gh-83923: Added os.getdtablesize function to os module

Doc/library/os.rst

@@ -2229,6 +2229,13 @@ features:
 
    Return a string representing the current working directory.
 
+.. function:: getdtablesize()
+
+   Return the maximum number of files a process can have open.
+
+   .. warning::
+
+      This function currently only supports unix-like system.
 
 .. function:: getcwdb()
 

Lib/test/test_os.py

@@ -113,6 +113,19 @@ def test_getcwd(self):
         cwd = os.getcwd()
         self.assertIsInstance(cwd, str)
 
+    def test_getdtablesize(self):
+        curr_system = platform.system()
+        if curr_system == 'Windows':
+            try:
+                size = os.getdtablesize()
+            except NotImplementedError as e:
+                self.assertIsInstance(e, NotImplementedError)
+            else:
+                self.fail('No NotImplementedError is thrown')
+        else:
+            size = os.getdtablesize()
+            self.assertIsInstance(size, int)
+
     def test_getcwd_long_path(self):
         # bpo-37412: On Linux, PATH_MAX is usually around 4096 bytes. On
         # Windows, MAX_PATH is defined as 260 characters, but Windows supports

Misc/NEWS.d/next/Library/2024-09-24-14-15-34.gh-issue-83923.YunOLX.rst

@@ -0,0 +1,2 @@
+Added :func:`os.getdtablesize` to :mod:`os` (supported only on unix-like
+systems)

Modules/posixmodule.c

@@ -4219,6 +4219,34 @@
 }
 
 
+/*[clinic input]
+os.getdtablesize
+
+Return the maximum number of files a process can have open.
+[clinic start generated code]*/
+
+static PyObject *
+os_getdtablesize_impl(PyObject *module)
+{
+    PyObject *max_fptable_size;
+    int size;
+
+#ifdef MS_WINDOWS
+    PyErr_SetString(PyExc_NotImplementedError,
+                    "this function is not supported on windows");
+    if (PyErr_Occurred()) {
+        return NULL;
+    }
+#else   /* !Unix-like */
+    size = getdtablesize();
+#endif   /* !MS_WINDOWS */
+    max_fptable_size = PyLong_FromLong(size);
+    if (max_fptable_size == NULL)
+        return NULL;
+
+    return max_fptable_size;
+}
+
 #if ((!defined(HAVE_LINK)) && defined(MS_WINDOWS))
 #define HAVE_LINK 1
 #endif
@@ -16843,6 +16871,7 @@
     OS_CTERMID_METHODDEF
     OS_GETCWD_METHODDEF
     OS_GETCWDB_METHODDEF
+    OS_GETDTABLESIZE_METHODDEF
     OS_LINK_METHODDEF
     OS_LISTDIR_METHODDEF
     OS_LISTDRIVES_METHODDEF