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explain_getrusage(3)	   Library Functions Manual	  explain_getrusage(3)

NAME
       explain_getrusage - explain getrusage(2)	errors

SYNOPSIS
       #include	<libexplain/getrusage.h>
       const char *explain_getrusage(int who, struct rusage *usage);
       const char *explain_errno_getrusage(int errnum, int who,	struct rusage
       *usage);
       void explain_message_getrusage(char *message, int message_size, int
       who, struct rusage *usage);
       void explain_message_errno_getrusage(char *message, int message_size,
       int errnum, int who, struct rusage *usage);

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

   explain_getrusage
       const char *explain_getrusage(int who, struct rusage *usage);

       The  explain_getrusage  function	is used	to obtain an explanation of an
       error returned by the getrusage(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.

       who     The  original who, exactly as passed to the getrusage(2)	system
	       call.

       usage   The original usage, exactly as passed to	the getrusage(2)  sys-
	       tem 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 buf-
       fer across all threads, and many	other functions	in this	library.

       Example:	This function is intended to be	used in	a fashion  similar  to
       the following example:
	      if (getrusage(who, usage)	< 0)
	      {
		  fprintf(stderr, "%s\n", explain_getrusage(who, usage));
		  exit(EXIT_FAILURE);
	      }

       The   above   code   example  is	 available  pre-packaged  as  the  ex-
       plain_getrusage_or_die(3) function.

   explain_errno_getrusage
       const char *explain_errno_getrusage(int errnum, int who,	struct rusage
       *usage);

       The  explain_errno_getrusage  function is used to obtain	an explanation
       of an error returned by the getrusage(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.

       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.

       who     The original who, exactly as passed to the getrusage(2)	system
	       call.

       usage   The  original usage, exactly as passed to the getrusage(2) sys-
	       tem 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 buf-
       fer across all threads, and many	other functions	in this	library.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      if (getrusage(who, usage)	< 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_getrusage(err, who,
		  usage));
		  exit(EXIT_FAILURE);
	      }

       The   above   code   example  is	 available  pre-packaged  as  the  ex-
       plain_getrusage_or_die(3) function.

   explain_message_getrusage
       void explain_message_getrusage(char *message, int message_size, int
       who, struct rusage *usage);

       The explain_message_getrusage function is used to obtain	an explanation
       of an error returned by the getrusage(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.

       message The location in which to	store the returned message. If a suit-
	       able 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.

       who     The original who, exactly as passed to the getrusage(2)	system
	       call.

       usage   The  original usage, exactly as passed to the getrusage(2) sys-
	       tem call.

       Example:	This function is intended to be	used in	a fashion  similar  to
       the following example:
	      if (getrusage(who, usage)	< 0)
	      {
		  char message[3000];
		  explain_message_getrusage(message, sizeof(message), who, us-
		  age);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The  above  code	 example  is  available	 pre-packaged	as   the   ex-
       plain_getrusage_or_die(3) function.

   explain_message_errno_getrusage
       void explain_message_errno_getrusage(char *message, int message_size,
       int errnum, int who, struct rusage *usage);

       The explain_message_errno_getrusage function is used to obtain  an  ex-
       planation  of  an  error	returned by the	getrusage(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.

       message The location in which to	store the returned message. If a suit-
	       able 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.

       who     The  original who, exactly as passed to the getrusage(2)	system
	       call.

       usage   The original usage, exactly as passed to	the getrusage(2)  sys-
	       tem call.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      if (getrusage(who, usage)	< 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_getrusage(message, sizeof(message),
		  err, who, usage);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The   above   code   example  is	 available  pre-packaged  as  the  ex-
       plain_getrusage_or_die(3) function.

SEE ALSO
       getrusage(2)
	       get resource usage

       explain_getrusage_or_die(3)
	       get resource usage and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2013 Peter	Miller

							  explain_getrusage(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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