libssh2/docs/libssh2_channel_read_ex.md

c, SPDX-License-Identifier, Title, Section, Source, See-also

c	SPDX-License-Identifier	Title	Section	Source	See-also
Copyright (C) The libssh2 project and its contributors.	BSD-3-Clause	libssh2_channel_read_ex	3	libssh2	libssh2_poll_channel_read(3)

NAME

libssh2_channel_read_ex - read data from a channel stream

SYNOPSIS

#include <libssh2.h>

ssize_t libssh2_channel_read_ex(LIBSSH2_CHANNEL *channel, int stream_id,
                                char *buf, size_t buflen);

ssize_t libssh2_channel_read(LIBSSH2_CHANNEL *channel,
                             char *buf, size_t buflen);

ssize_t libssh2_channel_read_stderr(LIBSSH2_CHANNEL *channel,
                                    char *buf, size_t buflen);

DESCRIPTION

Attempt to read data from an active channel stream. All channel streams have one standard I/O substream (stream_id == 0), and may have up to 2^32 extended data streams as identified by the selected stream_id. The SSH2 protocol currently defines a stream ID of 1 to be the stderr substream.

channel - active channel stream to read from.

stream_id - substream ID number (e.g. 0 or SSH_EXTENDED_DATA_STDERR)

buf - pointer to storage buffer to read data into

buflen - size of the buf storage

libssh2_channel_read(3) and libssh2_channel_read_stderr(3) are macros.

RETURN VALUE

Actual number of bytes read or negative on failure. 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.

Note that a return value of zero (0) can in fact be a legitimate value and only signals that no payload data was read. It is not an error.

ERRORS

LIBSSH2_ERROR_SOCKET_SEND - Unable to send data on socket.

LIBSSH2_ERROR_CHANNEL_CLOSED - The channel has been closed.