1UI_CREATE_METHOD(3) OpenSSL UI_CREATE_METHOD(3)
2
6 UI_METHOD, UI_create_method, UI_destroy_method, UI_method_set_opener,
7 UI_method_set_writer, UI_method_set_flusher, UI_method_set_reader,
8 UI_method_set_closer, UI_method_set_data_duplicator,
9 UI_method_set_prompt_constructor, UI_method_set_ex_data,
10 UI_method_get_opener, UI_method_get_writer, UI_method_get_flusher,
11 UI_method_get_reader, UI_method_get_closer,
12 UI_method_get_data_duplicator, UI_method_get_data_destructor,
13 UI_method_get_prompt_constructor, UI_method_get_ex_data - user
14 interface method creation and destruction
15
17 #include <openssl/ui.h>
18 typedef struct ui_method_st UI_METHOD;
20 UI_METHOD *UI_create_method(const char *name);
22 void UI_destroy_method(UI_METHOD *ui_method);
23 int UI_method_set_opener(UI_METHOD *method, int (*opener) (UI *ui));
24 int UI_method_set_writer(UI_METHOD *method,
25 int (*writer) (UI *ui, UI_STRING *uis));
26 int UI_method_set_flusher(UI_METHOD *method, int (*flusher) (UI *ui));
27 int UI_method_set_reader(UI_METHOD *method,
28 int (*reader) (UI *ui, UI_STRING *uis));
29 int UI_method_set_closer(UI_METHOD *method, int (*closer) (UI *ui));
30 int UI_method_set_data_duplicator(UI_METHOD *method,
31 void *(*duplicator) (UI *ui, void *ui_data),
32 void (*destructor)(UI *ui, void *ui_data));
33 int UI_method_set_prompt_constructor(UI_METHOD *method,
34 char *(*prompt_constructor) (UI *ui,
35 const char
36 *object_desc,
37 const char
38 *object_name));
39 int UI_method_set_ex_data(UI_METHOD *method, int idx, void *data);
40 int (*UI_method_get_opener(const UI_METHOD *method)) (UI *);
41 int (*UI_method_get_writer(const UI_METHOD *method)) (UI *, UI_STRING *);
42 int (*UI_method_get_flusher(const UI_METHOD *method)) (UI *);
43 int (*UI_method_get_reader(const UI_METHOD *method)) (UI *, UI_STRING *);
44 int (*UI_method_get_closer(const UI_METHOD *method)) (UI *);
45 char *(*UI_method_get_prompt_constructor(const UI_METHOD *method))
46 (UI *, const char *, const char *);
47 void *(*UI_method_get_data_duplicator(const UI_METHOD *method)) (UI *, void *);
48 void (*UI_method_get_data_destructor(const UI_METHOD *method)) (UI *, void *);
49 const void *UI_method_get_ex_data(const UI_METHOD *method, int idx);
50
52 A method contains a few functions that implement the low-level of the
53 User Interface. These functions are:
54 an opener
56 This function takes a reference to a UI and starts a session, for
57 example by opening a channel to a tty, or by creating a dialog box.
58 a writer
60 This function takes a reference to a UI and a UI String, and writes
61 the string where appropriate, maybe to the tty, maybe added as a
62 field label in a dialog box. Note that this gets fed all strings
63 associated with a UI, one after the other, so care must be taken
64 which ones it actually uses.
65 a flusher
67 This function takes a reference to a UI, and flushes everything
68 that has been output so far. For example, if the method builds up
69 a dialog box, this can be used to actually display it and accepting
70 input ended with a pressed button.
71 a reader
73 This function takes a reference to a UI and a UI string and reads
74 off the given prompt, maybe from the tty, maybe from a field in a
75 dialog box. Note that this gets fed all strings associated with a
76 UI, one after the other, so care must be taken which ones it
77 actually uses.
78 a closer
80 This function takes a reference to a UI, and closes the session,
81 maybe by closing the channel to the tty, maybe by destroying a
82 dialog box.
83 All of these functions are expected to return 0 on error, 1 on success,
85 or -1 on out-off-band events, for example if some prompting has been
86 cancelled (by pressing Ctrl-C, for example). Only the flusher or the
87 reader are expected to return -1. If returned by another of the
88 functions, it's treated as if 0 was returned.
89 Regarding the writer and the reader, don't assume the former should
91 only write and don't assume the latter should only read. This depends
92 on the needs of the method.
93 For example, a typical tty reader wouldn't write the prompts in the
95 write, but would rather do so in the reader, because of the sequential
96 nature of prompting on a tty. This is how the UI_OpenSSL() method does
97 it.
98 In contrast, a method that builds up a dialog box would add all prompt
100 text in the writer, have all input read in the flusher and store the
101 results in some temporary buffer, and finally have the reader just
102 fetch those results.
103 The central function that uses these method functions is UI_process(),
105 and it does it in five steps:
106 1. Open the session using the opener function if that one's defined.
108 If an error occurs, jump to 5.
109 2. For every UI String associated with the UI, call the writer
111 function if that one's defined. If an error occurs, jump to 5.
112 3. Flush everything using the flusher function if that one's defined.
114 If an error occurs, jump to 5.
115 4. For every UI String associated with the UI, call the reader
117 function if that one's defined. If an error occurs, jump to 5.
118 5. Close the session using the closer function if that one's defined.
120 UI_create_method() creates a new UI method with a given name.
122 UI_destroy_method() destroys the given UI method ui_method.
124 UI_method_set_opener(), UI_method_set_writer(),
126 UI_method_set_flusher(), UI_method_set_reader() and
127 UI_method_set_closer() set the five main method function to the given
128 function pointer.
129 UI_method_set_data_duplicator() sets the user data duplicator and
131 destructor. See UI_dup_user_data(3).
132 UI_method_set_prompt_constructor() sets the prompt constructor. See
134 UI_construct_prompt(3).
135 UI_method_set_ex_data() sets application specific data with a given
137 EX_DATA index. See CRYPTO_get_ex_new_index(3) for general information
138 on how to get that index.
139 UI_method_get_opener(), UI_method_get_writer(),
141 UI_method_get_flusher(), UI_method_get_reader(),
142 UI_method_get_closer(), UI_method_get_data_duplicator(),
143 UI_method_get_data_destructor() and UI_method_get_prompt_constructor()
144 return the different method functions.
145 UI_method_get_ex_data() returns the application data previously stored
147 with UI_method_set_ex_data().
148
150 UI_create_method() returns a UI_METHOD pointer on success, NULL on
151 error.
152 UI_method_set_opener(), UI_method_set_writer(),
154 UI_method_set_flusher(), UI_method_set_reader(),
155 UI_method_set_closer(), UI_method_set_data_duplicator() and
156 UI_method_set_prompt_constructor() return 0 on success, -1 if the given
157 method is NULL.
158 UI_method_set_ex_data() returns 1 on success and 0 on error (because
160 CRYPTO_set_ex_data() does so).
161 UI_method_get_opener(), UI_method_get_writer(),
163 UI_method_get_flusher(), UI_method_get_reader(),
164 UI_method_get_closer(), UI_method_get_data_duplicator(),
165 UI_method_get_data_destructor() and UI_method_get_prompt_constructor()
166 return the requested function pointer if it's set in the method,
167 otherwise NULL.
168 UI_method_get_ex_data() returns a pointer to the application specific
170 data associated with the method.
171
173 UI(3), CRYPTO_get_ex_data(3), UI_STRING(3)
174
176 The UI_method_set_data_duplicator(), UI_method_get_data_duplicator()
177 and UI_method_get_data_destructor() functions were added in OpenSSL
178 1.1.1.
179
181 Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
182 Licensed under the OpenSSL license (the "License"). You may not use
184 this file except in compliance with the License. You can obtain a copy
185 in the file LICENSE in the source distribution or at
186 <https://www.openssl.org/source/license.html>.
1871.1.1q 2023-07-20 UI_CREATE_METHOD(3)