UI_CREATE_METHOD(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💅 NAME 💅

Okay bestie, gather round — this is the 3ossl OpenSSL manual page for UI_METHOD, UI_create_method, UI_destroy_method, UI_method_set_opener, UI_method_set_writer, UI_method_set_flusher, UI_method_set_reader, UI_method_set_closer, UI_method_set_data_duplicator, UI_method_set_prompt_constructor, UI_method_set_ex_data, UI_method_get_opener, UI_method_get_writer, UI_method_get_flusher, UI_method_get_reader, UI_method_get_closer, UI_method_get_data_duplicator, UI_method_get_data_destructor, UI_method_get_prompt_constructor, and UI_method_get_ex_data — literally all about user interface method creation and destruction. Slay. 🎀

✨ SYNOPSIS ✨

Like, here's the whole cast list, no cap:

#include <openssl/ui.h>

typedef struct ui_method_st UI_METHOD;

UI_METHOD *UI_create_method(const char *name);
void UI_destroy_method(UI_METHOD *ui_method);
int UI_method_set_opener(UI_METHOD *method, int (*opener) (UI *ui));
int UI_method_set_writer(UI_METHOD *method,
                         int (*writer) (UI *ui, UI_STRING *uis));
int UI_method_set_flusher(UI_METHOD *method, int (*flusher) (UI *ui));
int UI_method_set_reader(UI_METHOD *method,
                         int (*reader) (UI *ui, UI_STRING *uis));
int UI_method_set_closer(UI_METHOD *method, int (*closer) (UI *ui));
int UI_method_set_data_duplicator(UI_METHOD *method,
                                  void *(*duplicator) (UI *ui, void *ui_data),
                                  void (*destructor)(UI *ui, void *ui_data));
int UI_method_set_prompt_constructor(UI_METHOD *method,
                                     char *(*prompt_constructor) (UI *ui,
                                                                  const char
                                                                  *object_desc,
                                                                  const char
                                                                  *object_name));
int UI_method_set_ex_data(UI_METHOD *method, int idx, void *data);
int (*UI_method_get_opener(const UI_METHOD *method)) (UI *);
int (*UI_method_get_writer(const UI_METHOD *method)) (UI *, UI_STRING *);
int (*UI_method_get_flusher(const UI_METHOD *method)) (UI *);
int (*UI_method_get_reader(const UI_METHOD *method)) (UI *, UI_STRING *);
int (*UI_method_get_closer(const UI_METHOD *method)) (UI *);
char *(*UI_method_get_prompt_constructor(const UI_METHOD *method))
    (UI *, const char *, const char *);
void *(*UI_method_get_data_duplicator(const UI_METHOD *method)) (UI *, void *);
void (*UI_method_get_data_destructor(const UI_METHOD *method)) (UI *, void *);
const void *UI_method_get_ex_data(const UI_METHOD *method, int idx);

🌸 DESCRIPTION 🌸

So a method is basically a little squad of functions that implement the low-level of the User Interface. It's giving backstage crew energy. 👑

Here's who's on the team:

  • an opener — this function takes a reference to a UI and starts a session. Like, for example, by opening a channel to a tty, or by creating a dialog box. Opening the group chat, basically. 🫶
  • a writer — this function takes a reference to a UI and a UI String, and writes the string where appropriate. Maybe to the tty, maybe added as a field label in a dialog box. Important: this gets fed all strings associated with a UI, one after the other, so care must be taken which ones it actually uses. Don't let it accidentally post the whole draft, bestie. 😭
  • a flusher — this function takes a reference to a UI, and flushes everything that has been output so far. For example, if the method builds up a dialog box, this can be used to actually display it and accepting input ended with a pressed button. The "send it" button energy. ✨
  • a reader — this function takes a reference to a UI and a UI string and reads off the given prompt. Maybe from the tty, maybe from a field in a dialog box. And again: this gets fed all strings associated with a UI, one after the other, so care must be taken which ones it actually uses. Read the room, literally. 🙈
  • a closer — this function takes a reference to a UI, and closes the session. Maybe by closing the channel to the tty, maybe by destroying a dialog box. Say bye, icon. 👋

All of these functions are expected to return 0 on error, 1 on success, or -1 on out-of-band events — for example if some prompting has been cancelled (by pressing Ctrl+C, for example). Only the flusher or the reader are expected to return -1. If returned by another of the functions, it's treated as if 0 was returned. So like, don't get cute with -1 from the wrong function. 💀

Regarding the writer and the reader: don't assume the former should only write and don't assume the latter should only read. This depends on the needs of the method. Highkey flexible, lowkey chaotic. 🌈

For example, a typical tty reader wouldn't write the prompts in the write, but would rather do so in the reader, because of the sequential nature of prompting on a tty. This is how the UI_OpenSSL() method does it.

In contrast, a method that builds up a dialog box would add all prompt text in the writer, have all input read in the flusher and store the results in some temporary buffer, and finally have the reader just fetch those results. Main character planning energy. 💅

The central function that uses these method functions is UI_process(), and it does it in five steps:

  1. Open the session using the opener function if that one's defined. If an error occurs, jump to 5.
  2. For every UI String associated with the UI, call the writer function if that one's defined. If an error occurs, jump to 5.
  3. Flush everything using the flusher function if that one's defined. If an error occurs, jump to 5.
  4. For every UI String associated with the UI, call the reader function if that one's defined. If an error occurs, jump to 5.
  5. Close the session using the closer function if that one's defined.

Now the actual functions, because yes, we're doing all of them. 🎀

UI_create_method() creates a new UI method with a given name.

UI_destroy_method() destroys the given UI method ui_method.

UI_method_set_opener(), UI_method_set_writer(), UI_method_set_flusher(), UI_method_set_reader() and UI_method_set_closer() set the five main method function to the given function pointer. Five little slots, one iconic group. 👑

UI_method_set_data_duplicator() sets the user data duplicator and destructor. See UI_dup_user_data(3).

UI_method_set_prompt_constructor() sets the prompt constructor. See UI_construct_prompt(3).

UI_method_set_ex_data() sets application specific data with a given EX_DATA index. See CRYPTO_get_ex_new_index(3) for general information on how to get that index.

UI_method_get_opener(), UI_method_get_writer(), UI_method_get_flusher(), UI_method_get_reader(), UI_method_get_closer(), UI_method_get_data_duplicator(), UI_method_get_data_destructor() and UI_method_get_prompt_constructor() return the different method functions. Get you a method who can do both — well, all of these. 🦋

UI_method_get_ex_data() returns the application data previously stored with UI_method_set_ex_data().

🔥 RETURN VALUES 🔥

UI_create_method() returns a UI_METHOD pointer on success, NULL on error. Bestie said "new method, who dis." 💖

UI_method_set_opener(), UI_method_set_writer(), UI_method_set_flusher(), UI_method_set_reader(), UI_method_set_closer(), UI_method_set_data_duplicator() and UI_method_set_prompt_constructor() return 0 on success, -1 if the given method is NULL. Rude but fair. 😤

UI_method_set_ex_data() returns 1 on success and 0 on error (because CRYPTO_set_ex_data() does so). Blame the other function, not me. 💀

UI_method_get_opener(), UI_method_get_writer(), UI_method_get_flusher(), UI_method_get_reader(), UI_method_get_closer(), UI_method_get_data_duplicator(), UI_method_get_data_destructor() and UI_method_get_prompt_constructor() return the requested function pointer if it's set in the method, otherwise NULL. If it's not there, it's not there — vibe check failed. 🫠

UI_method_get_ex_data() returns a pointer to the application specific data associated with the method.

👀 SEE ALSO 👀

UI(3), CRYPTO_get_ex_data(3), UI_STRING(3) — go read those next, bestie, iykyk. 🌸

⭐ HISTORY ⭐

The UI_method_set_data_duplicator(), UI_method_get_data_duplicator() and UI_method_get_data_destructor() functions were added in OpenSSL 1.1.1. Vintage, but make it cute. ✨

Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

And that's the whole page, bestie — OpenSSL 3.5.0, dated 2026-09-25, filed under UI_CREATE_METHOD(3ossl). Periodt. 💅💖✨

📦 where this page comes from