libssh2_sftp_write(3)						  libssh2 manual					     libssh2_sftp_write(3)

NAME

       libssh2_sftp_write - write SFTP data

SYNOPSIS

       #include <libssh2.h>
       #include <libssh2_sftp.h>

       ssize_t libssh2_sftp_write(LIBSSH2_SFTP_HANDLE *handle,
				  const char *buffer,
				  size_t count);

DESCRIPTION

       libssh2_sftp_write(3)  writes a block of data to the SFTP server. This method is modeled after the POSIX write() function and uses the same
       calling semantics.

       handle - SFTP file handle as returned by libssh2_sftp_open_ex(3).

       buffer - points to the data to send off.

       count - Number of bytes from 'buffer' to write. Note that it may not be possible to write all bytes as requested.

       libssh2_sftp_handle(3) will use as much as possible of the buffer and put it into a single SFTP protocol packet. This  means  that  to  get
       maximum performance when sending larger files, you should try to always pass in at least 32K of data to this function.

WRITE AHEAD

       Starting  in  libssh2 version 1.2.8, the default behavior of libssh2 is to create several smaller outgoing packets for all data you pass to
       this function and it will return a positive number as soon as the first packet is acknowledged from the server.

       This has the effect that sometimes more data has been sent off but isn't acked yet when this function returns, and when	this  function	is
       subsequently called again to write more data, libssh2 will immediately figure out that the data is already received remotely.

       In  most  normal  situation this should not cause any problems, but it should be noted that if you've once called libssh2_sftp_write() with
       data and it returns short, you MUST still assume that the rest of the data might've been cached so you need to make sure  you  don't  alter
       that data and think that the version you have in your next function invoke will be detected or used.

       The  reason  for  this  funny  behavior is that SFTP can only send 32K data in each packet and it gets all packets acked individually. This
       means we cannot use a simple serial approach if we want to reach high performance even on high latency connections. And we want that.

RETURN VALUE

       Actual number of bytes written or negative on failure.

       If used in non-blocking mode, it returns LIBSSH2_ERROR_EAGAIN when it would otherwise block. While LIBSSH2_ERROR_EAGAIN is a negative  num-
       ber, it isn't really a failure per se.

       If this function returns 0 (zero) it should not be considered an error, but simply that there was no error but yet no payload data got sent
       to the other end.

ERRORS

       LIBSSH2_ERROR_ALLOC -  An internal memory allocation call failed.

       LIBSSH2_ERROR_SOCKET_SEND - Unable to send data on socket.

       LIBSSH2_ERROR_SOCKET_TIMEOUT -

       LIBSSH2_ERROR_SFTP_PROTOCOL - An invalid SFTP protocol response was received on the socket, or an SFTP operation caused an errorcode to	be
       returned by the server.

SEE ALSO

       libssh2_sftp_open_ex(3)

libssh2 0.15							    1 Jun 2007						     libssh2_sftp_write(3)