source: asp3_tinet_ecnl_arm/trunk/musl-1.1.18/src/malloc/malloc.~c@ 352

#define _GNU_SOURCE
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <stdint.h>
#include <errno.h>
#include <sys/mman.h>
#include "libc.h"
#include "atomic.h"
#include "pthread_impl.h"

#if defined(__GNUC__) && defined(__PIC__)
#define inline inline __attribute__((always_inline))
#endif

void *__mmap(void *, size_t, int, int, int, off_t);
int __munmap(void *, size_t);
void *__mremap(void *, size_t, size_t, int, ...);
int __madvise(void *, size_t, int);

struct chunk {
        size_t psize, csize;
        struct chunk *next, *prev;
};

struct bin {
        volatile int lock[2];
        struct chunk *head;
        struct chunk *tail;
};

static struct {
        volatile uint64_t binmap;
        struct bin bins[64];
        volatile int free_lock[2];
} mal;


#define SIZE_ALIGN (4*sizeof(size_t))
#define SIZE_MASK (-SIZE_ALIGN)
#define OVERHEAD (2*sizeof(size_t))
#define MMAP_THRESHOLD (0x1c00*SIZE_ALIGN)
#define DONTCARE 16
#define RECLAIM 163840

#define CHUNK_SIZE(c) ((c)->csize & -2)
#define CHUNK_PSIZE(c) ((c)->psize & -2)
#define PREV_CHUNK(c) ((struct chunk *)((char *)(c) - CHUNK_PSIZE(c)))
#define NEXT_CHUNK(c) ((struct chunk *)((char *)(c) + CHUNK_SIZE(c)))
#define MEM_TO_CHUNK(p) (struct chunk *)((char *)(p) - OVERHEAD)
#define CHUNK_TO_MEM(c) (void *)((char *)(c) + OVERHEAD)
#define BIN_TO_CHUNK(i) (MEM_TO_CHUNK(&mal.bins[i].head))

#define C_INUSE  ((size_t)1)

#define IS_MMAPPED(c) !((c)->csize & (C_INUSE))


/* Synchronization tools */

static inline void lock(volatile int *lk)
{
        if (libc.threads_minus_1)
                while(a_swap(lk, 1)) __wait(lk, lk+1, 1, 1);
}

static inline void unlock(volatile int *lk)
{
        if (lk[0]) {
                a_store(lk, 0);
                if (lk[1]) __wake(lk, 1, 1);
        }
}

static inline void lock_bin(int i)
{
        lock(mal.bins[i].lock);
        if (!mal.bins[i].head)
                mal.bins[i].head = mal.bins[i].tail = BIN_TO_CHUNK(i);
}

static inline void unlock_bin(int i)
{
        unlock(mal.bins[i].lock);
}

static int first_set(uint64_t x)
{
#if 1
        return a_ctz_64(x);
#else
        static const char debruijn64[64] = {
                0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
                62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
                63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
                51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
        };
        static const char debruijn32[32] = {
                0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13,
                31, 22, 28, 18, 26, 10, 7, 12, 21, 17, 9, 6, 16, 5, 15, 14
        };
        if (sizeof(long) < 8) {
                uint32_t y = x;
                if (!y) {
                        y = x>>32;
                        return 32 + debruijn32[(y&-y)*0x076be629 >> 27];
                }
                return debruijn32[(y&-y)*0x076be629 >> 27];
        }
        return debruijn64[(x&-x)*0x022fdd63cc95386dull >> 58];
#endif
}

static const unsigned char bin_tab[60] = {
                    32,33,34,35,36,36,37,37,38,38,39,39,
        40,40,40,40,41,41,41,41,42,42,42,42,43,43,43,43,
        44,44,44,44,44,44,44,44,45,45,45,45,45,45,45,45,
        46,46,46,46,46,46,46,46,47,47,47,47,47,47,47,47,
};

static int bin_index(size_t x)
{
        x = x / SIZE_ALIGN - 1;
        if (x <= 32) return x;
        if (x < 512) return bin_tab[x/8-4];
        if (x > 0x1c00) return 63;
        return bin_tab[x/128-4] + 16;
}

static int bin_index_up(size_t x)
{
        x = x / SIZE_ALIGN - 1;
        if (x <= 32) return x;
        x--;
        if (x < 512) return bin_tab[x/8-4] + 1;
        return bin_tab[x/128-4] + 17;
}

#if 0
void __dump_heap(int x)
{
        struct chunk *c;
        int i;
        for (c = (void *)mal.heap; CHUNK_SIZE(c); c = NEXT_CHUNK(c))
                fprintf(stderr, "base %p size %zu (%d) flags %d/%d\n",
                        c, CHUNK_SIZE(c), bin_index(CHUNK_SIZE(c)),
                        c->csize & 15,
                        NEXT_CHUNK(c)->psize & 15);
        for (i=0; i<64; i++) {
                if (mal.bins[i].head != BIN_TO_CHUNK(i) && mal.bins[i].head) {
                        fprintf(stderr, "bin %d: %p\n", i, mal.bins[i].head);
                        if (!(mal.binmap & 1ULL<<i))
                                fprintf(stderr, "missing from binmap!\n");
                } else if (mal.binmap & 1ULL<<i)
                        fprintf(stderr, "binmap wrongly contains %d!\n", i);
        }
}
#endif

void *__expand_heap(size_t *);

static struct chunk *expand_heap(size_t n)
{
        static int heap_lock[2];
        static void *end;
        void *p;
        struct chunk *w;

        /* The argument n already accounts for the caller's chunk
         * overhead needs, but if the heap can't be extended in-place,
         * we need room for an extra zero-sized sentinel chunk. */
        n += SIZE_ALIGN;

        lock(heap_lock);

        p = __expand_heap(&n);
        if (!p) {
                unlock(heap_lock);
                return 0;
        }

        /* If not just expanding existing space, we need to make a
         * new sentinel chunk below the allocated space. */
        if (p != end) {
                /* Valid/safe because of the prologue increment. */
                n -= SIZE_ALIGN;
                p = (char *)p + SIZE_ALIGN;
                w = MEM_TO_CHUNK(p);
                w->psize = 0 | C_INUSE;
        }

        /* Record new heap end and fill in footer. */
        end = (char *)p + n;
        w = MEM_TO_CHUNK(end);
        w->psize = n | C_INUSE;
        w->csize = 0 | C_INUSE;

        /* Fill in header, which may be new or may be replacing a
         * zero-size sentinel header at the old end-of-heap. */
        w = MEM_TO_CHUNK(p);
        w->csize = n | C_INUSE;

        unlock(heap_lock);

        return w;
}

static int adjust_size(size_t *n)
{
        /* Result of pointer difference must fit in ptrdiff_t. */
        if (*n-1 > PTRDIFF_MAX - SIZE_ALIGN - PAGE_SIZE) {
                if (*n) {
                        errno = ENOMEM;
                        return -1;
                } else {
                        *n = SIZE_ALIGN;
                        return 0;
                }
        }
        *n = (*n + OVERHEAD + SIZE_ALIGN - 1) & SIZE_MASK;
        return 0;
}

static void unbin(struct chunk *c, int i)
{
        if (c->prev == c->next)
                a_and_64(&mal.binmap, ~(1ULL<<i));
        c->prev->next = c->next;
        c->next->prev = c->prev;
        c->csize |= C_INUSE;
        NEXT_CHUNK(c)->psize |= C_INUSE;
}

static int alloc_fwd(struct chunk *c)
{
        int i;
        size_t k;
        while (!((k=c->csize) & C_INUSE)) {
                i = bin_index(k);
                lock_bin(i);
                if (c->csize == k) {
                        unbin(c, i);
                        unlock_bin(i);
                        return 1;
                }
                unlock_bin(i);
        }
        return 0;
}

static int alloc_rev(struct chunk *c)
{
        int i;
        size_t k;
        while (!((k=c->psize) & C_INUSE)) {
                i = bin_index(k);
                lock_bin(i);
                if (c->psize == k) {
                        unbin(PREV_CHUNK(c), i);
                        unlock_bin(i);
                        return 1;
                }
                unlock_bin(i);
        }
        return 0;
}


/* pretrim - trims a chunk _prior_ to removing it from its bin.
 * Must be called with i as the ideal bin for size n, j the bin
 * for the _free_ chunk self, and bin j locked. */
static int pretrim(struct chunk *self, size_t n, int i, int j)
{
        size_t n1;
        struct chunk *next, *split;

        /* We cannot pretrim if it would require re-binning. */
        if (j < 40) return 0;
        if (j < i+3) {
                if (j != 63) return 0;
                n1 = CHUNK_SIZE(self);
                if (n1-n <= MMAP_THRESHOLD) return 0;
        } else {
                n1 = CHUNK_SIZE(self);
        }
        if (bin_index(n1-n) != j) return 0;

        next = NEXT_CHUNK(self);
        split = (void *)((char *)self + n);

        split->prev = self->prev;
        split->next = self->next;
        split->prev->next = split;
        split->next->prev = split;
        split->psize = n | C_INUSE;
        split->csize = n1-n;
        next->psize = n1-n;
        self->csize = n | C_INUSE;
        return 1;
}

static void trim(struct chunk *self, size_t n)
{
        size_t n1 = CHUNK_SIZE(self);
        struct chunk *next, *split;

        if (n >= n1 - DONTCARE) return;

        next = NEXT_CHUNK(self);
        split = (void *)((char *)self + n);

        split->psize = n | C_INUSE;
        split->csize = n1-n | C_INUSE;
        next->psize = n1-n | C_INUSE;
        self->csize = n | C_INUSE;

        free(CHUNK_TO_MEM(split));
}

void *malloc(size_t n)
{
        struct chunk *c;
        int i, j;

        if (adjust_size(&n) < 0) return 0;

        if (n > MMAP_THRESHOLD) {
                size_t len = n + OVERHEAD + PAGE_SIZE - 1 & -PAGE_SIZE;
                char *base = __mmap(0, len, PROT_READ|PROT_WRITE,
                        MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
                if (base == (void *)-1) return 0;
                c = (void *)(base + SIZE_ALIGN - OVERHEAD);
                c->csize = len - (SIZE_ALIGN - OVERHEAD);
                c->psize = SIZE_ALIGN - OVERHEAD;
                return CHUNK_TO_MEM(c);
        }

        i = bin_index_up(n);
        for (;;) {
                uint64_t mask = mal.binmap & -(1ULL<<i);
                if (!mask) {
                        c = expand_heap(n);
                        if (!c) return 0;
                        if (alloc_rev(c)) {
                                struct chunk *x = c;
                                c = PREV_CHUNK(c);
                                NEXT_CHUNK(x)->psize = c->csize =
                                        x->csize + CHUNK_SIZE(c);
                        }
                        break;
                }
                j = first_set(mask);
                lock_bin(j);
                c = mal.bins[j].head;
                if (c != BIN_TO_CHUNK(j)) {
                        if (!pretrim(c, n, i, j)) unbin(c, j);
                        unlock_bin(j);
                        break;
                }
                unlock_bin(j);
        }

        /* Now patch up in case we over-allocated */
        trim(c, n);

        return CHUNK_TO_MEM(c);
}

void *__malloc0(size_t n)
{
        void *p = malloc(n);
        if (p && !IS_MMAPPED(MEM_TO_CHUNK(p))) {
                size_t *z;
                n = (n + sizeof *z - 1)/sizeof *z;
                for (z=p; n; n--, z++) if (*z) *z=0;
        }
        return p;
}

void *realloc(void *p, size_t n)
{
        struct chunk *self, *next;
        size_t n0, n1;
        void *new;

        if (!p) return malloc(n);

        if (adjust_size(&n) < 0) return 0;

        self = MEM_TO_CHUNK(p);
        n1 = n0 = CHUNK_SIZE(self);

        if (IS_MMAPPED(self)) {
                size_t extra = self->psize;
                char *base = (char *)self - extra;
                size_t oldlen = n0 + extra;
                size_t newlen = n + extra;
                /* Crash on realloc of freed chunk */
                if (extra & 1) a_crash();
                if (newlen < PAGE_SIZE && (new = malloc(n))) {
                        memcpy(new, p, n-OVERHEAD);
                        free(p);
                        return new;
                }
                newlen = (newlen + PAGE_SIZE-1) & -PAGE_SIZE;
                if (oldlen == newlen) return p;
                base = __mremap(base, oldlen, newlen, MREMAP_MAYMOVE);
                if (base == (void *)-1)
                        goto copy_realloc;
                self = (void *)(base + extra);
                self->csize = newlen - extra;
                return CHUNK_TO_MEM(self);
        }

        next = NEXT_CHUNK(self);

        /* Crash on corrupted footer (likely from buffer overflow) */
        if (next->psize != self->csize) a_crash();

        /* Merge adjacent chunks if we need more space. This is not
         * a waste of time even if we fail to get enough space, because our
         * subsequent call to free would otherwise have to do the merge. */
        if (n > n1 && alloc_fwd(next)) {
                n1 += CHUNK_SIZE(next);
                next = NEXT_CHUNK(next);
        }
        /* FIXME: find what's wrong here and reenable it..? */
        if (0 && n > n1 && alloc_rev(self)) {
                self = PREV_CHUNK(self);
                n1 += CHUNK_SIZE(self);
        }
        self->csize = n1 | C_INUSE;
        next->psize = n1 | C_INUSE;

        /* If we got enough space, split off the excess and return */
        if (n <= n1) {
                //memmove(CHUNK_TO_MEM(self), p, n0-OVERHEAD);
                trim(self, n);
                return CHUNK_TO_MEM(self);
        }

copy_realloc:
        /* As a last resort, allocate a new chunk and copy to it. */
        new = malloc(n-OVERHEAD);
        if (!new) return 0;
        memcpy(new, p, n0-OVERHEAD);
        free(CHUNK_TO_MEM(self));
        return new;
}

void free(void *p)
{
        struct chunk *self, *next;
        size_t final_size, new_size, size;
        int reclaim=0;
        int i;

        if (!p) return;

        self = MEM_TO_CHUNK(p);

        if (IS_MMAPPED(self)) {
                size_t extra = self->psize;
                char *base = (char *)self - extra;
                size_t len = CHUNK_SIZE(self) + extra;
                /* Crash on double free */
                if (extra & 1) a_crash();
                __munmap(base, len);
                return;
        }

        final_size = new_size = CHUNK_SIZE(self);
        next = NEXT_CHUNK(self);

        /* Crash on corrupted footer (likely from buffer overflow) */
        if (next->psize != self->csize) a_crash();

        for (;;) {
                if (self->psize & next->csize & C_INUSE) {
                        self->csize = final_size | C_INUSE;
                        next->psize = final_size | C_INUSE;
                        i = bin_index(final_size);
                        lock_bin(i);
                        lock(mal.free_lock);
                        if (self->psize & next->csize & C_INUSE)
                                break;
                        unlock(mal.free_lock);
                        unlock_bin(i);
                }

                if (alloc_rev(self)) {
                        self = PREV_CHUNK(self);
                        size = CHUNK_SIZE(self);
                        final_size += size;
                        if (new_size+size > RECLAIM && (new_size+size^size) > size)
                                reclaim = 1;
                }

                if (alloc_fwd(next)) {
                        size = CHUNK_SIZE(next);
                        final_size += size;
                        if (new_size+size > RECLAIM && (new_size+size^size) > size)
                                reclaim = 1;
                        next = NEXT_CHUNK(next);
                }
        }

        if (!(mal.binmap & 1ULL<<i))
                a_or_64(&mal.binmap, 1ULL<<i);

        self->csize = final_size;
        next->psize = final_size;
        unlock(mal.free_lock);

        self->next = BIN_TO_CHUNK(i);
        self->prev = mal.bins[i].tail;
        self->next->prev = self;
        self->prev->next = self;

        /* Replace middle of large chunks with fresh zero pages */
        if (reclaim) {
                uintptr_t a = (uintptr_t)self + SIZE_ALIGN+PAGE_SIZE-1 & -PAGE_SIZE;
                uintptr_t b = (uintptr_t)next - SIZE_ALIGN & -PAGE_SIZE;
#if 1
                __madvise((void *)a, b-a, MADV_DONTNEED);
#else
                __mmap((void *)a, b-a, PROT_READ|PROT_WRITE,
                        MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0);
#endif
        }

        unlock_bin(i);
}