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explain_fwrite(3)	   Library Functions Manual	     explain_fwrite(3)

NAME
       explain_fwrite -	explain	fwrite(3) errors

SYNOPSIS
       #include	<libexplain/fwrite.h>
       const  char *explain_fwrite(const void *ptr, size_t size, size_t	nmemb,
       FILE *fp);
       const char *explain_errno_fwrite(int errnum, const  void	 *ptr,	size_t
       size, size_t nmemb, FILE	*fp);
       void explain_message_fwrite(char	*message, int message_size, const void
       *ptr, size_t size, size_t nmemb,	FILE *fp);
       void explain_message_errno_fwrite(char *message,	int message_size,  int
       errnum, const void *ptr,	size_t size, size_t nmemb, FILE	*fp);

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

   explain_fwrite
       const char *explain_fwrite(const	void *ptr, size_t size,	size_t	nmemb,
       FILE *fp);

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

       This  function  is intended to be used in a fashion similar to the fol-
       lowing example:
	      if (fwrite(ptr, size, nmemb, fp) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_fwrite(ptr, size, nmemb, fp));
		  exit(EXIT_FAILURE);
	      }

       ptr     The original ptr, exactly as passed  to	the  fwrite(3)	system
	       call.

       size    The  original  size,  exactly as	passed to the fwrite(3)	system
	       call.

       nmemb   The original nmemb, exactly as passed to	the  fwrite(3)	system
	       call.

       fp      The  original  fp,  exactly  as	passed to the fwrite(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, 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_fwrite
       const  char  *explain_errno_fwrite(int  errnum, const void *ptr,	size_t
       size, size_t nmemb, FILE	*fp);

       The explain_errno_fwrite	function is used to obtain an  explanation  of
       an  error returned by the fwrite(3) 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 (fwrite(ptr, size, nmemb, fp) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_fwrite(err,
		      ptr, size, nmemb,	fp));
		  exit(EXIT_FAILURE);
	      }

       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.

       ptr     The original ptr, exactly as passed  to	the  fwrite(3)	system
	       call.

       size    The  original  size,  exactly as	passed to the fwrite(3)	system
	       call.

       nmemb   The original nmemb, exactly as passed to	the  fwrite(3)	system
	       call.

       fp      The  original  fp,  exactly  as	passed to the fwrite(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, 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_fwrite
       void explain_message_fwrite(char	*message, int message_size, const void
       *ptr, size_t size, size_t nmemb,	FILE *fp);

       The explain_message_fwrite function may be used to  obtain an  explana-
       tion  of	an error returned by the fwrite(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.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (fwrite(ptr, size, nmemb, fp) < 0)
	      {
		  char message[3000];
		  explain_message_fwrite(message, sizeof(message), ptr,	size, nmemb, fp);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       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.

       ptr     The original ptr, exactly as passed  to	the  fwrite(3)	system
	       call.

       size    The  original  size,  exactly as	passed to the fwrite(3)	system
	       call.

       nmemb   The original nmemb, exactly as passed to	the  fwrite(3)	system
	       call.

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

   explain_message_errno_fwrite
       void explain_message_errno_fwrite(char *message,	int message_size,  int
       errnum, const void *ptr,	size_t size, size_t nmemb, FILE	*fp);

       The  explain_message_errno_fwrite function may be used to obtain	an ex-
       planation of an error returned by the fwrite(3) 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  de-
       tail.

       This  function  is intended to be used in a fashion similar to the fol-
       lowing example:
	      if (fwrite(ptr, size, nmemb, fp) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_fwrite(message,	sizeof(message), err,
		      ptr, size, nmemb,	fp);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       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.

       ptr     The  original  ptr,  exactly  as	passed to the fwrite(3)	system
	       call.

       size    The original size, exactly as passed to	the  fwrite(3)	system
	       call.

       nmemb   The  original  nmemb, exactly as	passed to the fwrite(3)	system
	       call.

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

SEE ALSO
       fwrite(3)
	       binary stream output

       explain_fwrite_or_die(3)
	       binary stream output and	report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2008 Peter	Miller

							     explain_fwrite(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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