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explain_snprintf(3)	   Library Functions Manual	   explain_snprintf(3)

NAME
       explain_snprintf	- explain snprintf(3) errors

SYNOPSIS
       #include	<libexplain/snprintf.h>
       const char *explain_snprintf(char *data,	size_t data_size, const	char
       *format);
       const char *explain_errno_snprintf(int errnum, char *data, size_t
       data_size, const	char *format);
       void explain_message_snprintf(char *message, int	message_size, char
       *data, size_t data_size,	const char *format);
       void explain_message_errno_snprintf(char	*message, int message_size,
       int errnum, char	*data, size_t data_size, const char *format);

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

   explain_snprintf
       const char *explain_snprintf(char *data,	size_t data_size, const	char
       *format);

       The  explain_snprintf  function	is used	to obtain an explanation of an
       error returned by the snprintf(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.

       data    The  original data, exactly as passed to	the snprintf(3)	system
	       call.

       data_size
	       The original data_size, exactly as passed  to  the  snprintf(3)
	       system call.

       format  The  original format, exactly as	passed to the snprintf(3) sys-
	       tem 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;
	      int result = snprintf(data, data_size, format);
	      if (result < 0 &&	errno != 0)
	      {
		  fprintf(stderr, "%s\n", explain_snprintf(data, data_size,
		  format));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_snprintf
       const char *explain_errno_snprintf(int errnum, char *data, size_t
       data_size, const	char *format);

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

       data    The original data, exactly as passed to the snprintf(3)	system
	       call.

       data_size
	       The  original  data_size,  exactly as passed to the snprintf(3)
	       system call.

       format  The original format, exactly as passed to the snprintf(3)  sys-
	       tem 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;
	      int result = snprintf(data, data_size, format);
	      if (result < 0 &&	errno != 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_snprintf(err, data,
		  data_size, format));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_snprintf
       void explain_message_snprintf(char *message, int	message_size, char
       *data, size_t data_size,	const char *format);

       The explain_message_snprintf function is	used to	obtain an  explanation
       of  an  error  returned	by the snprintf(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.

       data    The  original data, exactly as passed to	the snprintf(3)	system
	       call.

       data_size
	       The original data_size, exactly as passed  to  the  snprintf(3)
	       system call.

       format  The  original format, exactly as	passed to the snprintf(3) sys-
	       tem call.

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

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

   explain_message_errno_snprintf
       void explain_message_errno_snprintf(char	*message, int message_size,
       int errnum, char	*data, size_t data_size, const char *format);

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

       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    The  original data, exactly as passed to	the snprintf(3)	system
	       call.

       data_size
	       The original data_size, exactly as passed  to  the  snprintf(3)
	       system call.

       format  The  original format, exactly as	passed to the snprintf(3) sys-
	       tem call.

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

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

SEE ALSO
       snprintf(3)
	       formatted output	conversion

       explain_snprintf_or_die(3)
	       formatted output	conversion and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2010 Peter	Miller

							   explain_snprintf(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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