Subversion Repositories or1k

/*

  This is a version (aka dlmalloc) of malloc/free/realloc written by

  Doug Lea and released to the public domain.  Use, modify, and

  redistribute this code without permission or acknowledgement in any

  way you wish.  Send questions, comments, complaints, performance

  data, etc to dl@cs.oswego.edu

  VERSION 2.7.2 Sat Aug 17 09:07:30 2002  Doug Lea  (dl at gee)

  Note: There may be an updated version of this malloc obtainable at

           ftp://gee.cs.oswego.edu/pub/misc/malloc.c

  Check before installing!

  Hacked up for uClibc by Erik Andersen <andersen@codepoet.org>

*/

#define _GNU_SOURCE

#include "malloc.h"

#ifdef __UCLIBC_HAS_THREADS__

pthread_mutex_t __malloc_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;

#endif

/*

   There is exactly one instance of this struct in this malloc.

   If you are adapting this malloc in a way that does NOT use a static

   malloc_state, you MUST explicitly zero-fill it before using. This

   malloc relies on the property that malloc_state is initialized to

   all zeroes (as is true of C statics).

*/

struct malloc_state __malloc_state;  /* never directly referenced */

/* forward declaration */

static int __malloc_largebin_index(unsigned int sz);

#ifdef __MALLOC_DEBUGGING

/*

  Debugging support

  Because freed chunks may be overwritten with bookkeeping fields, this

  malloc will often die when freed memory is overwritten by user

  programs.  This can be very effective (albeit in an annoying way)

  in helping track down dangling pointers.

  If you compile with -D__MALLOC_DEBUGGING, a number of assertion checks are

  enabled that will catch more memory errors. You probably won't be

  able to make much sense of the actual assertion errors, but they

  should help you locate incorrectly overwritten memory.  The

  checking is fairly extensive, and will slow down execution

  noticeably. Calling malloc_stats or mallinfo with __MALLOC_DEBUGGING set will

  attempt to check every non-mmapped allocated and free chunk in the

  course of computing the summmaries. (By nature, mmapped regions

  cannot be checked very much automatically.)

  Setting __MALLOC_DEBUGGING may also be helpful if you are trying to modify

  this code. The assertions in the check routines spell out in more

  detail the assumptions and invariants underlying the algorithms.

  Setting __MALLOC_DEBUGGING does NOT provide an automated mechanism for checking

  that all accesses to malloced memory stay within their

  bounds. However, there are several add-ons and adaptations of this

  or other mallocs available that do this.

*/

/* Properties of all chunks */

void __do_check_chunk(mchunkptr p)

{

    mstate av = get_malloc_state();

#ifdef __DOASSERTS__

    /* min and max possible addresses assuming contiguous allocation */

    char* max_address = (char*)(av->top) + chunksize(av->top);

    char* min_address = max_address - av->sbrked_mem;

    unsigned long  sz = chunksize(p);

#endif

    if (!chunk_is_mmapped(p)) {

        /* Has legal address ... */

        if (p != av->top) {

            if (contiguous(av)) {

                assert(((char*)p) >= min_address);

                assert(((char*)p + sz) <= ((char*)(av->top)));

            }

        }

        else {

            /* top size is always at least MINSIZE */

            assert((unsigned long)(sz) >= MINSIZE);

            /* top predecessor always marked inuse */

            assert(prev_inuse(p));

        }

    }

    else {

        /* address is outside main heap  */

        if (contiguous(av) && av->top != initial_top(av)) {

            assert(((char*)p) < min_address || ((char*)p) > max_address);

        }

        /* chunk is page-aligned */

        assert(((p->prev_size + sz) & (av->pagesize-1)) == 0);

        /* mem is aligned */

        assert(aligned_OK(chunk2mem(p)));

    }

}

/* Properties of free chunks */

void __do_check_free_chunk(mchunkptr p)

{

    size_t sz = p->size & ~PREV_INUSE;

#ifdef __DOASSERTS__

    mstate av = get_malloc_state();

    mchunkptr next = chunk_at_offset(p, sz);

#endif

    __do_check_chunk(p);

    /* Chunk must claim to be free ... */

    assert(!inuse(p));

    assert (!chunk_is_mmapped(p));

    /* Unless a special marker, must have OK fields */

    if ((unsigned long)(sz) >= MINSIZE)

    {

        assert((sz & MALLOC_ALIGN_MASK) == 0);

        assert(aligned_OK(chunk2mem(p)));

        /* ... matching footer field */

        assert(next->prev_size == sz);

        /* ... and is fully consolidated */

        assert(prev_inuse(p));

        assert (next == av->top || inuse(next));

        /* ... and has minimally sane links */

        assert(p->fd->bk == p);

        assert(p->bk->fd == p);

    }

    else /* markers are always of size (sizeof(size_t)) */

        assert(sz == (sizeof(size_t)));

}

/* Properties of inuse chunks */

void __do_check_inuse_chunk(mchunkptr p)

{

    mstate av = get_malloc_state();

    mchunkptr next;

    __do_check_chunk(p);

    if (chunk_is_mmapped(p))

        return; /* mmapped chunks have no next/prev */

    /* Check whether it claims to be in use ... */

    assert(inuse(p));

    next = next_chunk(p);

    /* ... and is surrounded by OK chunks.

       Since more things can be checked with free chunks than inuse ones,

       if an inuse chunk borders them and debug is on, it's worth doing them.

       */

    if (!prev_inuse(p))  {

        /* Note that we cannot even look at prev unless it is not inuse */

        mchunkptr prv = prev_chunk(p);

        assert(next_chunk(prv) == p);

        __do_check_free_chunk(prv);

    }

    if (next == av->top) {

        assert(prev_inuse(next));

        assert(chunksize(next) >= MINSIZE);

    }

    else if (!inuse(next))

        __do_check_free_chunk(next);

}

/* Properties of chunks recycled from fastbins */

void __do_check_remalloced_chunk(mchunkptr p, size_t s)

{

#ifdef __DOASSERTS__

    size_t sz = p->size & ~PREV_INUSE;

#endif

    __do_check_inuse_chunk(p);

    /* Legal size ... */

    assert((sz & MALLOC_ALIGN_MASK) == 0);

    assert((unsigned long)(sz) >= MINSIZE);

    /* ... and alignment */

    assert(aligned_OK(chunk2mem(p)));

    /* chunk is less than MINSIZE more than request */

    assert((long)(sz) - (long)(s) >= 0);

    assert((long)(sz) - (long)(s + MINSIZE) < 0);

}

/* Properties of nonrecycled chunks at the point they are malloced */

void __do_check_malloced_chunk(mchunkptr p, size_t s)

{

    /* same as recycled case ... */

    __do_check_remalloced_chunk(p, s);

    /*

       ... plus,  must obey implementation invariant that prev_inuse is

       always true of any allocated chunk; i.e., that each allocated

       chunk borders either a previously allocated and still in-use

       chunk, or the base of its memory arena. This is ensured

       by making all allocations from the the `lowest' part of any found

       chunk.  This does not necessarily hold however for chunks

       recycled via fastbins.

       */

    assert(prev_inuse(p));

}

/*

  Properties of malloc_state.

  This may be useful for debugging malloc, as well as detecting user

  programmer errors that somehow write into malloc_state.

  If you are extending or experimenting with this malloc, you can

  probably figure out how to hack this routine to print out or

  display chunk addresses, sizes, bins, and other instrumentation.

*/

void __do_check_malloc_state(void)

{

    mstate av = get_malloc_state();

    int i;

    mchunkptr p;

    mchunkptr q;

    mbinptr b;

    unsigned int binbit;

    int empty;

    unsigned int idx;

    size_t size;

    unsigned long  total = 0;

    int max_fast_bin;

    /* internal size_t must be no wider than pointer type */

    assert(sizeof(size_t) <= sizeof(char*));

    /* alignment is a power of 2 */

    assert((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT-1)) == 0);

    /* cannot run remaining checks until fully initialized */

    if (av->top == 0 || av->top == initial_top(av))

        return;

    /* pagesize is a power of 2 */

    assert((av->pagesize & (av->pagesize-1)) == 0);

    /* properties of fastbins */

    /* max_fast is in allowed range */

    assert(get_max_fast(av) <= request2size(MAX_FAST_SIZE));

    max_fast_bin = fastbin_index(av->max_fast);

    for (i = 0; i < NFASTBINS; ++i) {

        p = av->fastbins[i];

        /* all bins past max_fast are empty */

        if (i > max_fast_bin)

            assert(p == 0);

        while (p != 0) {

            /* each chunk claims to be inuse */

            __do_check_inuse_chunk(p);

            total += chunksize(p);

            /* chunk belongs in this bin */

            assert(fastbin_index(chunksize(p)) == i);

            p = p->fd;

        }

    }

    if (total != 0)

        assert(have_fastchunks(av));

    else if (!have_fastchunks(av))

        assert(total == 0);

    /* check normal bins */

    for (i = 1; i < NBINS; ++i) {

        b = bin_at(av,i);

        /* binmap is accurate (except for bin 1 == unsorted_chunks) */

        if (i >= 2) {

            binbit = get_binmap(av,i);

            empty = last(b) == b;

            if (!binbit)

                assert(empty);

            else if (!empty)

                assert(binbit);

        }

        for (p = last(b); p != b; p = p->bk) {

            /* each chunk claims to be free */

            __do_check_free_chunk(p);

            size = chunksize(p);

            total += size;

            if (i >= 2) {

                /* chunk belongs in bin */

                idx = bin_index(size);

                assert(idx == i);

                /* lists are sorted */

                if ((unsigned long) size >= (unsigned long)(FIRST_SORTED_BIN_SIZE)) {

                    assert(p->bk == b ||

                            (unsigned long)chunksize(p->bk) >=

                            (unsigned long)chunksize(p));

                }

            }

            /* chunk is followed by a legal chain of inuse chunks */

            for (q = next_chunk(p);

                    (q != av->top && inuse(q) &&

                     (unsigned long)(chunksize(q)) >= MINSIZE);

                    q = next_chunk(q))

                __do_check_inuse_chunk(q);

        }

    }

    /* top chunk is OK */

    __do_check_chunk(av->top);

    /* sanity checks for statistics */

    assert(total <= (unsigned long)(av->max_total_mem));

    assert(av->n_mmaps >= 0);

    assert(av->n_mmaps <= av->max_n_mmaps);

    assert((unsigned long)(av->sbrked_mem) <=

            (unsigned long)(av->max_sbrked_mem));

    assert((unsigned long)(av->mmapped_mem) <=

            (unsigned long)(av->max_mmapped_mem));

    assert((unsigned long)(av->max_total_mem) >=

            (unsigned long)(av->mmapped_mem) + (unsigned long)(av->sbrked_mem));

}

#endif

/* ----------- Routines dealing with system allocation -------------- */

/*

  sysmalloc handles malloc cases requiring more memory from the system.

  On entry, it is assumed that av->top does not have enough

  space to service request for nb bytes, thus requiring that av->top

  be extended or replaced.

*/

static void* __malloc_alloc(size_t nb, mstate av)

{

    mchunkptr       old_top;        /* incoming value of av->top */

    size_t old_size;       /* its size */

    char*           old_end;        /* its end address */

    long            size;           /* arg to first MORECORE or mmap call */

    char*           brk;            /* return value from MORECORE */

    long            correction;     /* arg to 2nd MORECORE call */

    char*           snd_brk;        /* 2nd return val */

    size_t front_misalign; /* unusable bytes at front of new space */

    size_t end_misalign;   /* partial page left at end of new space */

    char*           aligned_brk;    /* aligned offset into brk */

    mchunkptr       p;              /* the allocated/returned chunk */

    mchunkptr       remainder;      /* remainder from allocation */

    unsigned long    remainder_size; /* its size */

    unsigned long    sum;            /* for updating stats */

    size_t          pagemask  = av->pagesize - 1;

    /*

       If there is space available in fastbins, consolidate and retry

       malloc from scratch rather than getting memory from system.  This

       can occur only if nb is in smallbin range so we didn't consolidate

       upon entry to malloc. It is much easier to handle this case here

       than in malloc proper.

       */

    if (have_fastchunks(av)) {

        assert(in_smallbin_range(nb));

        __malloc_consolidate(av);

        return malloc(nb - MALLOC_ALIGN_MASK);

    }

    /*

       If have mmap, and the request size meets the mmap threshold, and

       the system supports mmap, and there are few enough currently

       allocated mmapped regions, try to directly map this request

       rather than expanding top.

       */

    if ((unsigned long)(nb) >= (unsigned long)(av->mmap_threshold) &&

            (av->n_mmaps < av->n_mmaps_max)) {

        char* mm;             /* return value from mmap call*/

        /*

           Round up size to nearest page.  For mmapped chunks, the overhead

           is one (sizeof(size_t)) unit larger than for normal chunks, because there

           is no following chunk whose prev_size field could be used.

           */

        size = (nb + (sizeof(size_t)) + MALLOC_ALIGN_MASK + pagemask) & ~pagemask;

        /* Don't try if size wraps around 0 */

        if ((unsigned long)(size) > (unsigned long)(nb)) {

            mm = (char*)(MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE));

            if (mm != (char*)(MORECORE_FAILURE)) {

                /*

                   The offset to the start of the mmapped region is stored

                   in the prev_size field of the chunk. This allows us to adjust

                   returned start address to meet alignment requirements here

                   and in memalign(), and still be able to compute proper

                   address argument for later munmap in free() and realloc().

                   */

                front_misalign = (size_t)chunk2mem(mm) & MALLOC_ALIGN_MASK;

                if (front_misalign > 0) {

                    correction = MALLOC_ALIGNMENT - front_misalign;

                    p = (mchunkptr)(mm + correction);

                    p->prev_size = correction;

                    set_head(p, (size - correction) |IS_MMAPPED);

                }

                else {

                    p = (mchunkptr)mm;

                    p->prev_size = 0;

                    set_head(p, size|IS_MMAPPED);

                }

                /* update statistics */

                if (++av->n_mmaps > av->max_n_mmaps)

                    av->max_n_mmaps = av->n_mmaps;

                sum = av->mmapped_mem += size;

                if (sum > (unsigned long)(av->max_mmapped_mem))

                    av->max_mmapped_mem = sum;

                sum += av->sbrked_mem;

                if (sum > (unsigned long)(av->max_total_mem))

                    av->max_total_mem = sum;

                check_chunk(p);

                return chunk2mem(p);

            }

        }

    }

    /* Record incoming configuration of top */

    old_top  = av->top;

    old_size = chunksize(old_top);

    old_end  = (char*)(chunk_at_offset(old_top, old_size));

    brk = snd_brk = (char*)(MORECORE_FAILURE);

    /* If not the first time through, we require old_size to

     * be at least MINSIZE and to have prev_inuse set.  */

    assert((old_top == initial_top(av) && old_size == 0) ||

            ((unsigned long) (old_size) >= MINSIZE &&

             prev_inuse(old_top)));

    /* Precondition: not enough current space to satisfy nb request */

    assert((unsigned long)(old_size) < (unsigned long)(nb + MINSIZE));

    /* Precondition: all fastbins are consolidated */

    assert(!have_fastchunks(av));

    /* Request enough space for nb + pad + overhead */

    size = nb + av->top_pad + MINSIZE;

    /*

       If contiguous, we can subtract out existing space that we hope to

       combine with new space. We add it back later only if

       we don't actually get contiguous space.

       */

    if (contiguous(av))

        size -= old_size;

    /*

       Round to a multiple of page size.

       If MORECORE is not contiguous, this ensures that we only call it

       with whole-page arguments.  And if MORECORE is contiguous and

       this is not first time through, this preserves page-alignment of

       previous calls. Otherwise, we correct to page-align below.

       */

    size = (size + pagemask) & ~pagemask;

    /*

       Don't try to call MORECORE if argument is so big as to appear

       negative. Note that since mmap takes size_t arg, it may succeed

       below even if we cannot call MORECORE.

       */

    if (size > 0)

        brk = (char*)(MORECORE(size));

    /*

       If have mmap, try using it as a backup when MORECORE fails or

       cannot be used. This is worth doing on systems that have "holes" in

       address space, so sbrk cannot extend to give contiguous space, but

       space is available elsewhere.  Note that we ignore mmap max count

       and threshold limits, since the space will not be used as a

       segregated mmap region.

       */

    if (brk == (char*)(MORECORE_FAILURE)) {

        /* Cannot merge with old top, so add its size back in */

        if (contiguous(av))

            size = (size + old_size + pagemask) & ~pagemask;

        /* If we are relying on mmap as backup, then use larger units */

        if ((unsigned long)(size) < (unsigned long)(MMAP_AS_MORECORE_SIZE))

            size = MMAP_AS_MORECORE_SIZE;

        /* Don't try if size wraps around 0 */

        if ((unsigned long)(size) > (unsigned long)(nb)) {

            brk = (char*)(MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE));

            if (brk != (char*)(MORECORE_FAILURE)) {

                /* We do not need, and cannot use, another sbrk call to find end */

                snd_brk = brk + size;

                /* Record that we no longer have a contiguous sbrk region.

                   After the first time mmap is used as backup, we do not

                   ever rely on contiguous space since this could incorrectly

                   bridge regions.

                   */

                set_noncontiguous(av);

            }

        }

    }

    if (brk != (char*)(MORECORE_FAILURE)) {

        av->sbrked_mem += size;

        /*

           If MORECORE extends previous space, we can likewise extend top size.

           */

        if (brk == old_end && snd_brk == (char*)(MORECORE_FAILURE)) {

            set_head(old_top, (size + old_size) | PREV_INUSE);

        }

        /*

           Otherwise, make adjustments:

         * If the first time through or noncontiguous, we need to call sbrk

         just to find out where the end of memory lies.

         * We need to ensure that all returned chunks from malloc will meet

         MALLOC_ALIGNMENT

         * If there was an intervening foreign sbrk, we need to adjust sbrk

         request size to account for fact that we will not be able to

         combine new space with existing space in old_top.

         * Almost all systems internally allocate whole pages at a time, in

         which case we might as well use the whole last page of request.

         So we allocate enough more memory to hit a page boundary now,

         which in turn causes future contiguous calls to page-align.

         */

        else {

            front_misalign = 0;

            end_misalign = 0;

            correction = 0;

            aligned_brk = brk;

            /*

               If MORECORE returns an address lower than we have seen before,

               we know it isn't really contiguous.  This and some subsequent

               checks help cope with non-conforming MORECORE functions and

               the presence of "foreign" calls to MORECORE from outside of

               malloc or by other threads.  We cannot guarantee to detect

               these in all cases, but cope with the ones we do detect.

               */

            if (contiguous(av) && old_size != 0 && brk < old_end) {

                set_noncontiguous(av);

            }

            /* handle contiguous cases */

            if (contiguous(av)) {

                /* We can tolerate forward non-contiguities here (usually due

                   to foreign calls) but treat them as part of our space for

                   stats reporting.  */

                if (old_size != 0)

                    av->sbrked_mem += brk - old_end;

                /* Guarantee alignment of first new chunk made from this space */

                front_misalign = (size_t)chunk2mem(brk) & MALLOC_ALIGN_MASK;

                if (front_misalign > 0) {

                    /*

                       Skip over some bytes to arrive at an aligned position.

                       We don't need to specially mark these wasted front bytes.

                       They will never be accessed anyway because

                       prev_inuse of av->top (and any chunk created from its start)

                       is always true after initialization.

                       */

                    correction = MALLOC_ALIGNMENT - front_misalign;

                    aligned_brk += correction;

                }

                /*

                   If this isn't adjacent to existing space, then we will not

                   be able to merge with old_top space, so must add to 2nd request.

                   */

                correction += old_size;

                /* Extend the end address to hit a page boundary */

                end_misalign = (size_t)(brk + size + correction);

                correction += ((end_misalign + pagemask) & ~pagemask) - end_misalign;

                assert(correction >= 0);

                snd_brk = (char*)(MORECORE(correction));

                if (snd_brk == (char*)(MORECORE_FAILURE)) {

                    /*

                       If can't allocate correction, try to at least find out current

                       brk.  It might be enough to proceed without failing.

                       */

                    correction = 0;

                    snd_brk = (char*)(MORECORE(0));

                }

                else if (snd_brk < brk) {

                    /*

                       If the second call gives noncontiguous space even though

                       it says it won't, the only course of action is to ignore

                       results of second call, and conservatively estimate where

                       the first call left us. Also set noncontiguous, so this

                       won't happen again, leaving at most one hole.

                       Note that this check is intrinsically incomplete.  Because

                       MORECORE is allowed to give more space than we ask for,

                       there is no reliable way to detect a noncontiguity

                       producing a forward gap for the second call.

                       */

                    snd_brk = brk + size;

                    correction = 0;

                    set_noncontiguous(av);

                }

            }

            /* handle non-contiguous cases */

            else {

                /* MORECORE/mmap must correctly align */

                assert(aligned_OK(chunk2mem(brk)));

                /* Find out current end of memory */

                if (snd_brk == (char*)(MORECORE_FAILURE)) {

                    snd_brk = (char*)(MORECORE(0));

                    av->sbrked_mem += snd_brk - brk - size;

                }

            }

            /* Adjust top based on results of second sbrk */

            if (snd_brk != (char*)(MORECORE_FAILURE)) {

                av->top = (mchunkptr)aligned_brk;

                set_head(av->top, (snd_brk - aligned_brk + correction) | PREV_INUSE);

                av->sbrked_mem += correction;

                /*

                   If not the first time through, we either have a

                   gap due to foreign sbrk or a non-contiguous region.  Insert a

                   double fencepost at old_top to prevent consolidation with space

                   we don't own. These fenceposts are artificial chunks that are

                   marked as inuse and are in any case too small to use.  We need

                   two to make sizes and alignments work out.

                   */

                if (old_size != 0) {

                    /* Shrink old_top to insert fenceposts, keeping size a

                       multiple of MALLOC_ALIGNMENT. We know there is at least

                       enough space in old_top to do this.

                       */

                    old_size = (old_size - 3*(sizeof(size_t))) & ~MALLOC_ALIGN_MASK;

                    set_head(old_top, old_size | PREV_INUSE);

                    /*

                       Note that the following assignments completely overwrite

                       old_top when old_size was previously MINSIZE.  This is