GENERIC_FILE_SPLICE_(9) splice API GENERIC_FILE_SPLICE_(9)NAME
generic_file_splice_read - splice data from file to a pipe
SYNOPSIS
ssize_t generic_file_splice_read(struct file * in, loff_t * ppos, struct pipe_inode_info * pipe, size_t len, unsigned int flags);
ARGUMENTS
in
file to splice from
ppos
position in in
pipe
pipe to splice to
len
number of bytes to splice
flags
splice modifier flags
DESCRIPTION
Will read pages from given file and fill them into a pipe. Can be used as long as the address_space operations for the source implements a
readpage hook.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 GENERIC_FILE_SPLICE_(9)
Check Out this Related Man Page
TEE(2) Linux Programmer's Manual TEE(2)NAME
tee - duplicating pipe content
SYNOPSIS
#define _GNU_SOURCE
#include <fcntl.h>
ssize_t tee(int fd_in, int fd_out, size_t len, unsigned int flags);
DESCRIPTION
tee() duplicates up to len bytes of data from the pipe referred to by the file descriptor fd_in to the pipe referred to by the file
descriptor fd_out. It does not consume the data that is duplicated from fd_in; therefore, that data can be copied by a subsequent
splice(2).
flags is a series of modifier flags, which share the name space with splice(2) and vmsplice(2):
SPLICE_F_MOVE Currently has no effect for tee(); 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 tee(), but may be implemented in the future; see splice(2).
SPLICE_F_GIFT Unused for tee(); see vmsplice(2).
RETURN VALUE
Upon successful completion, tee() returns the number of bytes that were duplicated between the input and output. A return value of 0 means
that there was no data to transfer, and it would not make sense to block, because there are no writers connected to the write end of the
pipe referred to by fd_in.
On error, tee() returns -1 and errno is set to indicate the error.
ERRORS
EINVAL fd_in or fd_out does not refer to a pipe; or fd_in and fd_out refer to the same pipe.
ENOMEM Out of memory.
VERSIONS
The tee() system call first appeared in Linux 2.6.17.
CONFORMING TO
This system call is Linux-specific.
NOTES
Conceptually, tee() copies the data between the two pipes. In reality no real data copying takes place though: under the covers, tee()
assigns data in the output by merely grabbing a reference to the input.
EXAMPLE
The following example implements a basic tee(1) program using the tee() system call.
#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>
int
main(int argc, char *argv[])
{
int fd;
int len, slen;
if (argc != 2) {
fprintf(stderr, "Usage: %s <file>
", argv[0]);
exit(EXIT_FAILURE);
}
fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC, 0644);
if (fd == -1) {
perror("open");
exit(EXIT_FAILURE);
}
do {
/*
* tee stdin to stdout.
*/
len = tee(STDIN_FILENO, STDOUT_FILENO,
INT_MAX, SPLICE_F_NONBLOCK);
if (len < 0) {
if (errno == EAGAIN)
continue;
perror("tee");
exit(EXIT_FAILURE);
} else
if (len == 0)
break;
/*
* Consume stdin by splicing it to a file.
*/
while (len > 0) {
slen = splice(STDIN_FILENO, NULL, fd, NULL,
len, SPLICE_F_MOVE);
if (slen < 0) {
perror("splice");
break;
}
len -= slen;
}
} while (1);
close(fd);
exit(EXIT_SUCCESS);
}
SEE ALSO splice(2), vmsplice(2), feature_test_macros(7)COLOPHON
This page is part of release 3.27 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 TEE(2)