109 lines
3.1 KiB
C
109 lines
3.1 KiB
C
//
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// Created by rick on 06-02-21.
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//
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#include "mbr.h"
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#include <types.h>
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#include <drivers/ide.h>
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#include <libc/kprintf.h>
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#include <fs/blockdev.h>
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#include <libc/libc.h>
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#include <mem/malloc.h>
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#include <attributes.h>
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typedef struct {
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uint8_t bootable;
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uint8_t starting_head;
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uint8_t starting_sector: 6;
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uint16_t starting_cylinder: 10;
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uint8_t system_id;
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uint8_t ending_head;
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uint8_t ending_sector: 6;
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uint16_t ending_cylinder: 10;
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uint32_t start_lba;
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uint32_t num_lbas;
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} packed mbr_partition_table_entry;
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typedef struct {
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uint32_t unique_id;
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uint16_t reserved;
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mbr_partition_table_entry entries[4];
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uint8_t signature[2];
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} packed mbr_table;
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typedef struct {
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const block_device *device;
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uint32_t start_lba;
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} mbr_block_driver_info;
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uint8_t mbr_block_dev_access(const block_device *device, uint8_t direction, uint32_t lba, uint8_t sectors, void *target) {
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if (!device->flags.present || lba > device->num_lba) {
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return BLOCK_DEV_ACCESS_ERR;
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}
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const mbr_block_driver_info *info = device->device_info;
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const uint32_t actual_lba = info->start_lba + lba;
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if (actual_lba > info->device->num_lba) {
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return BLOCK_DEV_ACCESS_ERR;
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}
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// delegate to backing driver
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return info->device->access(info->device, direction, actual_lba, sectors, target);
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}
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uint8_t used mbr_check_device(const block_device *device, uint8_t *first_sector) {
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mbr_table table;
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memcpy((uint8_t *) &table, first_sector + (device->block_size - sizeof(mbr_table)), sizeof(mbr_table));
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if (table.signature[0] != 0x55 && table.signature[1] != 0xAA) { // AA 55 but in little endian
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return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
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}
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if (table.reserved != 0x0000 && table.reserved != 0x5A5A) {
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return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
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}
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for (int i = 0; i < 4; ++i) {
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if (table.entries[i].num_lbas > device->num_lba || table.entries[i].start_lba > device->num_lba) {
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return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
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}
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}
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for (int i = 0; i < 4; ++i) {
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if (table.entries[i].system_id == 0) continue;
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mbr_block_driver_info *info = malloc(sizeof(mbr_block_driver_info));
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info->device = device;
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info->start_lba = table.entries[i].start_lba;
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block_device logical_device = {
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.flags.present = 1,
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.num_lba = table.entries[i].num_lbas,
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.block_size = device->block_size,
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.access = mbr_block_dev_access,
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.device_info = info,
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};
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sprintf(logical_device.identifier, "%sp%d", device->identifier, i);
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block_dev_register(&logical_device);
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}
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return BLOCK_DEV_DRIVER_CHECK_OK;
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}
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void mbr_read_from_ide(uint8_t ide_drive) {
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char *mbr_data = malloc(0x200);
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ide_access(0, ide_drive, 0, 1, mbr_data);
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mbr_partition_table_entry *entry = (mbr_partition_table_entry *) (mbr_data + 0x1BE);
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printf("Start at %d, count: %d\n", entry->start_lba, entry->num_lbas);
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free(mbr_data);
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}
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BLOCK_DEV_DRIVER(
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.name = "mbr",
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.flags.root_only = 1,
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.check_device = mbr_check_device,
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.free_device = NULL, // todo
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);
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