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Diffstat (limited to 'com32/modules/ifmemdsk.c')
| -rw-r--r-- | com32/modules/ifmemdsk.c | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/com32/modules/ifmemdsk.c b/com32/modules/ifmemdsk.c new file mode 100644 index 00000000..cfed87f9 --- /dev/null +++ b/com32/modules/ifmemdsk.c @@ -0,0 +1,392 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2011 Shao Miller - All Rights Reserved + * + * 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., 51 Franklin St, Fifth Floor, + * Boston MA 02110-1301, USA; either version 2 of the License, or + * (at your option) any later version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +/**** + * @file ifmemdsk.c + * + * This COM32 module detects if there are MEMDISKs established. + */ + +static const char usage_text[] = "\ +Usage:\n\ + ifmemdsk.c32 [<option> [...]] --info [<option> [...]]\n\ + ifmemdsk.c32 [<option> [...]] [<detected_cmd>] -- [<not_detected_cmd>]\n\ +\n\ +Options:\n\ + --info . . . . . Displays info about MEMDISK(s)\n\ + --safe-hooks . . Will scan INT 13h \"safe hook\" chain\n\ + --mbfts . . . . . Will scan memory for MEMDISK mBFTs\n\ + --no-sequential Suppresses probing all drive numbers\n\ +\n\ +If a MEMDISK is found, or if a particular MEMDISK is sought by the options\n\ +and is found, then the 'detected_cmd' action will be taken, else the\n\ +'not_detected_cmd' action will be taken.\n\ +\n"; + +#include <stdio.h> +#include <string.h> +#include <alloca.h> +#include <com32.h> +#include <console.h> +#include <syslinux/boot.h> + +/* Pull in MEMDISK common structures */ +#include "../../memdisk/mstructs.h" + +/*** Macros */ +#define M_GET_DRIVE_PARAMS (0x08) +#define M_SEGOFFTOPTR(seg, off) (((seg) << 4) + (off)) +#define M_INT13H M_SEGOFFTOPTR(0x0000, 0x0013 * 4) +#define M_FREEBASEMEM M_SEGOFFTOPTR(0x0040, 0x0013) +#define M_TOP M_SEGOFFTOPTR(0x9FFF, 0x0000) + +/*** Object types */ +typedef struct mdi s_mdi; +typedef real_addr_t u_segoff; +typedef struct safe_hook s_safe_hook; +typedef struct mBFT s_mbft; + +/*** Function types */ +typedef int f_find(void); + +/*** Function declarations */ +static const s_mdi * installation_check(int); +static f_find scan_drives; +static f_find walk_safe_hooks; +static const s_safe_hook * is_safe_hook(const void *); +static const s_mdi * is_memdisk_hook(const s_safe_hook *); +static f_find scan_mbfts; +static const s_mbft * is_mbft(const void *); +static f_find do_nothing; +static void memdisk_info(const s_mdi *); +static void boot_args(char **); +static const char * bootloadername(uint8_t); + +/*** Structure/union definitions */ + +/*** Objects */ +static int show_info = 0; + +/*** Function definitions */ + +int main(int argc, char ** argv) { + static f_find * do_scan_drives = scan_drives; + static f_find * do_walk_safe_hooks = do_nothing; + static f_find * do_scan_mbfts = do_nothing; + char ** detected_cmd; + char ** not_detected_cmd; + char ** cmd; + char ** cur_arg; + int show_usage; + int found; + + (void) argc; + + openconsole(&dev_null_r, &dev_stdcon_w); + + detected_cmd = NULL; + not_detected_cmd = NULL; + show_usage = 1; + for (cur_arg = argv + 1; *cur_arg; ++cur_arg) { + /* Check for command divider */ + if (!strcmp(*cur_arg, "--")) { + show_usage = 0; + *cur_arg = NULL; + not_detected_cmd = cur_arg + 1; + break; + } + + /* Check for '--info' */ + if (!strcmp(*cur_arg, "--info")) { + show_usage = 0; + show_info = 1; + continue; + } + + /* Other options */ + if (!strcmp(*cur_arg, "--no-sequential")) { + do_scan_drives = do_nothing; + continue; + } + + if (!strcmp(*cur_arg, "--safe-hooks")) { + do_walk_safe_hooks = walk_safe_hooks; + continue; + } + + if (!strcmp(*cur_arg, "--mbfts")) { + do_scan_mbfts = scan_mbfts; + continue; + } + + /* Check for invalid option */ + if (!memcmp(*cur_arg, "--", sizeof "--" - 1)) { + puts("Invalid option!"); + show_usage = 1; + break; + } + + /* Set 'detected_cmd' if it's null */ + if (!detected_cmd) + detected_cmd = cur_arg; + + continue; + } + + if (show_usage) { + fprintf(stderr, usage_text); + return 1; + } + + found = 0; + found += do_walk_safe_hooks(); + found += do_scan_mbfts(); + found += do_scan_drives(); + + cmd = found ? detected_cmd : not_detected_cmd; + if (cmd && *cmd) + boot_args(cmd); + + return 0; + } + +static const s_mdi * installation_check(int drive) { + com32sys_t params, results; + int found; + + /* Set parameters for INT 0x13 call */ + memset(¶ms, 0, sizeof params); + params.eax.w[0] = M_GET_DRIVE_PARAMS << 8; + params.edx.w[0] = drive; + /* 'ME' 'MD' 'IS' 'K?' */ + params.eax.w[1] = 0x454D; + params.ecx.w[1] = 0x444D; + params.edx.w[1] = 0x5349; + params.ebx.w[1] = 0x3F4B; + + /* Perform the call */ + __intcall(0x13, ¶ms, &results); + + /* Check result */ + found = ( + /* '!M' 'EM' 'DI' 'SK' */ + results.eax.w[1] == 0x4D21 && + results.ecx.w[1] == 0x4D45 && + results.edx.w[1] == 0x4944 && + results.ebx.w[1] == 0x4B53 + ); + + if (found) + return MK_PTR(results.es, results.edi.w[0]); + + return NULL; + } + +static int scan_drives(void) { + int found, drive; + const s_mdi * mdi; + + for (found = drive = 0; drive <= 0xFF; ++drive) { + mdi = installation_check(drive); + if (!mdi) + continue; + + memdisk_info(mdi); + ++found; + continue; + } + + return found; + } + +static int walk_safe_hooks(void) { + static const u_segoff * const int13 = (void *) M_INT13H; + const void * addr; + int found; + const s_safe_hook * hook; + const s_mdi * mdi; + + /* INT 0x13 vector */ + addr = MK_PTR(int13->seg_off.segment, int13->seg_off.offset); + found = 0; + while (addr) { + hook = is_safe_hook(addr); + if (!hook) + break; + + mdi = is_memdisk_hook(hook); + if (mdi) { + memdisk_info(mdi); + ++found; + } + + addr = MK_PTR( + hook->old_hook.seg_off.segment, + hook->old_hook.seg_off.offset + ); + continue; + } + return found; + } + +static const s_safe_hook * is_safe_hook(const void * addr) { + static const char magic[] = "$INT13SF"; + const s_safe_hook * const test = addr; + + if (memcmp(test->signature, magic, sizeof magic - 1)) + return NULL; + + return test; + } + +static const s_mdi * is_memdisk_hook(const s_safe_hook * hook) { + static const char magic[] = "MEMDISK"; + const s_mbft * mbft; + + if (memcmp(hook->vendor, magic, sizeof magic - 1)) + return NULL; + + /* An mBFT is always aligned */ + mbft = MK_PTR(hook->mbft >> 4, 0); + return &mbft->mdi; + } + +static int scan_mbfts(void) { + static const uint16_t * const free_base_mem = (void *) M_FREEBASEMEM; + static const void * const top = (void *) M_TOP; + const void * addr; + const s_mbft * mbft; + int found; + + found = 0; + for (addr = MK_PTR(*free_base_mem << 4, 0); addr < top; addr += 1 << 4) { + if (!(mbft = is_mbft(addr))) + continue; + + memdisk_info(&mbft->mdi); + ++found; + continue; + } + + return found; + } + +static const s_mbft * is_mbft(const void * addr) { + static const char magic[] = "mBFT"; + const s_mbft * const test = addr; + const uint8_t * ptr, * end; + uint8_t chksum; + + if (memcmp(test->acpi.signature, magic, sizeof magic - 1)) + return NULL; + + if (test->acpi.length != sizeof *test) + return NULL; + + end = (void *) (test + 1); + chksum = 0; + for (ptr = addr; ptr < end; ++ptr) + chksum += *ptr; + if (chksum) + return NULL; + + /* Looks like it's an mBFT! */ + return test; + } + +static int do_nothing(void) { + return 0; + } + +static void memdisk_info(const s_mdi * mdi) { + const char * cmdline; + + if (!show_info) + return; + + cmdline = MK_PTR( + mdi->cmdline.seg_off.segment, + mdi->cmdline.seg_off.offset + ); + printf( + "Found MEMDISK version %u.%02u:\n" + " diskbuf == 0x%08X, disksize == %u sectors\n" + " bootloaderid == 0x%02X (%s),\n" + " cmdline: %s\n", + mdi->version_major, + mdi->version_minor, + mdi->diskbuf, + mdi->disksize, + mdi->bootloaderid, + bootloadername(mdi->bootloaderid), + cmdline + ); + return; + } + +/* This function copyright H. Peter Anvin */ +static void boot_args(char **args) +{ + int len = 0, a = 0; + char **pp; + const char *p; + char c, *q, *str; + + for (pp = args; *pp; pp++) + len += strlen(*pp) + 1; + + q = str = alloca(len); + for (pp = args; *pp; pp++) { + p = *pp; + while ((c = *p++)) + *q++ = c; + *q++ = ' '; + a = 1; + } + q -= a; + *q = '\0'; + + if (!str[0]) + syslinux_run_default(); + else + syslinux_run_command(str); +} + +/* This function copyright H. Peter Anvin */ +static 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; + } +} + |