sendfile.2 (2010 09)

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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 appli-

cations.

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

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 con-

nected, 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

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (2 pages)

PAGE 1
sendfile(2) sendfile(2) NAME sendfile() - send the contents of a file through a socket SYNOPSIS #include 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.
PAGE 2
sendfile(2) sendfile(2) process has established a signal handler for this signal, is to terminate the process. [EAGAIN] Nonblocking I/O is enabled using the O_NONBLOCK flag with fcntl(), and the requested operation would block. [EWOULDBLOCK] The socket is marked non-blocking and the requested operation would block. [ENOMEM] No memory is available in the system to perform the operation. [EOPNOTSUPP] The socket is not a TCP socket.