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explain_wait(3)		   Library Functions Manual	       explain_wait(3)

NAME
       explain_wait - explain wait(2) errors

SYNOPSIS
       #include	<libexplain/wait.h>
       const char *explain_wait(int *status);
       const char *explain_errno_wait(int errnum, int *status);
       void  explain_message_wait(char	*message,  int message_size, int *sta-
       tus);
       void explain_message_errno_wait(char *message,  int  message_size,  int
       errnum, int *status);

DESCRIPTION
       These  functions	may be used to obtain explanations for errors returned
       by the wait(2) system call.

   explain_wait
       const char *explain_wait(int *status);

       The explain_wait	function is used to obtain an explanation of an	 error
       returned	 by  the wait(2) system	call.  The least the message will con-
       tain is the value of strerror(errno), but usually it will do much  bet-
       ter, and	indicate the underlying	cause in more detail.

       The  errno global variable will be used to obtain the error value to be
       decoded.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (wait(status) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_wait(status));
		  exit(EXIT_FAILURE);
	      }

       status  The  original  status,  exactly as passed to the	wait(2)	system
	       call.

       Returns:
	       The message explaining  the  error.   This  message  buffer  is
	       shared by all libexplain	functions which	do not supply a	buffer
	       in their	argument list.	This will be overwritten by  the  next
	       call  to	 any libexplain	function which shares this buffer, in-
	       cluding other threads.

       Note: This function is not thread safe, because it shares a return buf-
       fer across all threads, and many	other functions	in this	library.

   explain_errno_wait
       const char *explain_errno_wait(int errnum, int *status);

       The  explain_errno_wait function	is used	to obtain an explanation of an
       error returned by the wait(2) system call.  The least the message  will
       contain	is  the	value of strerror(errnum), but usually it will do much
       better, and indicate the	underlying cause in more detail.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (wait(status) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_wait(err, status));
		  exit(EXIT_FAILURE);
	      }

       errnum  The  error value	to be decoded, usually obtained	from the errno
	       global variable just before this	function is called.   This  is
	       necessary  if you need to call any code between the system call
	       to be explained and this	function, because many libc  functions
	       will alter the value of errno.

       status  The  original  status,  exactly as passed to the	wait(2)	system
	       call.

       Returns:
	       The message explaining  the  error.   This  message  buffer  is
	       shared by all libexplain	functions which	do not supply a	buffer
	       in their	argument list.	This will be overwritten by  the  next
	       call  to	 any libexplain	function which shares this buffer, in-
	       cluding other threads.

       Note: This function is not thread safe, because it shares a return buf-
       fer across all threads, and many	other functions	in this	library.

   explain_message_wait
       void  explain_message_wait(char	*message,  int message_size, int *sta-
       tus);

       The explain_message_wait	function may be	used to	 obtain	an explanation
       of an error returned by the wait(2) system call.	 The least the message
       will contain is the value of strerror(errno), but usually  it  will  do
       much better, and	indicate the underlying	cause in more detail.

       The  errno global variable will be used to obtain the error value to be
       decoded.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (wait(status) < 0)
	      {
		  char message[3000];
		  explain_message_wait(message,	sizeof(message), status);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       message The  location  in  which	 to  store the returned	message.  If a
	       suitable	message	return buffer is supplied,  this  function  is
	       thread safe.

       message_size
	       The  size  in  bytes  of	the location in	which to store the re-
	       turned message.

       status  The original status, exactly as passed to  the  wait(2)	system
	       call.

   explain_message_errno_wait
       void  explain_message_errno_wait(char  *message,	 int message_size, int
       errnum, int *status);

       The explain_message_errno_wait function may be used to obtain an	expla-
       nation  of an error returned by the wait(2) system call.	 The least the
       message will contain is the value of strerror(errnum), but  usually  it
       will do much better, and	indicate the underlying	cause in more detail.

       This  function  is intended to be used in a fashion similar to the fol-
       lowing example:
	      if (wait(status) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_wait(message, sizeof(message), err, status);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       message The location in which to	store  the  returned  message.	 If  a
	       suitable	 message  return  buffer is supplied, this function is
	       thread safe.

       message_size
	       The size	in bytes of the	location in which  to  store  the  re-
	       turned message.

       errnum  The  error value	to be decoded, usually obtained	from the errno
	       global variable just before this	function is called.   This  is
	       necessary  if you need to call any code between the system call
	       to be explained and this	function, because many libc  functions
	       will alter the value of errno.

       status  The  original  status,  exactly as passed to the	wait(2)	system
	       call.

SEE ALSO
       wait(2) wait for	process	to change state

       explain_wait_or_die(3)
	       wait for	process	to change state	and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2008 Peter	Miller

							       explain_wait(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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