/*
 * Copyright (C) 2012 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
 */

/*
 * This is for functions like:
 *
 * int foo(int *x)
 * {
 *      if (*x == 42) {
 *              *x = 0;
 *              return 1;
 *      }
 *      return 0;
 * }
 *
 * If we return 1 that means the value of *x has been set to 0.  If we return
 * 0 then we have left *x alone.
 *
 */

#include "scope.h"
#include "smatch.h"
#include "smatch_slist.h"
#include "smatch_extra.h"

static int my_id;

static struct smatch_state *unmatched_state(struct sm_state *sm)
{
        return alloc_estate_empty();
}

static int parent_is_set(const char *name, struct symbol *sym, struct smatch_state *state)
{
        struct expression *faked;
        char *left_name;
        int ret = 0;
        int len;

        if (!__in_fake_assign)
                return 0;
        if (!is_whole_rl(estate_rl(state)))
                return 0;
        if (get_state(my_id, name, sym))
                return 0;

        faked = get_faked_expression();
        if (!faked)
                return 0;
        if ((faked->type == EXPR_PREOP || faked->type == EXPR_POSTOP) &&
            (faked->op == SPECIAL_INCREMENT || faked->op == SPECIAL_DECREMENT)) {
                faked = strip_expr(faked->unop);
                if (faked->type == EXPR_SYMBOL)
                        return 1;
                return 0;
        }
        if (faked->type != EXPR_ASSIGNMENT)
                return 0;

        left_name = expr_to_var(faked->left);
        if (!left_name)
                return 0;

        len = strlen(left_name);
        if (strncmp(name, left_name, len) == 0 && name[len] == '-')
                ret = 1;
        free_string(left_name);

        return ret;
}

static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
{
        if (parent_is_set(name, sym, state))
                return;
        if (get_param_num_from_sym(sym) < 0)
                return;
        set_state(my_id, name, sym, state);
}

/*
 * This function is is a dirty hack because extra_mod_hook is giving us a NULL
 *  sym instead of a vsl.
 */
static void match_array_assignment(struct expression *expr)
{
        struct expression *array, *offset;
        char *name;
        struct symbol *sym;
        struct range_list *rl;
        sval_t sval;
        char buf[256];

        if (__in_fake_assign)
                return;

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

        /* These are handled by extra_mod_hook() */
        if (get_value(offset, &sval))
                return;
        name = expr_to_var_sym(array, &sym);
        if (!name || !sym)
                goto free;
        if (get_param_num_from_sym(sym) < 0)
                goto free;
        get_absolute_rl(expr->right, &rl);
        rl = cast_rl(get_type(expr->left), rl);

        snprintf(buf, sizeof(buf), "*%s", name);
        set_state(my_id, buf, sym, alloc_estate_rl(rl));
free:
        free_string(name);
}

static char *get_two_dots(const char *name)
{
        static char buf[80];
        int i, cnt = 0;

        for (i = 0; i < sizeof(buf); i++) {
                if (name[i] == '.') {
                        cnt++;
                        if (cnt >= 2) {
                                buf[i] = '\0';
                                return buf;
                        }
                }
                buf[i] = name[i];
        }
        return NULL;
}

/*
 * This relies on the fact that these states are stored so that
 * foo->bar is before foo->bar->baz.
 */
static int parent_set(struct string_list *list, const char *name)
{
        char *tmp;
        int len;
        int ret;

        FOR_EACH_PTR(list, tmp) {
                len = strlen(tmp);
                ret = strncmp(tmp, name, len);
                if (ret < 0)
                        continue;
                if (ret > 0)
                        return 0;
                if (name[len] == '-')
                        return 1;
        } END_FOR_EACH_PTR(tmp);

        return 0;
}

static void print_return_value_param_helper(int return_id, char *return_ranges, struct expression *expr, int limit)
{
        struct sm_state *sm;
        struct smatch_state *extra;
        int param;
        struct range_list *rl;
        const char *param_name;
        struct string_list *set_list = NULL;
        char *math_str;
        char buf[256];
        char two_dot[80] = "";
        int count = 0;

        FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
                if (!estate_rl(sm->state))
                        continue;
                extra = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
                if (extra) {
                        rl = rl_intersection(estate_rl(sm->state), estate_rl(extra));
                        if (!rl)
                                continue;
                } else {
                        rl = estate_rl(sm->state);
                }

                param = get_param_num_from_sym(sm->sym);
                if (param < 0)
                        continue;
                param_name = get_param_name(sm);
                if (!param_name)
                        continue;
                if (strcmp(param_name, "$") == 0) {
                        insert_string(&set_list, (char *)sm->name);
                        continue;
                }
                if (is_recursive_member(param_name)) {
                        insert_string(&set_list, (char *)sm->name);
                        continue;
                }

                if (is_ignored_kernel_data(param_name)) {
                        insert_string(&set_list, (char *)sm->name);
                        continue;
                }
                if (limit) {
                        char *new = get_two_dots(param_name);

                        if (new) {
                                if (strcmp(new, two_dot) == 0)
                                        continue;
                                strncpy(two_dot, new, sizeof(two_dot));
                                sql_insert_return_states(return_id, return_ranges,
                                         PARAM_SET, param, new, "s64min-s64max");
                                continue;
                        }
                }

                math_str = get_value_in_terms_of_parameter_math_var_sym(sm->name, sm->sym);
                if (math_str) {
                        snprintf(buf, sizeof(buf), "%s[%s]", show_rl(rl), math_str);
                        insert_string(&set_list, (char *)sm->name);
                        sql_insert_return_states(return_id, return_ranges,
                                        param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
                                        param, param_name, buf);
                        continue;
                }

                /* no useful information here. */
                if (is_whole_rl(rl) && parent_set(set_list, sm->name))
                        continue;
                insert_string(&set_list, (char *)sm->name);

                sql_insert_return_states(return_id, return_ranges,
                                         param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
                                         param, param_name, show_rl(rl));
                if (limit && ++count > limit)
                        break;

        } END_FOR_EACH_SM(sm);

        free_ptr_list((struct ptr_list **)&set_list);
}

static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
{
        print_return_value_param_helper(return_id, return_ranges, expr, 0);
}

void print_limited_param_set(int return_id, char *return_ranges, struct expression *expr)
{
        print_return_value_param_helper(return_id, return_ranges, expr, 1000);
}

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

        FOR_EACH_PTR(sm->possible, tmp) {
                if (strcmp(tmp->name, "") == 0)
                        return 1;
        } END_FOR_EACH_PTR(tmp);
        return 0;
}

int param_was_set_var_sym(const char *name, struct symbol *sym)
{
        struct sm_state *sm;
        char buf[80];
        int len, i;

        if (!name)
                return 0;

        len = strlen(name);
        if (len >= sizeof(buf))
                len = sizeof(buf) - 1;

        for (i = 0; i <= len; i++) {
                if (name[i] != '-' && name[i] != '\0')
                        continue;

                memcpy(buf, name, i);
                buf[i] = '\0';

                sm = get_sm_state(my_id, buf, sym);
                if (!sm)
                        continue;
                if (possibly_empty(sm))
                        continue;
                return 1;
        }

        if (name[0] == '*')
                return param_was_set_var_sym(name + 1, sym);

        return 0;
}

int param_was_set(struct expression *expr)
{
        char *name;
        struct symbol *sym;
        int ret = 0;

        name = expr_to_var_sym(expr, &sym);
        if (!name || !sym)
                goto free;

        ret = param_was_set_var_sym(name, sym);
free:
        free_string(name);
        return ret;
}

void register_param_set(int id)
{
        my_id = id;

        set_dynamic_states(my_id);
        add_extra_mod_hook(&extra_mod_hook);
        add_hook(match_array_assignment, ASSIGNMENT_HOOK);
        add_unmatched_state_hook(my_id, &unmatched_state);
        add_merge_hook(my_id, &merge_estates);
        add_split_return_callback(&print_return_value_param);
}