VMSPLICE(2)		   Linux Programmers Manual		  VMSPLICE(2)



NAME
       vmsplice - splice user pages into a pipe

SYNOPSIS
       #define _GNU_SOURCE
       #include 
       #include 

       long vmsplice(int fd, const struct iovec *iov,
		     unsigned long nr_segs, unsigned int flags);

DESCRIPTION
       The vmsplice() system call maps nr_segs ranges of user memory described
       by iov into a pipe.  The file descriptor fd must refer to a pipe.

       The pointer iov points to an array of iovec structures  as  defined  in
       :

	   struct iovec {
	       void  *iov_base; 	   /* Starting address */
	       size_t iov_len;		   /* Number of bytes */
	   };

       The  flags  argument  is  a bit mask that is composed by ORing together
       zero or more of the following values:

       SPLICE_F_MOVE	  Unused for vmsplice(); see splice(2).

       SPLICE_F_NONBLOCK  Do not block	on  I/O;  see  splice(2)  for  further
			  details.

       SPLICE_F_MORE	  Currently  has  no effect for vmsplice(), but may be
			  implemented in the future; see splice(2).

       SPLICE_F_GIFT	  The user pages are a gift to the kernel.  The appli
			  cation  may  not  modify  this  memory ever, or page
			  cache and on-disk data may differ.  Gifting pages to
			  the	kernel	 means	that  a  subsequent  splice(2)
			  SPLICE_F_MOVE can successfully move  the  pages;  if
			  this	flag  is  not  specified,  then  a  subsequent
			  splice(2) SPLICE_F_MOVE must copy the  pages.   Data
			  must	also  be properly page aligned, both in memory
			  and length.

RETURN VALUE
       Upon successful completion, vmsplice()  returns	the  number  of  bytes
       transferred  to the pipe.  On error, vmsplice() returns -1 and errno is
       set to indicate the error.

ERRORS
       EBADF  fd either not valid, or doesnt refer to a pipe.

       EINVAL nr_segs is 0 or greater than IOV_MAX; or memory not  aligned  if
	      SPLICE_F_GIFT set.

       ENOMEM Out of memory.

VERSIONS
       The vmsplice() system call first appeared in Linux 2.6.17.

CONFORMING TO
       This system call is Linux-specific.

NOTES
       vmsplice()  follows the other vectorized read/write type functions when
       it comes to limitations on number of segments being  passed  in.   This
       limit  is  IOV_MAX as defined in .  At the time of this writ
       ing, that limit is 1024.

SEE ALSO
       splice(2), tee(2), feature_test_macros(7)

COLOPHON
       This page is part of release 3.05 of the Linux  man-pages  project.   A
       description  of	the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



Linux				  2006-04-28			   VMSPLICE(2)