sysdeps/posix/waitid.c

   1 /* Pseudo implementation of waitid.
   2    Copyright (C) 1997-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <signal.h>
  23 #define __need_NULL
  24 #include <stddef.h>
  25 #include <sys/wait.h>
  26 #include <sys/types.h>
  27 #include <sysdep-cancel.h>
  28
  29
  30 #ifdef DO_WAITID
  31 # define OUR_WAITID DO_WAITID
  32 #elif !defined NO_DO_WAITID
  33 # define OUR_WAITID do_waitid
  34 #endif
  35
  36 #ifdef OUR_WAITID
  37 static int
  38 OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)
  39 {
  40   pid_t pid, child;
  41   int status;
  42
  43   switch (idtype)
  44     {
  45     case P_PID:
  46       if(id <= 0)
  47         goto invalid;
  48       pid = (pid_t) id;
  49       break;
  50     case P_PGID:
  51       if (id < 0 || id == 1)
  52         goto invalid;
  53       pid = (pid_t) -id;
  54       break;
  55     case P_ALL:
  56       pid = -1;
  57       break;
  58     default:
  59     invalid:
  60       __set_errno (EINVAL);
  61       return -1;
  62     }
  63
  64   /* Technically we're supposed to return EFAULT if infop is bogus,
  65      but that would involve mucking with signals, which is
  66      too much hassle.  User will have to deal with SIGSEGV/SIGBUS.
  67      We just check for a null pointer. */
  68
  69   if (infop == NULL)
  70     {
  71       __set_errno (EFAULT);
  72       return -1;
  73     }
  74
  75   /* This emulation using waitpid cannot support the waitid modes in which
  76      we do not reap the child, or match only stopped and not dead children.  */
  77   if (0
  78 #ifdef WNOWAIT
  79       || (options & WNOWAIT)
  80 #endif
  81 #ifdef WEXITED
  82       || ((options & (WEXITED|WSTOPPED|WCONTINUED))
  83           != (WEXITED | (options & WUNTRACED)))
  84 #endif
  85       )
  86     {
  87       __set_errno (ENOTSUP);
  88       return -1;
  89     }
  90
  91   /* Note the waitid() is a cancellation point.  But since we call
  92      waitpid() which itself is a cancellation point we do not have
  93      to do anything here.  */
  94   child = __waitpid (pid, &status,
  95                      options
  96 #ifdef WEXITED
  97                      &~ WEXITED
  98 #endif
  99                      );
 100
 101   if (child == -1)
 102     /* `waitpid' set `errno' for us.  */
 103     return -1;
 104
 105   if (child == 0)
 106     {
 107       /* The WHOHANG bit in OPTIONS is set and there are children available
 108          but none has a status for us.  The XPG docs do not mention this
 109          case so we clear the `siginfo_t' struct and return successfully.  */
 110       infop->si_signo = 0;
 111       infop->si_code = 0;
 112       return 0;
 113     }
 114
 115   /* Decode the status field and set infop members... */
 116   infop->si_signo = SIGCHLD;
 117   infop->si_pid = child;
 118   infop->si_errno = 0;
 119
 120   if (WIFEXITED (status))
 121     {
 122       infop->si_code = CLD_EXITED;
 123       infop->si_status = WEXITSTATUS (status);
 124     }
 125   else if (WIFSIGNALED (status))
 126     {
 127       infop->si_code = WCOREDUMP (status) ? CLD_DUMPED : CLD_KILLED;
 128       infop->si_status = WTERMSIG (status);
 129     }
 130   else if (WIFSTOPPED (status))
 131     {
 132       infop->si_code = CLD_STOPPED;
 133       infop->si_status = WSTOPSIG (status);
 134     }
 135 #ifdef WIFCONTINUED
 136   else if (WIFCONTINUED (status))
 137     {
 138       infop->si_code = CLD_CONTINUED;
 139       infop->si_status = SIGCONT;
 140     }
 141 #endif
 142   else
 143     /* Can't happen. */
 144     assert (! "What?");
 145
 146   return 0;
 147 }
 148 #endif
 149
 150
 151 int
 152 __waitid (idtype, id, infop, options)
 153      idtype_t idtype;
 154      id_t id;
 155      siginfo_t *infop;
 156      int options;
 157 {
 158   if (SINGLE_THREAD_P)
 159     return do_waitid (idtype, id, infop, options);
 160
 161   int oldtype = LIBC_CANCEL_ASYNC ();
 162
 163   int result = do_waitid (idtype, id, infop, options);
 164
 165   LIBC_CANCEL_RESET (oldtype);
 166
 167   return result;
 168 }
 169 weak_alias (__waitid, waitid)
 170 strong_alias (__waitid, __libc_waitid)