[PATCH 2/2] tty: Add handler for local tty mirroring

[Joel Stanley]

On Thu, Apr 28, 2016 at 2:49 PM, Jeremy Kerr <jk at ozlabs.org> wrote:
> This change adds a simple handler for mirroring data to local tty
> device, like a hardware UART.
>
> This is specified through a new config parameter 'local-tty'.
>
> Signed-off-by: Jeremy Kerr <jk at ozlabs.org>

Reviewed-by: Joel Stanley <joel at jms.id.au>

> ---
>  Makefile.am              |   1 +
>  obmc-console.conf.sample |   3 ++
>  tty-handler.c            | 123 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 127 insertions(+)
>  create mode 100644 tty-handler.c
>
> diff --git a/Makefile.am b/Makefile.am
> index 5f0a1bb..2df24d8 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -34,6 +34,7 @@ obmc_console_server_SOURCES = \
>          config.c \
>          log-handler.c \
>          socket-handler.c \
> +        tty-handler.c \
>          console-socket.c
>
>  obmc_console_client_SOURCES = \
> diff --git a/obmc-console.conf.sample b/obmc-console.conf.sample
> index a5b8808..d473af2 100644
> --- a/obmc-console.conf.sample
> +++ b/obmc-console.conf.sample
> @@ -4,3 +4,6 @@ device = ttyUSB0
>  # For VUART devices, we can specify the LPC address and SIRQ parameters
>  lpc-address = 0x3f8
>  sirq = 4
> +
> +# To mirror to a local tty device (typically a hardware UART), set local-tty
> +# local-tty = ttyS0
> diff --git a/tty-handler.c b/tty-handler.c
> new file mode 100644
> index 0000000..00ada7a
> --- /dev/null
> +++ b/tty-handler.c
> @@ -0,0 +1,123 @@
> +/**
> + * Copyright © 2016 IBM Corporation
> + *
> + * Licensed under the Apache License, Version 2.0 (the "License");
> + * you may not use this file except in compliance with the License.
> + * You may obtain a copy of the License at
> + *
> + *     http://www.apache.org/licenses/LICENSE-2.0
> + *
> + * Unless required by applicable law or agreed to in writing, software
> + * distributed under the License is distributed on an "AS IS" BASIS,
> + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
> + * See the License for the specific language governing permissions and
> + * limitations under the License.
> + */
> +
> +#define _GNU_SOURCE
> +
> +#include <assert.h>
> +#include <err.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +
> +#include "console-server.h"
> +
> +struct tty_handler {
> +       struct handler  handler;
> +       struct console  *console;
> +       struct poller   *poller;
> +       int             fd;
> +};
> +
> +static struct tty_handler *to_tty_handler(struct handler *handler)
> +{
> +       return container_of(handler, struct tty_handler, handler);
> +}
> +
> +static enum poller_ret tty_poll(struct handler *handler,
> +               int events, void __attribute__((unused)) *data)
> +{
> +       struct tty_handler *th = to_tty_handler(handler);
> +       uint8_t buf[4096];
> +       ssize_t len;
> +
> +       if (!(events & POLLIN))
> +               return POLLER_OK;
> +
> +       len = read(th->fd, buf, sizeof(buf));
> +       if (len <= 0) {
> +               th->poller = NULL;
> +               close(th->fd);
> +               return POLLER_REMOVE;
> +       }
> +
> +       console_data_out(th->console, buf, len);
> +
> +       return POLLER_OK;
> +}
> +
> +static int tty_init(struct handler *handler, struct console *console,
> +               struct config *config __attribute__((unused)))
> +{
> +       struct tty_handler *th = to_tty_handler(handler);
> +       const char *tty_name;
> +       char *tty_path;
> +       int rc, flags;
> +
> +       tty_name = config_get_value(config, "local-tty");
> +       if (!tty_name)
> +               return -1;
> +
> +       rc = asprintf(&tty_path, "/dev/%s", tty_name);
> +       if (!rc)
> +               return -1;
> +
> +       th->fd = open(tty_path, O_RDWR);
> +       if (th->fd < 0) {
> +               warn("Can't open %s; disabling local tty", tty_name);
> +               free(tty_path);
> +               return -1;
> +       }
> +
> +       free(tty_path);
> +
> +       /* initial tty setup */
> +       flags = fcntl(th->fd, F_GETFL, 0);
> +       flags |= FNDELAY;
> +       fcntl(th->fd, F_SETFL, flags);
> +
> +       th->poller = console_register_poller(console, handler, tty_poll,
> +                       th->fd, POLLIN, NULL);
> +       th->console = console;
> +
> +       return 0;
> +}
> +
> +static int tty_data(struct handler *handler, uint8_t *buf, size_t len)
> +{
> +       struct tty_handler *th = to_tty_handler(handler);
> +       return write_buf_to_fd(th->fd, buf, len);
> +}
> +
> +static void tty_fini(struct handler *handler)
> +{
> +       struct tty_handler *th = to_tty_handler(handler);
> +       if (th->poller)
> +               console_unregister_poller(th->console, th->poller);
> +       close(th->fd);
> +}
> +
> +static struct tty_handler tty_handler = {
> +       .handler = {
> +               .name           = "tty",
> +               .init           = tty_init,
> +               .data_in        = tty_data,
> +               .fini           = tty_fini,
> +       },
> +};
> +
> +console_register_handler(&tty_handler.handler);
> +
> --
> 2.5.0
>
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