| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
VMSPLICE(2) Linux Programmer's Manual VMSPLICE(2)
vmsplice - splice user pages into a pipe
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <fcntl.h>
#include <sys/uio.h>
ssize_t vmsplice(int fd, const struct iovec *iov,
unsigned long nr_segs, unsigned int flags);
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
<sys/uio.h>:
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 application
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.
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.
EBADF fd either not valid, or doesn't 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.
The vmsplice() system call first appeared in Linux 2.6.17.
This system call is Linux-specific.
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 <limits.h>. At the time of this writing, that limit is
1024.
splice(2), tee(2)
This page is part of release 3.32 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 2009-09-15 VMSPLICE(2)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface