Handle assignmeents inside conditions better.

[smatch.git] / smatch_states.c

/*
 * sparse/smatch_states.c
 *
 * Copyright (C) 2006 Dan Carpenter.
 *
 *  Licensed under the Open Software License version 1.1
 *
 */

/*
 * You have a lists of states.  kernel = locked, foo = NULL, ...
 * When you hit an if {} else {} statement then you swap the list
 * of states for a different list of states.  The lists are stored
 * on stacks.
 *
 * At the beginning of this file there are list of the stacks that
 * we use.  Each function in this file does something to one of
 * of the stacks.
 *
 * So the smatch_flow.c understands code but it doesn't understand states.
 * smatch_flow calls functions in this file.  This file calls functions
 * in smatch_slist.c which just has boring generic plumbing for handling
 * state lists.  But really it's this file where all the magic happens.
 */


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

struct smatch_state undefined = { .name = "undefined" };
struct smatch_state true_state = { .name = "true" };
struct smatch_state false_state = { .name = "false" };

static struct state_list *cur_slist; /* current states */

static struct state_list_stack *true_stack; /* states after a t/f branch */
static struct state_list_stack *false_stack;
static struct state_list_stack *pre_cond_stack; /* states before a t/f branch */

static struct state_list_stack *cond_true_stack; /* states affected by a branch */
static struct state_list_stack *cond_false_stack;

static struct state_list_stack *break_stack;
static struct state_list_stack *switch_stack;
static struct state_list_stack *default_stack;
static struct state_list_stack *continue_stack;
static struct state_list_stack *false_only_stack;

struct slist_stack *goto_stack;

int debug_states;

void __print_slist(struct state_list *slist)
{
        struct sm_state *state;

        printf("dumping slist at %d\n", get_lineno());
        FOR_EACH_PTR(slist, state) {
                printf("'%s'=%s\n", state->name, show_state(state->state));
        } END_FOR_EACH_PTR(state);
        printf("---\n");
}

void __print_cur_slist()
{
        __print_slist(cur_slist);
}

void set_state(const char *name, int owner, struct symbol *sym,
               struct smatch_state *state)
{
        if (!name)
                return;
        
        if (debug_states) {
                struct smatch_state *s;
                
                s = get_state(name, owner, sym);
                if (!s)
                        printf("%d new state. name='%s' owner=%d: %s\n", 
                               get_lineno(), name, owner, show_state(state));
                else
                        printf("%d state change name='%s' owner=%d: %s => %s\n",
                               get_lineno(), name, owner, show_state(s),
                               show_state(state));
        }
        set_state_slist(&cur_slist, name, owner, sym, state);

        if (cond_true_stack) {
                set_state_stack(&cond_true_stack, name, owner, sym, state);
                set_state_stack(&cond_false_stack, name, owner, sym, state);
        }
}

struct smatch_state *get_state(const char *name, int owner, struct symbol *sym)
{
        return get_state_slist(cur_slist, name, owner, sym);
}

void delete_state(const char *name, int owner, struct symbol *sym)
{
        delete_state_slist(&cur_slist, name, owner, sym);
}

struct state_list *get_current_states(int owner)
{
        struct state_list *slist;
        struct sm_state *tmp;

        FOR_EACH_PTR(cur_slist, tmp) {
                if (tmp->owner == owner) {
                        add_ptr_list(&slist, tmp);
                }
        } END_FOR_EACH_PTR(tmp);

        return slist;
}

void set_true_false_states(const char *name, int owner, struct symbol *sym, 
                           struct smatch_state *true_state,
                           struct smatch_state *false_state)
{
        /* fixme.  save history */

        if (debug_states) {
                struct smatch_state *tmp;

                tmp = get_state(name, owner, sym);
                SM_DEBUG("%d set_true_false %s.  Was %s.  Now T:%s F:%s\n",
                         get_lineno(), name, show_state(tmp),
                         show_state(true_state), show_state(false_state));
        }

        if (!cond_false_stack || !cond_true_stack) {
                printf("Error:  missing true/false stacks\n");
                return;
        }

        if (true_state) {
                set_state_slist(&cur_slist, name, owner, sym, true_state);
                set_state_stack(&cond_true_stack, name, owner, sym, true_state);
        }
        if (false_state)
                set_state_stack(&cond_false_stack, name, owner, sym, false_state);
}

void nullify_path()
{
        del_slist(&cur_slist);
}

/*
 * At the start of every function we mark the path
 * as unnull.  That there is always at least one state
 * in the cur_slist until nullify_path is called.  This
 * is used in merge_slist() for the first null check.
 */

void __unnullify_path()
{
        set_state("unnull_path", 0, NULL, &true_state);
}

void clear_all_states()
{
        struct named_slist *named_slist;

        nullify_path();
        del_slist_stack(&true_stack);
        del_slist_stack(&false_stack);
        del_slist_stack(&false_only_stack);
        del_slist_stack(&pre_cond_stack);
        del_slist_stack(&cond_true_stack);
        del_slist_stack(&cond_false_stack);
        del_slist_stack(&break_stack);
        del_slist_stack(&switch_stack);
        del_slist_stack(&continue_stack);

        FOR_EACH_PTR(goto_stack, named_slist) {
                del_slist(&named_slist->slist);
        } END_FOR_EACH_PTR(named_slist);
        __free_ptr_list((struct ptr_list **)&goto_stack);
}


void __push_cond_stacks()
{
        push_slist(&cond_true_stack, NULL);
        push_slist(&cond_false_stack, NULL);
}

/*
 * This combines the pre cond states with either the true or false states.
 * For example:
 * a = kmalloc() ; if (a !! foo(a)
 * In the pre state a is possibly null.  In the true state it is non null.
 * In the false state it is null.  Combine the pre and the false to get
 * that when we call 'foo', 'a' is null.
 */

static void __use_cond_stack(struct state_list_stack **stack)
{
        struct state_list *slist;
        
        del_slist(&cur_slist);

        cur_slist = pop_slist(&pre_cond_stack);
        push_slist(&pre_cond_stack, clone_slist(cur_slist));

        slist = pop_slist(stack);
        overwrite_slist(slist, &cur_slist);
        push_slist(stack, slist);
}


void __use_cond_true_states()
{
        __use_cond_stack(&cond_true_stack);
}

void __use_cond_false_states()
{
        __use_cond_stack(&cond_false_stack);
}

void __negate_cond_stacks()
{
        struct state_list *old_false, *old_true;
        
        old_false = pop_slist(&cond_false_stack);
        old_true = pop_slist(&cond_true_stack);

        overwrite_slist(old_false, &cur_slist);

        push_slist(&cond_false_stack, old_true);
        push_slist(&cond_true_stack, old_false);
}


void __and_cond_states()
{
        struct state_list *tmp_slist;

        tmp_slist = pop_slist(&cond_true_stack);
        and_slist_stack(&cond_true_stack, tmp_slist);
        or_slist_stack(&cond_false_stack);
}

void __or_cond_states()
{
        struct state_list *tmp_slist;

        or_slist_stack(&cond_true_stack);
        tmp_slist = pop_slist(&cond_false_stack);
        and_slist_stack(&cond_false_stack, tmp_slist);
}


void __save_pre_cond_states()
{
        push_slist(&pre_cond_stack, clone_slist(cur_slist));
}

void __pop_pre_cond_states()
{
        struct state_list *tmp;
        
        tmp = pop_slist(&pre_cond_stack);
        del_slist(&tmp);
}

void __use_false_only_stack()
{
        struct state_list *slist;

        slist = pop_slist(&false_only_stack);
        overwrite_slist(slist, &cur_slist);
        del_slist(&slist);
}

void __pop_false_only_stack()
{
        struct state_list *slist;

        slist = pop_slist(&false_only_stack);
        del_slist(&slist);
}

void __use_cond_states()
{
        struct state_list *pre, *pre_clone, *true_states, *false_states;

        pre = pop_slist(&pre_cond_stack);
        pre_clone = clone_slist(pre);

        true_states = pop_slist(&cond_true_stack);
        overwrite_slist(true_states, &pre);
        /* we use the true states right away */
        del_slist(&cur_slist);
        cur_slist = pre;

        false_states = pop_slist(&cond_false_stack);    
        push_slist(&false_only_stack, clone_slist(false_states));
        overwrite_slist(false_states, &pre_clone);
        push_slist(&false_stack, pre_clone);
}

void __push_true_states()
{
        push_slist(&true_stack, clone_slist(cur_slist));
}

void __use_false_states()
{
        del_slist(&cur_slist);
        cur_slist = pop_slist(&false_stack);
}

void __pop_false_states()
{
        struct state_list *slist;

        slist = pop_slist(&false_stack);
        del_slist(&slist);
}

void __merge_false_states()
{
        struct state_list *slist;

        slist = pop_slist(&false_stack);
        merge_slist(&cur_slist, slist);
        del_slist(&slist);
}

void __merge_true_states()
{
        struct state_list *slist;

        slist = pop_slist(&true_stack);
        merge_slist(&cur_slist, slist);
        del_slist(&slist);
}

void __push_continues() 
{ 
        push_slist(&continue_stack, NULL);
}

void __pop_continues() 
{ 
        struct state_list *slist;

        slist = pop_slist(&continue_stack);
        del_slist(&slist);
}

void __process_continues()
{
        struct state_list *slist;

        slist = pop_slist(&continue_stack);
        if (!slist) {
                overwrite_slist(cur_slist, &slist);
        } else {
                merge_slist(&slist, cur_slist);
        }
        push_slist(&continue_stack, slist);
}

void __merge_continues()
{
        struct state_list *slist;

        slist = pop_slist(&continue_stack);
        merge_slist(&cur_slist, slist);
        del_slist(&slist);
}

void __push_breaks() 
{ 
        push_slist(&break_stack, NULL);
}

void __process_breaks()
{
        struct state_list *slist;
        
        slist = pop_slist(&break_stack);
        if (!slist) {
                overwrite_slist(cur_slist, &slist);
        } else {
                merge_slist(&slist, cur_slist);
        }
        push_slist(&break_stack, slist);
}

void __merge_breaks()
{
        struct state_list *slist;

        slist = pop_slist(&break_stack);
        merge_slist(&cur_slist, slist);
        del_slist(&slist);
}

void __use_breaks()
{
        del_slist(&cur_slist);
        cur_slist = pop_slist(&break_stack);
}

void __save_switch_states() 
{ 
        push_slist(&switch_stack, clone_slist(cur_slist));
}

void __merge_switches()
{
        struct state_list *slist;

        slist = pop_slist(&switch_stack);
        merge_slist(&cur_slist, slist);
        push_slist(&switch_stack, slist);
}

void __pop_switches() 
{ 
        struct state_list *slist;

        slist = pop_slist(&switch_stack);
        del_slist(&slist);
}

void __push_default()
{
        push_slist(&default_stack, NULL);
}

void __set_default()
{
        set_state_stack(&default_stack, "has_default", 0, NULL, &true_state);
}

int __pop_default()
{
        struct state_list *slist;

        slist = pop_slist(&default_stack);
        if (slist) {
                del_slist(&slist);
                return 1;
        }
        return 0;
}

static struct named_slist *alloc_named_slist(const char *name, 
                                             struct state_list *slist)
{
        struct named_slist *named_slist = __alloc_named_slist(0);

        named_slist->name = (char *)name;
        named_slist->slist = slist;
        return named_slist;
}

void __save_gotos(const char *name)
{
        struct state_list *slist;

        slist = get_slist_from_slist_stack(goto_stack, name);
        if (slist) {
                merge_slist(&slist, cur_slist);
                return;
        } else {
                struct state_list *slist;
                struct named_slist *named_slist;

                slist = clone_slist(cur_slist);
                named_slist = alloc_named_slist(name, slist);
                add_ptr_list(&goto_stack, named_slist);
        }
}

void __merge_gotos(const char *name)
{
        struct state_list *slist;
        
        slist = get_slist_from_slist_stack(goto_stack, name);
        if (slist)
                merge_slist(&cur_slist, slist);
}