/*-
 * Copyright 2015 Toomas Soome <tsoome@me.com>
 * 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.
 */

/*
 * Chain loader to load BIOS boot block either from MBR or PBR.
 *
 * Note the boot block location 0000:7c000 conflicts with loader, so we need to
 * read in to temporary space and relocate on exec, when btx is stopped.
 */

#include <stand.h>
#include <sys/param.h>
#include <sys/linker.h>
#include <sys/diskmbr.h>

#include "bootstrap.h"
#include "libi386/libi386.h"
#include "btxv86.h"

#ifdef LOADER_VERIEXEC_VECTX
#define VECTX_HANDLE(x) vctx
#else
#define VECTX_HANDLE(x) x
#endif

/*
 * The MBR/VBR is located in first sector of disk/partition.
 * Read 512B to temporary location and set up relocation. Then
 * exec relocator.
 */
#define SECTOR_SIZE     (512)

COMMAND_SET(chain, "chain", "chain load boot block from device", command_chain);

static int
command_chain(int argc, char *argv[])
{
        int fd, len, size = SECTOR_SIZE;
        struct stat st;
        vm_offset_t mem = 0x100000;
        struct i386_devdesc *rootdev;
#ifdef LOADER_VERIEXEC_VECTX
        struct vectx *vctx;
        int verror;
#endif

        if (argc == 1) {
                command_errmsg = "no device or file name specified";
                return (CMD_ERROR);
        }
        if (argc != 2) {
                command_errmsg = "invalid trailing arguments";
                return (CMD_ERROR);
        }

        fd = open(argv[1], O_RDONLY);
        if (fd == -1) {
                command_errmsg = "open failed";
                return (CMD_ERROR);
        }

#ifdef LOADER_VERIEXEC_VECTX
        vctx = vectx_open(fd, argv[1], 0L, NULL, &verror, __func__);
        if (verror) {
                sprintf(command_errbuf, "can't verify: %s", argv[1]);
                close(fd);
                free(vctx);
                return (CMD_ERROR);
        }
#else
#ifdef LOADER_VERIEXEC
        if (verify_file(fd, argv[1], 0, VE_MUST, __func__) < 0) {
                sprintf(command_errbuf, "can't verify: %s", argv[1]);
                close(fd);
                return (CMD_ERROR);
        }
#endif
#endif
        len = strlen(argv[1]);
        if (argv[1][len-1] != ':') {
                if (fstat(fd, &st) == -1) {
                        command_errmsg = "stat failed";
                        close(fd);
                        return (CMD_ERROR);
                }
                size = st.st_size;
        } else if (strncmp(argv[1], "disk", 4) != 0) {
                command_errmsg = "can only use disk device";
                close(fd);
                return (CMD_ERROR);
        }

        i386_getdev((void **)(&rootdev), argv[1], NULL);
        if (rootdev == NULL) {
                command_errmsg = "can't determine root device";
                close(fd);
                return (CMD_ERROR);
        }

        if (archsw.arch_readin(VECTX_HANDLE(fd), mem, size) != size) {
                command_errmsg = "failed to read disk";
                close(fd);
                return (CMD_ERROR);
        }
        close(fd);
#ifdef LOADER_VERIEXEC_VECTX
        verror = vectx_close(vctx, VE_MUST, __func__);
        if (verror) {
                free(vctx);
                return (CMD_ERROR);
        }
#endif
        if (argv[1][len-1] == ':' &&
            *((uint16_t *)PTOV(mem + DOSMAGICOFFSET)) != DOSMAGIC) {
                command_errmsg = "wrong magic";
                return (CMD_ERROR);
        }

        relocater_data[0].src = mem;
        relocater_data[0].dest = 0x7C00;
        relocater_data[0].size = size;

        relocator_edx = bd_unit2bios(rootdev);
        relocator_esi = relocater_size;
        relocator_ds = 0;
        relocator_es = 0;
        relocator_fs = 0;
        relocator_gs = 0;
        relocator_ss = 0;
        relocator_cs = 0;
        relocator_sp = 0x7C00;
        relocator_ip = 0x7C00;
        relocator_a20_enabled = 0;

        i386_copyin(relocater, 0x600, relocater_size);

        dev_cleanup();

        __exec((void *)0x600);

        panic("exec returned");
        return (CMD_ERROR);             /* not reached */
}