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explain_getpriority(3)	   Library Functions Manual	explain_getpriority(3)

NAME
       explain_getpriority - explain getpriority(2) errors

SYNOPSIS
       #include	<libexplain/getpriority.h>
       const char *explain_getpriority(int which, int who);
       const char *explain_errno_getpriority(int errnum, int which, int	who);
       void explain_message_getpriority(char *message, int message_size, int
       which, int who);
       void explain_message_errno_getpriority(char *message, int message_size,
       int errnum, int which, int who);

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

   explain_getpriority
       const char *explain_getpriority(int which, int who);

       The explain_getpriority function	is used	to obtain an explanation of an
       error returned by the getpriority(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.

       which   The original which, exactly as  passed  to  the	getpriority(2)
	       system call.

       who     The  original who, exactly as passed to the getpriority(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:
	      int result = getpriority(which, who);
	      if (result < 0)
	      {
		  fprintf(stderr, "%s\n", explain_getpriority(which, who));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_getpriority
       const char *explain_errno_getpriority(int errnum, int which, int	who);

       The explain_errno_getpriority function is used to obtain	an explanation
       of an error returned by the getpriority(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.

       which   The original which, exactly as  passed  to  the	getpriority(2)
	       system call.

       who     The  original who, exactly as passed to the getpriority(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:
	      int result = getpriority(which, who);
	      if (result < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_getpriority(err,
		  which, who));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_getpriority
       void explain_message_getpriority(char *message, int message_size, int
       which, int who);

       The  explain_message_getpriority	function is used to obtain an explana-
       tion of an error	returned by the	getpriority(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  de-
       tail.

       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.

       which   The  original  which,  exactly  as passed to the	getpriority(2)
	       system call.

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

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

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

   explain_message_errno_getpriority
       void explain_message_errno_getpriority(char *message, int message_size,
       int errnum, int which, int who);

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

       which   The original which, exactly as  passed  to  the	getpriority(2)
	       system call.

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

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

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

SEE ALSO
       getpriority(2)
	       get program scheduling priority

       explain_getpriority_or_die(3)
	       get program scheduling priority and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2013 Peter	Miller

							explain_getpriority(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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