Function init_mparams

system/lib/dlmalloc.c:3183–3270

Initialize mparams */

/* Initialize mparams */
static int init_mparams(void) {
#ifdef NEED_GLOBAL_LOCK_INIT
    if (malloc_global_mutex_status <= 0)
        init_malloc_global_mutex();
#endif
    
    ACQUIRE_MALLOC_GLOBAL_LOCK();
    if (mparams.magic == 0) {
        size_t magic;
        size_t psize;
        size_t gsize;
        
#ifndef WIN32
        psize = malloc_getpagesize;
        gsize = ((DEFAULT_GRANULARITY != 0)? DEFAULT_GRANULARITY : psize);
#else /* WIN32 */
        {
            SYSTEM_INFO system_info;
            GetSystemInfo(&system_info);
            psize = system_info.dwPageSize;
            gsize = ((DEFAULT_GRANULARITY != 0)?
                     DEFAULT_GRANULARITY : system_info.dwAllocationGranularity);
        }
#endif /* WIN32 */
        
        /* Sanity-check configuration:
         size_t must be unsigned and as wide as pointer type.
         ints must be at least 4 bytes.
         alignment must be at least 8.
         Alignment, min chunk size, and page size must all be powers of 2.
         */
        if ((sizeof(size_t) != sizeof(char*)) ||
            (MAX_SIZE_T < MIN_CHUNK_SIZE)  ||
            (sizeof(int) < 4)  ||
            (MALLOC_ALIGNMENT < (size_t)8U) ||
            ((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT-SIZE_T_ONE)) != 0) ||
            ((MCHUNK_SIZE      & (MCHUNK_SIZE-SIZE_T_ONE))      != 0) ||
            ((gsize            & (gsize-SIZE_T_ONE))            != 0) ||
            ((psize            & (psize-SIZE_T_ONE))            != 0))
            ABORT;
        mparams.granularity = gsize;
        mparams.page_size = psize;
        mparams.mmap_threshold = DEFAULT_MMAP_THRESHOLD;
        mparams.trim_threshold = DEFAULT_TRIM_THRESHOLD;
#if MORECORE_CONTIGUOUS
        mparams.default_mflags = USE_LOCK_BIT|USE_MMAP_BIT;
#else  /* MORECORE_CONTIGUOUS */
        mparams.default_mflags = USE_LOCK_BIT|USE_MMAP_BIT|USE_NONCONTIGUOUS_BIT;
#endif /* MORECORE_CONTIGUOUS */
        
#if !ONLY_MSPACES
        /* Set up lock for main malloc area */
        gm->mflags = mparams.default_mflags;
        (void)INITIAL_LOCK(&gm->mutex);
#endif
#if LOCK_AT_FORK
        pthread_atfork(&pre_fork, &post_fork_parent, &post_fork_child);
#endif