Function netbuf_alloc

components/net/lwip/lwip-1.4.1/src/api/netbuf.c:106–123

* Allocate memory for a packet buffer for a given netbuf. * * @param buf the netbuf for which to allocate a packet buffer * @param size the size of the packet buffer to allocate * @return pointer to the allocated memory * NULL if no memory could be allocated */

 *         NULL if no memory could be allocated
 */
void *
netbuf_alloc(struct netbuf *buf, u16_t size)
{
  LWIP_ERROR("netbuf_alloc: invalid buf", (buf != NULL), return NULL;);

  /* Deallocate any previously allocated memory. */
  if (buf->p != NULL) {
    pbuf_free(buf->p);
  }
  buf->p = pbuf_alloc(PBUF_TRANSPORT, size, PBUF_RAM);
  if (buf->p == NULL) {
     return NULL;
  }
  LWIP_ASSERT("check that first pbuf can hold size",
             (buf->p->len >= size));
  buf->ptr = buf->p;
  return buf->p->payload;
}

/**
 * Free the packet buffer included in a netbuf