1libssh2_sftp_write(3) libssh2 libssh2_sftp_write(3)
2
6 libssh2_sftp_write - write SFTP data
7
9 #include <libssh2.h>
10 #include <libssh2_sftp.h>
11 ssize_t
13 libssh2_sftp_write(LIBSSH2_SFTP_HANDLE *handle,
14 const char *buffer,
15 size_t count);
16
18 libssh2_sftp_write(3) writes a block of data to the SFTP server. This
19 method is modeled after the POSIX write() function and uses the same
20 calling semantics.
21 handle - SFTP file handle as returned by libssh2_sftp_open_ex(3).
23 buffer - points to the data to send off.
25 count - Number of bytes from 'buffer' to write. Note that it may not be
27 possible to write all bytes as requested.
28 libssh2_sftp_handle(3) will use as much as possible of the buffer and
30 put it into a single SFTP protocol packet. This means that to get maxi‐
31 mum performance when sending larger files, you should try to always
32 pass in at least 32K of data to this function.
33
35 Starting in libssh2 version 1.2.8, the default behavior of libssh2 is
36 to create several smaller outgoing packets for all data you pass to
37 this function and it will return a positive number as soon as the first
38 packet is acknowledged from the server.
39 This has the effect that sometimes more data has been sent off but is
41 not acked yet when this function returns, and when this function is
42 subsequently called again to write more data, libssh2 will immediately
43 figure out that the data is already received remotely.
44 In most normal situation this should not cause any problems, but it
46 should be noted that if you have once called libssh2_sftp_write() with
47 data and it returns short, you MUST still assume that the rest of the
48 data might have been cached so you need to make sure you do not alter
49 that data and think that the version you have in your next function in‐
50 voke will be detected or used.
51 The reason for this funny behavior is that SFTP can only send 32K data
53 in each packet and it gets all packets acked individually. This means
54 we cannot use a simple serial approach if we want to reach high perfor‐
55 mance even on high latency connections. And we want that.
56
58 Actual number of bytes written or negative on failure.
59 If used in non-blocking mode, it returns LIBSSH2_ERROR_EAGAIN when it
61 would otherwise block. While LIBSSH2_ERROR_EAGAIN is a negative number,
62 it is not really a failure per se.
63 If this function returns 0 (zero) it should not be considered an error,
65 but that there was no error but yet no payload data got sent to the
66 other end.
67
69 LIBSSH2_ERROR_ALLOC - An internal memory allocation call failed.
70 LIBSSH2_ERROR_SOCKET_SEND - Unable to send data on socket.
72 LIBSSH2_ERROR_SOCKET_TIMEOUT -
74 LIBSSH2_ERROR_SFTP_PROTOCOL - An invalid SFTP protocol response was re‐
76 ceived on the socket, or an SFTP operation caused an errorcode to be
77 returned by the server.
78
80 libssh2_sftp_open_ex(3)
81libssh2 0.15 1 Jun 2007 libssh2_sftp_write(3)