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sendfile(2)
NAME
  sendfile - Send the contents of a file through a socket

SYNOPSIS
  #include <sys/socket.h>

  ssize_t sendfile(
	  int socket,
	  int fd,
	  off_t offset,
	  size_t nbytes,
	  const struct iovec *hdtrl,
	  int flags );

PARAMETERS
  socket
      Specifies the socket file descriptor.

  fd  Specifies the file descriptor of the file that contains the contents to
      be sent.

  offset
      Specifies the point within the file (offset) at which to start the data
      transfer.

  nbytes
      Specifies the number of bytes to send from the file. If the value is
      zero (0), data from the offset to the end of the file is sent.

  hdtrl
      Points to a two-entry array of iovec structures. The first entry
      contains header information. If the iov_len member is non-zero, the
      contents of the buffer are sent before any data from the file.

      The second entry contains trailer information. If the iov_len member is
      non-zero, the contents of the buffer are sent after any data from the
      file.

      If both iov_len members are NULL or if hdtrl is a NULL pointer, only
      the specified file contents are transferred.

      See write(2) for information on the iovec structure.

  flags
      Not currently used.

DESCRIPTION
  The sendfile() function sends the specified contents of a file only through
  a connected socket.

RETURN VALUES
  Upon successful completion, the sendfile() function returns the number of
  bytes sent, including the header, trailer, and file contents. Otherwise,
  the function returns a value of -1 and sets errno to indicate the error.

ERRORS
  If the sendfile() function fails, errno may be set to one of the following
  values:

  [EAGAIN]
      Non-blocking I/O is enabled (O_NONBLOCK), and the requested operation
      would block.

  [EAFNOSUPPORT]
      Addresses in the specified address family cannot be used with this
      socket.

  [EBADF]
      The socket parameter or file descriptor is not valid.

  [EFAULT]
      The hdtrl parameter is not valid or there is an invalid pointer in the
      iovec structure.

  [EINTR]
      A signal interrupted sendfile before any data was transmitted.  If some
      data was transmitted, the function returns the number of bytes sent
      before the interrupt and does not set errno to [EINTR].

  [EINVAL]
      The offset or flags parameter is invalid.

      The hdtrl parameter, or a length in the iovec structure is invalid.

  [EMSGSIZE]
      There is insufficient space in the socket buffer.

  [ENOMEM]
      The system did not have sufficient memory to fulfill the request.

  [ENOTCONN]
      A socket is connection-oriented but is not connected, has not completed
      the connect sequence with its peer, or is no longer connected to its
      peer.

  [ENOTSOCK]
      The socket parameter refers to a file, not a socket.

  [EOPNOTSUPP]
      The socket is not a TCP socket.

  [EPIPE]
      You attempted to send on a socket that was connected, but either the
      remote peer or localhost has closed the connection. If the process does
      not have a signal handler for this signal (SIGPIPE), the default action
      is to terminate the process.

  [EWOULDBLOCK]
      The socket is marked nonblocking, and the requested operation would
      block.

SEE ALSO
  Functions: connect(2), read(2), send(2), shutdown(2), socket(2), write(2),
  tcp(7).

Index for Section 2

Alphabetical listing for S

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