/*
 * Copyright (C) 2009 Dan Carpenter.
 *
 * 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
 */

/*
 * There are a number of ways that variables are modified:
 * 1) assignment
 * 2) increment/decrement
 * 3) assembly
 * 4) inside functions.
 *
 * For setting stuff inside a function then, of course, it's more accurate if
 * you have the cross function database built.  Otherwise we are super
 * aggressive about marking things as modified and if you have "frob(foo);" then
 * we assume "foo->bar" is modified.
 */

#include <stdlib.h>
#include <stdio.h>
#include "smatch.h"
#include "smatch_extra.h"
#include "smatch_slist.h"

enum {
        EARLY = 0,
        LATE = 1,
        BOTH = 2
};

static modification_hook **hooks;
static modification_hook **hooks_late;

ALLOCATOR(modification_data, "modification data");

static int my_id;
static struct smatch_state *alloc_my_state(struct expression *expr, struct smatch_state *prev)
{
        struct smatch_state *state;
        struct modification_data *data;
        char *name;

        expr = strip_expr(expr);
        name = expr_to_str(expr);
        if (!name)
                return NULL;

        state = __alloc_smatch_state(0);
        state->name = alloc_sname(name);
        free_string(name);

        data = __alloc_modification_data(0);
        data->prev = prev;
        data->cur = expr;
        state->data = data;

        return state;
}

void add_modification_hook(int owner, modification_hook *call_back)
{
        if (hooks[owner])
                sm_fatal("multiple modification hooks for %s", check_name(owner));
        hooks[owner] = call_back;
}

void add_modification_hook_late(int owner, modification_hook *call_back)
{
        if (hooks_late[owner])
                sm_fatal("multiple late modification hooks for %s", check_name(owner));
        hooks_late[owner] = call_back;
}

static int matches(char *name, struct symbol *sym, struct sm_state *sm)
{
        int len;

        if (sym != sm->sym)
                return false;

        len = strlen(name);
        if (strncmp(sm->name, name, len) == 0) {
                if (sm->name[len] == '\0')
                        return true;
                if (sm->name[len] == '-' || sm->name[len] == '.')
                        return true;
        }
        if (sm->name[0] != '*')
                return false;
        if (strncmp(sm->name + 1, name, len) == 0) {
                if (sm->name[len + 1] == '\0')
                        return true;
                if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.')
                        return true;
        }
        return false;
}

static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr, int late)
{
        struct sm_state *sm;
        struct smatch_state *prev;
        int match;

        prev = get_state(my_id, name, sym);

        if (cur_func_sym && !__in_fake_assign)
                set_state(my_id, name, sym, alloc_my_state(mod_expr, prev));

        FOR_EACH_SM(__get_cur_stree(), sm) {
                if (sm->owner > num_checks)
                        continue;
                match = matches(name, sym, sm);
                if (!match)
                        continue;

                if (late == EARLY || late == BOTH) {
                        if (hooks[sm->owner])
                                (hooks[sm->owner])(sm, mod_expr);
                }
                if (late == LATE || late == BOTH) {
                        if (hooks_late[sm->owner])
                                (hooks_late[sm->owner])(sm, mod_expr);
                }

        } END_FOR_EACH_SM(sm);
}

static void call_modification_hooks(struct expression *expr, struct expression *mod_expr, int late)
{
        char *name;
        struct symbol *sym;

        name = expr_to_known_chunk_sym(expr, &sym);
        if (!name)
                goto free;
        call_modification_hooks_name_sym(name, sym, mod_expr, late);
free:
        free_string(name);
}

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

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

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

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

        __in_fake_assign++;
        call_modification_hooks_name_sym(name, sym, expr, BOTH);
        __in_fake_assign--;

        other_name = get_other_name_sym(name, sym, &other_sym);
        if (other_name) {
                __in_fake_assign++;
                call_modification_hooks_name_sym(other_name, other_sym, expr, BOTH);
                __in_fake_assign--;
                free_string(other_name);
        }

free:
        free_string(name);
}

static void match_assign(struct expression *expr, int late)
{
        call_modification_hooks(expr->left, expr, late);
}

static void unop_expr(struct expression *expr, int late)
{
        if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
                return;

        call_modification_hooks(expr->unop, expr, late);
}

static void match_call(struct expression *expr)
{
        struct expression *arg, *tmp;

        /* If we have the DB then trust the DB */
        if (!option_no_db)
                return;

        FOR_EACH_PTR(expr->args, arg) {
                tmp = strip_expr(arg);
                if (tmp->type == EXPR_PREOP && tmp->op == '&')
                        call_modification_hooks(tmp->unop, expr, BOTH);
                else
                        call_modification_hooks(deref_expression(tmp), expr, BOTH);
        } END_FOR_EACH_PTR(arg);
}

static void asm_expr(struct statement *stmt, int late)
{
        struct expression *expr;

        FOR_EACH_PTR(stmt->asm_outputs, expr) {
                if (expr->type != EXPR_ASM_OPERAND)
                        continue;
                call_modification_hooks(expr->expr, NULL, late);
        } END_FOR_EACH_PTR(expr);
}

static void match_assign_early(struct expression *expr)
{
        match_assign(expr, EARLY);
}

static void unop_expr_early(struct expression *expr)
{
        unop_expr(expr, EARLY);
}

static void asm_expr_early(struct statement *stmt)
{
        asm_expr(stmt, EARLY);
}

static void match_assign_late(struct expression *expr)
{
        match_assign(expr, LATE);
}

static void unop_expr_late(struct expression *expr)
{
        unop_expr(expr, LATE);
}

static void asm_expr_late(struct statement *stmt)
{
        asm_expr(stmt, LATE);
}

struct smatch_state *get_modification_state(struct expression *expr)
{
        return get_state_expr(my_id, expr);
}

void register_modification_hooks(int id)
{
        my_id = id;

        set_dynamic_states(my_id);

        hooks = malloc((num_checks + 1) * sizeof(*hooks));
        memset(hooks, 0, (num_checks + 1) * sizeof(*hooks));
        hooks_late = malloc((num_checks + 1) * sizeof(*hooks));
        memset(hooks_late, 0, (num_checks + 1) * sizeof(*hooks));

        add_hook(&match_assign_early, ASSIGNMENT_HOOK);
        add_hook(&unop_expr_early, OP_HOOK);
        add_hook(&asm_expr_early, ASM_HOOK);
}

void register_modification_hooks_late(int id)
{
        add_hook(&match_call, FUNCTION_CALL_HOOK);

        select_return_states_hook(PARAM_ADD, &db_param_add);
        select_return_states_hook(PARAM_SET, &db_param_add);

        add_hook(&match_assign_late, ASSIGNMENT_HOOK_AFTER);
        add_hook(&unop_expr_late, OP_HOOK);
        add_hook(&asm_expr_late, ASM_HOOK);
}