From c608ef01e0889e29679dc01f9aeadc5a2b390181 Mon Sep 17 00:00:00 2001
From: Zackery Spytz <zspytz@gmail.com>
Date: Fri, 17 Apr 2020 08:28:32 -0600
Subject: [PATCH] bpo-32494: Add gdbm.count()

gdbm_count() was added in GDBM 1.11.
---
 Doc/library/dbm.rst                           |  7 +++++
 Lib/test/test_dbm_gnu.py                      | 28 ++++++++++++++-----
 .../2020-04-17-08-28-08.bpo-32494.k4zxIG.rst  |  2 ++
 Modules/_gdbmmodule.c                         | 27 ++++++++++++++++++
 Modules/clinic/_gdbmmodule.c.h                | 28 ++++++++++++++++++-
 5 files changed, 84 insertions(+), 8 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2020-04-17-08-28-08.bpo-32494.k4zxIG.rst

diff --git a/Doc/library/dbm.rst b/Doc/library/dbm.rst
index 57ae547b833cc0..aad737566cb50b 100644
--- a/Doc/library/dbm.rst
+++ b/Doc/library/dbm.rst
@@ -237,6 +237,13 @@ supported.
 
       Close the ``gdbm`` database.
 
+   .. method:: gdbm.count()
+
+      Count the number of records in the database.  This method requires GNU
+      DBM version 1.11 or greater.
+
+      .. versionadded:: 3.9
+
 :mod:`dbm.ndbm` --- Interface based on ndbm
 -------------------------------------------
 
diff --git a/Lib/test/test_dbm_gnu.py b/Lib/test/test_dbm_gnu.py
index f1c7d34085c5ee..2a5b99f07b6387 100644
--- a/Lib/test/test_dbm_gnu.py
+++ b/Lib/test/test_dbm_gnu.py
@@ -4,19 +4,18 @@
 import os
 from test.support import TESTFN, TESTFN_NONASCII, unlink
 
+try:
+    from _gdbm import _GDBM_VERSION as gdbm_version
+except ImportError:
+    gdbm_version = None
 
 filename = TESTFN
 
 class TestGdbm(unittest.TestCase):
     @staticmethod
     def setUpClass():
-        if support.verbose:
-            try:
-                from _gdbm import _GDBM_VERSION as version
-            except ImportError:
-                pass
-            else:
-                print(f"gdbm version: {version}")
+        if support.verbose and gdbm_version:
+            print(f"gdbm version: {gdbm_version}")
 
     def setUp(self):
         self.g = None
@@ -162,6 +161,21 @@ def test_nonexisting_file(self):
         self.assertIn(nonexisting_file, str(cm.exception))
         self.assertEqual(cm.exception.filename, nonexisting_file)
 
+    @unittest.skipUnless(gdbm_version and gdbm_version >= (1, 11, 0),
+                         'needs >= 1.11')
+    def test_count(self):
+        self.g = gdbm.open(filename, 'c')
+        self.assertEqual(self.g.count(), 0)
+
+        self.g['a'] = 'a'
+        self.assertEqual(self.g.count(), 1)
+        self.g['b'] = 'b'
+        self.assertEqual(self.g.count(), 2)
+        del self.g['a']
+        self.assertEqual(self.g.count(), 1)
+        del self.g['b']
+        self.assertEqual(self.g.count(), 0)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2020-04-17-08-28-08.bpo-32494.k4zxIG.rst b/Misc/NEWS.d/next/Library/2020-04-17-08-28-08.bpo-32494.k4zxIG.rst
new file mode 100644
index 00000000000000..de82be31119ffb
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-04-17-08-28-08.bpo-32494.k4zxIG.rst
@@ -0,0 +1,2 @@
+Add :meth:`gdbm.count` to wrap the ``gdbm_count()`` function added in GDBM
+1.11.
diff --git a/Modules/_gdbmmodule.c b/Modules/_gdbmmodule.c
index 7a9649b54119b3..d78246e7786b7c 100644
--- a/Modules/_gdbmmodule.c
+++ b/Modules/_gdbmmodule.c
@@ -486,6 +486,32 @@ _gdbm_gdbm_sync_impl(dbmobject *self)
     Py_RETURN_NONE;
 }
 
+#if GDBM_VERSION_MAJOR >= 1 && GDBM_VERSION_MINOR >= 11
+/*[clinic input]
+_gdbm.gdbm.count
+
+Count the number of records in the database.
+[clinic start generated code]*/
+
+static PyObject *
+_gdbm_gdbm_count_impl(dbmobject *self)
+/*[clinic end generated code: output=8b62b02ae4c2fcee input=1b9d3f0877315a04]*/
+{
+    gdbm_count_t count;
+    check_dbmobject_open(self);
+    if (gdbm_count(self->di_dbm, &count) == -1) {
+        if (errno != 0) {
+            PyErr_SetFromErrno(DbmError);
+        }
+        else {
+            PyErr_SetString(DbmError, gdbm_strerror(gdbm_errno));
+        }
+        return NULL;
+    }
+    return PyLong_FromUnsignedLongLong(count);
+}
+#endif
+
 static PyObject *
 dbm__enter__(PyObject *self, PyObject *args)
 {
@@ -509,6 +535,7 @@ static PyMethodDef dbm_methods[] = {
     _GDBM_GDBM_SYNC_METHODDEF
     _GDBM_GDBM_GET_METHODDEF
     _GDBM_GDBM_SETDEFAULT_METHODDEF
+    _GDBM_GDBM_COUNT_METHODDEF
     {"__enter__", dbm__enter__, METH_NOARGS, NULL},
     {"__exit__",  dbm__exit__, METH_VARARGS, NULL},
     {NULL,              NULL}           /* sentinel */
diff --git a/Modules/clinic/_gdbmmodule.c.h b/Modules/clinic/_gdbmmodule.c.h
index aa37a24d3b2115..496308c8a2b966 100644
--- a/Modules/clinic/_gdbmmodule.c.h
+++ b/Modules/clinic/_gdbmmodule.c.h
@@ -211,6 +211,28 @@ _gdbm_gdbm_sync(dbmobject *self, PyObject *Py_UNUSED(ignored))
     return _gdbm_gdbm_sync_impl(self);
 }
 
+#if (GDBM_VERSION_MAJOR >= 1 && GDBM_VERSION_MINOR >= 11)
+
+PyDoc_STRVAR(_gdbm_gdbm_count__doc__,
+"count($self, /)\n"
+"--\n"
+"\n"
+"Count the number of records in the database.");
+
+#define _GDBM_GDBM_COUNT_METHODDEF    \
+    {"count", (PyCFunction)_gdbm_gdbm_count, METH_NOARGS, _gdbm_gdbm_count__doc__},
+
+static PyObject *
+_gdbm_gdbm_count_impl(dbmobject *self);
+
+static PyObject *
+_gdbm_gdbm_count(dbmobject *self, PyObject *Py_UNUSED(ignored))
+{
+    return _gdbm_gdbm_count_impl(self);
+}
+
+#endif /* (GDBM_VERSION_MAJOR >= 1 && GDBM_VERSION_MINOR >= 11) */
+
 PyDoc_STRVAR(dbmopen__doc__,
 "open($module, filename, flags=\'r\', mode=0o666, /)\n"
 "--\n"
@@ -298,4 +320,8 @@ dbmopen(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=2766471b2fa1a816 input=a9049054013a1b77]*/
+
+#ifndef _GDBM_GDBM_COUNT_METHODDEF
+    #define _GDBM_GDBM_COUNT_METHODDEF
+#endif /* !defined(_GDBM_GDBM_COUNT_METHODDEF) */
+/*[clinic end generated code: output=0373bfdb5c23b602 input=a9049054013a1b77]*/