Properly evaluate /etc/issue placeholders

kitty/utmp.c

@@ -0,0 +1,50 @@
+#if defined(__unix__)
+
+#define PY_SSIZE_T_CLEAN
+#include <Python.h>
+#include <stdbool.h>
+
+#include <utmp.h>
+
+static PyObject*
+num_users(PyObject *const self, PyObject *const args) {
+    (void)self; (void)args;
+    size_t users = 0;
+    Py_BEGIN_ALLOW_THREADS
+#ifdef UTENT_REENTRANT
+    struct utmp *result = NULL;
+    struct utmp buffer = { 0, };
+    while (true) {
+        if (getutent_r(&buffer, &result) == -1) {
+            Py_BLOCK_THREADS
+            return PyErr_SetFromErrno(PyExc_OSError);
+        }
+        if (result == NULL) { break; }
+        if (result->ut_type == USER_PROCESS) { users++; }
+    }
+#else
+    struct utmp *ut;
+    setutent();
+    while ((ut = getutent())) {
+        if (ut->ut_type == USER_PROCESS) {
+            users++;
+        }
+    }
+    endutent();
+#endif
+    Py_END_ALLOW_THREADS
+    return PyLong_FromSize_t(users);
+}
+
+static PyMethodDef UtmpMethods[] = {
+    {"num_users", num_users, METH_NOARGS, "Get the number of users using UTMP data" },
+    { NULL, NULL, 0, NULL },
+};
+
+bool
+init_utmp(PyObject *module) {
+    // 0 = success
+    return PyModule_AddFunctions(module, UtmpMethods) == 0;
+}
+
+#endif