.TH libssh2_sftp_write 3 "1 Jun 2007" "libssh2 0.15" "libssh2 manual".SH NAMElibssh2_sftp_write - write SFTP data.SH SYNOPSIS.nf#include <libssh2.h>#include <libssh2_sftp.h> ssize_t libssh2_sftp_write(LIBSSH2_SFTP_HANDLE *handle,                           const char *buffer,                           size_t count);.SH DESCRIPTION\fBlibssh2_sftp_write(3)\fP writes a block of data to the SFTP server. Thismethod is modeled after the POSIX write() function and uses the same callingsemantics. \fIhandle\fP - SFTP file handle as returned by \fIlibssh2_sftp_open_ex(3)\fP. \fIbuffer\fP - points to the data to send off. \fIcount\fP - Number of bytes from 'buffer' to write. Note that it may not bepossible to write all bytes as requested. \fIlibssh2_sftp_handle(3)\fP will use as much as possible of the buffer andput it into a single SFTP protocol packet. This means that to get maximumperformance when sending larger files, you should try to always pass in atleast 32K of data to this function. .SH WRITE AHEADStarting in libssh2 version 1.2.8, the default behavior of libssh2 is tocreate several smaller outgoing packets for all data you pass to this functionand it will return a positive number as soon as the first packet isacknowledged from the server. This has the effect that sometimes more data has been sent off but isn't ackedyet when this function returns, and when this function is subsequently calledagain to write more data, libssh2 will immediately figure out that the data isalready received remotely. In most normal situation this should not cause any problems, but it should benoted that if you've once called libssh2_sftp_write() with data and it returnsshort, you MUST still assume that the rest of the data might've been cached soyou need to make sure you don't alter that data and think that the version youhave 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 eachpacket and it gets all packets acked individually. This means we cannot use asimple serial approach if we want to reach high performance even on highlatency connections. And we want that..SH RETURN VALUEActual number of bytes written or negative on failure. If used in non-blocking mode, it returns LIBSSH2_ERROR_EAGAIN when it wouldotherwise block. While LIBSSH2_ERROR_EAGAIN is a negative number, it isn'treally a failure per se. If this function returns 0 (zero) it should not be considered an error, butsimply that there was no error but yet no payload data got sent to the otherend..SH ERRORS\fILIBSSH2_ERROR_ALLOC\fP -  An internal memory allocation call failed. \fILIBSSH2_ERROR_SOCKET_SEND\fP - Unable to send data on socket. \fILIBSSH2_ERROR_SOCKET_TIMEOUT\fP -  \fILIBSSH2_ERROR_SFTP_PROTOCOL\fP - An invalid SFTP protocol response was received on the socket, or an SFTP operation caused an errorcode to be returned by the server..SH SEE ALSO.BR libssh2_sftp_open_ex(3)