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explain_getgroups(3)	   Library Functions Manual	  explain_getgroups(3)

NAME
       explain_getgroups - explain getgroups(2)	errors

SYNOPSIS
       #include	<libexplain/getgroups.h>
       const char *explain_getgroups(int data_size, gid_t *data);
       const char *explain_errno_getgroups(int errnum, int data_size, gid_t
       *data);
       void explain_message_getgroups(char *message, int message_size, int
       data_size, gid_t	*data);
       void explain_message_errno_getgroups(char *message, int message_size,
       int errnum, int data_size, gid_t	*data);

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

   explain_getgroups
       const char *explain_getgroups(int data_size, gid_t *data);

       The  explain_getgroups  function	is used	to obtain an explanation of an
       error returned by the getgroups(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.

       data_size
	       The  original  data_size, exactly as passed to the getgroups(2)
	       system call.

       data    The original data, exactly as passed to the getgroups(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 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 (getgroups(data_size, data) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_getgroups(data_size, data));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_getgroups
       const char *explain_errno_getgroups(int errnum, int data_size, gid_t
       *data);

       The  explain_errno_getgroups  function is used to obtain	an explanation
       of an error returned by the getgroups(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.

       data_size
	       The original data_size, exactly as passed to  the  getgroups(2)
	       system call.

       data    The original data, exactly as passed to the getgroups(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 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 (getgroups(data_size, data) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_getgroups(err,
		  data_size, data));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_getgroups
       void explain_message_getgroups(char *message, int message_size, int
       data_size, gid_t	*data);

       The explain_message_getgroups function is used to obtain	an explanation
       of an error returned by the getgroups(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.

       data_size
	       The original data_size, exactly as passed to  the  getgroups(2)
	       system call.

       data    The original data, exactly as passed to the getgroups(2)	system
	       call.

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

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

   explain_message_errno_getgroups
       void explain_message_errno_getgroups(char *message, int message_size,
       int errnum, int data_size, gid_t	*data);

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

       data_size
	       The  original  data_size, exactly as passed to the getgroups(2)
	       system call.

       data    The original data, exactly as passed to the getgroups(2)	system
	       call.

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

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

SEE ALSO
       getgroups(2)
	       get/set list of supplementary group IDs

       explain_getgroups_or_die(3)
	       get/set list of supplementary group IDs and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2009 Peter	Miller

							  explain_getgroups(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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