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 number, 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)