start messing with fat32

Makefile

@@ -1,5 +1,5 @@
 # Define the object files
-OBJS = bin/boot.o bin/kernel.o bin/idt.o bin/isr.o bin/screen.o bin/utils.o bin/string.o bin/stdio.o bin/disk.o bin/pic.o bin/pit.o bin/keyboard.o bin/paging.o bin/page.o
+OBJS = bin/boot.o bin/kernel.o bin/idt.o bin/isr.o bin/screen.o bin/utils.o bin/string.o bin/stdio.o bin/disk.o bin/pic.o bin/pit.o bin/keyboard.o bin/paging.o bin/page.o bin/fat.o
 
 # Define the compiler and assembler
 CC = gcc -D__is_katauos
@@ -10,7 +10,7 @@ CFLAGS = -std=gnu99 -ffreestanding -O0 -Wall -Wextra -m32 -g
 ASFLAGS = -f elf32
 
 # Define the linker flags
-LDFLAGS = -ffreestanding -O0 -nostdlib -m32 -g
+LDFLAGS = -ffreestanding -O0 -nostdlib -m32 -g -lgcc
 LDSCRIPT = link.ld
 
 # Define the output file
@@ -18,9 +18,32 @@ OUTPUT = myos.bin
 
 all: $(OUTPUT)
 
-image:
+create-image:
 	cp myos.bin grubshit/boot/
-	grub-mkrescue -o boot.iso grubshit
+	#grub-mkrescue -o boot.iso grubshit
+	dd if=/dev/zero of=boot.iso bs=1M count=256
+	fdisk boot.iso
+	#sudo mkdosfs -F 32 -I boot.iso
+	sudo losetup /dev/loop0 boot.iso
+	sudo losetup /dev/loop1 boot.iso -o 1048576
+	#sudo mkdosfs -F32 -f 2 /dev/loop1
+	sudo mkfs.vfat -F 32 -f 2 /dev/loop1
+	sudo mount /dev/loop1 /mnt
+	sudo grub-install --root-directory=/mnt --no-floppy --modules="normal part_msdos ext2 multiboot biosdisk" /dev/loop0 #there was biosdev also
+	sudo cp -r grubshit/boot/ /mnt/
+	sync
+	sudo umount /mnt
+	sudo losetup -D
+
+image:
+	cp myos.bin grubshit/boot
+	sudo losetup /dev/loop0 boot.iso
+	sudo losetup /dev/loop1 boot.iso -o 1048576
+	sudo mount /dev/loop1 /mnt
+	sudo cp -r grubshit/boot /mnt/
+	sync
+	sudo umount /mnt
+	sudo losetup -D
 
 test:
 	qemu-system-i386 -drive file=boot.iso,media=disk,format=raw -m 512M -d int
@@ -73,6 +96,9 @@ bin/paging.o: src/paging.c
 bin/page.o: src/page.asm
 	$(AS) $(ASFLAGS) $< -o $@
 
+bin/fat.o: src/fat.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
 clean:
 	rm -rf bin/
 	rm -f $(OUTPUT)

include/disk.h

@@ -2,6 +2,7 @@
 #define DISK_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
 typedef struct {
     unsigned short cylinders;
@@ -11,7 +12,7 @@ typedef struct {
 
 void get_disk_info(disk_info *info);
 int ide_check_disk_present();
-uint8_t ata_read(uint8_t *buffer, uint32_t lba);
+bool ata_read(uint8_t *buffer, uint32_t lba);
-void ata_write(uint8_t *buffer, uint32_t lba);
+bool ata_write(const uint8_t *buffer, uint32_t lba);
 
 #endif

include/fat.h

@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// Copyright (c) 2025, Bjørn Brodtkorb. All rights reserved.
+
+#ifndef FAT_H
+#define FAT_H
+
+//------------------------------------------------------------------------------
+#include <stdbool.h>
+#include <stdint.h>
+//#include <stdio.h>
+#include <stdarg.h>
+
+//------------------------------------------------------------------------------
+#define SECT_SIZE 512
+
+//------------------------------------------------------------------------------
+enum
+{
+  FAT_ERR_NONE     =  0,
+  FAT_ERR_NOFAT    = -1,
+  FAT_ERR_BROKEN  = -2,
+  FAT_ERR_DISK     = -3,
+  FAT_ERR_PARAM    = -4,
+  FAT_ERR_PATH     = -5,
+  FAT_ERR_EOF      = -6,
+  FAT_ERR_DENIED   = -7,
+  FAT_ERR_FULL     = -8,
+};
+
+enum
+{
+  FAT_ATTR_NONE     = 0x00,
+  FAT_ATTR_RO       = 0x01,
+  FAT_ATTR_HIDDEN   = 0x02,
+  FAT_ATTR_SYS      = 0x04,
+  FAT_ATTR_LABEL    = 0x08,
+  FAT_ATTR_DIR      = 0x10,
+  FAT_ATTR_ARCHIVE  = 0x20,
+  FAT_ATTR_LFN      = 0x0f,
+};
+
+enum
+{
+  FAT_SEEK_SET,
+  FAT_SEEK_END,
+  FAT_SEEK_CURR,
+};
+
+//------------------------------------------------------------------------------
+typedef struct
+{
+  bool (*read)(uint8_t* buf, uint32_t sect);
+  bool (*write)(const uint8_t* buf, uint32_t sect);
+} disk_ops_t;
+
+typedef struct
+{
+  uint8_t hour;
+  uint8_t min;
+  uint8_t sec;
+
+  uint8_t day;
+  uint8_t month;
+  uint16_t year;
+} timestamp_t;
+
+typedef struct fat_t
+{
+  struct fat_t* next;
+  disk_ops_t ops;
+  char path[32];
+  int pathlen;
+
+  uint32_t sect_per_clust;
+  uint32_t clust_cnt;
+  uint32_t info_sect;
+  uint32_t fat_sect;
+  uint32_t data_sect;  
+  uint32_t root_sect;
+
+  uint32_t info_last;
+  uint32_t info_cnt;
+  bool info_dirty;
+
+  uint8_t win[SECT_SIZE];
+  uint32_t win_sect;
+  bool win_dirty;
+  
+  uint8_t name[260];
+  int namelen;
+  uint8_t crc;
+} fat_t;
+
+typedef struct
+{
+  timestamp_t created;
+  timestamp_t modified;
+
+  uint32_t size;
+  uint8_t attr;
+
+  char name[256];
+  int namelen;
+} dir_info_t;
+
+typedef struct
+{
+  fat_t* fat;
+  uint8_t attr;
+  uint32_t first_clust;
+  uint32_t clust;
+  uint32_t sect;
+  int idx;
+} dir_t;
+
+typedef struct
+{
+  dir_t dir;
+  uint32_t first_clust;
+  uint32_t clust;
+  uint32_t sect;
+  uint32_t off;
+  uint32_t size;
+
+  uint8_t buf[SECT_SIZE];
+  uint32_t buf_sect;
+  bool buf_dirty;
+
+  bool modified;
+  bool accessed;
+  bool read;
+  bool write;
+} file_t;
+
+//------------------------------------------------------------------------------
+int fat_mount(disk_ops_t* ops, int part_num, fat_t* fs, const char* path);
+int fat_umount(fat_t* fs);
+
+int fat_fopen(file_t* file, const char* path, const char* mode);
+int fat_fclose(file_t* file);
+int fat_fread(file_t* file, void* buf, int len);
+int fat_fwrite(file_t* file, const void* buf, int len);
+int fat_fprintf(file_t* file, const char* str, ...);
+int fat_fseek(file_t* file, int offset, int seek);
+int fat_ftell(file_t* file);
+int fat_fsize(file_t* file);
+int fat_fsync(file_t* file);
+int fat_unlink(const char* path);
+
+int fat_mkdir(const char* path);
+int fat_opendir(dir_t* dir, const char* path);
+int fat_readdir(dir_t* dir, dir_info_t* info);
+int fat_nextdir(dir_t* dir);
+
+const char* fat_get_error(int err);
+
+void fat_get_timestamp(timestamp_t* dt);
+
+#endif

src/disk.c

@@ -161,8 +161,9 @@ void ata_poll()
 
 //https://wiki.osdev.org/ATA_PIO_Mode
 //x86 directions section
-uint8_t ata_read(uint8_t *buffer, uint32_t lba)
+bool ata_read(uint8_t *buffer, uint32_t lba)
 {
+    printf("ata_read: 0x%X\n", lba);
 	outb(0x1F6, 0xE0 | ((lba >> 24) & 0x0F));//E0 is for master, F0 is for slave
 	//outb(0x1F1, 0x00);//TODO: this is probably ignored so could be removed maybe?
 	outb(0x1F2, 1);//1 is sector count, how many sectors are we reading
@@ -177,9 +178,10 @@ uint8_t ata_read(uint8_t *buffer, uint32_t lba)
 		*(uint16_t*)(buffer+i*2) = data;
 	}
 	ata_400ns_delay();
+	return true;
 }
 
-void ata_write(uint8_t *buffer, uint32_t lba)
+bool ata_write(const uint8_t *buffer, uint32_t lba)
 {
 	outb(0x1F6, 0xE0 | ((lba >> 24) & 0x0F));
 
@@ -197,4 +199,5 @@ void ata_write(uint8_t *buffer, uint32_t lba)
 		ata_400ns_delay();
 	}
 	outb(0x1F7, 0xE7);//Cache flush
+	return true;
 }

src/kernel.c

@@ -7,9 +7,90 @@
 #include "../include/pic.h"
 #include "../include/pit.h"
 #include "../include/paging.h"
+#include "../include/fat.h"
 
 #include <stdint.h>
 
+disk_ops_t ops =
+{
+	.read = ata_read,
+	.write = ata_write,
+};
+
+static fat_t g_fat;
+static const char* months[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
+
+static int cat(const char* path)
+{
+  file_t file;
+  int err = fat_fopen(&file, path, "r");
+  if (err)
+    return err;
+
+  uint8_t buf[512];
+  for (;;)
+  {
+    int cnt = fat_fread(&file, buf, 512);
+    if (cnt < 0)
+      return cnt;
+
+    printf("%.*s\n", cnt, buf);
+    if (cnt < 512)
+      break;
+  }
+
+  return fat_fclose(&file);
+}
+
+static int ls(const char* path)
+{
+  dir_t dir;
+  dir_info_t info;
+
+  printf("\nListing items in %s:\n\n", path);
+
+  int err = fat_opendir(&dir, path);
+  printf("opening %s\n", path);
+  if (err)
+    return err;
+
+  for (;;)
+  {
+    printf("reading dir...\n");
+
+    err = fat_readdir(&dir, &info);
+    if (err == FAT_ERR_EOF)
+      return FAT_ERR_NONE;
+    if (err)
+      return err;
+        
+    printf("%X   %s %d   %d:%d   %s%c\n",
+      info.size, months[info.modified.month], info.modified.day,
+      info.modified.hour, info.modified.min, 
+      info.namelen, info.name, info.attr & FAT_ATTR_DIR ? '/' : ' ');
+    
+    err = fat_nextdir(&dir);
+    if (err)
+      return err;
+  }
+}
+
+void file_fuckery()
+{
+	int err;
+	err = fat_mount(&ops, 0, &g_fat, "/");
+
+	if(err)
+		printf("KATYAKATYAKATYAKATYAKATYA: %X\n", err);
+	
+	printf("%X\n", FAT_ERR_NOFAT);
+
+	err = ls(".");
+	//err = fat_fclose(&file);
+	if(err)
+		printf("ERROR! %X\n", err);
+}
+
 void apply_pic_masks()
 {
 	//0x21 is master pic, 0xa1 is slave pic
@@ -37,6 +118,7 @@ void kmain()
 	disk_info info;
 	get_disk_info(&info);
 	printf("CYL HEAD SECT: %X %X %X\n", info.cylinders, info.heads, info.sectors);
+	file_fuckery();
 	while(1)
 	{
 /*		if(inportb(0x64) & 0x1)