gz_iface.c

机器人人3D仿真工具,可以加入到Simbad仿真环境下应用。

/*
 *  Gazebo - Outdoor Multi-Robot Simulator
 *  Copyright (C) 2003  
 *     Nate Koenig & Andrew Howard
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
/*
 * Desc: Generic interface support
 * Author: Andrew Howard
 * Date: 21 Apr 2003
 * CVS: $Id: gz_iface.c,v 1.19 2006/10/01 18:48:26 natepak Exp $
 */

#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <sys/file.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#include "gazebo.h"
#include "gz_error.h"

// Work out the filename
static const char *gz_iface_filename(gz_iface_t *self, const char *type, const char *id);


//////////////////////////////////////////////////////////////////////////////
// Create an interface
gz_iface_t *gz_iface_alloc()
{
  gz_iface_t *self;

  self = calloc(1, sizeof(gz_iface_t));

  return self;
}


//////////////////////////////////////////////////////////////////////////////
// Destroy an interface
void gz_iface_free(gz_iface_t *self)
{
  free(self->filename);
  free(self);
  return;
}


//////////////////////////////////////////////////////////////////////////////
// Work out the filename
const char *gz_iface_filename(gz_iface_t *self, const char *type, const char *id)
{
  char filename[128];

  if (self->server != NULL)
  {
    snprintf(filename, sizeof(filename), "%s/%s.%s",
             self->server->filename, type, id);
  }
  else if (self->client != NULL)
  {
    snprintf(filename, sizeof(filename), "%s/%s.%s",
             self->client->filename, type, id);
  }
  else
    assert(0);

  if (self->filename)
    free(self->filename);
  self->filename = strdup(filename);  

  return self->filename;
}


//////////////////////////////////////////////////////////////////////////////
// Create an interface (server)
int gz_iface_create(gz_iface_t *self, gz_server_t *server, const char *type,
                    const char *id, size_t size)
{
  self->server = server;

  // Went cant have null id's
  if (id == NULL)
  {
    GZ_ERROR1("interface [%s] id is NULL", type);
    return -1;
  }

  // We cannot have id with '.'
  if (strchr(id, '.'))
  {
    GZ_ERROR1("invalid id [%s] (must not contain '.')", id);
    return -1;
  }
  
  // Work out the filename
  gz_iface_filename(self, type, id);
  
  // Create and open the file
  self->mmap_fd = open(self->filename, O_RDWR | O_CREAT | O_TRUNC, S_IREAD | S_IWRITE);
  if (self->mmap_fd < 0)
  {
    GZ_ERROR1("error creating mmap file: %s", strerror(errno));
    return -1;
  }

  // Set the file to the correct size
  if (ftruncate(self->mmap_fd, size) < 0)
  {
    GZ_ERROR1("error setting size of mmap file: %s", strerror(errno));
    return -1;
  }

  // Map the file into memory
  self->mmap = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, self->mmap_fd, 0);
  if (self->mmap == MAP_FAILED)
  {
    GZ_ERROR1("error mapping mmap file: %s", strerror(errno));
    return -1;
  }
  memset(self->mmap, 0, size);

  ((gz_data_t*) self->mmap)->version = LIBGAZEBO_VERSION;
  ((gz_data_t*) self->mmap)->size = size;

  // Print the name, version info
  GZ_MSG3(5, "creating %s %03X %d", self->filename,
          ((gz_data_t*) self->mmap)->version,
          ((gz_data_t*) self->mmap)->size);
  
  return 0;
}


//////////////////////////////////////////////////////////////////////////////
// Destroy the interface (server)
int gz_iface_destroy(gz_iface_t *self)
{
  // Unmap the file
  munmap(self->mmap, sizeof(gz_iface_t));
  self->mmap = NULL;

  // Close the file
  close(self->mmap_fd);

  // Delete the file
  GZ_MSG1(5, "deleting %s", self->filename);  
  if (unlink(self->filename))
  {
    GZ_ERROR1("error deleting mmap file: %s", strerror(errno));
    return -1;
  }
  return 0;
}


//////////////////////////////////////////////////////////////////////////////
// Open an existing interface (client)
int gz_iface_open(gz_iface_t *self, gz_client_t *client, const char *type,
                  const char *id, size_t size)
{
  self->client = client;
  
  // Work out the filename
  gz_iface_filename(self, type, id);

  // Open the mmap file
  self->mmap_fd = open(self->filename, O_RDWR);
  if (self->mmap_fd <= 0)
  {
    GZ_ERROR2("error opening device file %s : %s", self->filename, strerror(errno));
    return -1;
  }

  // Map the mmap file
  self->mmap = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, self->mmap_fd, 0);
  if (self->mmap == MAP_FAILED)
  {
    GZ_ERROR1("error mapping device file: %s", strerror(errno));
    return -1;
  }    

  // Make sure everything is consistent
  if (((gz_data_t*) self->mmap)->size < size)
  {
    GZ_ERROR2("expected file size: %d < %d", ((gz_data_t*) self->mmap)->size, size);
    return -1;
  }

  // Print the name, version info
  GZ_MSG3(5, "opening %s %03X %d", self->filename,
          ((gz_data_t*) self->mmap)->version,
          ((gz_data_t*) self->mmap)->size);
  
  return 0;
}  


//////////////////////////////////////////////////////////////////////////////
// Close the interface (client)
int gz_iface_close(gz_iface_t *self)
{
  // Unmap the file
  munmap(self->mmap, sizeof(gz_iface_t));
  self->mmap = NULL;

  // Close the file
  GZ_MSG1(5, "closing %s", self->filename);  
  close(self->mmap_fd);

  return 0;
}


//////////////////////////////////////////////////////////////////////////////
// Lock the interface.
int gz_iface_lock(gz_iface_t *self, int blocking)
{
  // Some 2.4 kernels seem to screw up the lock count somehow; keep an eye out
  
  //printf("  lock %p %s\n", self, self->filename);

  // Lock the file
  if (flock(self->mmap_fd, LOCK_EX) != 0)
  {
    GZ_ERROR2("flock %s error: %s", self->filename, strerror(errno));
    return -1;
  }
  return 0;
}


//////////////////////////////////////////////////////////////////////////////
// Unlock the interface
void gz_iface_unlock(gz_iface_t *self)
{
  //printf("unlock %p %s\n", self, self->filename);
  
  // Unlock the file
  if (flock(self->mmap_fd, LOCK_UN) != 0)
  {
    GZ_ERROR1("flock error: %s", strerror(errno));
    return;
  }
  return;
}


//////////////////////////////////////////////////////////////////////////////
// Tell clients that new data is available
int gz_iface_post(gz_iface_t *self)
{
  assert(self->server);
  return gz_server_post(self->server);
}