Handle fork() failures more gracefully

kitty/child.c

@@ -51,7 +51,8 @@ spawn(PyObject *self UNUSED, PyObject *args) {
 
 #define exit_on_err(m) { write_to_stderr(m); write_to_stderr(": "); write_to_stderr(strerror(errno)); exit(EXIT_FAILURE); }
     pid_t pid = fork();
-    if (pid == 0) {
+    switch(pid) {
+        case 0:
             // child
             // Use only signal-safe functions (man 7 signal-safety)
             if (chdir(cwd) != 0) { if (chdir("/") != 0) {} };  // ignore failure to chdir to /
@@ -85,11 +86,17 @@ spawn(PyObject *self UNUSED, PyObject *args) {
             write_to_stderr("\nPress Enter to exit.\n");
             execlp("sh", "sh", "-c", "read w", NULL);
             exit(EXIT_FAILURE);
-    } else {
-        free(argv);
-        free(env);
+            break;
+        case -1:
+            PyErr_SetFromErrno(PyExc_OSError);
+            break;
+        default:
+            break;
     }
 #undef exit_on_err
+    free(argv);
+    free(env);
+    if (pid == -1) return NULL;
     return PyLong_FromLong(pid);
 }