoc_STRVAR(posix_dup__doc__,
 "dup(fd) -> fd2\n\n\
 Return a duplicate of a file descriptor.");
@@ -8451,6 +8469,7 @@ static PyMethodDef posix_methods[] = {
 #endif /* HAVE_TCSETPGRP */
 	{"open",	posix_open, METH_VARARGS, posix_open__doc__},
 	{"close",	posix_close, METH_VARARGS, posix_close__doc__},
+	{"closerange",	posix_closerange, METH_VARARGS, posix_closerange__doc__},
 	{"dup",		posix_dup, METH_VARARGS, posix_dup__doc__},
 	{"dup2",	posix_dup2, METH_VARARGS, posix_dup2__doc__},
 	{"lseek",	posix_lseek, METH_VARARGS, posix_lseek__doc__},