Function init_mparams

dlmalloc/dlmalloc.c:2496–2570

Initialize mparams */

/* Initialize mparams */
static int init_mparams(void) {
  if (mparams.page_size == 0) {
    size_t s;

    mparams.nice = 1;
    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 (FOOTERS && !INSECURE)
    {
#if USE_DEV_RANDOM
      int fd;
      unsigned char buf[sizeof(size_t)];
      /* Try to use /dev/urandom, else fall back on using time */
      if ((fd = open("/dev/urandom", O_RDONLY)) >= 0 &&
          read(fd, buf, sizeof(buf)) == sizeof(buf)) {
        s = *((size_t *) buf);
        close(fd);
      }
      else
#endif /* USE_DEV_RANDOM */
        s = (size_t)(time(0) ^ (size_t)0x55555555U);

      s |= (size_t)8U;    /* ensure nonzero */
      s &= ~(size_t)7U;   /* improve chances of fault for bad values */

    }
#else /* (FOOTERS && !INSECURE) */
    s = (size_t)0x58585858U;
#endif /* (FOOTERS && !INSECURE) */
    ACQUIRE_MAGIC_INIT_LOCK();
    if (mparams.magic == 0) {
      mparams.magic = s;
      /* Set up lock for main malloc area */
      INITIAL_LOCK(&gm->mutex);
      gm->mflags = mparams.default_mflags;
    }
    RELEASE_MAGIC_INIT_LOCK();

#ifndef WIN32
    mparams.page_size = malloc_getpagesize;
    mparams.granularity = ((DEFAULT_GRANULARITY != 0)?
                           DEFAULT_GRANULARITY : mparams.page_size);
#else /* WIN32 */
    {
      SYSTEM_INFO system_info;
      GetSystemInfo(&system_info);
      mparams.page_size = system_info.dwPageSize;
      mparams.granularity = system_info.dwAllocationGranularity;
    }
#endif /* WIN32 */

    /* Sanity-check configuration: