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explain_vsnprintf(3)	   Library Functions Manual	  explain_vsnprintf(3)

NAME
       explain_vsnprintf - explain vsnprintf(3)	errors

SYNOPSIS
       #include	<libexplain/vsnprintf.h>
       const char *explain_vsnprintf(char *data, size_t	data_size, const char
       *format,	va_list	ap);
       const char *explain_errno_vsnprintf(int errnum, char *data, size_t
       data_size, const	char *format, va_list ap);
       void explain_message_vsnprintf(char *message, int message_size, char
       *data, size_t data_size,	const char *format, va_list ap);
       void explain_message_errno_vsnprintf(char *message, int message_size,
       int errnum, char	*data, size_t data_size, const char *format, va_list
       ap);

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

   explain_vsnprintf
       const char *explain_vsnprintf(char *data, size_t	data_size, const char
       *format,	va_list	ap);

       The explain_vsnprintf function is used to obtain	an explanation	of  an
       error  returned	by the vsnprintf(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 vsnprintf(3)	system
	       call.

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

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

       ap      The  original  ap, exactly as passed to the vsnprintf(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;
	      int result = vsnprintf(data, data_size, format, ap);
	      if (result < 0 &&	errno != 0)
	      {
		  fprintf(stderr, "%s\n", explain_vsnprintf(data, data_size,
		  format, ap));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_vsnprintf
       const char *explain_errno_vsnprintf(int errnum, char *data, size_t
       data_size, const	char *format, va_list ap);

       The  explain_errno_vsnprintf  function is used to obtain	an explanation
       of an error returned by the vsnprintf(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.

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

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

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

       ap      The  original  ap, exactly as passed to the vsnprintf(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;
	      int result = vsnprintf(data, data_size, format, ap);
	      if (result < 0 &&	errno != 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_vsnprintf(err, data,
		  data_size, format, ap));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_vsnprintf
       void explain_message_vsnprintf(char *message, int message_size, char
       *data, size_t data_size,	const char *format, va_list ap);

       The explain_message_vsnprintf function is used to obtain	an explanation
       of an error returned by the vsnprintf(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 vsnprintf(3)	system
	       call.

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

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

       ap      The  original  ap, exactly as passed to the vsnprintf(3)	system
	       call.

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

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

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

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

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

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

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

       ap      The  original  ap, exactly as passed to the vsnprintf(3)	system
	       call.

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

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

SEE ALSO
       vsnprintf(3)
	       formatted output	conversion

       explain_vsnprintf_or_die(3)
	       formatted output	conversion and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2010 Peter	Miller

							  explain_vsnprintf(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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