SENDFILE(2)         Linux Programmer's Manual         SENDFILE(2)


NAME
       sendfile - transfer data between file descriptors

SYNOPSIS
       #include <unistd.h>

       int  sendfile(int out_fd, int in_fd, off_t *offset, size_t
       count)


DESCRIPTION
       This call copies data between  file  descriptor  and  file
       descriptor  or  socket.   in_fd  should be file descriptor
       opened for reading.  out_fd should  be  descriptor  opened
       for  writing  or connected socket.  offset is a pointer to
       variable holding input file pointer  position  from  which
       sendfile(2)  will  start reading data. After sendfile fin-
       ished this variable points to the byte after the last byte
       that  was  read.  count is number of bytes to copy between
       file descriptors.


NOTES
       Sendfile does not  modify  the  current  file  pointer  of
       in_fd, but does for out_fd.

       If  you  plan  to  use sendfile for sending files to a TCP
       socket, but need to send some header data in front of  the
       file contents, please see the TCP_CORK option in tcp(4)


RETURN VALUE
       If  the transfer was succeeded, number of bytes written to
       out_fd is returned. On error, -1 is returned, and errno is
       set appropriately.


ERRORS
       EBADF   Input  file  was  not opened for reading or output
               file was not opened for writing.

       EINVAL  Descriptor is not valid or locked.

       ENOMEM  Insufficient memory for reading from in_fd

       EIO     Unspecified error while reading from in_fd

VERSIONS
       sendfile(2) is a new feature in Linux 2.2

SEE ALSO
       socket(2), open(2)





Linux Man Page              1 Dec 1998                          1