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explain_getsockopt(3)	   Library Functions Manual	 explain_getsockopt(3)

NAME
       explain_getsockopt - explain getsockopt(2) errors

SYNOPSIS
       #include	<libexplain/getsockopt.h>
       const  char  *explain_getsockopt(int  fildes, int level,	int name, void
       *data, socklen_t	*data_size);
       const char *explain_errno_getsockopt(int	errnum,	int fildes, int	level,
       int name, void *data, socklen_t *data_size);
       void  explain_message_getsockopt(char  *message,	 int message_size, int
       fildes, int level, int name, void *data,	socklen_t *data_size);
       void explain_message_errno_getsockopt(char *message, int	 message_size,
       int  errnum,  int  fildes,  int	level, int name, void *data, socklen_t
       *data_size);

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

   explain_getsockopt
       const  char  *explain_getsockopt(int  fildes, int level,	int name, void
       *data, socklen_t	*data_size);

       The explain_getsockopt function is used to obtain an explanation	of  an
       error returned by the getsockopt(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.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (getsockopt(fildes, level, name, data,	data_size) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_getsockopt(fildes,
		      level, name, data, data_size));
		  exit(EXIT_FAILURE);
	      }

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

       fildes  The original fildes, exactly as	passed	to  the	 getsockopt(2)
	       system call.

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

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

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

       data_size
	       The original data_size, exactly as passed to the	 getsockopt(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,  in-
	       cluding 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.

   explain_errno_getsockopt
       const char *explain_errno_getsockopt(int	errnum,	int fildes, int	level,
       int name, void *data, socklen_t *data_size);

       The  explain_errno_getsockopt function is used to obtain	an explanation
       of an error returned by the getsockopt(2) system	call.  The  least  the
       message	will  contain is the value of strerror(errnum),	but usually it
       will do much better, and	indicate the underlying	cause in more detail.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (getsockopt(fildes, level, name, data,	data_size) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_getsockopt(err,
		      fildes, level, name, data, data_size));
		  exit(EXIT_FAILURE);
	      }

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

       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.

       fildes  The original fildes, exactly as	passed	to  the	 getsockopt(2)
	       system call.

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

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

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

       data_size
	       The original data_size, exactly as passed to the	 getsockopt(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,  in-
	       cluding 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.

   explain_message_getsockopt
       void explain_message_getsockopt(char *message,  int  message_size,  int
       fildes, int level, int name, void *data,	socklen_t *data_size);

       The  explain_message_getsockopt	function may be	used to	 obtain	an ex-
       planation of an error returned by the getsockopt(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.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (getsockopt(fildes, level, name, data,	data_size) < 0)
	      {
		  char message[3000];
		  explain_message_getsockopt(message, sizeof(message),
		      fildes, level, name, data, data_size);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

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

       message The location in which to	store  the  returned  message.	 If  a
	       suitable	 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.

       fildes  The  original  fildes,  exactly	as passed to the getsockopt(2)
	       system call.

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

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

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

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

   explain_message_errno_getsockopt
       void explain_message_errno_getsockopt(char *message, int	 message_size,
       int  errnum,  int  fildes,  int	level, int name, void *data, socklen_t
       *data_size);

       The explain_message_errno_getsockopt function may be used to obtain  an
       explanation of an error returned	by the getsockopt(2) system call.  The
       least the message will contain is the value  of	strerror(errnum),  but
       usually	it  will  do much better, and indicate the underlying cause in
       more detail.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (getsockopt(fildes, level, name, data,	data_size) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_getsockopt(message, sizeof(message),
		      err, fildes, level, name,	data, data_size);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

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

       message The location in which to	store  the  returned  message.	 If  a
	       suitable	 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.

       fildes  The  original  fildes,  exactly	as passed to the getsockopt(2)
	       system call.

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

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

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

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

SEE ALSO
       getsockopt(2)
	       get and set options on sockets

       explain_getsockopt_or_die(3)
	       get and set options on sockets and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2009 Peter	Miller

							 explain_getsockopt(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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