ux_flow_engine.c

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/*******************************************************************************
 *   Ledger Nano S - Secure firmware
 *   (c) 2022 Ledger
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 ********************************************************************************/
 
#include "ux.h"
#include "os_helpers.h"
#include "os_pic.h"
#include "ux_flow_engine.h"
 
#include <string.h>
 
#ifdef HAVE_UX_FLOW
 
// check if flow is valid (has valid length and in correct stack slot)
static unsigned int ux_flow_check_valid(void)
{
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    if (G_ux.stack_count > UX_STACK_SLOT_COUNT || G_ux.flow_stack[top_stack_slot].length == 0) {
        return 0;
    }
    return 1;
}
 
// to hide the left tick or not
unsigned int ux_flow_is_first(void)
{
    // no previous ?
    unsigned int top_stack_slot = G_ux.stack_count - 1;
    if (!ux_flow_check_valid() || G_ux.flow_stack[top_stack_slot].steps == NULL
        || (G_ux.flow_stack[top_stack_slot].index == 0
            && G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].length - 1]
                   != FLOW_LOOP)) {
        return 1;
    }
 
    // previous is a flow barrier ?
    if (G_ux.flow_stack[top_stack_slot].length > 0
        && G_ux.flow_stack[top_stack_slot].index < G_ux.flow_stack[top_stack_slot].length
        && G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index - 1]
               == FLOW_BARRIER) {
        return 1;
    }
 
    // not the first, for sure
    return 0;
}
 
unsigned int ux_flow_is_last(void)
{
    // last ?
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    if (!ux_flow_check_valid() || G_ux.flow_stack[top_stack_slot].steps == NULL
        || G_ux.flow_stack[top_stack_slot].length == 0
        || G_ux.flow_stack[top_stack_slot].index >= G_ux.flow_stack[top_stack_slot].length - 1) {
        return 1;
    }
 
    // followed by a flow barrier ?
    if (G_ux.flow_stack[top_stack_slot].length > 0
        && G_ux.flow_stack[top_stack_slot].index < G_ux.flow_stack[top_stack_slot].length - 2
        && G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index + 1]
               == FLOW_BARRIER) {
        return 1;
    }
 
    // is not last
    return 0;
}
 
ux_flow_direction_t ux_flow_direction(void)
{
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    if (G_ux.stack_count) {
        if (G_ux.flow_stack[top_stack_slot].index > G_ux.flow_stack[top_stack_slot].prev_index) {
            return FLOW_DIRECTION_FORWARD;
        }
        else if (G_ux.flow_stack[top_stack_slot].index
                 < G_ux.flow_stack[top_stack_slot].prev_index) {
            return FLOW_DIRECTION_BACKWARD;
        }
    }
    return FLOW_DIRECTION_START;
}
 
const ux_flow_step_t *ux_flow_get_current(void)
{
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    if (!ux_flow_check_valid() || G_ux.flow_stack[top_stack_slot].steps == NULL
        || G_ux.flow_stack[top_stack_slot].index >= G_ux.flow_stack[top_stack_slot].length
        || G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index]
               == FLOW_BARRIER
        || G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index] == FLOW_LOOP
        || G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index]
               == FLOW_END_STEP) {
        return NULL;
    }
    return STEPPIC(G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index]);
}
 
static void ux_flow_engine_init_step(unsigned int stack_slot)
{
    // invalid ux_flow_length ??? (previous check shall have exited earlier)
    if (G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index] == FLOW_END_STEP) {
        return;
    }
    // this shall not have occurred due to previous checks
    if (G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index] == FLOW_BARRIER) {
        return;
    }
    // this shall not have occurred due to previous checks
    if (G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index] == FLOW_LOOP) {
        return;
    }
    // if init function is set, call it
    if (STEPPIC(G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index])->init) {
        INITPIC(STEPPIC(G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index])->init)
        (stack_slot);
    }
    else {
        // if init method is not set, jump to referenced flow and step
        ux_flow_init(
            stack_slot,
            STEPSPIC(STEPPIC(G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index])
                         ->validate_flow),
            (const ux_flow_step_t *) PIC(
                STEPPIC(G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index])
                    ->params));
    }
}
 
static void ux_flow_next_internal(unsigned int display_step)
{
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    // last reached already (need validation, not next)
    if (!ux_flow_check_valid() || G_ux.flow_stack[top_stack_slot].steps == NULL
        || G_ux.flow_stack[top_stack_slot].length <= 1
        || G_ux.flow_stack[top_stack_slot].index >= G_ux.flow_stack[top_stack_slot].length - 1) {
        return;
    }
 
    // followed by a flow barrier ? => need validation instead of next
    if (G_ux.flow_stack[top_stack_slot].index <= G_ux.flow_stack[top_stack_slot].length - 2) {
        if (G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index + 1]
            == FLOW_BARRIER) {
            return;
        }
 
        // followed by a flow barrier ? => need validation instead of next
        if (G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index + 1]
            == FLOW_LOOP) {
            // display first step, fake direction as forward
            G_ux.flow_stack[top_stack_slot].prev_index = G_ux.flow_stack[top_stack_slot].index = 0;
            ux_flow_engine_init_step(top_stack_slot);
            return;
        }
    }
 
    // advance flow pointer and display it (skip META STEPS)
    G_ux.flow_stack[top_stack_slot].prev_index = G_ux.flow_stack[top_stack_slot].index;
    G_ux.flow_stack[top_stack_slot].index++;
    if (display_step) {
        ux_flow_engine_init_step(top_stack_slot);
    }
}
 
void ux_flow_next_no_display(void)
{
    ux_flow_next_internal(0);
}
 
void ux_flow_next(void)
{
    ux_flow_next_internal(1);
}
 
void ux_flow_prev(void)
{
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    // first reached already
    if (!ux_flow_check_valid() || G_ux.flow_stack[top_stack_slot].steps == NULL
        || G_ux.flow_stack[top_stack_slot].length <= 1
        || (G_ux.flow_stack[top_stack_slot].index == 0
            && G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].length - 1]
                   != FLOW_LOOP)) {
        return;
    }
 
    // loop in flow (before checking barrier as there is no prestep when looping)
    if (G_ux.flow_stack[top_stack_slot].index == 0
        && G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].length - 1]
               == FLOW_LOOP) {
        // display last step (shall skip BARRIER if any, but a flow finishing with a BARRIER is
        // cryptic)
        G_ux.flow_stack[top_stack_slot].index = G_ux.flow_stack[top_stack_slot].length - 2;
        // fact direction as backward
        G_ux.flow_stack[top_stack_slot].prev_index = G_ux.flow_stack[top_stack_slot].index + 1;
        ux_flow_engine_init_step(top_stack_slot);
        return;
    }
 
    // previous item is a flow barrier ?
    if (G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index - 1]
        == FLOW_BARRIER) {
        return;
    }
 
    // advance flow pointer and display it (skip META STEPS)
    G_ux.flow_stack[top_stack_slot].prev_index = G_ux.flow_stack[top_stack_slot].index;
    G_ux.flow_stack[top_stack_slot].index--;
 
    ux_flow_engine_init_step(top_stack_slot);
}
 
void ux_flow_validate(void)
{
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    // no flow ?
    if (!ux_flow_check_valid() || G_ux.flow_stack[top_stack_slot].steps == NULL
        || G_ux.flow_stack[top_stack_slot].length == 0
        || G_ux.flow_stack[top_stack_slot].index >= G_ux.flow_stack[top_stack_slot].length) {
        return;
    }
 
    // no validation flow ?
    if (STEPPIC(G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index])
            ->validate_flow
        != NULL) {
        // execute validation flow
        ux_flow_init(top_stack_slot,
                     STEPSPIC(STEPPIC(G_ux.flow_stack[top_stack_slot]
                                          .steps[G_ux.flow_stack[top_stack_slot].index])
                                  ->validate_flow),
                     NULL);
    }
    else {
        // if next is a barrier, then proceed to the item after the barrier
        // if NOT followed by a barrier, then validation is only performed through
        // a validate_flow specified in the step, else ignored
        if (G_ux.flow_stack[top_stack_slot].length > 0
            && G_ux.flow_stack[top_stack_slot].index
                   <= G_ux.flow_stack[top_stack_slot].length - 2) {
            if (G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index + 1]
                == FLOW_BARRIER) {
                // take into account multi barrier at once, kthx poor code review
                while (G_ux.flow_stack[top_stack_slot].length > 0
                       && G_ux.flow_stack[top_stack_slot].index
                              <= G_ux.flow_stack[top_stack_slot].length - 2
                       && G_ux.flow_stack[top_stack_slot]
                                  .steps[G_ux.flow_stack[top_stack_slot].index + 1]
                              == FLOW_BARRIER) {
                    G_ux.flow_stack[top_stack_slot].index++;
                }
                // skip to next step
                G_ux.flow_stack[top_stack_slot].prev_index = G_ux.flow_stack[top_stack_slot].index;
                G_ux.flow_stack[top_stack_slot].index++;
 
                // execute reached step
                ux_flow_engine_init_step(top_stack_slot);
            }
            // reached the last step, but step if FLOW_LOOP
            else if (G_ux.flow_stack[top_stack_slot]
                         .steps[G_ux.flow_stack[top_stack_slot].index + 1]
                     == FLOW_LOOP) {
                // we go the forward direction
                G_ux.flow_stack[top_stack_slot].prev_index = G_ux.flow_stack[top_stack_slot].index
                    = 0;
                // execute reached step
                ux_flow_engine_init_step(top_stack_slot);
            }
        }
    }
}
 
void ux_flow_error(unsigned int error)
{
    UNUSED(error);
 
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    if (G_ux.flow_stack[top_stack_slot].steps == NULL || G_ux.flow_stack[top_stack_slot].length == 0
        || G_ux.flow_stack[top_stack_slot].index >= G_ux.flow_stack[top_stack_slot].length) {
        return;
    }
 
    if (STEPPIC(G_ux.flow_stack[top_stack_slot].steps[G_ux.flow_stack[top_stack_slot].index])
            ->error_flow
        != NULL) {
        ux_flow_init(top_stack_slot,
                     STEPSPIC(STEPPIC(G_ux.flow_stack[top_stack_slot]
                                          .steps[G_ux.flow_stack[top_stack_slot].index])
                                  ->error_flow),
                     NULL);
    }
}
 
void ux_flow_init(unsigned int                 stack_slot,
                  const ux_flow_step_t *const *steps,
                  const ux_flow_step_t *const  start_step)
{
    if (stack_slot >= UX_STACK_SLOT_COUNT) {
        return;
    }
 
    G_ux.flow_stack[stack_slot].length      = G_ux.flow_stack[stack_slot].prev_index
        = G_ux.flow_stack[stack_slot].index = 0;
    G_ux.flow_stack[stack_slot].steps       = NULL;
 
    // reset paging to avoid troubles if first step is a paginated step
    memset(&G_ux.layout_paging, 0, sizeof(G_ux.layout_paging));
 
    if (steps) {
        G_ux.flow_stack[stack_slot].steps = STEPSPIC(steps);
        while (G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].length]
               != FLOW_END_STEP) {
            G_ux.flow_stack[stack_slot].length++;
        }
        if (start_step != NULL) {
            const ux_flow_step_t *const start_step2 = STEPPIC(start_step);
            while (G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index]
                       != FLOW_END_STEP
                   && STEPPIC(G_ux.flow_stack[stack_slot].steps[G_ux.flow_stack[stack_slot].index])
                          != start_step2) {
                G_ux.flow_stack[stack_slot].prev_index = G_ux.flow_stack[stack_slot].index;
                G_ux.flow_stack[stack_slot].index++;
            }
        }
 
        // init step
        ux_flow_engine_init_step(stack_slot);
    }
}
 
void ux_flow_uninit(unsigned int stack_slot)
{
    if (stack_slot < UX_STACK_SLOT_COUNT) {
        memset(&G_ux.flow_stack[stack_slot], 0, sizeof(G_ux.flow_stack[stack_slot]));
    }
}
 
unsigned int ux_flow_button_callback(unsigned int button_mask, unsigned int button_mask_counter)
{
    UNUSED(button_mask_counter);
    switch (button_mask) {
        case BUTTON_EVT_RELEASED | BUTTON_LEFT:
            ux_flow_prev();
            break;
        case BUTTON_EVT_RELEASED | BUTTON_RIGHT:
            ux_flow_next();
            break;
        case BUTTON_EVT_RELEASED | BUTTON_LEFT | BUTTON_RIGHT:
            ux_flow_validate();
            break;
    }
    return 0;
}
 
const void *ux_stack_get_step_params(unsigned int stack_slot)
{
    if (stack_slot >= UX_STACK_SLOT_COUNT) {
        return NULL;
    }
 
    if (G_ux.flow_stack[stack_slot].length == 0) {
        return NULL;
    }
 
    if (G_ux.flow_stack[stack_slot].index >= G_ux.flow_stack[stack_slot].length) {
        return NULL;
    }
 
    return PIC(
        STEPPIC(STEPSPIC(G_ux.flow_stack[stack_slot].steps)[G_ux.flow_stack[stack_slot].index])
            ->params);
}
 
const void *ux_stack_get_current_step_params(void)
{
    unsigned int top_stack_slot = G_ux.stack_count - 1;
 
    return ux_stack_get_step_params(top_stack_slot);
}
 
unsigned int ux_flow_relayout(void)
{
    // if a flow is defined and valid
    if (ux_flow_get_current() != NULL) {
        unsigned int top_stack_slot = G_ux.stack_count - 1;
 
        ux_flow_engine_init_step(top_stack_slot);
        return 1;
    }
    return 0;
}
 
#endif  // HAVE_UX_FLOW