feat: moved file system code around

kernel/vfs/part/mbr.c

@@ -0,0 +1,115 @@
+//
+// Created by rick on 06-02-21.
+//
+
+#include <attributes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include <myke/drivers/pci/ide.h>
+#include <myke/vfs/blockdev.h>
+#include <myke/vfs/part/mbr.h>
+
+typedef struct {
+    uint8_t bootable;
+    uint8_t starting_head;
+    uint8_t starting_sector: 6;
+    uint16_t starting_cylinder: 10;
+    uint8_t system_id;
+    uint8_t ending_head;
+    uint8_t ending_sector: 6;
+    uint16_t ending_cylinder: 10;
+    uint32_t start_lba;
+    uint32_t num_lbas;
+}  att_packed mbr_partition_table_entry;
+
+typedef struct {
+    uint32_t unique_id;
+    uint16_t reserved;
+    mbr_partition_table_entry entries[4];
+    uint8_t signature[2];
+} att_packed mbr_table;
+
+typedef struct {
+    const block_device_t *device;
+    uint32_t start_lba;
+} mbr_block_driver_info;
+
+uint8_t
+mbr_block_dev_access(const block_device_t *device, uint8_t direction, uint32_t lba, uint8_t sectors, void *target) {
+    if (!device->flags.present || lba > device->num_lba) {
+        return BLOCK_DEV_ACCESS_ERR;
+    }
+    const mbr_block_driver_info *info = device->device_info;
+    const uint32_t actual_lba = info->start_lba + lba;
+    if (actual_lba > info->device->num_lba) {
+        return BLOCK_DEV_ACCESS_ERR;
+    }
+
+    // delegate to backing driver
+    return info->device->access(info->device, direction, actual_lba, sectors, target);
+}
+
+uint8_t att_used mbr_check_device(const block_device_t *device, uint8_t *first_sector) {
+    mbr_table table;
+    memcpy((uint8_t *) &table, first_sector + (device->block_size - sizeof(mbr_table)), sizeof(mbr_table));
+    if (table.signature[0] != 0x55 && table.signature[1] != 0xAA) { // AA 55 but in little endian
+        return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
+    }
+
+    if (table.reserved != 0x0000 && table.reserved != 0x5A5A) {
+        return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
+    }
+
+    for (int i = 0; i < 4; ++i) {
+        if (table.entries[i].num_lbas > device->num_lba || table.entries[i].start_lba > device->num_lba) {
+            return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
+        }
+    }
+
+    int num_parts = 0;
+    for (int i = 0; i < 4; ++i) {
+        if (table.entries[i].system_id == 0) continue;
+        num_parts += 1;
+
+        mbr_block_driver_info *info = malloc(sizeof(mbr_block_driver_info));
+        info->device = device;
+        info->start_lba = table.entries[i].start_lba;
+
+        block_device_t logical_device = {
+                .flags.present = 1,
+
+                .num_lba = table.entries[i].num_lbas,
+                .block_size = device->block_size,
+                .access = mbr_block_dev_access,
+                .device_info = info,
+        };
+
+        sprintf(logical_device.identifier, "%sp%d", device->identifier, i);
+
+        block_dev_register(&logical_device);
+    }
+
+    if (num_parts == 0) {
+        return BLOCK_DEV_DRIVER_CHECK_NO_MATCH;
+    }
+
+    return BLOCK_DEV_DRIVER_CHECK_OK;
+}
+
+void mbr_read_from_ide(uint8_t ide_drive) {
+    char *mbr_data = malloc(0x200);
+    ide_access(0, ide_drive, 0, 1, mbr_data);
+    mbr_partition_table_entry *entry = (mbr_partition_table_entry *) (mbr_data + 0x1BE);
+    printf("Start at %d, count: %d\n", entry->start_lba, entry->num_lbas);
+    free(mbr_data);
+}
+
+BLOCK_DEV_DRIVER(200) = {
+        .name = "mbr",
+        .flags.partitioning = 1,
+        .check_device = mbr_check_device,
+        .free_device = NULL, // todo
+};