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explain_getgrouplist(3)	   Library Functions Manual    explain_getgrouplist(3)

NAME
       explain_getgrouplist - explain getgrouplist(3) errors

SYNOPSIS
       #include	<libexplain/getgrouplist.h>
       const char *explain_getgrouplist(const char *user, gid_t	group, gid_t
       *groups,	int *ngroups);
       const char *explain_errno_getgrouplist(int errnum, const	char *user,
       gid_t group, gid_t *groups, int *ngroups);
       void explain_message_getgrouplist(char *message,	int message_size,
       const char *user, gid_t group, gid_t *groups, int *ngroups);
       void explain_message_errno_getgrouplist(char *message, int mes-
       sage_size, int errnum, const char *user,	gid_t group, gid_t *groups,
       int *ngroups);

DESCRIPTION
       These functions may be used to obtain explanations for errors  returned
       by the getgrouplist(3) system call.

   explain_getgrouplist
       const char *explain_getgrouplist(const char *user, gid_t	group, gid_t
       *groups,	int *ngroups);

       The explain_getgrouplist	function is used to obtain an  explanation  of
       an  error  returned  by	the getgrouplist(3) 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.

       user    The original user, exactly as  passed  to  the  getgrouplist(3)
	       system call.

       group   The  original  group,  exactly as passed	to the getgrouplist(3)
	       system call.

       groups  The original groups, exactly as passed to  the  getgrouplist(3)
	       system call.

       ngroups The  original ngroups, exactly as passed	to the getgrouplist(3)
	       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:
	      errno = 0;
	      if (getgrouplist(user, group, groups, ngroups) < 0 && errno !=
	      0)
	      {
		  fprintf(stderr, "%s\n", explain_getgrouplist(user, group,
		  groups, ngroups));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_getgrouplist
       const char *explain_errno_getgrouplist(int errnum, const	char *user,
       gid_t group, gid_t *groups, int *ngroups);

       The explain_errno_getgrouplist function is used to obtain  an  explana-
       tion of an error	returned by the	getgrouplist(3)	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.

       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.

       user    The original user, exactly as  passed  to  the  getgrouplist(3)
	       system call.

       group   The  original  group,  exactly as passed	to the getgrouplist(3)
	       system call.

       groups  The original groups, exactly as passed to  the  getgrouplist(3)
	       system call.

       ngroups The  original ngroups, exactly as passed	to the getgrouplist(3)
	       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:
	      errno = 0;
	      if (getgrouplist(user, group, groups, ngroups) < 0 && errno !=
	      0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_getgrouplist(err,
		  user,	group, groups, ngroups));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_getgrouplist
       void explain_message_getgrouplist(char *message,	int message_size,
       const char *user, gid_t group, gid_t *groups, int *ngroups);

       The explain_message_getgrouplist	function is used to obtain an explana-
       tion of an error	returned by the	getgrouplist(3)	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.

       user    The original user, exactly as  passed  to  the  getgrouplist(3)
	       system call.

       group   The  original  group,  exactly as passed	to the getgrouplist(3)
	       system call.

       groups  The original groups, exactly as passed to  the  getgrouplist(3)
	       system call.

       ngroups The  original ngroups, exactly as passed	to the getgrouplist(3)
	       system call.

       Example:	This function is intended to be	used in	a fashion  similar  to
       the following example:
	      errno = 0;
	      if (getgrouplist(user, group, groups, ngroups) < 0 && errno !=
	      0)
	      {
		  char message[3000];
		  explain_message_getgrouplist(message,	sizeof(message), user,
		  group, groups, ngroups);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_errno_getgrouplist
       void explain_message_errno_getgrouplist(char *message, int mes-
       sage_size, int errnum, const char *user,	gid_t group, gid_t *groups,
       int *ngroups);

       The explain_message_errno_getgrouplist function is used	to  obtain  an
       explanation  of	an  error returned by the getgrouplist(3) 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.

       user    The  original  user,  exactly  as passed	to the getgrouplist(3)
	       system call.

       group   The original group, exactly as passed  to  the  getgrouplist(3)
	       system call.

       groups  The  original  groups, exactly as passed	to the getgrouplist(3)
	       system call.

       ngroups The original ngroups, exactly as	passed to the  getgrouplist(3)
	       system call.

       Example:	 This  function	is intended to be used in a fashion similar to
       the following example:
	      errno = 0;
	      if (getgrouplist(user, group, groups, ngroups) < 0 && errno !=
	      0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_getgrouplist(message, sizeof(message),
		  err, user, group, groups, ngroups);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

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

SEE ALSO
       getgrouplist(3)
	       get list	of groups to which a user belongs

       explain_getgrouplist_or_die(3)
	       get list	of groups to which a user belongs and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2013 Peter	Miller

						       explain_getgrouplist(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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