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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 maxi-
       mum 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 in-
       voke 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 perfor-
       mance 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 re-
       ceived 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)

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