/*      $OpenBSD: disk.c,v 1.3 2023/10/20 18:53:12 kettenis Exp $       */

/*
 * Copyright (c) 2019 Visa Hankala
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/disklabel.h>
#include <sys/dkio.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/sysctl.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>

#include "cmd.h"

int     disk_proberoot(const char *);

int mounted = 0;
int rdroot = -1;                /* fd that points to the root of the ramdisk */

void
disk_init(void)
{
        char rootdevs[1024];
        char *devname, *disknames, *ptr;
        size_t size;
        int mib[2];

        rdroot = open("/", O_RDONLY);
        if (rdroot == -1)
                err(1, "failed to open root directory fd");

        if (strlen(cmd.bootdev) != 0)
                return;

        mib[0] = CTL_HW;
        mib[1] = HW_DISKNAMES;
        size = 0;
        if (sysctl(mib, 2, NULL, &size, NULL, 0) == -1) {
                fprintf(stderr, "%s: cannot get hw.disknames: %s\n", __func__,
                    strerror(errno));
                return;
        }
        disknames = malloc(size);
        if (disknames == NULL) {
                fprintf(stderr, "%s: out of memory\n", __func__);
                return;
        }
        if (sysctl(mib, 2, disknames, &size, NULL, 0) == -1) {
                fprintf(stderr, "%s: cannot get hw.disknames: %s\n", __func__,
                    strerror(errno));
                free(disknames);
                return;
        }

        printf("probing disks\n");
        rootdevs[0] = '\0';
        ptr = disknames;
        while ((devname = strsep(&ptr, ",")) != NULL) {
                char *duid;

                duid = strchr(devname, ':');
                if (duid == NULL)
                        continue;
                *duid++ = '\0';

                /* Disk without a duid cannot be a root device. */
                if (strlen(duid) == 0)
                        continue;

                if (disk_proberoot(devname)) {
                        if (strlen(cmd.bootdev) == 0) {
                                snprintf(cmd.bootdev, sizeof(cmd.bootdev),
                                    "%sa", devname);
                        }
                        (void)strlcat(rootdevs, " ", sizeof(rootdevs));
                        (void)strlcat(rootdevs, devname, sizeof(rootdevs));
                }
        }
        if (strlen(rootdevs) != 0)
                printf("available root devices:%s\n", rootdevs);
        else
                printf("no root devices found\n");
}

int
disk_proberoot(const char *devname)
{
        static const char *const names[] = {
                "bin", "dev", "etc", "home", "mnt", "root", "sbin", "tmp",
                "usr", "var", NULL
        };
        struct ufs_args ffs_args;
        struct stat st;
        char path[32];
        int i, is_root = 1;

        snprintf(path, sizeof(path), "/dev/%sa", devname);
        memset(&ffs_args, 0, sizeof(ffs_args));
        ffs_args.fspec = path;
        if (mount(MOUNT_FFS, "/mnt", MNT_RDONLY, &ffs_args) == -1)
                return 0;
        for (i = 0; names[i] != NULL; i++) {
                snprintf(path, sizeof(path), "/mnt/%s", names[i]);
                if (stat(path, &st) == -1 || !S_ISDIR(st.st_mode)) {
                        is_root = 0;
                        break;
                }
        }
        (void)unmount("/mnt", 0);

        return is_root;
}

const char *
disk_open(const char *path)
{
        struct ufs_args ffs_args;
        struct disklabel label;
        char devname[32];
        char *devpath;
        const char *ptr;
        int fd;

        if (mounted) {
                fprintf(stderr, "%s: cannot nest\n", __func__);
                return NULL;
        }

        ptr = strchr(path, ':');
        if (ptr != NULL) {
                snprintf(devname, sizeof(devname), "%.*s",
                    (int)(ptr - path), path);
                ptr++;  /* skip ':' */
        } else {
                strlcpy(devname, cmd.bootdev, sizeof(devname));
                ptr = path;
        }
        if (strlen(devname) == 0) {
                fprintf(stderr, "no device specified\n");
                return NULL;
        }

        cmd.hasduid = 0;
        fd = opendev(devname, O_RDONLY, OPENDEV_BLCK, &devpath);
        if (fd != -1) {
                if (ioctl(fd, DIOCGDINFO, &label) != -1) {
                        memcpy(cmd.bootduid, label.d_uid, 8);
                        cmd.hasduid = 1;
                }
                close(fd);
        } else {
                fprintf(stderr, "failed to open device %s: %s\n", devname,
                    strerror(errno));
                return NULL;
        }

        memset(&ffs_args, 0, sizeof(ffs_args));
        ffs_args.fspec = devpath;
        if (mount(MOUNT_FFS, "/mnt", MNT_NOATIME, &ffs_args) == -1) {
                if (mount(MOUNT_FFS, "/mnt", MNT_RDONLY, &ffs_args) == -1) {
                        fprintf(stderr, "failed to mount %s: %s\n", devpath,
                            strerror(errno));
                        return NULL;
                }
                fprintf(stderr, "%s: mounted read-only\n", devpath);
        }
        if (chroot("/mnt") == -1) {
                fprintf(stderr, "failed to chroot: %s\n", strerror(errno));
                (void)unmount("/mnt", 0);
                return NULL;
        }
        mounted = 1;

        return ptr;
}

void
disk_close(void)
{
        if (mounted) {
                (void)fchdir(rdroot);
                (void)chroot(".");
                mounted = 0;
                (void)unmount("/mnt", 0);
        }
}