smatch: relicense to GPLv2+

[smatch.git] / smatch_slist.c

/*
 * Copyright (C) 2008,2009 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
 */

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

#undef CHECKORDER

ALLOCATOR(smatch_state, "smatch state");
ALLOCATOR(sm_state, "sm state");
ALLOCATOR(named_slist, "named slist");
__DO_ALLOCATOR(char, 1, 4, "state names", sname);

static int sm_state_counter;

char *show_sm(struct sm_state *sm)
{
        static char buf[256];
        struct sm_state *tmp;
        int pos;
        int i;

        pos = snprintf(buf, sizeof(buf), "[%s] '%s' = %s (",
                       check_name(sm->owner), sm->name, show_state(sm->state));
        if (pos > sizeof(buf))
                goto truncate;

        i = 0;
        FOR_EACH_PTR(sm->possible, tmp) {
                if (i++)
                        pos += snprintf(buf + pos, sizeof(buf) - pos, ", ");
                if (pos > sizeof(buf))
                        goto truncate;
                pos += snprintf(buf + pos, sizeof(buf) - pos, "%s",
                               show_state(tmp->state));
                if (pos > sizeof(buf))
                        goto truncate;
        } END_FOR_EACH_PTR(tmp);
        snprintf(buf + pos, sizeof(buf) - pos, ")");

        return buf;

truncate:
        for (i = 0; i < 3; i++)
                buf[sizeof(buf) - 2 - i] = '.';
        return buf;
}

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

        printf("dumping slist at %d\n", get_lineno());
        FOR_EACH_PTR(slist, sm) {
                printf("%s\n", show_sm(sm));
        } END_FOR_EACH_PTR(sm);
        printf("---\n");
}

/* NULL states go at the end to simplify merge_slist */
int cmp_tracker(const struct sm_state *a, const struct sm_state *b)
{
        int ret;

        if (a == b)
                return 0;
        if (!b)
                return -1;
        if (!a)
                return 1;

        if (a->owner > b->owner)
                return -1;
        if (a->owner < b->owner)
                return 1;

        ret = strcmp(a->name, b->name);
        if (ret)
                return ret;

        if (!b->sym && a->sym)
                return -1;
        if (!a->sym && b->sym)
                return 1;
        if (a->sym > b->sym)
                return -1;
        if (a->sym < b->sym)
                return 1;

        return 0;
}

static int cmp_sm_states(const struct sm_state *a, const struct sm_state *b, int preserve)
{
        int ret;

        ret = cmp_tracker(a, b);
        if (ret)
                return ret;

        /* todo:  add hook for smatch_extra.c */
        if (a->state > b->state)
                return -1;
        if (a->state < b->state)
                return 1;
        /* This is obviously a massive disgusting hack but we need to preserve
         * the unmerged states for smatch extra because we use them in
         * smatch_db.c.  Meanwhile if we preserve all the other unmerged states
         * then it uses a lot of memory and we don't use it.  Hence this hack.
         *
         * Also sometimes even just preserving every possible SMATCH_EXTRA state
         * takes too much resources so we have to cap that.  Capping is probably
         * not often a problem in real life.
         */
        if (a->owner == SMATCH_EXTRA && preserve) {
                if (a == b)
                        return 0;
                if (a->merged == 1 && b->merged == 0)
                        return -1;
                if (a->merged == 0)
                        return 1;
        }

        return 0;
}

static struct sm_state *alloc_sm_state(int owner, const char *name,
                             struct symbol *sym, struct smatch_state *state)
{
        struct sm_state *sm_state = __alloc_sm_state(0);

        sm_state_counter++;

        sm_state->name = alloc_sname(name);
        sm_state->owner = owner;
        sm_state->sym = sym;
        sm_state->state = state;
        sm_state->line = get_lineno();
        sm_state->merged = 0;
        sm_state->implied = 0;
        sm_state->pool = NULL;
        sm_state->left = NULL;
        sm_state->right = NULL;
        sm_state->nr_children = 1;
        sm_state->possible = NULL;
        add_ptr_list(&sm_state->possible, sm_state);
        return sm_state;
}

static struct sm_state *alloc_state_no_name(int owner, const char *name,
                                     struct symbol *sym,
                                     struct smatch_state *state)
{
        struct sm_state *tmp;

        tmp = alloc_sm_state(owner, NULL, sym, state);
        tmp->name = name;
        return tmp;
}

int too_many_possible(struct sm_state *sm)
{
        if (ptr_list_size((struct ptr_list *)sm->possible) >= 100)
                return 1;
        return 0;
}

void add_possible_sm(struct sm_state *to, struct sm_state *new)
{
        struct sm_state *tmp;
        int preserve = 1;

        if (too_many_possible(to))
                preserve = 0;

        FOR_EACH_PTR(to->possible, tmp) {
                if (cmp_sm_states(tmp, new, preserve) < 0)
                        continue;
                else if (cmp_sm_states(tmp, new, preserve) == 0) {
                        return;
                } else {
                        INSERT_CURRENT(new, tmp);
                        return;
                }
        } END_FOR_EACH_PTR(tmp);
        add_ptr_list(&to->possible, new);
}

static void copy_possibles(struct sm_state *to, struct sm_state *from)
{
        struct sm_state *tmp;

        FOR_EACH_PTR(from->possible, tmp) {
                add_possible_sm(to, tmp);
        } END_FOR_EACH_PTR(tmp);
}

char *alloc_sname(const char *str)
{
        char *tmp;

        if (!str)
                return NULL;
        tmp = __alloc_sname(strlen(str) + 1);
        strcpy(tmp, str);
        return tmp;
}

int out_of_memory()
{
        /*
         * I decided to use 50M here based on trial and error.
         * It works out OK for the kernel and so it should work
         * for most other projects as well.
         */
        if (sm_state_counter * sizeof(struct sm_state) >= 50000000)
                return 1;
        return 0;
}

int low_on_memory(void)
{
        if (sm_state_counter * sizeof(struct sm_state) >= 25000000)
                return 1;
        return 0;
}

static void free_sm_state(struct sm_state *sm)
{
        free_slist(&sm->possible);
        /*
         * fixme.  Free the actual state.
         * Right now we leave it until the end of the function
         * because we don't want to double free it.
         * Use the freelist to not double free things
         */
}

static void free_all_sm_states(struct allocation_blob *blob)
{
        unsigned int size = sizeof(struct sm_state);
        unsigned int offset = 0;

        while (offset < blob->offset) {
                free_sm_state((struct sm_state *)(blob->data + offset));
                offset += size;
        }
}

/* At the end of every function we free all the sm_states */
void free_every_single_sm_state(void)
{
        struct allocator_struct *desc = &sm_state_allocator;
        struct allocation_blob *blob = desc->blobs;

        desc->blobs = NULL;
        desc->allocations = 0;
        desc->total_bytes = 0;
        desc->useful_bytes = 0;
        desc->freelist = NULL;
        while (blob) {
                struct allocation_blob *next = blob->next;
                free_all_sm_states(blob);
                blob_free(blob, desc->chunking);
                blob = next;
        }
        clear_sname_alloc();
        clear_smatch_state_alloc();

        sm_state_counter = 0;
}

struct sm_state *clone_sm(struct sm_state *s)
{
        struct sm_state *ret;

        ret = alloc_state_no_name(s->owner, s->name, s->sym, s->state);
        ret->merged = s->merged;
        ret->implied = s->implied;
        ret->line = s->line;
        /* clone_sm() doesn't copy the pools.  Each state needs to have
           only one pool. */
        ret->possible = clone_slist(s->possible);
        ret->left = s->left;
        ret->right = s->right;
        ret->nr_children = s->nr_children;
        return ret;
}

int is_merged(struct sm_state *sm)
{
        return sm->merged;
}

int is_implied(struct sm_state *sm)
{
        return sm->implied;
}

int slist_has_state(struct state_list *slist, struct smatch_state *state)
{
        struct sm_state *tmp;

        FOR_EACH_PTR(slist, tmp) {
                if (tmp->state == state)
                        return 1;
        } END_FOR_EACH_PTR(tmp);
        return 0;
}

static void check_order(struct state_list *slist)
{
#ifdef CHECKORDER
        struct sm_state *sm;
        struct sm_state *last = NULL;
        int printed = 0;

        FOR_EACH_PTR(slist, sm) {
                if (last && cmp_tracker(sm, last) <= 0) {
                        printf("Error.  Unsorted slist %d vs %d, %p vs %p, "
                               "%s vs %s\n", last->owner, sm->owner,
                               last->sym, sm->sym, last->name, sm->name);
                        printed = 1;
                }
                last = sm;
        } END_FOR_EACH_PTR(sm);

        if (printed)
                printf("======\n");
#endif
}

struct state_list *clone_slist(struct state_list *from_slist)
{
        struct sm_state *sm;
        struct state_list *to_slist = NULL;

        FOR_EACH_PTR(from_slist, sm) {
                add_ptr_list(&to_slist, sm);
        } END_FOR_EACH_PTR(sm);
        return to_slist;
}

struct state_list_stack *clone_stack(struct state_list_stack *from_stack)
{
        struct state_list *slist;
        struct state_list_stack *to_stack = NULL;

        FOR_EACH_PTR(from_stack, slist) {
                push_slist(&to_stack, slist);
        } END_FOR_EACH_PTR(slist);
        return to_stack;
}

struct smatch_state *merge_states(int owner, const char *name,
                                  struct symbol *sym,
                                  struct smatch_state *state1,
                                  struct smatch_state *state2)
{
        struct smatch_state *ret;

        if (state1 == state2)
                ret = state1;
        else if (__has_merge_function(owner))
                ret = __client_merge_function(owner, state1, state2);
        else if (!state1 || !state2)
                ret = &undefined;
        else
                ret = &merged;
        return ret;
}

struct sm_state *merge_sm_states(struct sm_state *one, struct sm_state *two)
{
        struct smatch_state *s;
        struct sm_state *result;

        if (one == two)
                return one;
        s = merge_states(one->owner, one->name, one->sym, one->state, two->state);
        result = alloc_state_no_name(one->owner, one->name, one->sym, s);
        result->merged = 1;
        result->left = one;
        result->right = two;
        result->nr_children = one->nr_children + two->nr_children;
        copy_possibles(result, one);
        copy_possibles(result, two);

        if (option_debug ||
            strcmp(check_name(one->owner), option_debug_check) == 0) {
                struct sm_state *tmp;
                int i = 0;

                printf("%d merge [%s] '%s' %s(L %d) + %s(L %d) => %s (",
                        get_lineno(), check_name(one->owner), one->name,
                        show_state(one->state), one->line,
                        show_state(two->state), two->line,
                        show_state(s));

                FOR_EACH_PTR(result->possible, tmp) {
                        if (i++)
                                printf(", ");
                        printf("%s", show_state(tmp->state));
                } END_FOR_EACH_PTR(tmp);
                printf(")\n");
        }

        return result;
}

struct sm_state *get_sm_state_slist(struct state_list *slist, int owner, const char *name,
                                struct symbol *sym)
{
        struct sm_state *sm;

        if (!name)
                return NULL;

        FOR_EACH_PTR(slist, sm) {
                if (sm->owner == owner && sm->sym == sym && !strcmp(sm->name, name))
                        return sm;
        } END_FOR_EACH_PTR(sm);
        return NULL;
}

struct smatch_state *get_state_slist(struct state_list *slist,
                                int owner, const char *name,
                                struct symbol *sym)
{
        struct sm_state *sm;

        sm = get_sm_state_slist(slist, owner, name, sym);
        if (sm)
                return sm->state;
        return NULL;
}

void overwrite_sm_state(struct state_list **slist, struct sm_state *new)
{
        struct sm_state *tmp;

        FOR_EACH_PTR(*slist, tmp) {
                if (cmp_tracker(tmp, new) < 0)
                        continue;
                else if (cmp_tracker(tmp, new) == 0) {
                        REPLACE_CURRENT_PTR(tmp, new);
                        return;
                } else {
                        INSERT_CURRENT(new, tmp);
                        return;
                }
        } END_FOR_EACH_PTR(tmp);
        add_ptr_list(slist, new);
}

void overwrite_sm_state_stack(struct state_list_stack **stack,
                        struct sm_state *sm)
{
        struct state_list *slist;

        slist = pop_slist(stack);
        overwrite_sm_state(&slist, sm);
        push_slist(stack, slist);
}

struct sm_state *set_state_slist(struct state_list **slist, int owner, const char *name,
                     struct symbol *sym, struct smatch_state *state)
{
        struct sm_state *tmp;
        struct sm_state *new = alloc_sm_state(owner, name, sym, state);

        FOR_EACH_PTR(*slist, tmp) {
                if (cmp_tracker(tmp, new) < 0)
                        continue;
                else if (cmp_tracker(tmp, new) == 0) {
                        REPLACE_CURRENT_PTR(tmp, new);
                        return new;
                } else {
                        INSERT_CURRENT(new, tmp);
                        return new;
                }
        } END_FOR_EACH_PTR(tmp);
        add_ptr_list(slist, new);
        return new;
}

void delete_state_slist(struct state_list **slist, int owner, const char *name,
                        struct symbol *sym)
{
        struct sm_state *sm;

        FOR_EACH_PTR(*slist, sm) {
                if (sm->owner == owner && sm->sym == sym && !strcmp(sm->name, name)) {
                        DELETE_CURRENT_PTR(sm);
                        return;
                }
        } END_FOR_EACH_PTR(sm);
}

void delete_state_stack(struct state_list_stack **stack, int owner, const char *name,
                        struct symbol *sym)
{
        struct state_list *slist;

        slist = pop_slist(stack);
        delete_state_slist(&slist, owner, name, sym);
        push_slist(stack, slist);
}

void push_slist(struct state_list_stack **list_stack, struct state_list *slist)
{
        add_ptr_list(list_stack, slist);
}

struct state_list *pop_slist(struct state_list_stack **list_stack)
{
        struct state_list *slist;

        slist = last_ptr_list((struct ptr_list *)*list_stack);
        delete_ptr_list_last((struct ptr_list **)list_stack);
        return slist;
}

void free_slist(struct state_list **slist)
{
        __free_ptr_list((struct ptr_list **)slist);
}

void free_stack(struct state_list_stack **stack)
{
        __free_ptr_list((struct ptr_list **)stack);
}

void free_stack_and_slists(struct state_list_stack **slist_stack)
{
        struct state_list *slist;

        FOR_EACH_PTR(*slist_stack, slist) {
                free_slist(&slist);
        } END_FOR_EACH_PTR(slist);
        free_stack(slist_stack);
}

/*
 * set_state_stack() sets the state for the top slist on the stack.
 */
struct sm_state *set_state_stack(struct state_list_stack **stack, int owner, const char *name,
                                struct symbol *sym, struct smatch_state *state)
{
        struct state_list *slist;
        struct sm_state *sm;

        slist = pop_slist(stack);
        sm = set_state_slist(&slist, owner, name, sym, state);
        push_slist(stack, slist);

        return sm;
}

/*
 * get_sm_state_stack() gets the state for the top slist on the stack.
 */
struct sm_state *get_sm_state_stack(struct state_list_stack *stack,
                                int owner, const char *name,
                                struct symbol *sym)
{
        struct state_list *slist;
        struct sm_state *ret;

        slist = pop_slist(&stack);
        ret = get_sm_state_slist(slist, owner, name, sym);
        push_slist(&stack, slist);
        return ret;
}

struct smatch_state *get_state_stack(struct state_list_stack *stack,
                                int owner, const char *name,
                                struct symbol *sym)
{
        struct sm_state *sm;

        sm = get_sm_state_stack(stack, owner, name, sym);
        if (sm)
                return sm->state;
        return NULL;
}

static void match_states(struct state_list **one, struct state_list **two)
{
        struct sm_state *one_sm;
        struct sm_state *two_sm;
        struct sm_state *tmp;
        struct smatch_state *tmp_state;
        struct state_list *add_to_one = NULL;
        struct state_list *add_to_two = NULL;

        PREPARE_PTR_LIST(*one, one_sm);
        PREPARE_PTR_LIST(*two, two_sm);
        for (;;) {
                if (!one_sm && !two_sm)
                        break;
                if (cmp_tracker(one_sm, two_sm) < 0) {
                        __set_fake_cur_slist_fast(*two);
                        tmp_state = __client_unmatched_state_function(one_sm);
                        __pop_fake_cur_slist_fast();
                        tmp = alloc_state_no_name(one_sm->owner, one_sm->name,
                                                  one_sm->sym, tmp_state);
                        add_ptr_list(&add_to_two, tmp);
                        NEXT_PTR_LIST(one_sm);
                } else if (cmp_tracker(one_sm, two_sm) == 0) {
                        NEXT_PTR_LIST(one_sm);
                        NEXT_PTR_LIST(two_sm);
                } else {
                        __set_fake_cur_slist_fast(*one);
                        tmp_state = __client_unmatched_state_function(two_sm);
                        __pop_fake_cur_slist_fast();
                        tmp = alloc_state_no_name(two_sm->owner, two_sm->name,
                                                  two_sm->sym, tmp_state);
                        add_ptr_list(&add_to_one, tmp);
                        NEXT_PTR_LIST(two_sm);
                }
        }
        FINISH_PTR_LIST(two_sm);
        FINISH_PTR_LIST(one_sm);

        overwrite_slist(add_to_one, one);
        overwrite_slist(add_to_two, two);
}

static void clone_pool_havers(struct state_list *slist)
{
        struct sm_state *sm;
        struct sm_state *new;

        FOR_EACH_PTR(slist, sm) {
                if (sm->pool) {
                        new = clone_sm(sm);
                        REPLACE_CURRENT_PTR(sm, new);
                }
        } END_FOR_EACH_PTR(sm);
}

int __slist_id;
/*
 * Sets the first state to the slist_id.
 */
static void set_slist_id(struct state_list *slist)
{
        struct smatch_state *state;
        struct sm_state *tmp, *new;

        state = alloc_state_num(++__slist_id);
        new = alloc_sm_state(-1, "unnull_path", NULL, state);

        FOR_EACH_PTR(slist, tmp) {
                if (tmp->owner != (unsigned short)-1)
                        return;
                REPLACE_CURRENT_PTR(tmp, new);
                return;
        } END_FOR_EACH_PTR(tmp);
}

int get_slist_id(struct state_list *slist)
{
        struct sm_state *tmp;

        FOR_EACH_PTR(slist, tmp) {
                if (tmp->owner != (unsigned short)-1)
                        return 0;
                return PTR_INT(tmp->state->data);
        } END_FOR_EACH_PTR(tmp);
        return 0;
}

/*
 * merge_slist() is called whenever paths merge, such as after
 * an if statement.  It takes the two slists and creates one.
 */
void merge_slist(struct state_list **to, struct state_list *slist)
{
        struct sm_state *one_sm, *two_sm, *tmp;
        struct state_list *results = NULL;
        struct state_list *implied_one = NULL;
        struct state_list *implied_two = NULL;

        if (out_of_memory())
                return;

        check_order(*to);
        check_order(slist);

        /* merging a null and nonnull path gives you only the nonnull path */
        if (!slist)
                return;

        if (!*to) {
                *to = clone_slist(slist);
                return;
        }

        implied_one = clone_slist(*to);
        implied_two = clone_slist(slist);

        match_states(&implied_one, &implied_two);

        clone_pool_havers(implied_one);
        clone_pool_havers(implied_two);

        set_slist_id(implied_one);
        set_slist_id(implied_two);

        PREPARE_PTR_LIST(implied_one, one_sm);
        PREPARE_PTR_LIST(implied_two, two_sm);
        for (;;) {
                if (!one_sm && !two_sm)
                        break;
                if (cmp_tracker(one_sm, two_sm) < 0) {
                        sm_msg("error:  Internal smatch error.");
                        NEXT_PTR_LIST(one_sm);
                } else if (cmp_tracker(one_sm, two_sm) == 0) {
                        if (one_sm != two_sm) {
                                one_sm->pool = implied_one;
                                two_sm->pool = implied_two;
                        }

                        tmp = merge_sm_states(one_sm, two_sm);
                        add_ptr_list(&results, tmp);
                        NEXT_PTR_LIST(one_sm);
                        NEXT_PTR_LIST(two_sm);
                } else {
                        sm_msg("error:  Internal smatch error.");
                        NEXT_PTR_LIST(two_sm);
                }
        }
        FINISH_PTR_LIST(two_sm);
        FINISH_PTR_LIST(one_sm);

        free_slist(to);
        *to = results;
}

/*
 * filter_slist() removes any sm states "slist" holds in common with "filter"
 */
void filter_slist(struct state_list **slist, struct state_list *filter)
{
        struct sm_state *one_sm, *two_sm;
        struct state_list *results = NULL;

        PREPARE_PTR_LIST(*slist, one_sm);
        PREPARE_PTR_LIST(filter, two_sm);
        for (;;) {
                if (!one_sm && !two_sm)
                        break;
                if (cmp_tracker(one_sm, two_sm) < 0) {
                        add_ptr_list(&results, one_sm);
                        NEXT_PTR_LIST(one_sm);
                } else if (cmp_tracker(one_sm, two_sm) == 0) {
                        if (one_sm != two_sm)
                                add_ptr_list(&results, one_sm);
                        NEXT_PTR_LIST(one_sm);
                        NEXT_PTR_LIST(two_sm);
                } else {
                        NEXT_PTR_LIST(two_sm);
                }
        }
        FINISH_PTR_LIST(two_sm);
        FINISH_PTR_LIST(one_sm);

        free_slist(slist);
        *slist = results;
}

/*
 * and_slist_stack() pops the top two slists, overwriting the one with
 * the other and pushing it back on the stack.
 */
void and_slist_stack(struct state_list_stack **slist_stack)
{
        struct sm_state *tmp;
        struct state_list *right_slist = pop_slist(slist_stack);

        FOR_EACH_PTR(right_slist, tmp) {
                overwrite_sm_state_stack(slist_stack, tmp);
        } END_FOR_EACH_PTR(tmp);
        free_slist(&right_slist);
}

/*
 * or_slist_stack() is for if we have:  if (foo || bar) { foo->baz;
 * It pops the two slists from the top of the stack and merges them
 * together in a way that preserves the things they have in common
 * but creates a merged state for most of the rest.
 * You could have code that had:  if (foo || foo) { foo->baz;
 * It's this function which ensures smatch does the right thing.
 */
void or_slist_stack(struct state_list_stack **pre_conds,
                    struct state_list *cur_slist,
                    struct state_list_stack **slist_stack)
{
        struct state_list *new;
        struct state_list *old;
        struct state_list *pre_slist;
        struct state_list *res;
        struct state_list *tmp_slist;

        new = pop_slist(slist_stack);
        old = pop_slist(slist_stack);

        pre_slist = pop_slist(pre_conds);
        push_slist(pre_conds, clone_slist(pre_slist));

        res = clone_slist(pre_slist);
        overwrite_slist(old, &res);

        tmp_slist = clone_slist(cur_slist);
        overwrite_slist(new, &tmp_slist);

        merge_slist(&res, tmp_slist);
        filter_slist(&res, pre_slist);

        push_slist(slist_stack, res);
        free_slist(&tmp_slist);
        free_slist(&pre_slist);
        free_slist(&new);
        free_slist(&old);
}

/*
 * get_slist_from_named_stack() is only used for gotos.
 */
struct state_list **get_slist_from_named_stack(struct named_stack *stack,
                                              const char *name)
{
        struct named_slist *tmp;

        FOR_EACH_PTR(stack, tmp) {
                if (!strcmp(tmp->name, name))
                        return &tmp->slist;
        } END_FOR_EACH_PTR(tmp);
        return NULL;
}

void overwrite_slist(struct state_list *from, struct state_list **to)
{
        struct sm_state *tmp;

        FOR_EACH_PTR(from, tmp) {
                overwrite_sm_state(to, tmp);
        } END_FOR_EACH_PTR(tmp);
}