diff options
Diffstat (limited to 'grub-core/loader/i386/pc/freedos.c')
| -rw-r--r-- | grub-core/loader/i386/pc/freedos.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/grub-core/loader/i386/pc/freedos.c b/grub-core/loader/i386/pc/freedos.c new file mode 100644 index 0000000..aac6c97 --- /dev/null +++ b/grub-core/loader/i386/pc/freedos.c @@ -0,0 +1,190 @@ +/* chainloader.c - boot another boot loader */ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2002,2004,2007,2009,2010 Free Software Foundation, Inc. + * + * GRUB is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * GRUB is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GRUB. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <grub/loader.h> +#include <grub/file.h> +#include <grub/err.h> +#include <grub/device.h> +#include <grub/disk.h> +#include <grub/misc.h> +#include <grub/types.h> +#include <grub/partition.h> +#include <grub/dl.h> +#include <grub/command.h> +#include <grub/machine/biosnum.h> +#include <grub/i18n.h> +#include <grub/video.h> +#include <grub/mm.h> +#include <grub/cpu/relocator.h> +#include <grub/machine/chainloader.h> + +GRUB_MOD_LICENSE ("GPLv3+"); + +static grub_dl_t my_mod; +static struct grub_relocator *rel; +static grub_uint32_t ebx = 0xffffffff; + +#define GRUB_FREEDOS_SEGMENT 0x60 +#define GRUB_FREEDOS_ADDR (GRUB_FREEDOS_SEGMENT << 4) +#define GRUB_FREEDOS_STACK_SEGMENT 0x1fe0 +#define GRUB_FREEDOS_STACK_BPB_POINTER 0x7c00 +#define GRUB_FREEDOS_BPB_ADDR ((GRUB_FREEDOS_STACK_SEGMENT << 4) \ + + GRUB_FREEDOS_STACK_BPB_POINTER) + +/* FreeDOS boot.asm passes register sp as exactly this. Importantly, + it must point below the BPB (to avoid overwriting any of it). */ +#define GRUB_FREEDOS_STACK_POINTER (GRUB_FREEDOS_STACK_BPB_POINTER \ + - 0x60) + +/* In this, the additional 8192 bytes are the stack reservation; the + remaining parts trivially give the maximum allowed size. */ +#define GRUB_FREEDOS_MAX_SIZE ((GRUB_FREEDOS_STACK_SEGMENT << 4) \ + + GRUB_FREEDOS_STACK_POINTER \ + - GRUB_FREEDOS_ADDR \ + - 8192) + +static grub_err_t +grub_freedos_boot (void) +{ + struct grub_relocator16_state state = { + .cs = GRUB_FREEDOS_SEGMENT, + .ip = 0, + + .ds = GRUB_FREEDOS_STACK_SEGMENT, + .es = 0, + .fs = 0, + .gs = 0, + .ss = GRUB_FREEDOS_STACK_SEGMENT, + .sp = GRUB_FREEDOS_STACK_POINTER, + .ebp = GRUB_FREEDOS_STACK_BPB_POINTER, + .ebx = ebx, + .edx = ebx, + .a20 = 1 + }; + grub_video_set_mode ("text", 0, 0); + + return grub_relocator16_boot (rel, state); +} + +static grub_err_t +grub_freedos_unload (void) +{ + grub_relocator_unload (rel); + rel = NULL; + grub_dl_unref (my_mod); + return GRUB_ERR_NONE; +} + +static grub_err_t +grub_cmd_freedos (grub_command_t cmd __attribute__ ((unused)), + int argc, char *argv[]) +{ + grub_file_t file = 0; + grub_err_t err; + void *bs, *kernelsys; + grub_size_t kernelsyssize; + grub_device_t dev; + + if (argc == 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected")); + + grub_dl_ref (my_mod); + + rel = grub_relocator_new (); + if (!rel) + goto fail; + + file = grub_file_open (argv[0], GRUB_FILE_TYPE_FREEDOS); + if (! file) + goto fail; + + { + grub_relocator_chunk_t ch; + err = grub_relocator_alloc_chunk_addr (rel, &ch, GRUB_FREEDOS_BPB_ADDR, + GRUB_DISK_SECTOR_SIZE); + if (err) + goto fail; + bs = get_virtual_current_address (ch); + } + + ebx = grub_get_root_biosnumber (); + dev = grub_device_open (0); + + if (dev && dev->disk) + { + err = grub_disk_read (dev->disk, 0, 0, GRUB_DISK_SECTOR_SIZE, bs); + if (err) + { + grub_device_close (dev); + goto fail; + } + grub_chainloader_patch_bpb (bs, dev, ebx); + } + + if (dev) + grub_device_close (dev); + + kernelsyssize = grub_file_size (file); + + if (kernelsyssize > GRUB_FREEDOS_MAX_SIZE) + { + grub_error (GRUB_ERR_BAD_OS, + N_("the size of `%s' is too large"), argv[0]); + goto fail; + } + + { + grub_relocator_chunk_t ch; + err = grub_relocator_alloc_chunk_addr (rel, &ch, GRUB_FREEDOS_ADDR, + kernelsyssize); + if (err) + goto fail; + kernelsys = get_virtual_current_address (ch); + } + + if (grub_file_read (file, kernelsys, kernelsyssize) + != (grub_ssize_t) kernelsyssize) + goto fail; + + grub_loader_set (grub_freedos_boot, grub_freedos_unload, 1); + return GRUB_ERR_NONE; + + fail: + + if (file) + grub_file_close (file); + + grub_freedos_unload (); + + return grub_errno; +} + +static grub_command_t cmd; + +GRUB_MOD_INIT(freedos) +{ + cmd = grub_register_command ("freedos", grub_cmd_freedos, + 0, N_("Load FreeDOS kernel.sys.")); + my_mod = mod; +} + +GRUB_MOD_FINI(freedos) +{ + grub_unregister_command (cmd); +} |