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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 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
       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 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 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 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)

NAME | SYNOPSIS | DESCRIPTION | WRITE AHEAD | RETURN VALUE | ERRORS | SEE ALSO

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