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explain_readv(3)	   Library Functions Manual	      explain_readv(3)

NAME
       explain_readv - explain readv(2)	errors

SYNOPSIS
       #include	<libexplain/readv.h>
       const char *explain_readv(int fildes, const struct iovec	*iov, int
       iovcnt);
       const char *explain_errno_readv(int errnum, int fildes, const struct
       iovec *iov, int iovcnt);
       void explain_message_readv(char *message, int message_size, int fildes,
       const struct iovec *iov,	int iovcnt);
       void explain_message_errno_readv(char *message, int message_size, int
       errnum, int fildes, const struct	iovec *iov, int	iovcnt);

DESCRIPTION
       These  functions	may be used to obtain explanations for errors returned
       by the readv(2) system call.

   explain_readv
       const char *explain_readv(int fildes, const struct iovec	*iov, int
       iovcnt);

       The explain_readv function is used to obtain an explanation of an error
       returned	by the readv(2)	system call. The least the message  will  con-
       tain  is	the value of strerror(errno), but usually it will do much bet-
       ter, and	indicate the underlying	cause in more detail.

       The errno global	variable will be used to obtain	the error value	to  be
       decoded.

       fildes  The  original  fildes, exactly as passed	to the readv(2)	system
	       call.

       iov     The original iov, exactly as  passed  to	 the  readv(2)	system
	       call.

       iovcnt  The  original  iovcnt, exactly as passed	to the readv(2)	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:
	      ssize_t result = readv(fildes, iov, iovcnt);
	      if (result < 0)
	      {
		  fprintf(stderr, "%s\n", explain_readv(fildes,	iov, iovcnt));
		  exit(EXIT_FAILURE);
	      }

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

   explain_errno_readv
       const char *explain_errno_readv(int errnum, int fildes, const struct
       iovec *iov, int iovcnt);

       The explain_errno_readv function	is used	to obtain an explanation of an
       error  returned by the readv(2) 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.

       fildes  The  original  fildes, exactly as passed	to the readv(2)	system
	       call.

       iov     The original iov, exactly as  passed  to	 the  readv(2)	system
	       call.

       iovcnt  The  original  iovcnt, exactly as passed	to the readv(2)	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:
	      ssize_t result = readv(fildes, iov, iovcnt);
	      if (result < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_readv(err, fildes,
		  iov, iovcnt));
		  exit(EXIT_FAILURE);
	      }

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

   explain_message_readv
       void explain_message_readv(char *message, int message_size, int fildes,
       const struct iovec *iov,	int iovcnt);

       The  explain_message_readv function is used to obtain an	explanation of
       an error	returned by the	readv(2) 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.

       fildes  The original fildes, exactly as passed to the  readv(2)	system
	       call.

       iov     The  original  iov,  exactly  as	 passed	to the readv(2)	system
	       call.

       iovcnt  The original iovcnt, exactly as passed to the  readv(2)	system
	       call.

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

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

   explain_message_errno_readv
       void explain_message_errno_readv(char *message, int message_size, int
       errnum, int fildes, const struct	iovec *iov, int	iovcnt);

       The  explain_message_errno_readv	function is used to obtain an explana-
       tion of an error	returned by the	readv(2) 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.

       fildes  The  original  fildes, exactly as passed	to the readv(2)	system
	       call.

       iov     The original iov, exactly as  passed  to	 the  readv(2)	system
	       call.

       iovcnt  The  original  iovcnt, exactly as passed	to the readv(2)	system
	       call.

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

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

SEE ALSO
       readv(2)
	       read data into multiple buffers

       explain_readv_or_die(3)
	       read data into multiple buffers and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2009 Peter	Miller

							      explain_readv(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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