/*-
 * Copyright (c) 2011 Google, Inc.
 * Copyright (c) 2023-2024 Juniper Networks, Inc.
 * 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 THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR 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 <sys/disk.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <dirent.h>
#include <dlfcn.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <inttypes.h>
#include <libgen.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>

#include <userboot.h>

char **vars;

char *host_base = NULL;
struct termios term, oldterm;
char *image;
size_t image_size;

uint64_t regs[16];
uint64_t pc;
int *disk_fd;
int disk_index = -1;

void test_exit(void *arg, int v);

/*
 * Console i/o
 */

void
test_putc(void *arg, int ch)
{
        char c = ch;

        write(1, &c, 1);
}

int
test_getc(void *arg)
{
        char c;

        if (read(0, &c, 1) == 1)
                return c;
        return -1;
}

int
test_poll(void *arg)
{
        int n;

        if (ioctl(0, FIONREAD, &n) >= 0)
                return (n > 0);
        return (0);
}

/*
 * Host filesystem i/o
 */

struct test_file {
        int tf_isdir;
        size_t tf_size;
        struct stat tf_stat;
        union {
                int fd;
                DIR *dir;
        } tf_u;
};

static int
test_open_internal(void *arg, const char *filename, void **h_return,
    struct test_file *tf, int depth)
{
        char path[PATH_MAX];
        char linkpath[PATH_MAX];
        char *component, *cp, *linkptr;
        ssize_t slen;
        int comp_fd, dir_fd, error;
        char c;
        bool openbase;

        if (depth++ >= MAXSYMLINKS)
                return (ELOOP);

        openbase = false;
        error = EINVAL;
        if (tf == NULL) {
                tf = calloc(1, sizeof(struct test_file));
                if (tf == NULL)
                        return (error);
                openbase = true;
        } else if (tf->tf_isdir) {
                if (filename[0] == '/') {
                        closedir(tf->tf_u.dir);
                        openbase = true;
                }
        } else
                return (error);

        if (openbase) {
                dir_fd = open(host_base, O_RDONLY);
                if (dir_fd < 0)
                        goto out;

                tf->tf_isdir = 1;
                tf->tf_u.dir = fdopendir(dir_fd);

                if (fstat(dir_fd, &tf->tf_stat) < 0) {
                        error = errno;
                        goto out;
                }
                tf->tf_size = tf->tf_stat.st_size;
        }

        strlcpy(path, filename, sizeof(path));
        cp = path;
        while (*cp) {
                /*
                 * The test file should be a directory at this point.
                 * If it is not, then the caller provided an invalid filename.
                 */
                if (!tf->tf_isdir)
                        goto out;

                /* Trim leading slashes */
                while (*cp == '/')
                        cp++;

                /* If we reached the end, we are done */
                if (*cp == '\0')
                        break;

                /* Get the file descriptor for the directory */
                dir_fd = dirfd(tf->tf_u.dir);

                /* Get the next component path */
                component = cp;
                while ((c = *cp) != '\0' && c != '/')
                        cp++;
                if (c == '/')
                        *cp++ = '\0';

                /* Get status of the component */
                if (fstatat(dir_fd, component, &tf->tf_stat,
                    AT_SYMLINK_NOFOLLOW) < 0) {
                        error = errno;
                        goto out;
                }
                tf->tf_size = tf->tf_stat.st_size;

                /*
                 * Check that the path component is a directory, regular file,
                 * or a symlink.
                 */
                if (!S_ISDIR(tf->tf_stat.st_mode) &&
                    !S_ISREG(tf->tf_stat.st_mode) &&
                    !S_ISLNK(tf->tf_stat.st_mode))
                        goto out;

                /* For anything that is not a symlink, open it */
                if (!S_ISLNK(tf->tf_stat.st_mode)) {
                        comp_fd = openat(dir_fd, component, O_RDONLY);
                        if (comp_fd < 0)
                                goto out;
                }

                if (S_ISDIR(tf->tf_stat.st_mode)) {
                        /* Directory */

                        /* close the parent directory */
                        closedir(tf->tf_u.dir);

                        /* Open the directory from the component descriptor */
                        tf->tf_isdir = 1;
                        tf->tf_u.dir = fdopendir(comp_fd);
                        if (!tf->tf_u.dir)
                                goto out;
                } else if (S_ISREG(tf->tf_stat.st_mode)) {
                        /* Regular file */

                        /* close the parent directory */
                        closedir(tf->tf_u.dir);

                        /* Stash the component descriptor */
                        tf->tf_isdir = 0;
                        tf->tf_u.fd = comp_fd;
                } else if (S_ISLNK(tf->tf_stat.st_mode)) {
                        /* Symlink */

                        /* Read what the symlink points to */
                        slen = readlinkat(dir_fd, component, linkpath,
                            sizeof(linkpath));
                        if (slen < 0)
                                goto out;
                        /* NUL-terminate the string */
                        linkpath[(size_t)slen] = '\0';

                        /* Open the thing that the symlink points to */
                        error = test_open_internal(arg, linkpath, NULL,
                            tf, depth);
                        if (error != 0)
                                goto out;
                }
        }

        /* Completed the entire path and have a good file/directory */
        if (h_return != NULL)
                *h_return = tf;
        return (0);

out:
        /* Failure of some sort, clean up */
        if (tf->tf_isdir)
                closedir(tf->tf_u.dir);
        else
                close(tf->tf_u.fd);
        free(tf);
        return (error);
}

int
test_open(void *arg, const char *filename, void **h_return)
{
        if (host_base == NULL)
                return (ENOENT);

        return (test_open_internal(arg, filename, h_return, NULL, 0));
}

int
test_close(void *arg, void *h)
{
        struct test_file *tf = h;

        if (tf->tf_isdir)
                closedir(tf->tf_u.dir);
        else
                close(tf->tf_u.fd);
        free(tf);

        return (0);
}

int
test_isdir(void *arg, void *h)
{
        struct test_file *tf = h;

        return (tf->tf_isdir);
}

int
test_read(void *arg, void *h, void *dst, size_t size, size_t *resid_return)
{
        struct test_file *tf = h;
        ssize_t sz;

        if (tf->tf_isdir)
                return (EINVAL);
        sz = read(tf->tf_u.fd, dst, size);
        if (sz < 0)
                return (EINVAL);
        *resid_return = size - sz;
        return (0);
}

int
test_readdir(void *arg, void *h, uint32_t *fileno_return, uint8_t *type_return,
    size_t *namelen_return, char *name)
{
        struct test_file *tf = h;
        struct dirent *dp;

        if (!tf->tf_isdir)
                return (EINVAL);

        dp = readdir(tf->tf_u.dir);
        if (!dp)
                return (ENOENT);

        /*
         * Note: d_namlen is in the range 0..255 and therefore less
         * than PATH_MAX so we don't need to test before copying.
         */
        *fileno_return = dp->d_fileno;
        *type_return = dp->d_type;
        *namelen_return = dp->d_namlen;
        memcpy(name, dp->d_name, dp->d_namlen);
        name[dp->d_namlen] = 0;

        return (0);
}

int
test_seek(void *arg, void *h, uint64_t offset, int whence)
{
        struct test_file *tf = h;

        if (tf->tf_isdir)
                return (EINVAL);
        if (lseek(tf->tf_u.fd, offset, whence) < 0)
                return (errno);
        return (0);
}

int
test_stat(void *arg, void *h, struct stat *stp)
{
        struct test_file *tf = h;

        if (!stp)
                return (-1);
        memset(stp, 0, sizeof(struct stat));
        stp->st_mode = tf->tf_stat.st_mode;
        stp->st_uid = tf->tf_stat.st_uid;
        stp->st_gid = tf->tf_stat.st_gid;
        stp->st_size = tf->tf_stat.st_size;
        stp->st_ino = tf->tf_stat.st_ino;
        stp->st_dev = tf->tf_stat.st_dev;
        stp->st_mtime = tf->tf_stat.st_mtime;
        return (0);
}

/*
 * Disk image i/o
 */

int
test_diskread(void *arg, int unit, uint64_t offset, void *dst, size_t size,
    size_t *resid_return)
{
        ssize_t n;

        if (unit > disk_index || disk_fd[unit] == -1)
                return (EIO);
        n = pread(disk_fd[unit], dst, size, offset);
        if (n == 0) {
                printf("%s: end of disk (%ju)\n", __func__, (intmax_t)offset);
                return (EIO);
        }

        if (n < 0)
                return (errno);
        *resid_return = size - n;
        return (0);
}

int
test_diskwrite(void *arg, int unit, uint64_t offset, void *src, size_t size,
    size_t *resid_return)
{
        ssize_t n;

        if (unit > disk_index || disk_fd[unit] == -1)
                return (EIO);
        n = pwrite(disk_fd[unit], src, size, offset);
        if (n < 0)
                return (errno);
        *resid_return = size - n;
        return (0);
}

int
test_diskioctl(void *arg, int unit, u_long cmd, void *data)
{
        struct stat sb;

        if (unit > disk_index || disk_fd[unit] == -1)
                return (EBADF);
        switch (cmd) {
        case DIOCGSECTORSIZE:
                *(u_int *)data = 512;
                break;
        case DIOCGMEDIASIZE:
                if (fstat(disk_fd[unit], &sb) == 0)
                        *(off_t *)data = sb.st_size;
                else
                        return (ENOTTY);
                break;
        default:
                return (ENOTTY);
        }
        return (0);
}

/*
 * Guest virtual machine i/o
 *
 * Note: guest addresses are kernel virtual
 */

int
test_copyin(void *arg, const void *from, uint64_t to, size_t size)
{

        to &= 0x7fffffff;
        if (to > image_size)
                return (EFAULT);
        if (to + size > image_size)
                size = image_size - to;
        memcpy(&image[to], from, size);
        return(0);
}

int
test_copyout(void *arg, uint64_t from, void *to, size_t size)
{

        from &= 0x7fffffff;
        if (from > image_size)
                return (EFAULT);
        if (from + size > image_size)
                size = image_size - from;
        memcpy(to, &image[from], size);
        return(0);
}

void
test_setreg(void *arg, int r, uint64_t v)
{

        if (r < 0 || r >= 16)
                return;
        regs[r] = v;
}

void
test_setmsr(void *arg, int r, uint64_t v)
{
}

void
test_setcr(void *arg, int r, uint64_t v)
{
}

void
test_setgdt(void *arg, uint64_t v, size_t sz)
{
}

void
test_exec(void *arg, uint64_t pc)
{
        printf("Execute at 0x%"PRIx64"\n", pc);
        test_exit(arg, 0);
}

/*
 * Misc
 */

void
test_delay(void *arg, int usec)
{

        usleep(usec);
}

void
test_exit(void *arg, int v)
{

        tcsetattr(0, TCSAFLUSH, &oldterm);
        exit(v);
}

void
test_getmem(void *arg, uint64_t *lowmem, uint64_t *highmem)
{

        *lowmem = 128*1024*1024;
        *highmem = 0;
}

char *
test_getenv(void *arg, int idx)
{
        static char *myvars[] = {
                "USERBOOT=1"
        };
        static const int num_myvars = nitems(myvars);

        if (idx < num_myvars)
                return (myvars[idx]);
        else
                return (vars[idx - num_myvars]);
}

struct loader_callbacks cb = {
        .putc = test_putc,
        .getc = test_getc,
        .poll = test_poll,

        .open = test_open,
        .close = test_close,
        .isdir = test_isdir,
        .read = test_read,
        .readdir = test_readdir,
        .seek = test_seek,
        .stat = test_stat,

        .diskread = test_diskread,
        .diskwrite = test_diskwrite,
        .diskioctl = test_diskioctl,

        .copyin = test_copyin,
        .copyout = test_copyout,
        .setreg = test_setreg,
        .setmsr = test_setmsr,
        .setcr = test_setcr,
        .setgdt = test_setgdt,
        .exec = test_exec,

        .delay = test_delay,
        .exit = test_exit,
        .getmem = test_getmem,

        .getenv = test_getenv,
};

void
usage()
{

        printf("usage: [-b <userboot shared object>] [-d <disk image path>] [-h <host filesystem path>\n");
        exit(1);
}

int
main(int argc, char** argv, char ** environment)
{
        void *h;
        void (*func)(struct loader_callbacks *, void *, int, int) __dead2;
        int opt;
        const char *userboot_obj = "/boot/userboot.so";
        int oflag = O_RDONLY;

        vars = environment;

        while ((opt = getopt(argc, argv, "wb:d:h:")) != -1) {
                switch (opt) {
                case 'b':
                        userboot_obj = optarg;
                        break;

                case 'd':
                        disk_index++;
                        disk_fd = reallocarray(disk_fd, disk_index + 1,
                            sizeof (int));
                        disk_fd[disk_index] = open(optarg, oflag);
                        if (disk_fd[disk_index] < 0)
                                err(1, "Can't open disk image '%s'", optarg);
                        break;

                case 'h':
                        host_base = optarg;
                        break;

                case 'w':
                        oflag = O_RDWR;
                        break;

                case '?':
                        usage();
                }
        }

        h = dlopen(userboot_obj, RTLD_LOCAL);
        if (!h) {
                printf("%s\n", dlerror());
                return (1);
        }
        func = dlsym(h, "loader_main");
        if (!func) {
                printf("%s\n", dlerror());
                return (1);
        }

        image_size = 128*1024*1024;
        image = malloc(image_size);

        tcgetattr(0, &term);
        oldterm = term;
        term.c_iflag &= ~(ICRNL);
        term.c_lflag &= ~(ICANON|ECHO);
        tcsetattr(0, TCSAFLUSH, &term);

        func(&cb, NULL, USERBOOT_VERSION_3, disk_index + 1);
}