mirror of
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b889b39945
To render in Git webviews as-is, to make it easier to edit, verify,
and to sync up with curl.
- add options to not build the `.3` man pages:
- autotools: `--disable-docs`
- cmake: `LIBSSH2_BUILD_DOCS=OFF`
- building `.3` man pages requires Perl after this patch.
- drop `mansyntax` and the shell / `grep` / GNU `man` tool requirements with it.
- scripts and most logic were copied from curl.
- add `cd2nroff` from curl, with edits to relax curl-specific checks.
- used `nroff2cd` (from curl) to convert from `.3` to `.md`. Then
manually fixed copyrights, inline function references and a couple
of other things.
Credits-to: Daniel Stenberg
Ref: eefcc1bda4
Ref: https://github.com/curl/curl/pull/12730
Ref: https://github.com/libssh2/www/issues/25#issuecomment-3289431671
Closes #1660
90 lines
3.0 KiB
Markdown
90 lines
3.0 KiB
Markdown
---
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c: Copyright (C) The libssh2 project and its contributors.
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SPDX-License-Identifier: BSD-3-Clause
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Title: libssh2_sftp_write
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Section: 3
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Source: libssh2
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See-also:
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- libssh2_sftp_open_ex(3)
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---
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# NAME
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libssh2_sftp_write - write SFTP data
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# SYNOPSIS
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~~~c
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#include <libssh2.h>
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#include <libssh2_sftp.h>
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ssize_t
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libssh2_sftp_write(LIBSSH2_SFTP_HANDLE *handle,
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const char *buffer,
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size_t count);
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~~~
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# DESCRIPTION
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**libssh2_sftp_write(3)** writes a block of data to the SFTP server. This
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method is modeled after the POSIX write() function and uses the same calling
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semantics.
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*handle* - SFTP file handle as returned by *libssh2_sftp_open_ex(3)*.
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*buffer* - points to the data to send off.
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*count* - Number of bytes from 'buffer' to write. Note that it may not be
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possible to write all bytes as requested.
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*libssh2_sftp_handle(3)* will use as much as possible of the buffer and
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put it into a single SFTP protocol packet. This means that to get maximum
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performance when sending larger files, you should try to always pass in at
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least 32K of data to this function.
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# WRITE AHEAD
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Starting in libssh2 version 1.2.8, the default behavior of libssh2 is to
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create several smaller outgoing packets for all data you pass to this function
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and it will return a positive number as soon as the first packet is
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acknowledged from the server.
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This has the effect that sometimes more data has been sent off but is not acked
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yet when this function returns, and when this function is subsequently called
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again to write more data, libssh2 will immediately figure out that the data is
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already received remotely.
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In most normal situation this should not cause any problems, but it should be
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noted that if you have once called libssh2_sftp_write() with data and it returns
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short, you MUST still assume that the rest of the data might have been cached so
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you need to make sure you do not alter that data and think that the version you
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have in your next function invoke will be detected or used.
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The reason for this funny behavior is that SFTP can only send 32K data in each
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packet and it gets all packets acked individually. This means we cannot use a
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simple serial approach if we want to reach high performance even on high
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latency connections. And we want that.
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# RETURN VALUE
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Actual number of bytes written or negative on failure.
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If used in non-blocking mode, it returns LIBSSH2_ERROR_EAGAIN when it would
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otherwise block. While LIBSSH2_ERROR_EAGAIN is a negative number, it is not
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really a failure per se.
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If this function returns 0 (zero) it should not be considered an error, but
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that there was no error but yet no payload data got sent to the other end.
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# ERRORS
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*LIBSSH2_ERROR_ALLOC* - An internal memory allocation call failed.
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*LIBSSH2_ERROR_SOCKET_SEND* - Unable to send data on socket.
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*LIBSSH2_ERROR_SOCKET_TIMEOUT* -
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*LIBSSH2_ERROR_SFTP_PROTOCOL* - An invalid SFTP protocol response was
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received on the socket, or an SFTP operation caused an errorcode to
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be returned by the server.
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