examples/libs/l4re/c++/shared_ds/ds_clnt.cc

Sharing memory between applications, client side.

Sharing memory between applications, client side.

/*
 * (c) 2009 Adam Lackorzynski <adam@os.inf.tu-dresden.de>,
 *          Alexander Warg <warg@os.inf.tu-dresden.de>
 *     economic rights: Technische Universität Dresden (Germany)
 *
 * This file is part of TUD:OS and distributed under the terms of the
 * GNU General Public License 2.
 * Please see the COPYING-GPL-2 file for details.
 */
 
#include <l4/re/util/cap_alloc> // L4::Cap
#include <l4/re/dataspace>      // L4Re::Dataspace
#include <l4/re/rm>             // L4::Rm
#include <l4/re/env>            // L4::Env
#include <l4/sys/cache.h>
 
#include <cstring>
#include <cstdio>
#include <unistd.h>
 
#include "interface.h"
 
int main()
{
  /*
   * Try to get server interface cap.
   */
 
  L4::Cap<My_interface> svr = L4Re::Env::env()->get_cap<My_interface>("shm");
  if (!svr.is_valid())
    {
      printf("Could not get the server capability\n");
      return 1;
    }
 
  /*
   * Alloc data space cap slot
   */
  L4::Cap<L4Re::Dataspace> ds = L4Re::Util::cap_alloc.alloc<L4Re::Dataspace>();
  if (!ds.is_valid())
    {
      printf("Could not get capability slot!\n");
      return 1;
    }
 
  /*
   * Alloc server notifier IRQ cap slot
   */
  L4::Cap<L4::Irq> irq = L4Re::Util::cap_alloc.alloc<L4::Irq>();
  if (!irq.is_valid())
    {
      printf("Could not get capability slot!\n");
      return 1;
    }
 
  /*
   * Request shared data-space cap.
   */
  if (svr->get_shared_buffer(ds, irq))
    {
      printf("Could not get shared memory dataspace!\n");
      return 1;
    }
 
  /*
   * Attach to arbitrary region
   */
  char *addr = 0;
  int err = L4Re::Env::env()->rm()->attach(&addr, ds->size(),
                                           L4Re::Rm::F::Search_addr | L4Re::Rm::F::RW,
                                           L4::Ipc::make_cap_rw(ds));
  if (err < 0)
    {
      printf("Error attaching data space: %s\n", l4sys_errtostr(err));
      return 1;
    }
 
  printf("Content: %s\n", addr);
 
  // wait a bit for the demo effect
  printf("Sleeping a bit...\n");
  sleep(1);
 
  /*
   * Fill in new stuff
   */
  memset(addr, 0, ds->size());
  char const * const msg = "Hello from client, too!";
  printf("Setting new content in shared memory\n");
  snprintf(addr, strlen(msg)+1, msg);
  l4_cache_clean_data((unsigned long)addr,
                      (unsigned long)addr + strlen(msg) + 1);
 
  // notify the server
  irq->trigger();
 
  /*
   * Detach region containing addr, result should be Detached_ds (other results
   * only apply if we split regions etc.).
   */
  err = L4Re::Env::env()->rm()->detach(addr, 0);
  if (err)
    printf("Failed to detach region\n");
 
  /* Free objects and capabilties, just for completeness. */
  L4Re::Util::cap_alloc.free(ds, L4Re::This_task);
  L4Re::Util::cap_alloc.free(irq, L4Re::This_task);
 
  return 0;
}