HP-UX Reference (11i v3 07/02) - 2 System Calls (vol 5)

s
sendfile(2) sendfile(2)
NAME
sendfile() - send the contents of a file through a socket
SYNOPSIS
#include <sys/socket.h>
sbsize_t sendfile(int s, int fd, off_t offset, bsize_t nbytes,
const struct iovec *hdtrl, int flags);
DESCRIPTION
The sendfile() system call transmits the contents of a file associated with the file descriptor fd, plus an
optional header and trailer buffers across a socket connection specified by s.
sendfile() can be used
only when the socket is in a connected state.
offset specifies the offset within the file at which to start the file data transfer.
nbytes is the number of bytes to be sent from the file. If this parameter is set to zero, data from the offset
to the end of the file will be sent.
hdtrl points to a two entry
iovec structure. See write(2) for a description of the iovec
structure. The
first entry is for header information. If this pointer is non-NULL, the contents of the buffer are sent before
sending any data from the file. The second entry is for trailer information. If this pointer is non-NULL,
the contents of the buffer will be sent after the data from the file. If both pointers are NULL, or hdtrl is a
NULL pointer, only the specified range of the file will be transferred.
At the end of the call, the socket connection will be left completely open for both reading and writing,
unless the flags parameter is set to:
SF_DISCONNECT Disallow further sends and receives.
Notes
If no buffer space is available to hold the data to be transmitted, sendfile()
blocks unless nonblocking
mode is enabled. See send(2) for a description of the nonblocking mode behavior.
See sendfile64(2) for a description of how sendfile can be used with large file (over 2GB) with 32-bit applica-
tions.
Note that the types
sbsize_t and bsize_t are similar to ssize_t and size_t except they are
defined as 64-bit values when compiled with the _FILE_OFFSET_BITS=64
compile flag. See
sendfile64(2).
RETURN VALUE
Upon successful completion,
sendfile() returns the number of bytes sent. This includes the header,
trailer, and the file contents. Otherwise, −1 is returned and errno is set to indicate the error.
ERRORS
If
sendfile() fails, errno is set to one of the following values.
[EBADF] An invalid socket descriptor s, or file descriptor fd is specified.
[ENOTSOCK] s is a valid file descriptor, but it is not a socket.
[EFAULT] An invalid pointer was specified in the hdtrl parameter or the
iovec structure.
[ENOBUFS] No buffer space is available in the system to perform the operation.
[EINTR] The operation was interrupted by a signal before any data was sent. (If some data
was sent, sendfile() returns the number of bytes sent before the signal, and
[EINTR] is not set.)
[EINVAL] The offset or flags parameter is invalid.
The hdtrl parameter, or a length in the iovec structure is invalid.
[ENOTCONN] A sendfile() on a socket that is not connected, or a sendfile() on a socket
that has not completed the connect sequence with its peer, or is no longer connected
to its peer.
[EPIPE] With SIGPIPE signal. An attempt was made to send on a socket that was connected,
but the connection has been shut down either by the remote peer or by this side of the
connection. Note that the default action for SIGPIPE, unless the process has
382 Hewlett-Packard Company − 1 − HP-UX 11i Version 3: February 2007