include/sys/wait.h

   1 #ifndef _SYS_WAIT_H_
   2 #define _SYS_WAIT_H_
   3
   4 #include <sys/cdefs.h>
   5 #include <sys/types.h>
   6 #include <sys/featuretest.h>
   7
   8 /* The <sys/wait.h> header contains macros related to wait(). The value
   9  * returned by wait() and waitpid() depends on whether the process
  10  * terminated by an exit() call, was killed by a signal, or was stopped
  11  * due to job control, as follows:
  12  *
  13  *                               High byte   Low byte
  14  *                              +---------------------+
  15  *      exit(status)            |  status  |    0     |
  16  *                              +---------------------+
  17  *      killed by signal        |    0     |  signal  |
  18  *                              +---------------------+
  19  *      stopped (job control)   |  signal  |   0177   |
  20  *                              +---------------------+
  21  */
  22
  23 /*
  24  * Macros to test the exit status returned by wait
  25  * and extract the relevant values.
  26  */
  27
  28 #define _LOW(v)         ( (v) & 0377)
  29 #define _HIGH(v)        ( ((v) >> 8) & 0377)
  30
  31 #define WIFEXITED(s)    (_LOW(s) == 0)                      /* normal exit */
  32 #define WEXITSTATUS(s)  (_HIGH(s))                          /* exit status */
  33 #define WTERMSIG(s)     (_LOW(s) & 0177)                    /* sig value */
  34 #define WIFSIGNALED(s)  ((((unsigned int)(s)-1) & 0xFFFFU) < 0xFFU) /* signaled */
  35 #define WIFSTOPPED(s)   (_LOW(s) == 0177)                   /* stopped */
  36 #define WSTOPSIG(s)     (_HIGH(s) & 0377)                   /* stop signal */
  37
  38 /*
  39  * Option bits for the third argument of waitpid.  WNOHANG causes the
  40  * wait to not hang if there are no stopped or terminated processes, rather
  41  * returning an error indication in this case (pid==0).  WUNTRACED
  42  * indicates that the caller should receive status about untraced children
  43  * which stop due to signals.  If children are stopped and a wait without
  44  * this option is done, it is as though they were still running... nothing
  45  * about them is returned.
  46  */
  47 #define WNOHANG         0x00000001      /* don't hang in wait */
  48 #define WUNTRACED       0x00000002      /* tell about stopped,
  49                                            untraced children */
  50
  51 /* POSIX extensions and 4.2/4.3 compatibility: */
  52
  53 /*
  54  * Tokens for special values of the "pid" parameter to waitpid.
  55  */
  56 #define WAIT_ANY        (-1)    /* any process */
  57 #define WAIT_MYPGRP     0       /* any process in my process group */
  58
  59 __BEGIN_DECLS
  60 pid_t   wait(int *);
  61 pid_t   waitpid(pid_t, int *, int);
  62 __END_DECLS
  63
  64 #endif /* !_SYS_WAIT_H_ */