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libssh2_sftp_write(3)               libssh2              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 is
       not 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 have once called libssh2_sftp_write() with
       data and it returns short, you MUST still assume that the rest of the
       data might have been cached so you need to make sure you do not 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 number,
       it is not really a failure per se.

       If this function returns 0 (zero) it should not be considered an error,
       but 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)