1  /*
       2   * plymouth-ctrl.c	Simply communications with plymouthd
       3   *			to avoid forked sub processes and/or
       4   *			missed plymouth send commands tool
       5   *			due a plymouthd replacement.
       6   *
       7   * Copyright (c) 2016 SUSE Linux GmbH, All rights reserved.
       8   * Copyright (c) 2016 Werner Fink <werner@suse.de>
       9   *
      10   * This program is free software; you can redistribute it and/or modify
      11   * it under the terms of the GNU General Public License as published by
      12   * the Free Software Foundation; either version 2, or (at your option)
      13   * any later version.
      14   *
      15   * This program is distributed in the hope that it will be useful,
      16   * but WITHOUT ANY WARRANTY; without even the implied warranty of
      17   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      18   * GNU General Public License for more details.
      19   *
      20   * You should have received a copy of the GNU General Public License
      21   * along with this program (see the file COPYING); if not, write to the
      22   * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
      23   * MA 02110-1301, USA.
      24   *
      25   * Author: Werner Fink <werner@suse.de>
      26   */
      27  
      28  #include <errno.h>
      29  #include <limits.h>
      30  #include <poll.h>
      31  #include <signal.h>
      32  #include <stdarg.h>
      33  #include <stdlib.h>
      34  #include <sys/mman.h>
      35  #include <sys/socket.h>
      36  #include <sys/types.h>
      37  #include <sys/un.h>
      38  #include <unistd.h>
      39  
      40  #include "all-io.h"
      41  #include "c.h"
      42  #include "nls.h"
      43  #include "plymouth-ctrl.h"
      44  
      45  static int can_read(int fd, const long timeout)
      46  {
      47  	struct pollfd fds = {
      48  		.fd = fd,
      49  		.events = POLLIN|POLLPRI,
      50  		.revents = 0,
      51  	};
      52  	int ret;
      53  
      54  	do {
      55  		ret = poll(&fds, 1, timeout);
      56  	} while ((ret < 0) && (errno == EINTR));
      57  
      58  	return (ret == 1) && (fds.revents & (POLLIN|POLLPRI));
      59  }
      60  
      61  static int open_un_socket_and_connect(void)
      62  {
      63  	/* The abstract UNIX socket of plymouth */
      64  	struct sockaddr_un su = {
      65  		.sun_family = AF_UNIX,
      66  		.sun_path = PLYMOUTH_SOCKET_PATH,
      67  	};
      68  	const int one = 1;
      69  	int fd, ret;
      70  
      71  	fd = socket(PF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
      72  	if (fd < 0) {
      73  		warnx(_("cannot open UNIX socket"));
      74  		goto err;
      75  	}
      76  
      77  	ret = setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
      78  	if (ret < 0) {
      79  		warnx(_("cannot set option for UNIX socket"));
      80  		close(fd);
      81  		fd = -1;
      82  		goto err;
      83  	}
      84  
      85  	/* Note, the abstract PLYMOUTH_SOCKET_PATH has a leading NULL byte */
      86  	ret = connect(fd, (struct sockaddr *) &su,
      87  		offsetof(struct sockaddr_un, sun_path) + 1 + strlen(su.sun_path+1));
      88  	if (ret < 0) {
      89  		if (errno != ECONNREFUSED)
      90  			warnx(_("cannot connect on UNIX socket"));
      91  		close(fd);
      92  		fd = -1;
      93  		goto err;
      94  	}
      95  err:
      96  	return fd;
      97  }
      98  
      99  int plymouth_command(int cmd, ...)
     100  {
     101  	uint8_t answer[2], command[2];
     102  	struct sigaction sp, op;
     103  	int fdsock = -1, ret = 0;
     104  
     105  	sigemptyset (&sp.sa_mask);
     106  	sp.sa_handler = SIG_IGN;
     107  	sp.sa_flags = SA_RESTART;
     108  	sigaction(SIGPIPE, &sp, &op);
     109  
     110  	/* The plymouthd does read at least two bytes. */
     111  	command[1] = '\0';
     112  	switch (cmd) {
     113  	case MAGIC_PING:
     114  		fdsock = open_un_socket_and_connect();
     115  		if (fdsock >= 0) {
     116  			command[0] = cmd;
     117  			write_all(fdsock, command, sizeof(command));
     118  		}
     119  		break;
     120  	case MAGIC_QUIT:
     121  		fdsock = open_un_socket_and_connect();
     122  		if (fdsock >= 0) {
     123  			command[0] = cmd;
     124  			write_all(fdsock, command, sizeof(command));
     125  		}
     126  		break;
     127  	default:
     128  		warnx(_("the plymouth request %c is not implemented"), cmd);
     129  	case '?':
     130  		goto err;
     131  	}
     132  
     133  	answer[0] = '\0';
     134  	if (fdsock >= 0) {
     135  		if (can_read(fdsock, 1000))
     136  			read_all(fdsock, (char *) &answer[0], sizeof(answer));
     137  		close(fdsock);
     138  	}
     139  	sigaction(SIGPIPE, &op, NULL);
     140  	ret = (answer[0] == ANSWER_ACK) ? 1 : 0;
     141  err:
     142  	return ret;
     143  }
     144