/* -*- c -*- ------------------------------------------------------------- *
*
* Copyright 2003-2008 H. Peter Anvin - All Rights Reserved
* Portions copyright 2010 Shao Miller
*
* This program 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, Inc., 53 Temple Place Ste 330,
* Boston MA 02111-1307, USA; either version 2 of the License, or
* (at your option) any later version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
/*
* mdiskchk.c
*
* DOS program to check for the existence of a memdisk.
*
* This program can be compiled for DOS with the OpenWatcom compiler
* (http://www.openwatcom.org/):
*
* wcl -3 -osx -mt mdiskchk.c
*/
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <i86.h> /* For MK_FP() */
typedef unsigned long uint32_t;
typedef unsigned short uint16_t;
typedef unsigned char uint8_t;
/* Pull in MEMDISK common structures */
#include "../memdisk/mstructs.h"
struct memdiskinfo {
struct mdi mdi;
/* We add our own fields at the end */
int cylinders;
int heads;
int sectors;
};
struct memdiskinfo *query_memdisk(int drive)
{
static struct memdiskinfo mm;
uint32_t _eax, _ebx, _ecx, _edx;
uint16_t _es, _di;
unsigned char _dl = drive;
uint16_t bytes;
__asm {
.386;
mov eax, 454d0800h;
mov ecx, 444d0000h;
mov edx, 53490000h;
mov dl, _dl;
mov ebx, 3f4b0000h;
int 13h;
mov _eax, eax;
mov _ecx, ecx;
mov _edx, edx;
mov _ebx, ebx;
mov _es, es;
mov _di, di;
}
if (_eax >> 16 != 0x4d21 ||
_ecx >> 16 != 0x4d45 || _edx >> 16 != 0x4944 || _ebx >> 16 != 0x4b53)
return NULL;
memset(&mm, 0, sizeof mm);
bytes = *(uint16_t far *) MK_FP(_es, _di);
/* 27 is the most we know how to handle */
if (bytes > 27)
bytes = 27;
_fmemcpy((void far *)&mm, (void far *)MK_FP(_es, _di), bytes);
mm.cylinders = ((_ecx >> 8) & 0xff) + ((_ecx & 0xc0) << 2) + 1;
mm.heads = ((_edx >> 8) & 0xff) + 1;
mm.sectors = (_ecx & 0x3f);
return &mm;
}
const char *bootloadername(uint8_t id)
{
static const struct {
uint8_t id, mask;
const char *name;
} *lp, list[] = {
{0x00, 0xf0, "LILO"},
{0x10, 0xf0, "LOADLIN"},
{0x31, 0xff, "SYSLINUX"},
{0x32, 0xff, "PXELINUX"},
{0x33, 0xff, "ISOLINUX"},
{0x34, 0xff, "EXTLINUX"},
{0x30, 0xf0, "SYSLINUX family"},
{0x40, 0xf0, "Etherboot"},
{0x50, 0xf0, "ELILO"},
{0x70, 0xf0, "GrUB"},
{0x80, 0xf0, "U-Boot"},
{0xA0, 0xf0, "Gujin"},
{0xB0, 0xf0, "Qemu"},
{0x00, 0x00, "unknown"}
};
for (lp = list;; lp++) {
if (((id ^ lp->id) & lp->mask) == 0)
return lp->name;
}
}
/* The function type for an output function */
#define OUTPUT_FUNC_DECL(x) \
void x(const int d, const struct memdiskinfo * const m)
typedef OUTPUT_FUNC_DECL((*output_func));
/* Show MEMDISK information for the passed structure */
static OUTPUT_FUNC_DECL(normal_output)
{
if (m == NULL)
return;
printf("Drive %02X is MEMDISK %u.%02u:\n"
"\tAddress = 0x%08lx, len = %lu sectors, chs = %u/%u/%u,\n"
"\tloader = 0x%02x (%s),\n"
"\tcmdline = %Fs\n",
d, m->mdi.version_major, m->mdi.version_minor,
m->mdi.diskbuf, m->mdi.disksize, m->cylinders, m->heads, m->sectors,
m->mdi.bootloaderid, bootloadername(m->mdi.bootloaderid),
MK_FP(m->mdi.cmdline.seg_off.segment,
m->mdi.cmdline.seg_off.offset));
}
/* Yield DOS SET command(s) as output for each MEMDISK kernel argument */
static OUTPUT_FUNC_DECL(batch_output)
{
if (m != NULL) {
char buf[256], *bc;
const char far *c =
MK_FP(m->mdi.cmdline.seg_off.segment,
m->mdi.cmdline.seg_off.offset);
const char *have_equals, is_set[] = "=1";
while (*c != '\0') {
/* Skip whitespace */
while (isspace(*c))
c++;
if (*c == '\0')
/* Trailing whitespace. That's enough processing */
break;
/* Walk the kernel arguments while filling the buffer,
* looking for space or NUL or checking for a full buffer
*/
bc = buf;
have_equals = is_set;
while ((*c != '\0') && !isspace(*c) &&
(bc < &buf[sizeof(buf) - 1])) {
/* Check if the param is "x=y" */
if (*c == '=')
/* "=1" not needed */
have_equals = &is_set[sizeof(is_set) - 1];
*bc = *c;
c++;
bc++;
}
/* Found the end of the parameter and optional value sequence */
*bc = '\0';
printf("set %s%s\n", buf, have_equals);
}
}
}
/* We do not output batch file output by default. We show MEMDISK info */
static output_func show_memdisk = normal_output;
/* A generic function type */
#define MDISKCHK_FUNC_DECL(x) \
void x(void)
typedef MDISKCHK_FUNC_DECL((*mdiskchk_func));
static MDISKCHK_FUNC_DECL(do_nothing)
{
return;
}
static MDISKCHK_FUNC_DECL(show_usage)
{
printf("\nUsage: mdiskchk [--safe-hooks] [--mbfts] [--batch-output]\n"
"\n"
"Action: --safe-hooks . . Will scan INT 13h \"safe hook\" chain\n"
" --mbfts . . . . Will scan memory for MEMDISK mBFTs\n"
" --batch-output . Will output SET command output based\n"
" on MEMDISK kernel arguments\n"
" --no-sequential Suppresses probing all drive numbers\n");
}
/* Search memory for mBFTs and report them via the output method */
static MDISKCHK_FUNC_DECL(show_mbfts)
{
const uint16_t far * const free_base_mem =
MK_FP(0x0040, 0x0013);
int seg;
uint8_t chksum;
uint32_t i;
const struct mBFT far *mbft;
struct memdiskinfo m;
struct patch_area far *patch_area;
for (seg = *free_base_mem / 16; seg < 0x9FFF; seg++) {
mbft = MK_FP(seg, 0);
/* Check for signature */
if (mbft->acpi.signature[0] != 'm' ||
mbft->acpi.signature[1] != 'B' ||
mbft->acpi.signature[2] != 'F' ||
mbft->acpi.signature[3] != 'T')
continue;
if (mbft->acpi.length != sizeof(struct mBFT))
continue;
/* Check sum */
chksum = 0;
for (i = 0; i < sizeof(struct mBFT); i++)
chksum += ((const uint8_t far *)mbft)[i];
if (chksum)
continue;
/* Copy the MDI from the mBFT */
_fmemcpy((void far *)&m, &mbft->mdi, sizeof(struct mdi));
/* Adjust C/H/S since we actually know
* it directly for any MEMDISK with an mBFT
*/
patch_area = (struct patch_area far *)&mbft->mdi;
m.cylinders = patch_area->cylinders;
m.heads = patch_area->heads;
m.sectors = patch_area->sectors;
show_memdisk(patch_area->driveno, &m);
}
}
/* Walk the "safe hook" chain as far as possible
* and report MEMDISKs that we find via the output method
*/
static MDISKCHK_FUNC_DECL(show_safe_hooks)
{
const real_addr_t far * const int13 =
MK_FP(0x0000, 0x0013 * sizeof(real_addr_t));
const struct safe_hook far *hook =
MK_FP(int13->seg_off.segment, int13->seg_off.offset);
while ((hook->signature[0] == '$') &&
(hook->signature[1] == 'I') &&
(hook->signature[2] == 'N') &&
(hook->signature[3] == 'T') &&
(hook->signature[4] == '1') &&
(hook->signature[5] == '3') &&
(hook->signature[6] == 'S') &&
(hook->signature[7] == 'F')) {
/* Found a valid "safe hook" */
if ((hook->vendor[0] == 'M') &&
(hook->vendor[1] == 'E') &&
(hook->vendor[2] == 'M') &&
(hook->vendor[3] == 'D') &&
(hook->vendor[4] == 'I') &&
(hook->vendor[5] == 'S') &&
(hook->vendor[6] == 'K')) {
/* Found a valid MEMDISK "safe hook". It will have an mBFT */
const struct mBFT far *mbft;
struct memdiskinfo m;
struct patch_area far *patch_area;
/* Copy the MDI from the mBFT. Offset is a misnomer here */
mbft = MK_FP(hook->mbft >> 4, 0); /* Always aligned */
_fmemcpy((void far *)&m, &mbft->mdi, sizeof(struct mdi));
/* Adjust C/H/S since we actually know
* it directly for any MEMDISK with an mBFT
*/
patch_area = (struct patch_area far *)&mbft->mdi;
m.cylinders = patch_area->cylinders;
m.heads = patch_area->heads;
m.sectors = patch_area->sectors;
show_memdisk(patch_area->driveno, &m);
} /* if */
/* Step to the next hook in the "safe hook" chain */
hook = MK_FP(hook->old_hook.seg_off.segment,
hook->old_hook.seg_off.offset);
} /* while */
}
int main(int argc, char *argv[])
{
int d;
int found = 0;
int sequential_scan = 1; /* Classic behaviour */
const struct memdiskinfo *m;
/* Default behaviour */
mdiskchk_func usage = do_nothing,
safe_hooks = do_nothing,
mbfts = do_nothing;
/* For each argument */
while (--argc) {
/* Argument should begin with one of these chars */
if ((*argv[argc] != '/') && (*argv[argc] != '-')) {
/* It doesn't. Print usage soon */
usage = show_usage;
break;
}
argv[argc]++;
/* Next char might be '-' as in "--safe-hooks" */
if (*argv[argc] == '-')
argv[argc]++;
switch (*argv[argc]) {
case 'S':
case 's':
safe_hooks = show_safe_hooks;
break;
case 'M':
case 'm':
mbfts = show_mbfts;
break;
case 'B':
case 'b':
show_memdisk = batch_output;
break;
case 'N':
case 'n':
sequential_scan = 0;
break;
default:
usage = show_usage;
} /* switch */
} /* while */
safe_hooks();
mbfts();
if (!sequential_scan)
goto skip_sequential;
for (d = 0; d <= 0xff; d++) {
m = query_memdisk(d);
if (m != NULL) {
found++;
show_memdisk(d, m);
}
}
skip_sequential:
usage();
return found;
}
