open.c

linux 操作系统下对系统资源监控程序的编写

/* $Id: open.c,v 1.39 2003/10/20 15:19:41 hadess Exp $ */

/* Copyright (C) 1998-99 Martin Baulig
   This file is part of LibGTop 1.0.

   Contributed by Martin Baulig <[e-mail]>, April 1998.

   LibGTop 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.

   LibGTop 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 LibGTop; see the file COPYING. If not, write to the
   Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.
*/

#include <glibtop.h>
#include <glibtop/open.h>
#include <glibtop/version.h>
#include <glibtop/sysdeps.h>
#include <glibtop/command.h>

#include <glibtop/gnuserv.h>

/* Opens pipe to gtop server. Returns 0 on success and -1 on error. */

void
glibtop_open_l (glibtop *server, const char *program_name,
		const unsigned long features, const unsigned flags)
{
	int connect_type;

	server->name = program_name;

	/* It is important to set _GLIBTOP_INIT_STATE_OPEN here when we
	 * do recursive calls to glibtop_init_r (). */

	server->flags |= _GLIBTOP_INIT_STATE_OPEN;

	server->error_method = GLIBTOP_ERROR_METHOD_DEFAULT;

#ifdef DEBUG
	fprintf (stderr, "SIZEOF: %u - %u - %u - %u - %u - %u\n",
		 sizeof (glibtop_command), sizeof (glibtop_response),
		 sizeof (glibtop_mountentry), sizeof (glibtop_union),
		 sizeof (glibtop_sysdeps), sizeof (glibtop_response_union));
#endif

	switch (server->method) {
	case GLIBTOP_METHOD_DIRECT:
		server->features = 0;
		break;
	case GLIBTOP_METHOD_INET:
#ifdef DEBUG
		fprintf (stderr, "Connecting to '%s' port %ld.\n",
			 server->server_host, server->server_port);
#endif
		
		connect_type = glibtop_make_connection
			(server->server_host, server->server_port,
			 &server->socket);
		
#ifdef DEBUG
		fprintf (stderr, "Connect Type is %d.\n", connect_type);
#endif
		
		server->flags |= _GLIBTOP_INIT_STATE_SERVER;
		
		server->features = -1;
		break;
	case GLIBTOP_METHOD_UNIX:
#ifdef DEBUG
		fprintf (stderr, "Connecting to Unix Domain Socket.\n");
#endif

		connect_type = glibtop_make_connection
			("unix", 0, &server->socket);

#ifdef DEBUG		
		fprintf (stderr, "Connect Type is %d.\n", connect_type);
#endif

		server->flags |= _GLIBTOP_INIT_STATE_SERVER;

		server->features = -1;
		break;
	case GLIBTOP_METHOD_PIPE:
#ifdef DEBUG
		fprintf (stderr, "Opening pipe to server (%s).\n",
			 LIBGTOP_SERVER);
#endif

		if (pipe (server->input) || pipe (server->output))
			glibtop_error_io_r (server, "cannot make a pipe");

		server->pid  = fork ();
		
		if (server->pid < 0) {
			glibtop_error_io_r (server, "fork failed");
		} else if (server->pid == 0) {
			close (0); close (1);
			close (server->input [0]); close (server->output [1]);
			dup2 (server->input [1], 1);
			dup2 (server->output [0], 0);
			execl (LIBGTOP_SERVER, "libgtop-server", NULL);
			glibtop_error_io_r (server, "execl (%s)",
					    LIBGTOP_SERVER);
			_exit (2);
		}

		close (server->input [1]);
		close (server->output [0]);

		server->flags |= _GLIBTOP_INIT_STATE_SERVER;
		
		server->features = -1;
		break;
	}

	/* If the server has been started, ask it for its features. */

	if (server->flags & _GLIBTOP_INIT_STATE_SERVER) {
		char version [BUFSIZ], buffer [BUFSIZ];
		glibtop_sysdeps sysdeps;
		size_t size, nbytes;

		/* First check whether the server version is correct. */

		sprintf (version, LIBGTOP_VERSION_STRING,
			 LIBGTOP_VERSION, LIBGTOP_SERVER_VERSION,
			 sizeof (glibtop_command),
			 sizeof (glibtop_response),
			 sizeof (glibtop_union),
			 sizeof (glibtop_sysdeps));

		size = strlen (version) + 1;
	
		glibtop_read_l (server, sizeof (nbytes), &nbytes);

		if (nbytes != size)
			glibtop_error_r (server,
					 "Requested %u bytes but got %u.",
					 size, nbytes);
		
		glibtop_read_l (server, nbytes, buffer);
		
		if (memcmp (version, buffer, size))
			glibtop_error_r (server, "server version is not %s",
					 LIBGTOP_VERSION);

		/* Now ask it for its features. */
		
		glibtop_call_l (server, GLIBTOP_CMND_SYSDEPS, 0, NULL,
				sizeof (glibtop_sysdeps), &sysdeps);
		
		server->features = sysdeps.features;

		memcpy (&server->sysdeps, &sysdeps, sizeof (glibtop_sysdeps));

#ifdef DEBUG
		fprintf (stderr, "Server features are %lu.\n",
			 server->features);
#endif
	}

	/* In any case, we call the open functions of our own sysdeps
	 * directory. */

#ifdef DEBUG
	fprintf (stderr, "Calling sysdeps open function.\n");
#endif
	
	glibtop_init_s (&server, features, flags);
}