duktape-1.5.2/src-separate/duk_hbuffer_alloc.c

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/*
 *  duk_hbuffer allocation and freeing.
 */
 
#include "duk_internal.h"
 
/* Allocate a new duk_hbuffer of a certain type and return a pointer to it
 * (NULL on error).  Write buffer data pointer to 'out_bufdata' (only if
 * allocation successful).
 */
DUK_INTERNAL duk_hbuffer *duk_hbuffer_alloc(duk_heap *heap, duk_size_t size, duk_small_uint_t flags, void **out_bufdata) {
    duk_hbuffer *res = NULL;
    duk_size_t header_size;
    duk_size_t alloc_size;
 
    DUK_ASSERT(heap != NULL);
    DUK_ASSERT(out_bufdata != NULL);
 
    DUK_DDD(DUK_DDDPRINT("allocate hbuffer"));
 
    /* Size sanity check.  Should not be necessary because caller is
     * required to check this, but we don't want to cause a segfault
     * if the size wraps either in duk_size_t computation or when
     * storing the size in a 16-bit field.
     */
    if (size > DUK_HBUFFER_MAX_BYTELEN) {
        DUK_D(DUK_DPRINT("hbuffer alloc failed: size too large: %ld", (long) size));
        return NULL;  /* no need to write 'out_bufdata' */
    }
 
    if (flags & DUK_BUF_FLAG_EXTERNAL) {
        header_size = sizeof(duk_hbuffer_external);
        alloc_size = sizeof(duk_hbuffer_external);
    } else if (flags & DUK_BUF_FLAG_DYNAMIC) {
        header_size = sizeof(duk_hbuffer_dynamic);
        alloc_size = sizeof(duk_hbuffer_dynamic);
    } else {
        header_size = sizeof(duk_hbuffer_fixed);
        alloc_size = sizeof(duk_hbuffer_fixed) + size;
        DUK_ASSERT(alloc_size >= sizeof(duk_hbuffer_fixed));  /* no wrapping */
    }
 
    res = (duk_hbuffer *) DUK_ALLOC(heap, alloc_size);
    if (!res) {
        goto error;
    }
 
    /* zero everything unless requested not to do so */
#if defined(DUK_USE_ZERO_BUFFER_DATA)
    DUK_MEMZERO((void *) res,
                (flags & DUK_BUF_FLAG_NOZERO) ? header_size : alloc_size);
#else
    DUK_MEMZERO((void *) res, header_size);
#endif
 
    if (flags & DUK_BUF_FLAG_EXTERNAL) {
        duk_hbuffer_external *h;
        h = (duk_hbuffer_external *) res;
        DUK_UNREF(h);
        *out_bufdata = NULL;
#if defined(DUK_USE_EXPLICIT_NULL_INIT)
#if defined(DUK_USE_HEAPPTR16)
/* the compressed pointer is zeroed which maps to NULL, so nothing to do. */
#else
        DUK_HBUFFER_EXTERNAL_SET_DATA_PTR(heap, h, NULL);
#endif
#endif
        DUK_ASSERT(DUK_HBUFFER_EXTERNAL_GET_DATA_PTR(heap, h) == NULL);
    } else if (flags & DUK_BUF_FLAG_DYNAMIC) {
        duk_hbuffer_dynamic *h = (duk_hbuffer_dynamic *) res;
        void *ptr;
 
        if (size > 0) {
            DUK_ASSERT(!(flags & DUK_BUF_FLAG_EXTERNAL));  /* alloc external with size zero */
            DUK_DDD(DUK_DDDPRINT("dynamic buffer with nonzero size, alloc actual buffer"));
#ifdef DUK_USE_ZERO_BUFFER_DATA
            ptr = DUK_ALLOC_ZEROED(heap, size);
#else
            ptr = DUK_ALLOC(heap, size);
#endif
            if (!ptr) {
                /* Because size > 0, NULL check is correct */
                goto error;
            }
            *out_bufdata = ptr;
 
            DUK_HBUFFER_DYNAMIC_SET_DATA_PTR(heap, h, ptr);
        } else {
            *out_bufdata = NULL;
#if defined(DUK_USE_EXPLICIT_NULL_INIT)
#if defined(DUK_USE_HEAPPTR16)
/* the compressed pointer is zeroed which maps to NULL, so nothing to do. */
#else
            DUK_HBUFFER_DYNAMIC_SET_DATA_PTR(heap, h, NULL);
#endif
#endif
            DUK_ASSERT(DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(heap, h) == NULL);
        }
    } else {
        *out_bufdata = (void *) ((duk_hbuffer_fixed *) res + 1);
    }
 
    DUK_HBUFFER_SET_SIZE(res, size);
 
    DUK_HEAPHDR_SET_TYPE(&res->hdr, DUK_HTYPE_BUFFER);
    if (flags & DUK_BUF_FLAG_DYNAMIC) {
        DUK_HBUFFER_SET_DYNAMIC(res);
        if (flags & DUK_BUF_FLAG_EXTERNAL) {
            DUK_HBUFFER_SET_EXTERNAL(res);
        }
    } else {
        DUK_ASSERT(!(flags & DUK_BUF_FLAG_EXTERNAL));
    }
        DUK_HEAP_INSERT_INTO_HEAP_ALLOCATED(heap, &res->hdr);
 
    DUK_DDD(DUK_DDDPRINT("allocated hbuffer: %p", (void *) res));
    return res;
 
 error:
    DUK_DD(DUK_DDPRINT("hbuffer allocation failed"));
 
    DUK_FREE(heap, res);
    return NULL;  /* no need to write 'out_bufdata' */
}
 
/* For indirect allocs. */
 
DUK_INTERNAL void *duk_hbuffer_get_dynalloc_ptr(duk_heap *heap, void *ud) {
    duk_hbuffer_dynamic *buf = (duk_hbuffer_dynamic *) ud;
    DUK_UNREF(heap);
    return (void *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(heap, buf);
}