sysdeps/unix/sysv/linux/wait4.c

   1 /* Wait for process to change state.  Linux version.
   2    Copyright (C) 2019-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sys/wait.h>
  20 #include <sys/resource.h>
  21 #include <sys/types.h>
  22 #include <sysdep-cancel.h>
  23 #include <tv32-compat.h>
  24
  25 pid_t
  26 __wait4_time64 (pid_t pid, int *stat_loc, int options, struct __rusage64 *usage)
  27 {
  28 #ifdef __NR_wait4
  29 # if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
  30   return SYSCALL_CANCEL (wait4, pid, stat_loc, options, usage);
  31 # else
  32   pid_t ret;
  33   struct __rusage32 usage32;
  34
  35   ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options,
  36                         usage != NULL ? &usage32 : NULL);
  37
  38   if (ret > 0 && usage != NULL)
  39     rusage32_to_rusage64 (&usage32, usage);
  40
  41   return ret;
  42 # endif
  43 #elif defined (__ASSUME_WAITID_PID0_P_PGID)
  44   idtype_t idtype = P_PID;
  45
  46   if (pid < -1)
  47     {
  48       idtype = P_PGID;
  49       pid *= -1;
  50     }
  51   else if (pid == -1)
  52     idtype = P_ALL;
  53   else if (pid == 0)
  54     idtype = P_PGID;
  55
  56   options |= WEXITED;
  57
  58   siginfo_t infop;
  59
  60 # if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
  61   if (SYSCALL_CANCEL (waitid, idtype, pid, &infop, options, usage) < 0)
  62     return -1;
  63 # else
  64   {
  65     struct __rusage32 usage32;
  66     if (SYSCALL_CANCEL (waitid, idtype, pid, &infop, options, &usage32) < 0)
  67       return -1;
  68     if (usage != NULL)
  69       rusage32_to_rusage64 (&usage32, usage);
  70   }
  71 # endif
  72
  73   if (stat_loc)
  74     {
  75       switch (infop.si_code)
  76         {
  77         case CLD_EXITED:
  78           *stat_loc = W_EXITCODE (infop.si_status, 0);
  79           break;
  80         case CLD_DUMPED:
  81           *stat_loc = WCOREFLAG | infop.si_status;
  82           break;
  83         case CLD_KILLED:
  84           *stat_loc = infop.si_status;
  85           break;
  86         case CLD_TRAPPED:
  87         case CLD_STOPPED:
  88           *stat_loc = W_STOPCODE (infop.si_status);
  89           break;
  90         case CLD_CONTINUED:
  91           *stat_loc = __W_CONTINUED;
  92           break;
  93         default:
  94           *stat_loc = 0;
  95           break;
  96         }
  97     }
  98
  99   return infop.si_pid;
 100 #else
 101 /* Linux waitid prior kernel 5.4 does not support waiting for the current
 102    process.  It is possible to emulate wait4 it by calling getpgid for
 103    PID 0, however, it would require an additional syscall and it is inherent
 104    racy: after the current process group is received and before it is passed
 105    to waitid a signal could arrive causing the current process group to
 106    change.  */
 107 # error "The kernel ABI does not provide a way to implement wait4"
 108 #endif
 109 }
 110
 111 #if __TIMESIZE != 64
 112 libc_hidden_def (__wait4_time64)
 113
 114 pid_t
 115 __wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
 116 {
 117   pid_t ret;
 118   struct __rusage64 usage64;
 119
 120   ret = __wait4_time64 (pid, stat_loc, options,
 121                         usage != NULL ? &usage64 : NULL);
 122
 123   if (ret > 0 && usage != 0)
 124     rusage64_to_rusage (&usage64, usage);
 125
 126   return ret;
 127 }
 128 #endif
 129 libc_hidden_def (__wait4);
 130 weak_alias (__wait4, wait4)