explain_waitpid(3)					     Library Functions Manual						explain_waitpid(3)

NAME

       explain_waitpid - explain waitpid(2) errors

SYNOPSIS

       #include <libexplain/waitpid.h>
       const char *explain_waitpid(int pid, int *status, int options);
       const char *explain_errno_waitpid(int errnum, int pid, int *status, int options);
       void explain_message_waitpid(char *message, int message_size, int pid, int *status, int options);
       void explain_message_errno_waitpid(char *message, int message_size, int errnum, int pid, int *status, int options);

DESCRIPTION

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

   explain_waitpid
       const char *explain_waitpid(int pid, int *status, int options);

       The  explain_waitpid  function  is used to obtain an explanation of an error returned by the waitpid(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 following example:
	      if (waitpid(pid, status, options) < 0)
	      {
		  fprintf(stderr, "%s
", explain_waitpid(pid, status, options));
		  exit(EXIT_FAILURE);
	      }

       pid     The original pid, exactly as passed to the waitpid(2) system call.

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

       options The original options, exactly as passed to the waitpid(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, including other
	       threads.

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

   explain_errno_waitpid
       const char *explain_errno_waitpid(int errnum, int pid, int *status, int options);

       The explain_errno_waitpid function is used to obtain an explanation of an error returned by the waitpid(2) system call.	The least the mes-
       sage 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 following example:
	      if (waitpid(pid, status, options) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s
", explain_errno_waitpid(err,
		      pid, status, options));
		  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 neces-
	       sary 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.

       pid     The original pid, exactly as passed to the waitpid(2) system call.

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

       options The original options, exactly as passed to the waitpid(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,  including  other
	       threads.

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

   explain_message_waitpid
       void explain_message_waitpid(char *message, int message_size, int pid, int *status, int options);

       The  explain_message_waitpid  function may be used to  obtain an explanation of an error returned by the waitpid(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 following example:
	      if (waitpid(pid, status, options) < 0)
	      {
		  char message[3000];
		  explain_message_waitpid(message, sizeof(message), pid, status, options);
		  fprintf(stderr, "%s
", 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 returned message.

       pid     The original pid, exactly as passed to the waitpid(2) system call.

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

       options The original options, exactly as passed to the waitpid(2) system call.

   explain_message_errno_waitpid
       void explain_message_errno_waitpid(char *message, int message_size, int errnum, int pid, int *status, int options);

       The explain_message_errno_waitpid function may be used to obtain an explanation of an error returned by the waitpid(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 following example:
	      if (waitpid(pid, status, options) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_waitpid(message, sizeof(message), err,
		      pid, status, options);
		  fprintf(stderr, "%s
", 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 returned message.

       errnum  The error value to be decoded, usually obtained from the errno global variable just before this function is called.  This is neces-
	       sary 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.

       pid     The original pid, exactly as passed to the waitpid(2) system call.

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

       options The original options, exactly as passed to the waitpid(2) system call.

SEE ALSO

       waitpid(2)
	       wait for process to change state

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

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2008 Peter Miller

																explain_waitpid(3)