.\" $OpenBSD: UI_create_method.3,v 1.2 2017/03/26 12:31:27 jmc Exp $ .\" OpenSSL UI_create_method.pod 8e3d46e5 Mar 11 10:51:04 2017 +0100 .\" .\" This file was written by Richard Levitte . .\" Copyright (c) 2017 The OpenSSL Project. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. 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IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: March 26 2017 $ .Dt UI_CREATE_METHOD 3 .Os .Sh NAME .Nm UI_create_method , .Nm UI_destroy_method , .Nm UI_method_set_opener , .Nm UI_method_set_writer , .Nm UI_method_set_flusher , .Nm UI_method_set_reader , .Nm UI_method_set_closer , .Nm UI_method_set_prompt_constructor , .Nm UI_method_get_opener , .Nm UI_method_get_writer , .Nm UI_method_get_flusher , .Nm UI_method_get_reader , .Nm UI_method_get_closer , .Nm UI_method_get_prompt_constructor .Nd user interface method creation and destruction .Sh SYNOPSIS .In openssl/ui.h .Ft UI_METHOD * .Fo UI_create_method .Fa "char *name" .Fc .Ft void .Fo UI_destroy_method .Fa "UI_METHOD *ui_method" .Fc .Ft int .Fo UI_method_set_opener .Fa "UI_METHOD *method" .Fa "int (*opener)(UI *ui)" .Fc .Ft int .Fo UI_method_set_writer .Fa "UI_METHOD *method" .Fa "int (*writer)(UI *ui, UI_STRING *uis)" .Fc .Ft int .Fo UI_method_set_flusher .Fa "UI_METHOD *method" .Fa "int (*flusher)(UI *ui)" .Fc .Ft int .Fo UI_method_set_reader .Fa "UI_METHOD *method" .Fa "int (*reader)(UI *ui, UI_STRING *uis)" .Fc .Ft int .Fo UI_method_set_closer .Fa "UI_METHOD *method" .Fa "int (*closer)(UI *ui)" .Fc .Ft int .Fo UI_method_set_prompt_constructor .Fa "UI_METHOD *method" .Fa "char *(*prompt_constructor)(UI *ui, const char *object_desc,\ const char *object_name)" .Fc .Ft int .Fo "(*UI_method_get_opener(const UI_METHOD *method))" .Fa "UI *"; .Fc .Ft int .Fo "(*UI_method_get_writer(const UI_METHOD *method))" .Fa "UI *" .Fa "UI_STRING *" .Fc .Ft int .Fo "(*UI_method_get_flusher(const UI_METHOD *method))" .Fa "UI *" .Fc .Ft int .Fo "(*UI_method_get_reader(const UI_METHOD *method))" .Fa "UI *" .Fa "UI_STRING *" .Fc .Ft int .Fo "(*UI_method_get_closer(const UI_METHOD *method))" .Fa "UI *" .Fc .Ft char * .Fo "(*UI_method_get_prompt_constructor(UI_METHOD *method))" .Fa "UI *" .Fa "const char *" .Fa "const char *" .Fc .Sh DESCRIPTION A method contains a few functions that implement the low level of the User Interface. These functions are: .Bl -tag -width Ds .It an opener This function takes a reference to a UI and starts a session, for example by opening a channel to a tty, or by creating a dialog box. .It 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. Note that this gets fed all strings associated with a UI, one after the other, so care must be taken which ones it actually uses. .It 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. .It 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. Note that this gets fed all strings associated with a UI, one after the other, so care must be taken which ones it actually uses. .It 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. .El .Pp All of these functions are expected to return 0 on error, 1 on success, or -1 on out-off-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. .Pp 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. .Pp 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 .Xr UI_OpenSSL 3 method does it. .Pp 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. .Pp The central function that uses these method functions is .Xr UI_process 3 , and it does it in five steps: .Bl -enum .It Open the session using the opener function if that one is defined. If an error occurs, jump to 5. .It For every UI String associated with the UI, call the writer function if that one is defined. If an error occurs, jump to 5. .It Flush everything using the flusher function if that one is defined. If an error occurs, jump to 5. .It For every UI String associated with the UI, call the reader function if that one is defined. If an error occurs, jump to 5. .It Close the session using the closer function if that one is defined. .El .Pp .Fn UI_create_method creates a new UI method with a given .Fa name . .Pp .Fn UI_destroy_method destroys the given .Fa ui_method . .Pp .Fn UI_method_set_opener , .Fn UI_method_set_writer , .Fn UI_method_set_flusher , .Fn UI_method_set_reader and .Fn UI_method_set_closer set one of the five main methods to the given function pointer. .Pp .Fn UI_method_set_prompt_constructor sets the prompt constructor, see .Xr UI_construct_prompt 3 . .Sh RETURN VALUES .Fn UI_create_method returns a .Vt UI_METHOD pointer on success or .Dv NULL on error. .Pp .Fn UI_method_set_opener , .Fn UI_method_set_writer , .Fn UI_method_set_flusher , .Fn UI_method_set_reader , .Fn UI_method_set_closer , and .Fn UI_method_set_prompt_constructor return 0 on success or -1 if the given method is .Dv NULL . .Pp .Fn UI_method_get_opener , .Fn UI_method_get_writer , .Fn UI_method_get_flusher , .Fn UI_method_get_reader , .Fn UI_method_get_closer , and .Fn UI_method_get_prompt_constructor return the requested function pointer if it is set in the method, or otherwise .Dv NULL . .Sh SEE ALSO .Xr UI_get_string_type 3 , .Xr UI_new 3