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explain_setregid(3)	   Library Functions Manual	   explain_setregid(3)

NAME
       explain_setregid	- explain setregid(2) errors

SYNOPSIS
       #include	<libexplain/setregid.h>
       const char *explain_setregid(gid_t rgid,	gid_t egid);
       const char *explain_errno_setregid(int errnum, gid_t rgid, gid_t	egid);
       void explain_message_setregid(char *message, int	message_size, gid_t
       rgid, gid_t egid);
       void explain_message_errno_setregid(char	*message, int message_size,
       int errnum, gid_t rgid, gid_t egid);

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

   explain_setregid
       const char *explain_setregid(gid_t rgid,	gid_t egid);

       The explain_setregid function is	used to	obtain an  explanation	of  an
       error  returned	by  the	setregid(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.

       rgid    The original rgid, exactly as passed to the setregid(2)	system
	       call.

       egid    The  original egid, exactly as passed to	the setregid(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.

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

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

   explain_errno_setregid
       const char *explain_errno_setregid(int errnum, gid_t rgid, gid_t	egid);

       The explain_errno_setregid function is used to obtain an	explanation of
       an  error  returned by the setregid(2) system call.  The	least the mes-
       sage 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.

       rgid    The  original rgid, exactly as passed to	the setregid(2)	system
	       call.

       egid    The original egid, exactly as passed to the setregid(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.

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

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

   explain_message_setregid
       void explain_message_setregid(char *message, int	message_size, gid_t
       rgid, gid_t egid);

       The explain_message_setregid function is	used to	obtain an  explanation
       of  an  error  returned	by the setregid(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.

       rgid    The  original rgid, exactly as passed to	the setregid(2)	system
	       call.

       egid    The original egid, exactly as passed to the setregid(2)	system
	       call.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      if (setregid(rgid, egid) < 0)
	      {
		  char message[3000];
		  explain_message_setregid(message, sizeof(message), rgid,
		  egid);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_errno_setregid
       void explain_message_errno_setregid(char	*message, int message_size,
       int errnum, gid_t rgid, gid_t egid);

       The explain_message_errno_setregid function is used to obtain an	expla-
       nation  of an error returned by the setregid(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.

       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.

       rgid    The  original rgid, exactly as passed to	the setregid(2)	system
	       call.

       egid    The original egid, exactly as passed to the setregid(2)	system
	       call.

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

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

SEE ALSO
       setregid(2)
	       set real	and/or effective group ID

       explain_setregid_or_die(3)
	       set real	and/or effective group ID and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2012 Peter	Miller

							   explain_setregid(3)

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