compiler/posixc/waitpid.c

   1 /*
   2     Copyright © 2004-2012, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #define DEBUG 0
   7
   8 #include <aros/debug.h>
   9 #include <proto/exec.h>
  10 #include <exec/lists.h>
  11 #include <exec/tasks.h>
  12
  13 #include <errno.h>
  14
  15 /*****************************************************************************
  16
  17     NAME */
  18 #include <sys/wait.h>
  19
  20         pid_t waitpid(
  21
  22 /*  SYNOPSIS */
  23         pid_t pid,
  24         int *status,
  25         int options)
  26
  27 /*  FUNCTION
  28         Waits for child process with given process id to change state. State
  29         change is one of the following events: child has exited, child was
  30         terminated by a signal, child was stopped by a signal, child was
  31         resumed by a signal.
  32
  33         The function stores status of the process that changed state in the
  34         pointer given as status argument.
  35
  36         The following macros can be used to extract information from the
  37         status value:
  38
  39         WIFEXITED(status)    - true if the process has exited
  40         WEXITSTATUS(status)  - exit status of the exited process
  41         WIFSIGNALED(status)  - true if the child process was terminated by a
  42                                signal
  43         WTERMSIG(status)     - number of the signal that caused process
  44                                termination
  45         WIFSTOPPED(status)   - true if the child process was stopped by a
  46                                signal
  47         WSTOPSIG(status)     - number of the signal that caused child process
  48                                stop
  49         WIFCONTINUED(status) - true if the child process was resumed by the
  50                                SIGCONT signal.
  51
  52         Unless WNOHANG option is set, parent process will be suspended until a
  53         child changes state. If a child process has already changed state,
  54         function returns immediately.
  55
  56     INPUTS
  57         pid - Process id of the process you want to wait for or -1 to wait for
  58                 any child process
  59         status - Pointer to int where child status will be stored or NULL if
  60                 you don't want to store status.
  61         options - ORed zero or more of the following constants:
  62
  63             WNOHANG - return immediately if no child process changed state
  64
  65     RESULT
  66         Process id of the child process on success or -1 on error. If an error
  67         occurred, the global variable errno is set.
  68
  69     NOTES
  70         This function will work only for child processeses notifying parent
  71         process of their death, for example processes created by vfork() call.
  72         If you want to use it for other processes, remember to set the
  73         NP_NotifyOnDeath tag value to TRUE during child process creation.
  74
  75     EXAMPLE
  76
  77     BUGS
  78
  79     SEE ALSO
  80         wait()
  81
  82     INTERNALS
  83         Since POSIX signals are not yet implemented, WIFSIGNALED, WIFSTOPPED
  84         and WIFCONTINUED macros always return 0. WIFEXITED always returns 1.
  85
  86         The et_UniqueID field of the ETask structure is used as process id.
  87
  88 ******************************************************************************/
  89 {
  90     struct ETask *et;
  91     ULONG tid = pid;
  92     pid_t ret = -1;
  93     int exchildno;
  94
  95     D(bug("waitpid(%d, %p, %d)\n", pid, status, options));
  96
  97     et = GetETask(FindTask(NULL));
  98     if(!et)
  99     {
 100         /* only ETasks are fertile */
 101         errno = ECHILD;
 102         return -1;
 103     }
 104
 105     if (pid < -1 || pid == 0)
 106     {
 107         /* process groups not yet supported */
 108         errno = EINVAL;
 109         return -1;
 110     }
 111
 112     if (pid == -1)
 113         tid = 0;
 114
 115     if(tid != 0 && ChildStatus(tid) == CHILD_NOTFOUND)
 116     {
 117         /* error if there's no such child */
 118         errno = ECHILD;
 119         return -1;
 120     }
 121
 122     if (options & ~WNOHANG)
 123     {
 124         /* option not yet supported */
 125         errno = EINVAL;
 126         return -1;
 127     }
 128
 129     /* not very pretty, perhaps we need a function for counting dead
 130        children? */
 131     ListLength(&et->et_TaskMsgPort.mp_MsgList, exchildno);
 132     if ((options & WNOHANG) && (
 133         (tid != 0 && ChildStatus(tid) != CHILD_EXITED) ||
 134         (tid == 0 && exchildno == 0)
 135     ))
 136     {
 137         D(bug("waitpid: no dead children\n"));
 138         /* no dead children atm */
 139         return 0;
 140     }
 141
 142     D(bug("waitpid: wait for %d to die\n", tid));
 143     et = (struct ETask *)ChildWait(tid);
 144     if (et != (struct ETask *)CHILD_NOTNEW)
 145     {
 146         if(status)
 147         {
 148             *status = et->et_Result1;
 149         }
 150         ret = et->et_UniqueID;
 151         ChildFree(et->et_UniqueID);
 152     }
 153     else
 154         errno = ECHILD;
 155
 156     D(bug("waitpid: leaving (%d)\n", ret));
 157
 158     return ret;
 159 }