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explain_vasprintf(3)	   Library Functions Manual	  explain_vasprintf(3)

NAME
       explain_vasprintf - explain vasprintf(3)	errors

SYNOPSIS
       #include	<libexplain/vasprintf.h>
       const char *explain_vasprintf(char **data, const	char *format, va_list
       ap);
       const char *explain_errno_vasprintf(int errnum, char **data, const char
       *format,	va_list	ap);
       void explain_message_vasprintf(char *message, int message_size, char
       **data, const char *format, va_list ap);
       void explain_message_errno_vasprintf(char *message, int message_size,
       int errnum, char	**data,	const char *format, va_list ap);

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

   explain_vasprintf
       const char *explain_vasprintf(char **data, const	char *format, va_list
       ap);

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

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

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

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

   explain_errno_vasprintf
       const char *explain_errno_vasprintf(int errnum, char **data, const char
       *format,	va_list	ap);

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

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

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

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

   explain_message_vasprintf
       void explain_message_vasprintf(char *message, int message_size, char
       **data, const char *format, va_list ap);

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

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

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

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

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

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

       The explain_message_errno_vasprintf function is used to obtain  an  ex-
       planation  of  an  error	returned by the	vasprintf(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 vasprintf(3)	system
	       call.

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

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

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

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

SEE ALSO
       vasprintf(3)
	       print to	allocated string

       explain_vasprintf_or_die(3)
	       print to	allocated string and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2013 Peter	Miller

							  explain_vasprintf(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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