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UI_new(3)                           OpenSSL                          UI_new(3)



NAME
       UI, UI_new, UI_new_method, UI_free, UI_add_input_string,
       UI_dup_input_string, UI_add_verify_string, UI_dup_verify_string,
       UI_add_input_boolean, UI_dup_input_boolean, UI_add_info_string,
       UI_dup_info_string, UI_add_error_string, UI_dup_error_string,
       UI_construct_prompt, UI_add_user_data, UI_dup_user_data,
       UI_get0_user_data, UI_get0_result, UI_get_result_length, UI_process,
       UI_ctrl, UI_set_default_method, UI_get_default_method, UI_get_method,
       UI_set_method, UI_OpenSSL, UI_null - user interface

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/ui.h>

        typedef struct ui_st UI;

        UI *UI_new(void);
        UI *UI_new_method(const UI_METHOD *method);
        void UI_free(UI *ui);

        int UI_add_input_string(UI *ui, const char *prompt, int flags,
                                char *result_buf, int minsize, int maxsize);
        int UI_dup_input_string(UI *ui, const char *prompt, int flags,
                                char *result_buf, int minsize, int maxsize);
        int UI_add_verify_string(UI *ui, const char *prompt, int flags,
                                 char *result_buf, int minsize, int maxsize,
                                 const char *test_buf);
        int UI_dup_verify_string(UI *ui, const char *prompt, int flags,
                                 char *result_buf, int minsize, int maxsize,
                                 const char *test_buf);
        int UI_add_input_boolean(UI *ui, const char *prompt, const char *action_desc,
                                 const char *ok_chars, const char *cancel_chars,
                                 int flags, char *result_buf);
        int UI_dup_input_boolean(UI *ui, const char *prompt, const char *action_desc,
                                 const char *ok_chars, const char *cancel_chars,
                                 int flags, char *result_buf);
        int UI_add_info_string(UI *ui, const char *text);
        int UI_dup_info_string(UI *ui, const char *text);
        int UI_add_error_string(UI *ui, const char *text);
        int UI_dup_error_string(UI *ui, const char *text);

        char *UI_construct_prompt(UI *ui_method,
               const char *object_desc, const char *object_name);

        void *UI_add_user_data(UI *ui, void *user_data);
        int UI_dup_user_data(UI *ui, void *user_data);
        void *UI_get0_user_data(UI *ui);

        const char *UI_get0_result(UI *ui, int i);
        int UI_get_result_length(UI *ui, int i);

        int UI_process(UI *ui);

        int UI_ctrl(UI *ui, int cmd, long i, void *p, void (*f)());

        void UI_set_default_method(const UI_METHOD *meth);
        const UI_METHOD *UI_get_default_method(void);
        const UI_METHOD *UI_get_method(UI *ui);
        const UI_METHOD *UI_set_method(UI *ui, const UI_METHOD *meth);

        UI_METHOD *UI_OpenSSL(void);
        const UI_METHOD *UI_null(void);

DESCRIPTION
       UI stands for User Interface, and is general purpose set of routines to
       prompt the user for text-based information.  Through user-written
       methods (see UI_create_method(3)), prompting can be done in any way
       imaginable, be it plain text prompting, through dialog boxes or from a
       cell phone.

       All the functions work through a context of the type UI.  This context
       contains all the information needed to prompt correctly as well as a
       reference to a UI_METHOD, which is an ordered vector of functions that
       carry out the actual prompting.

       The first thing to do is to create a UI with UI_new() or
       UI_new_method(), then add information to it with the UI_add or UI_dup
       functions.  Also, user-defined random data can be passed down to the
       underlying method through calls to UI_add_user_data() or
       UI_dup_user_data().  The default UI method doesn't care about these
       data, but other methods might.  Finally, use UI_process() to actually
       perform the prompting and UI_get0_result() and UI_get_result_length()
       to find the result to the prompt and its length.

       A UI can contain more than one prompt, which are performed in the given
       sequence.  Each prompt gets an index number which is returned by the
       UI_add and UI_dup functions, and has to be used to get the
       corresponding result with UI_get0_result() and UI_get_result_length().

       UI_process() can be called more than once on the same UI, thereby
       allowing a UI to have a long lifetime, but can just as well have a
       short lifetime.

       The functions are as follows:

       UI_new() creates a new UI using the default UI method.  When done with
       this UI, it should be freed using UI_free().

       UI_new_method() creates a new UI using the given UI method.  When done
       with this UI, it should be freed using UI_free().

       UI_OpenSSL() returns the built-in UI method (note: not necessarily the
       default one, since the default can be changed.  See further on).  This
       method is the most machine/OS dependent part of OpenSSL and normally
       generates the most problems when porting.

       UI_null() returns a UI method that does nothing.  Its use is to avoid
       getting internal defaults for passed UI_METHOD pointers.

       UI_free() removes a UI from memory, along with all other pieces of
       memory that's connected to it, like duplicated input strings, results
       and others.  If ui is NULL nothing is done.

       UI_add_input_string() and UI_add_verify_string() add a prompt to the
       UI, as well as flags and a result buffer and the desired minimum and
       maximum sizes of the result, not counting the final NUL character.  The
       given information is used to prompt for information, for example a
       password, and to verify a password (i.e. having the user enter it twice
       and check that the same string was entered twice).
       UI_add_verify_string() takes and extra argument that should be a
       pointer to the result buffer of the input string that it's supposed to
       verify, or verification will fail.

       UI_add_input_boolean() adds a prompt to the UI that's supposed to be
       answered in a boolean way, with a single character for yes and a
       different character for no.  A set of characters that can be used to
       cancel the prompt is given as well.  The prompt itself is divided in
       two, one part being the descriptive text (given through the prompt
       argument) and one describing the possible answers (given through the
       action_desc argument).

       UI_add_info_string() and UI_add_error_string() add strings that are
       shown at the same time as the prompt for extra information or to show
       an error string.  The difference between the two is only conceptual.
       With the builtin method, there's no technical difference between them.
       Other methods may make a difference between them, however.

       The flags currently supported are UI_INPUT_FLAG_ECHO, which is relevant
       for UI_add_input_string() and will have the users response be echoed
       (when prompting for a password, this flag should obviously not be used,
       and UI_INPUT_FLAG_DEFAULT_PWD, which means that a default password of
       some sort will be used (completely depending on the application and the
       UI method).

       UI_dup_input_string(), UI_dup_verify_string(), UI_dup_input_boolean(),
       UI_dup_info_string() and UI_dup_error_string() are basically the same
       as their UI_add counterparts, except that they make their own copies of
       all strings.

       UI_construct_prompt() is a helper function that can be used to create a
       prompt from two pieces of information: an description and a name.  The
       default constructor (if there is none provided by the method used)
       creates a string "Enter description for name:".  With the description
       "pass phrase" and the file name "foo.key", that becomes "Enter pass
       phrase for foo.key:".  Other methods may create whatever string and may
       include encodings that will be processed by the other method functions.

       UI_add_user_data() adds a user data pointer for the method to use at
       any time.  The builtin UI method doesn't care about this info.  Note
       that several calls to this function doesn't add data, it replaces the
       previous blob with the one given as argument.

       UI_dup_user_data() duplicates the user data and works as an alternative
       to UI_add_user_data() when the user data needs to be preserved for a
       longer duration, perhaps even the lifetime of the application.  The UI
       object takes ownership of this duplicate and will free it whenever it
       gets replaced or the UI is destroyed.  UI_dup_user_data() returns 0 on
       success, or -1 on memory allocation failure or if the method doesn't
       have a duplicator function.

       UI_get0_user_data() retrieves the data that has last been given to the
       UI with UI_add_user_data() or UI_dup_user_data.

       UI_get0_result() returns a pointer to the result buffer associated with
       the information indexed by i.

       UI_get_result_length() returns the length of the result buffer
       associated with the information indexed by i.

       UI_process() goes through the information given so far, does all the
       printing and prompting and returns the final status, which is -2 on
       out-of-band events (Interrupt, Cancel, ...), -1 on error and 0 on
       success.

       UI_ctrl() adds extra control for the application author.  For now, it
       understands two commands: UI_CTRL_PRINT_ERRORS, which makes
       UI_process() print the OpenSSL error stack as part of processing the
       UI, and UI_CTRL_IS_REDOABLE, which returns a flag saying if the used UI
       can be used again or not.

       UI_set_default_method() changes the default UI method to the one given.
       This function is not thread-safe and should not be called at the same
       time as other OpenSSL functions.

       UI_get_default_method() returns a pointer to the current default UI
       method.

       UI_get_method() returns the UI method associated with a given UI.

       UI_set_method() changes the UI method associated with a given UI.

NOTES
       The resulting strings that the built in method UI_OpenSSL() generate
       are assumed to be encoded according to the current locale or (for
       Windows) code page.  For applications having different demands, these
       strings need to be converted appropriately by the caller.  For Windows,
       if the OPENSSL_WIN32_UTF8 environment variable is set, the built-in
       method UI_OpenSSL() will produce UTF-8 encoded strings instead.

RETURN VALUES
       UI_new() and UI_new_method() return a valid UI structure or NULL if an
       error occurred.

       UI_add_input_string(), UI_dup_input_string(), UI_add_verify_string(),
       UI_dup_verify_string(), UI_add_input_boolean(), UI_dup_input_boolean(),
       UI_add_info_string(), UI_dup_info_string(), UI_add_error_string() and
       UI_dup_error_string() return a positive number on success or a value
       which is less than or equal to 0 otherwise.

       UI_construct_prompt() returns a string or NULL if an error occurred.

       UI_dup_user_data() returns 0 on success or -1 on error.

       UI_get0_result() returns a string or NULL on error.

       UI_get_result_length() returns a positive integer or 0 on success;
       otherwise it returns -1 on error.

       UI_process() returns 0 on success or a negative value on error.

       UI_ctrl() returns a mask on success or -1 on error.

       UI_get_default_method(), UI_get_method(), UI_Openssl(), UI_null() and
       UI_set_method() return either a valid UI_METHOD structure or NULL
       respectively.

HISTORY
       UI_dup_user_data() was added in OpenSSL 1.1.1.

COPYRIGHT
       Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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>.



1.1.1                             2018-09-17                         UI_new(3)