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explain_ftello(3)	   Library Functions Manual	     explain_ftello(3)

NAME
       explain_ftello -	explain	ftello(3) errors

SYNOPSIS
       #include	<libexplain/ftello.h>
       const char *explain_ftello(FILE *fp);
       const char *explain_errno_ftello(int errnum, FILE *fp);
       void explain_message_ftello(char	*message, int message_size, FILE *fp);
       void explain_message_errno_ftello(char *message,	int message_size, int
       errnum, FILE *fp);

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

   explain_ftello
       const char *explain_ftello(FILE *fp);

       The  explain_ftello function is used to obtain an explanation of	an er-
       ror returned by the ftello(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.

       fp      The  original  fp,  exactly  as	passed to the ftello(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:
	      off_t result = ftello(fp);
	      if (result < 0)
	      {
		  fprintf(stderr, "%s\n", explain_ftello(fp));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_ftello
       const char *explain_errno_ftello(int errnum, FILE *fp);

       The  explain_errno_ftello  function is used to obtain an	explanation of
       an error	returned by the	ftello(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.

       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.

       fp      The original fp,	exactly	as  passed  to	the  ftello(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:
	      off_t result = ftello(fp);
	      if (result < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_ftello(err, fp));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_ftello
       void explain_message_ftello(char	*message, int message_size, FILE *fp);

       The explain_message_ftello function is used to obtain an	explanation of
       an  error  returned by the ftello(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.

       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.

       fp      The  original  fp,  exactly  as	passed to the ftello(3)	system
	       call.

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

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

   explain_message_errno_ftello
       void explain_message_errno_ftello(char *message,	int message_size, int
       errnum, FILE *fp);

       The explain_message_errno_ftello	function is used to obtain an explana-
       tion of an error	returned by the	ftello(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.

       fp      The  original  fp,  exactly  as	passed to the ftello(3)	system
	       call.

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

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

SEE ALSO
       ftello(3)
	       get stream position

       explain_ftello_or_die(3)
	       get stream position and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2013 Peter	Miller

							     explain_ftello(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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