/*
 * Copyright (C) 2018 Oracle.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
 */

#include "smatch.h"
#include "smatch_slist.h"

static int my_id;
static int param_set_id;

STATE(terminated);
STATE(unterminated);
STATE(set);

static void set_terminated_var_sym(const char *name, struct symbol *sym, struct smatch_state *state)
{
        if (get_param_num_from_sym(sym) >= 0)
                set_state(param_set_id, name, sym, &set);
        set_state(my_id, name, sym, state);
}

static void set_terminated(struct expression *expr, struct smatch_state *state)
{
        struct symbol *sym;
        char *name;

        name = expr_to_var_sym(expr, &sym);
        if (!name || !sym)
                return;
        set_terminated_var_sym(name, sym, state);
        free_string(name);
}

static void match_nul_assign(struct expression *expr)
{
        struct expression *array;
        struct symbol *type;
        sval_t sval;

        if (expr->op != '=')
                return;

        if (!get_value(expr->right, &sval) || sval.value != 0)
                return;

        array = get_array_base(expr->left);
        if (!array)
                return;

        type = get_type(array);
        if (!type)
                return;
        type = get_real_base_type(type);
        if (type != &char_ctype)
                return;
        set_terminated(array, &terminated);
}

static struct smatch_state *get_terminated_state_var_sym(const char *name, struct symbol *sym)
{
        struct sm_state *sm, *tmp;

        sm = get_sm_state(my_id, name, sym);
        if (!sm)
                return NULL;
        if (sm->state == &terminated || sm->state == &unterminated)
                return sm->state;

        FOR_EACH_PTR(sm->possible, tmp) {
                if (tmp->state == &unterminated)
                        return &unterminated;
        } END_FOR_EACH_PTR(tmp);

        return NULL;
}

static struct smatch_state *get_terminated_state(struct expression *expr)
{
        struct sm_state *sm, *tmp;

        if (!expr)
                return NULL;
        if (expr->type == EXPR_STRING)
                return &terminated;
        sm = get_sm_state_expr(my_id, expr);
        if (!sm)
                return NULL;
        if (sm->state == &terminated || sm->state == &unterminated)
                return sm->state;

        FOR_EACH_PTR(sm->possible, tmp) {
                if (tmp->state == &unterminated)
                        return &unterminated;
        } END_FOR_EACH_PTR(tmp);

        return NULL;
}

static void match_string_assign(struct expression *expr)
{
        struct smatch_state *state;

        if (expr->op != '=')
                return;
        state = get_terminated_state(expr->right);
        if (!state)
                return;
        set_terminated(expr->left, state);
}

static int sm_to_term(struct sm_state *sm)
{
        struct sm_state *tmp;

        if (!sm)
                return -1;
        if (sm->state == &terminated)
                return 1;

        FOR_EACH_PTR(sm->possible, tmp) {
                if (tmp->state == &unterminated)
                        return 0;
        } END_FOR_EACH_PTR(tmp);

        return -1;
}

static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
{
        int term;

        term = sm_to_term(sm);
        if (term < 0)
                return;

        sql_insert_caller_info(call, TERMINATED, param, printed_name, term ? "1" : "0");
}

static void match_call_info(struct expression *expr)
{
        struct smatch_state *state;
        struct expression *arg;
        int i;

        i = -1;
        FOR_EACH_PTR(expr->args, arg) {
                i++;

                state = get_terminated_state(arg);
                if (!state)
                        continue;
                sql_insert_caller_info(expr, TERMINATED, i, "$",
                                       (state == &terminated) ? "1" : "0");
        } END_FOR_EACH_PTR(arg);
}

static void caller_info_terminated(const char *name, struct symbol *sym, char *key, char *value)
{
        char fullname[256];

        if (strcmp(key, "*$") == 0)
                snprintf(fullname, sizeof(fullname), "*%s", name);
        else if (strncmp(key, "$", 1) == 0)
                snprintf(fullname, 256, "%s%s", name, key + 1);
        else
                return;

        set_state(my_id, fullname, sym, (*value == '1') ? &terminated : &unterminated);
}

static void split_return_info(int return_id, char *return_ranges, struct expression *expr)
{
        struct symbol *returned_sym;
        struct sm_state *tmp, *sm;
        const char *param_name;
        int param;
        int term;

        FOR_EACH_MY_SM(param_set_id, __get_cur_stree(), tmp) {
                sm = get_sm_state(my_id, tmp->name, tmp->sym);
                if (!sm)
                        continue;
                term = sm_to_term(sm);
                if (term < 0)
                        continue;
                param = get_param_num_from_sym(tmp->sym);
                if (param < 0)
                        continue;

                param_name = get_param_name(sm);
                if (!param_name)
                        continue;
                if (strcmp(param_name, "$") == 0)
                        continue;

                sql_insert_return_states(return_id, return_ranges, TERMINATED,
                                         param, param_name, term ? "1" : "0");
        } END_FOR_EACH_SM(tmp);

        returned_sym = expr_to_sym(expr);
        if (!returned_sym)
                return;

        FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
                if (sm->sym != returned_sym)
                        continue;
                term = sm_to_term(sm);
                if (term < 0)
                        continue;
                param_name = get_param_name(sm);
                if (!param_name)
                        continue;
                sql_insert_return_states(return_id, return_ranges, TERMINATED,
                                         -1, param_name, term ? "1" : "0");
        } END_FOR_EACH_SM(sm);
}

static void return_info_terminated(struct expression *expr, int param, char *key, char *value)
{
        struct expression *arg;
        char *name;
        struct symbol *sym;

        if (param == -1) {
                arg = expr->left;
        } else {
                struct expression *call = expr;

                while (call->type == EXPR_ASSIGNMENT)
                        call = strip_expr(call->right);
                if (call->type != EXPR_CALL)
                        return;

                arg = get_argument_from_call_expr(call->args, param);
                if (!arg)
                        return;
        }

        name = get_variable_from_key(arg, key, &sym);
        if (!name || !sym)
                goto free;

        set_terminated_var_sym(name, sym, (*value == '1') ? &terminated : &unterminated);
free:
        free_string(name);
}

bool is_nul_terminated_var_sym(const char *name, struct symbol *sym)
{
        if (get_terminated_state_var_sym(name, sym) == &terminated)
                return 1;
        return 0;
}

bool is_nul_terminated(struct expression *expr)
{
        if (get_terminated_state(expr) == &terminated)
                return 1;
        return 0;
}

static void match_strnlen_test(struct expression *expr)
{
        struct expression *left, *tmp, *arg;
        int cnt;

        if (expr->type != EXPR_COMPARE)
                return;
        if (expr->op != SPECIAL_EQUAL && expr->op != SPECIAL_NOTEQUAL)
                return;

        left = strip_expr(expr->left);
        cnt = 0;
        while ((tmp = get_assigned_expr(left))) {
                if (cnt++ > 3)
                        break;
                left = tmp;
        }

        if (left->type != EXPR_CALL)
                return;
        if (!sym_name_is("strnlen", left->fn))
                return;
        arg = get_argument_from_call_expr(left->args, 0);
        set_true_false_states_expr(my_id, arg,
                        (expr->op == SPECIAL_EQUAL) ? &terminated : NULL,
                        (expr->op == SPECIAL_NOTEQUAL) ? &terminated : NULL);
        if (get_param_num(arg) >= 0)
                set_true_false_states_expr(param_set_id, arg,
                                (expr->op == SPECIAL_EQUAL) ? &terminated : NULL,
                                (expr->op == SPECIAL_NOTEQUAL) ? &terminated : NULL);
}

void register_nul_terminator(int id)
{
        my_id = id;

        add_hook(&match_nul_assign, ASSIGNMENT_HOOK);
        add_hook(&match_string_assign, ASSIGNMENT_HOOK);

        add_hook(&match_call_info, FUNCTION_CALL_HOOK);
        add_member_info_callback(my_id, struct_member_callback);
        add_split_return_callback(&split_return_info);

        select_caller_info_hook(caller_info_terminated, TERMINATED);
        select_return_states_hook(TERMINATED, return_info_terminated);

        add_hook(&match_strnlen_test, CONDITION_HOOK);
}

void register_nul_terminator_param_set(int id)
{
        param_set_id = id;
}