sysdeps/mach/hurd/kill.c

   1 /* Copyright (C) 1991-2018 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <sys/types.h>
  20 #include <signal.h>
  21 #include <hurd.h>
  22 #include <hurd/port.h>
  23 #include <hurd/signal.h>
  24 #include <hurd/msg.h>
  25
  26 /* Send signal SIG to process number PID.  If PID is zero,
  27    send SIG to all processes in the current process's process group.
  28    If PID is < -1, send SIG to all processes in process group - PID.  */
  29 int
  30 __kill (pid_t pid, int sig)
  31 {
  32   int delivered = 0;            /* Set when we deliver any signal.  */
  33   error_t err;
  34   mach_port_t proc;
  35   struct hurd_userlink ulink;
  36
  37   void kill_pid (pid_t pid) /* Kill one PID.  */
  38     {
  39       /* SIGKILL is not delivered as a normal signal.
  40          Sending SIGKILL to a process means to terminate its task.  */
  41       if (sig == SIGKILL)
  42         /* Fetch the process's task port and terminate the task.  We
  43            loop in case the process execs and changes its task port.
  44            If the old task port dies after we fetch it but before we
  45            send the RPC, we get MACH_SEND_INVALID_DEST; if it dies
  46            after we send the RPC request but before it is serviced, we
  47            get MIG_SERVER_DIED.  */
  48         do
  49           {
  50             task_t refport;
  51             err = __proc_pid2task (proc, pid, &refport);
  52             /* Ignore zombies.  */
  53             if (!err && refport != MACH_PORT_NULL)
  54               {
  55                 err = __task_terminate (refport);
  56                 __mach_port_deallocate (__mach_task_self (), refport);
  57               }
  58           } while (err == MACH_SEND_INVALID_DEST ||
  59                    err == MIG_SERVER_DIED);
  60       else
  61         {
  62           error_t taskerr;
  63           error_t kill_port (mach_port_t msgport, mach_port_t refport)
  64             {
  65               if (msgport != MACH_PORT_NULL)
  66                 /* Send a signal message to his message port.  */
  67                 return __msg_sig_post (msgport, sig, 0, refport);
  68
  69               /* The process has no message port.  Perhaps try direct
  70                  frobnication of the task.  */
  71
  72               if (taskerr)
  73                 /* If we could not get the task port, we can do nothing.  */
  74                 return taskerr;
  75
  76               if (refport == MACH_PORT_NULL)
  77                 /* proc_pid2task returned success with a null task port.
  78                    That means the process is a zombie.  Signals
  79                    to zombies should return success and do nothing.  */
  80                 return 0;
  81
  82               /* For user convenience in the case of a task that has
  83                  not registered any message port with the proc server,
  84                  translate a few signals to direct task operations.  */
  85               switch (sig)
  86                 {
  87                   /* The only signals that really make sense for an
  88                      unregistered task are kill, suspend, and continue.  */
  89                 case SIGSTOP:
  90                 case SIGTSTP:
  91                   return __task_suspend (refport);
  92                 case SIGCONT:
  93                   return __task_resume (refport);
  94                 case SIGTERM:
  95                 case SIGQUIT:
  96                 case SIGINT:
  97                   return __task_terminate (refport);
  98                 default:
  99                   /* We have full permission to send signals, but there is
 100                      no meaningful way to express this signal.  */
 101                   return EPERM;
 102                 }
 103             }
 104           err = HURD_MSGPORT_RPC (__proc_getmsgport (proc, pid, &msgport),
 105                                   (taskerr = __proc_pid2task (proc, pid,
 106                                                               &refport)) ?
 107                                   __proc_getsidport (proc, &refport) : 0, 1,
 108                                   kill_port (msgport, refport));
 109         }
 110       if (! err)
 111         delivered = 1;
 112     }
 113
 114   proc = _hurd_port_get (&_hurd_ports[INIT_PORT_PROC], &ulink);
 115
 116   if (pid <= 0)
 117     {
 118       /* Send SIG to each process in pgrp (- PID).  */
 119       pid_t pidbuf[10], *pids = pidbuf;
 120       mach_msg_type_number_t i, npids = sizeof (pidbuf) / sizeof (pidbuf[0]);
 121
 122       err = __proc_getpgrppids (proc, - pid, &pids, &npids);
 123       if (!err)
 124         {
 125           for (i = 0; i < npids; ++i)
 126             {
 127               kill_pid (pids[i]);
 128               if (err == ESRCH)
 129                 /* The process died already.  Ignore it.  */
 130                 err = 0;
 131             }
 132           if (pids != pidbuf)
 133             __vm_deallocate (__mach_task_self (),
 134                              (vm_address_t) pids, npids * sizeof (pids[0]));
 135         }
 136     }
 137   else
 138     kill_pid (pid);
 139
 140   _hurd_port_free (&_hurd_ports[INIT_PORT_PROC], &ulink, proc);
 141
 142   /* If we delivered no signals, but ERR is clear, this must mean that
 143      every kill_pid call failed with ESRCH, meaning all the processes in
 144      the pgrp died between proc_getpgrppids and kill_pid; in that case we
 145      fail with ESRCH.  */
 146   return delivered ? 0 : __hurd_fail (err ?: ESRCH);
 147 }
 148
 149 libc_hidden_def (__kill)
 150 weak_alias (__kill, kill)