Libssh2 issue

Help
1

I’m getting this issue when trying to use a function from libssh2. Not too sure why?

    const ssh_channel = ssh.libssh2_channel_open_session(ssh_session);

compiler error:
/home/wizard/projects/zig/sshz/.zig-cache/o/26c0322c148abb5a740835e0b76b8de5/cimport.zig:2027:42: error: unable to translate C
expr: unexpected token ‘a string literal’
pub const libssh2_channel_open_session = @compileError(“unable to translate C expr: unexpected token ‘a string literal’”);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

translate-c definition:

pub const libssh2_channel_open_session = @compileError("unable to translate C expr: unexpected token 'a string literal'");

I’m linking against my system library I’m too sure if that is the issue. Any help would be much appreciated!

2

There’s something in the file that the Zig C translation code can’t handle. What does libssh2_channel_open_session look like in the .h file?

To work around whatever the Zig limitation might be, you may have to manually write wrappers that you can use from Zig.

3

Hey thanks for a quick response. Seems like it is a macro. I never wrote a wrapper before. Does anyone have good examples for Zig?

#define libssh2_channel_open_session(session) \
    libssh2_channel_open_ex((session), "session", sizeof("session") - 1, \
                            LIBSSH2_CHANNEL_WINDOW_DEFAULT, \
                            LIBSSH2_CHANNEL_PACKET_DEFAULT, NULL, 0)
4

Every time a C programmer writes a preprocessor macro, a kitten dies.

Try writing your own translation of that particular macro, like:

fn libssh2_channel_open_session(session: *c.LIBSSH2_SESSION) ?*c.LIBSSH2_SESSION {
    const channel_type = "session";
    return c.libssh2_channel_open_ex(
        session,
        channel_type.ptr,
        channel_type.len - 1,
        c.LIBSSH2_CHANNEL_WINDOW_DEFAULT,
        c.LIBSSH2_CHANNEL_PACKET_DEFAULT,
        null,
        0,
    );
}
5

You could always create a new C file with an exported function that wraps the macro, and use the function from your Zig code, leaving the macro to be compiled by the C compiler.