2.9BSD - /usr/include/wait.h

   1: /*
   2:  * this file holds definitions relevent to the (new) wait2 system call
   3:  * this system call is similar to the standard "wait" system call
   4:  * except that it has a second argument whose bits indicate certain
   5:  * options to the behavior of the system call
   6:  */
   7: 
   8: /*
   9:  * structure of the int returned in the "int" pointed to by the
  10:  * first argument to the system call.  two substructures are distinguished
  11:  * by a test: if (w_stopval == WSTOPPED) then the second one applies
  12:  * other wise the first one applies.
  13:  */
  14: 
  15: union   wait    {
  16:     int w_status;       /* to keep lint happy - used
  17: 					   (with &) in actual syscall*/
  18:     struct {            /* to keep the code readable? */
  19:         short   w_Termsig:7;    /* termination signal */
  20:         short   w_Coredump:1;   /* core dump indicator */
  21:         short   w_Retcode:8;    /* program return code via exit
  22: 					   valid if w_termsig == 0 */
  23:     } w_T;              /* terminated process status */
  24:     struct {
  25:         short   w_Stopval:8;    /* stop value flag */
  26:         short   w_Stopsig:8;    /* signal that stopped us */
  27:     } w_S;              /* stopped process status */
  28: };
  29: #define w_termsig   w_T.w_Termsig
  30: #define w_coredump  w_T.w_Coredump
  31: #define w_retcode   w_T.w_Retcode
  32: #define w_stopval   w_S.w_Stopval
  33: #define w_stopsig   w_S.w_Stopsig
  34: 
  35: 
  36: #define WSTOPPED    0177    /* value of s.stopval if process is stopped */
  37: 
  38: #define WNOHANG     1   /* option bit indicating that the caller should
  39: 				   not hang if no child processes have stopped
  40: 				   or terminated, but rather return zero as th
  41: 				   process id */
  42: #define WUNTRACED   2   /* option bit indicating that the caller should
  43: 				   receive status about untraced children that
  44: 				   stop due to signals. The default is that
  45: 				   the caller never sees status for such
  46: 				   processes, thus they appear to stay in the
  47: 				   running state even though they are in fact
  48: 				   stopped. */
  49: #define WIFSTOPPED(x)   ((x).w_stopval == WSTOPPED)
  50: #define WIFSIGNALED(x)  ((x).w_stopval != WSTOPPED && (x).w_termsig != 0)
  51: #define WIFEXITED(x)    ((x).w_stopval != WSTOPPED && (x).w_termsig == 0)

Defined union's

Defined macros

Usage of this include