/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 NetApp, Inc.
 * Copyright (c) 2013 Neel Natu <neel@freebsd.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>

#include <machine/vmm.h>

#include <assert.h>
#ifndef WITHOUT_CAPSICUM
#include <capsicum_helpers.h>
#endif
#include <err.h>
#include <errno.h>
#include <pthread.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <termios.h>
#include <unistd.h>
#ifndef __FreeBSD__
#include <sys/socket.h>
#include <fcntl.h>
#endif


#include "debug.h"
#include "mevent.h"
#include "uart_backend.h"
#include "uart_emul.h"

struct ttyfd {
        bool    opened;
        int     rfd;            /* fd for reading */
        int     wfd;            /* fd for writing, may be == rfd */
};

#ifndef __FreeBSD__
struct sockfd {
        bool    sock;
        int     clifd;          /* console client unix domain socket */
        int     servfd;         /* console server unix domain socket */
        struct mevent *servmev; /* mevent for server socket */
        void (*drain)(int, enum ev_type, void *);
        void *drainarg;
};
#endif

#define FIFOSZ  16

struct fifo {
        uint8_t buf[FIFOSZ];
        int     rindex;         /* index to read from */
        int     windex;         /* index to write to */
        int     num;            /* number of characters in the fifo */
        int     size;           /* size of the fifo */
};

struct uart_softc {
        struct ttyfd    tty;
#ifndef __FreeBSD__
        struct sockfd   usc_sock;
#endif
        struct fifo     rxfifo;
        struct mevent   *mev;
        pthread_mutex_t mtx;
};

static bool uart_stdio;         /* stdio in use for i/o */
static struct termios tio_stdio_orig;

static void
ttyclose(void)
{
        tcsetattr(STDIN_FILENO, TCSANOW, &tio_stdio_orig);
}

static void
ttyopen(struct ttyfd *tf)
{
        struct termios orig, new;

        tcgetattr(tf->rfd, &orig);
        new = orig;
        cfmakeraw(&new);
        new.c_cflag |= CLOCAL;
        tcsetattr(tf->rfd, TCSANOW, &new);
        if (uart_stdio) {
                tio_stdio_orig = orig;
                atexit(ttyclose);
        }
        raw_stdio = 1;
}

static int
ttyread(struct ttyfd *tf)
{
        unsigned char rb;

        if (read(tf->rfd, &rb, 1) == 1)
                return (rb);
        else
                return (-1);
}

static void
ttywrite(struct ttyfd *tf, unsigned char wb)
{
        (void)write(tf->wfd, &wb, 1);
}

#ifndef __FreeBSD__
static void
sockwrite(struct uart_softc *sc, unsigned char wb)
{
        (void) write(sc->usc_sock.clifd, &wb, 1);
}
#endif

static bool
rxfifo_available(struct uart_softc *sc)
{
        return (sc->rxfifo.num < sc->rxfifo.size);
}

int
uart_rxfifo_getchar(struct uart_softc *sc)
{
        struct fifo *fifo;
        int c, error, wasfull;

        wasfull = 0;
        fifo = &sc->rxfifo;
        if (fifo->num > 0) {
                if (!rxfifo_available(sc))
                        wasfull = 1;
                c = fifo->buf[fifo->rindex];
                fifo->rindex = (fifo->rindex + 1) % fifo->size;
                fifo->num--;
                if (wasfull) {
                        if (sc->tty.opened) {
                                error = mevent_enable(sc->mev);
                                assert(error == 0);
                        }
#ifndef __FreeBSD__
                        if (sc->usc_sock.sock && sc->usc_sock.clifd != -1) {
                                error = mevent_enable(sc->mev);
                                assert(error == 0);
                        }
#endif /* __FreeBSD__ */
                }
                return (c);
        } else
                return (-1);
}

int
uart_rxfifo_numchars(struct uart_softc *sc)
{
        return (sc->rxfifo.num);
}

static int
rxfifo_putchar(struct uart_softc *sc, uint8_t ch)
{
        struct fifo *fifo;
        int error;

        fifo = &sc->rxfifo;

        if (fifo->num < fifo->size) {
                fifo->buf[fifo->windex] = ch;
                fifo->windex = (fifo->windex + 1) % fifo->size;
                fifo->num++;
                if (!rxfifo_available(sc)) {
                        if (sc->tty.opened) {
                                /*
                                 * Disable mevent callback if the FIFO is full.
                                 */
                                error = mevent_disable(sc->mev);
                                assert(error == 0);
                        }
#ifndef __FreeBSD__
                        if (sc->usc_sock.sock && sc->usc_sock.clifd != -1) {
                                /*
                                 * Disable mevent callback if the FIFO is full.
                                 */
                                error = mevent_disable(sc->mev);
                                assert(error == 0);
                        }
#endif /* __FreeBSD__ */
                }
                return (0);
        } else
                return (-1);
}

void
uart_rxfifo_drain(struct uart_softc *sc, bool loopback)
{
        int ch;

        if (loopback) {
                (void)ttyread(&sc->tty);
        } else {
                while (rxfifo_available(sc) &&
                    ((ch = ttyread(&sc->tty)) != -1))
                        rxfifo_putchar(sc, ch);
        }
}

#ifndef __FreeBSD__
void
uart_rxfifo_sock_drain(struct uart_softc *sc, bool loopback)
{
        int ch;

        if (loopback) {
                (void) read(sc->usc_sock.clifd, &ch, 1);
        } else {
                bool err_close = false;

                while (rxfifo_available(sc)) {
                        int res;

                        res = read(sc->usc_sock.clifd, &ch, 1);
                        if (res == 0) {
                                err_close = true;
                                break;
                        } else if (res == -1) {
                                if (errno != EAGAIN && errno != EINTR) {
                                        err_close = true;
                                }
                                break;
                        }

                        rxfifo_putchar(sc, ch);
                }

                if (err_close) {
                        (void) fprintf(stderr, "uart: closing client conn\n");
                        (void) shutdown(sc->usc_sock.clifd, SHUT_RDWR);
                        mevent_delete_close(sc->mev);
                        sc->mev = NULL;
                        sc->usc_sock.clifd = -1;
                }
        }
}
#endif

int
uart_rxfifo_putchar(struct uart_softc *sc, uint8_t ch, bool loopback)
{
        if (loopback) {
                return (rxfifo_putchar(sc, ch));
        } else if (sc->tty.opened) {
                ttywrite(&sc->tty, ch);
                return (0);
#ifndef __FreeBSD__
        } else if (sc->usc_sock.sock) {
                sockwrite(sc, ch);
                return (0);
#endif
        } else {
                /* Drop on the floor. */
                return (0);
        }
}

void
uart_rxfifo_reset(struct uart_softc *sc, int size)
{
        char flushbuf[32];
        struct fifo *fifo;
        ssize_t nread;
        int error;

        fifo = &sc->rxfifo;
        bzero(fifo, sizeof(struct fifo));
        fifo->size = size;

        if (sc->tty.opened) {
                /*
                 * Flush any unread input from the tty buffer.
                 */
                while (1) {
                        nread = read(sc->tty.rfd, flushbuf, sizeof(flushbuf));
                        if (nread != sizeof(flushbuf))
                                break;
                }

                /*
                 * Enable mevent to trigger when new characters are available
                 * on the tty fd.
                 */
                error = mevent_enable(sc->mev);
                assert(error == 0);
        }
#ifndef __FreeBSD__
        if (sc->usc_sock.sock && sc->usc_sock.clifd != -1) {
                /* Flush any unread input from the socket buffer. */
                do {
                        nread = read(sc->usc_sock.clifd, flushbuf,
                            sizeof (flushbuf));
                } while (nread == sizeof (flushbuf));

                /* Enable mevent to trigger when new data available on sock */
                error = mevent_enable(sc->mev);
                assert(error == 0);
        }
#endif /* __FreeBSD__ */
}

int
uart_rxfifo_size(struct uart_softc *sc __unused)
{
        return (FIFOSZ);
}

#ifdef BHYVE_SNAPSHOT
int
uart_rxfifo_snapshot(struct uart_softc *sc, struct vm_snapshot_meta *meta)
{
        int ret;

        SNAPSHOT_VAR_OR_LEAVE(sc->rxfifo.rindex, meta, ret, done);
        SNAPSHOT_VAR_OR_LEAVE(sc->rxfifo.windex, meta, ret, done);
        SNAPSHOT_VAR_OR_LEAVE(sc->rxfifo.num, meta, ret, done);
        SNAPSHOT_VAR_OR_LEAVE(sc->rxfifo.size, meta, ret, done);
        SNAPSHOT_BUF_OR_LEAVE(sc->rxfifo.buf, sizeof(sc->rxfifo.buf),
            meta, ret, done);

done:
        return (ret);
}
#endif

static int
uart_stdio_backend(struct uart_softc *sc)
{
#ifndef WITHOUT_CAPSICUM
        cap_rights_t rights;
        cap_ioctl_t cmds[] = { TIOCGETA, TIOCSETA, TIOCGWINSZ };
#endif

        if (uart_stdio)
                return (-1);

        sc->tty.rfd = STDIN_FILENO;
        sc->tty.wfd = STDOUT_FILENO;
        sc->tty.opened = true;

        if (fcntl(sc->tty.rfd, F_SETFL, O_NONBLOCK) != 0)
                return (-1);
        if (fcntl(sc->tty.wfd, F_SETFL, O_NONBLOCK) != 0)
                return (-1);

#ifndef WITHOUT_CAPSICUM
        cap_rights_init(&rights, CAP_EVENT, CAP_IOCTL, CAP_READ);
        if (caph_rights_limit(sc->tty.rfd, &rights) == -1)
                errx(EX_OSERR, "Unable to apply rights for sandbox");
        if (caph_ioctls_limit(sc->tty.rfd, cmds, nitems(cmds)) == -1)
                errx(EX_OSERR, "Unable to apply rights for sandbox");
#endif

        uart_stdio = true;

        return (0);
}

static int
uart_tty_backend(struct uart_softc *sc, const char *path)
{
#ifndef WITHOUT_CAPSICUM
        cap_rights_t rights;
        cap_ioctl_t cmds[] = { TIOCGETA, TIOCSETA, TIOCGWINSZ };
#endif
        int fd;

        fd = open(path, O_RDWR | O_NONBLOCK);
        if (fd < 0)
                return (-1);

        if (!isatty(fd)) {
                close(fd);
                return (-1);
        }

        sc->tty.rfd = sc->tty.wfd = fd;
        sc->tty.opened = true;

#ifndef WITHOUT_CAPSICUM
        cap_rights_init(&rights, CAP_EVENT, CAP_IOCTL, CAP_READ, CAP_WRITE);
        if (caph_rights_limit(fd, &rights) == -1)
                errx(EX_OSERR, "Unable to apply rights for sandbox");
        if (caph_ioctls_limit(fd, cmds, nitems(cmds)) == -1)
                errx(EX_OSERR, "Unable to apply rights for sandbox");
#endif

        return (0);
}

#ifndef __FreeBSD__
static void
uart_sock_accept(int fd, enum ev_type ev, void *arg)
{
        struct uart_softc *sc = arg;
        int connfd;

        connfd = accept(sc->usc_sock.servfd, NULL, NULL);
        if (connfd == -1) {
                return;
        }

        /*
         * Do client connection management under protection of the softc lock
         * to avoid racing with concurrent UART events.
         */
        pthread_mutex_lock(&sc->mtx);

        if (sc->usc_sock.clifd != -1) {
                /* we're already handling a client */
                (void) fprintf(stderr, "uart: unexpected client conn\n");
                (void) shutdown(connfd, SHUT_RDWR);
                (void) close(connfd);
        } else {
                if (fcntl(connfd, F_SETFL, O_NONBLOCK) < 0) {
                        perror("uart: fcntl(O_NONBLOCK)");
                        (void) shutdown(connfd, SHUT_RDWR);
                        (void) close(connfd);
                } else {
                        sc->usc_sock.clifd = connfd;
                        sc->mev = mevent_add(sc->usc_sock.clifd, EVF_READ,
                            sc->usc_sock.drain, sc->usc_sock.drainarg);
                }
        }

        pthread_mutex_unlock(&sc->mtx);
}

static int
init_sock(const char *path)
{
        int servfd;
        struct sockaddr_un servaddr;

        bzero(&servaddr, sizeof (servaddr));
        servaddr.sun_family = AF_UNIX;

        if (strlcpy(servaddr.sun_path, path, sizeof (servaddr.sun_path)) >=
            sizeof (servaddr.sun_path)) {
                (void) fprintf(stderr, "uart: path '%s' too long\n",
                    path);
                return (-1);
        }

        if ((servfd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
                (void) fprintf(stderr, "uart: socket() error - %s\n",
                    strerror(errno));
                return (-1);
        }
        (void) unlink(servaddr.sun_path);

        if (bind(servfd, (struct sockaddr *)&servaddr,
            sizeof (servaddr)) == -1) {
                (void) fprintf(stderr, "uart: bind() error - %s\n",
                    strerror(errno));
                goto out;
        }

        if (listen(servfd, 1) == -1) {
                (void) fprintf(stderr, "uart: listen() error - %s\n",
                    strerror(errno));
                goto out;
        }
        return (servfd);

out:
        (void) unlink(servaddr.sun_path);
        (void) close(servfd);
        return (-1);
}

static int
uart_sock_backend(struct uart_softc *sc, const char *inopts,
    void (*drain)(int, enum ev_type, void *), void *drainarg)
{
        char *opts, *tofree;
        char *opt;
        char *nextopt;
        char *path = NULL;

        if (strncmp(inopts, "socket,", 7) != 0) {
                return (-1);
        }
        if ((opts = strdup(inopts + 7)) == NULL) {
                return (-1);
        }

        tofree = nextopt = opts;
        for (opt = strsep(&nextopt, ","); opt != NULL;
            opt = strsep(&nextopt, ",")) {
                if (path == NULL && *opt == '/') {
                        path = opt;
                        continue;
                }
                /*
                 * XXX check for server and client options here.  For now,
                 * everything is a server
                 */
                free(tofree);
                return (-1);
        }

        sc->usc_sock.clifd = -1;
        if ((sc->usc_sock.servfd = init_sock(path)) == -1) {
                free(tofree);
                return (-1);
        }
        sc->usc_sock.sock = true;
        sc->tty.rfd = sc->tty.wfd = -1;
        sc->usc_sock.servmev = mevent_add(sc->usc_sock.servfd, EVF_READ,
            uart_sock_accept, sc);
        assert(sc->usc_sock.servmev != NULL);

        sc->usc_sock.drain = drain;
        sc->usc_sock.drainarg = drainarg;

        free(tofree);
        return (0);
}
#endif /* not __FreeBSD__ */

struct uart_softc *
uart_init(void)
{
        struct uart_softc *sc = calloc(1, sizeof(struct uart_softc));
        if (sc == NULL)
                return (NULL);

        pthread_mutex_init(&sc->mtx, NULL);

        return (sc);
}

int
uart_tty_open(struct uart_softc *sc, const char *path,
    void (*drain)(int, enum ev_type, void *), void *arg)
{
        int retval;

#ifndef __FreeBSD__
        if (strncmp("socket,", path, 7) == 0)
                return (uart_sock_backend(sc, path, drain, arg));
#endif
        if (strcmp("stdio", path) == 0)
                retval = uart_stdio_backend(sc);
        else
                retval = uart_tty_backend(sc, path);
        if (retval == 0) {
                ttyopen(&sc->tty);
                sc->mev = mevent_add(sc->tty.rfd, EVF_READ, drain, arg);
                assert(sc->mev != NULL);
        }

        return (retval);
}

void
uart_softc_lock(struct uart_softc *sc)
{
        pthread_mutex_lock(&sc->mtx);
}

void
uart_softc_unlock(struct uart_softc *sc)
{
        pthread_mutex_unlock(&sc->mtx);
}