Implemented custom filesystem and got it to compile. It seems that it isn't loading the 3rd stage bootloader though

docs/fs-spec.txt

@@ -4,28 +4,29 @@ Sector = 512 Bytes
 Block  = 4096 Bytes
 
 Reserved sectors:
- Sector    0 - Bootsector, will be loaded by the Bios into memory and executed  (512B)
+ Sector 0..3 - Bootblock, will be loaded by the Bios into memory and executed   (512B)
- Sector 1..4 - Superblock, contains metadata about the filesystem itself        (4KiB)
+ Sector 4..7 - Superblock, contains metadata about the filesystem itself        (4KiB)
 
 Superblock structure: (4096B)
- FS Name
+ Device ID
- FS Size (Sector)
+ Max File Size
- FS Size (Block)
  INode Count
- INodes per sector
  INode Bitmap Block
- Data Bitmap Block
  INodes Start
+ INode Block Count
+ INodes per sector
+ Data Bitmap Block
  Data Start
- Root INode Number
+ Data Block Count
- Extents per indirect
+ Root INode Pointer
+ First Unreserved INode
 
 INode structure: (64B)
  Type
  Size (bytes)
- Block Count (size in blocks)
+ Sector Count (size in sectors)
  Mode
- Extents[]
+ Extent[4]
  Single Indirect
  Double Indirect?
 
@@ -37,3 +38,11 @@ Directory Entry: (64B)
  INode Number
  Name (max length 60 Bytes)
 
+Filetypes:
+ File
+ Directory
+ #TODO
+ Link
+ Device
+ Stream?
+

include/fs/fs.h

@@ -1,90 +1,83 @@
 #ifndef FS_H
 #define FS_H
 
+/*
+ * For info, read the fs-spec.txt document inside of docs/
+ */
+
 #include <stdint.h>
 
-#define FS_BLOCK_SIZE  4096
+// FS Definitions
 #define FS_SECTOR_SIZE 512
+#define FS_BLOCK_SIZE 4096
 
-#define FILETYPE_FILE 0
+// Conversion Macros (beatiful)
-#define FILETYPE_DIR  1
+#define BYTES2BLOCKS(_n)  ( (_n) == 0 ? 0 : \
+                            (_n) <= (FS_BLOCK_SIZE) ? 1 : \
+                            ((_n) / FS_BLOCK_SIZE) + (((_n) % FS_BLOCK_SIZE) > 0 ? 1 : 0) )
 
-// Filesystem structures
+#define BYTES2SECTORS(_n) ( (_n) == 0 ? 0 : \
-typedef struct {
+                            (_n) <= (FS_SECTOR_SIZE) ? 1 : \
-    uint8_t second;
+                            ((_n) / FS_SECTOR_SIZE) + (((_n) % FS_SECTOR_SIZE) > 0 ? 1 : 0) )
-    uint8_t minute;
+
-    uint8_t hour;
+// Filetypes
-    uint8_t day;
+#define FT_FILE 0
-    uint8_t month;
+#define FT_DIR  1
-    uint16_t year;
+
-    uint8_t reserved;
+// FS Structures
-} __attribute__ ((packed)) fsDatetime_t;
+// TODO: datetime_t?
 
 typedef struct {
     uint8_t sectors[FS_BLOCK_SIZE / FS_SECTOR_SIZE][FS_SECTOR_SIZE];
-} __attribute__ ((packed)) bootBlock_t;
+} __attribute__ ((packed)) bootblock_t;
 
+// Superblock - Padded to 4096 Bytes
 typedef struct {
+    // Constant data
+    uint16_t deviceId;
+    uint16_t extentsPerIndirect;
+    uint32_t maxFileSize;
+    uint16_t inodesPerSector;
+
+    // INode data
     uint32_t inodeCount;
+    uint32_t inodeBitmapBlock;
+    uint32_t inodesStart;
+    uint32_t inodeBlockCount;
 
-    uint16_t firstINodeBitmapBlock;
+    // Data data :)
-    uint16_t firstDataBitmapBlock;
+    uint32_t dataBitmapBlock;
-    uint16_t inodeBitmapBlockCount;
+    uint32_t dataStart;
-    uint16_t dataBitmapBlockCount;
+    uint32_t dataBlockCount;
-    uint32_t firstINodeBlock;
-    uint32_t firstDataBlock;
-    uint16_t inodeBlockCount;
-    uint16_t dataBlockCount;
 
-    uint32_t maxFileSize; // in bytes
+    // Other
-    uint16_t blockSize; // in bytes
+    uint32_t rootInodePtr;
-    uint8_t inodeSize; // in bytes
+    uint32_t firstUnreservedInode;
-    
+} __attribute__ ((packed)) superblock_t;
-    uint32_t rootINodePtr;
-    uint8_t inodesPerBlock;
-    uint8_t directExtentsPerINode;
-    uint16_t extentsPerIndirectBlock;
-    uint32_t firstFreeINodeBit;
-    uint32_t firstFreeDataBit;
-    uint16_t deviceNumber;
-    uint8_t firstUnreservedINode;
-
-    uint8_t reserved[14];
-} __attribute__ ((packed)) superBlock_t;
 
+// Extent - 8 Bytes
 typedef struct {
-    uint32_t firstBlock;
+    uint32_t block;
     uint32_t length;
 } __attribute__ ((packed)) extent_t;
 
+// INode - 64 Bytes
 typedef struct {
-    uint32_t id;        // Idetifier
+    uint32_t id;
-    uint8_t filetype;
+    uint8_t type;
-    uint32_t sizeBytes;
+    uint32_t sizeBytes; // Size in bytes
-    uint32_t sizeSectors;
+    uint32_t sizeSectors; // Size in sectors
-    fsDatetime_t timestamp;
+    uint8_t mode; // Access permisions
     extent_t extent[4];
-    uint32_t singleIndirectBlock;
+    uint32_t singleIndirect;
-    uint32_t doubleIndirectBlock;
+    uint32_t doubleIndirect;
-    uint8_t refCount;
+
-    uint8_t reserved[2];
+    uint8_t reserved[10];
 } __attribute__ ((packed)) inode_t;
 
 typedef struct {
-    uint32_t id;        // Matching ID with INode
     char name[60];
+    uint32_t id;
 } __attribute__ ((packed)) dirEntry_t;
 
-// Utility functions
-uint32_t bytesToBlocks(uint32_t bytes) {
-    if (bytes == 0) return 0;
-    if (bytes <= FS_BLOCK_SIZE) return 1;
-    return (bytes / FS_BLOCK_SIZE) + ((bytes % FS_BLOCK_SIZE) > 0 ? 1 : 0);
-}
-
-uint32_t bytesToSectors(uint32_t bytes) {
-    if (bytes == 0) return 0;
-    if (bytes <= FS_SECTOR_SIZE) return 1;
-    return (bytes / FS_SECTOR_SIZE) + ((bytes % FS_SECTOR_SIZE) > 0 ? 1 : 0);
-}
 #endif

include/fs/impl.h

@@ -1,44 +1,36 @@
 #ifndef IMPL_H
 #define IMPL_H
 
-#include <disk/disk.h>
 #include <fs/fs.h>
 #include <memory/addresses.h>
+#include <disk/disk.h>
 #include <stdint.h>
-#include <string.h>
 
 char* currentDir;
-inode_t currentDirINode;
 
-char tempSector[FS_SECTOR_SIZE];
+inode_t* getInode(char* path) {
-char tempBlock[FS_BLOCK_SIZE];
+    dirEntry_t* dentry = (dirEntry_t*)SCRATCH_BLOCK_LOC;
 
-inode_t rootINode;
+    while (dentry->name[0] != '\0') {
-
+        if (strcmp(dentry->name, path)) break;
-inode_t* getINode(char* path) {
+        dentry++;
-    dirEntry_t* dirEntry = (dirEntry_t*)SCRATCH_BLOCK_LOC;
-    while (dirEntry->name[0] != '\0') {
-        if (strcmp(dirEntry->name, path) == 0) break;
-        dirEntry++;
     }
 
-    if (dirEntry->name[0] == '\0') return NULL;
+    if (dentry->name[0] == '\0') return NULL;
 
     inode_t* inode = (inode_t*)BOOT_FIRST_INODE_LOC;
-    while (inode->id != dirEntry->id) {
+    while (inode->id != dentry->id) { inode++; }
-        inode++;
-    }
 
     return inode;
 }
 
 uint8_t loadFile(inode_t* inode, void* dest) {
-    uint32_t totalBlocks = bytesToBlocks(inode->sizeBytes);
+    uint32_t totalBlocks = BYTES2BLOCKS(inode->sizeBytes);
-    uint32_t addressOffset = 0;
+    uint32_t offset = 0;
 
     for (uint8_t i = 0; i < 4 && totalBlocks > 0; i++) {
-        diskRead(inode->extent[i].firstBlock * 8, inode->extent[i].length * 8, dest + addressOffset);
+        diskRead(inode->extent[i].block * 8, inode->extent[i].length * 8, dest + offset);
-        addressOffset += inode->extent[i].length * FS_BLOCK_SIZE;
+        offset += inode->extent[i].length * FS_BLOCK_SIZE;
         totalBlocks -= inode->extent[i].length;
     }
 

include/memory/addresses.h

@@ -12,9 +12,10 @@
  * 0x6000-0x6fff - VBE info area
  * 0x7000-0x7bff - SMAP Area
  * 0x7c00-0x8bff - Bootblock
- * 0x8c00-0x9bff - Superblock (i think)
+ * 0x8c00-0x9bff - Superblock
  * 0x9c00-0xafff - Free
  * 0xb000-0xbfff - Bootloader first INode
+ * 0xc000-0xcfff - Scratch INode block
  */
 
 // Global Variables 0x1800-0x1fff

makedisk.c

@@ -31,7 +31,7 @@ fileInfo_t files[] = { // TODO: Not have to list all of the files, loop through
     { BIN_DIR"editor.bin" },
 };
 
-superBlock_t superblock = { 0 };
+superblock_t superblock = { 0 };
 
 FILE* imagePtr;
 uint32_t diskSize = DISK_SIZE;
@@ -63,11 +63,11 @@ int main(int argc, char** argv) {
         fseek(files[i].fp, 0, SEEK_END);
         files[i].size = ftell(files[i].fp);
         rewind(files[i].fp);
-        fileBlocks += bytesToBlocks(files[i].size);
+        fileBlocks += BYTES2BLOCKS(files[i].size);
     }
 
     printf("Building disk image %s...\n", IMAGE_NAME);
-    printf("Block size: %d Bytes, Total disk blocks: %d (%d Bytes)\n\n", FS_BLOCK_SIZE, bytesToBlocks(diskSize), diskSize);
+    printf("Block size: %d Bytes, Total disk blocks: %d (%d Bytes)\n\n", FS_BLOCK_SIZE, BYTES2BLOCKS(diskSize), diskSize);
 
     printf("%d files (2 hidden)\n", fileCount); // Stage 1 and 2 is hidden
     
@@ -79,12 +79,12 @@ int main(int argc, char** argv) {
     writeINodeBlocks();
     writeDataBlocks();
 
-    uint32_t writtenBlocks = 2 + superblock.inodeBitmapBlockCount + superblock.dataBitmapBlockCount + superblock.inodeBlockCount + superblock.dataBlockCount; 
+    uint32_t writtenBlocks = 4 + superblock.inodeBlockCount + superblock.dataBlockCount; 
     printf("\nWritten blocks: %d (%d Bytes)\n", writtenBlocks, writtenBlocks * FS_BLOCK_SIZE);
-    printf("Free blocks: %d (%d Bytes)\n", bytesToBlocks(diskSize) - writtenBlocks, diskSize - writtenBlocks * FS_BLOCK_SIZE);
+    printf("Free blocks: %d (%d Bytes)\n", BYTES2BLOCKS(diskSize) - writtenBlocks, diskSize - writtenBlocks * FS_BLOCK_SIZE);
 
     // Pad out to the whole disk size
-    for (uint32_t i = 0; i < bytesToBlocks(diskSize) - writtenBlocks; i++) {
+    for (uint32_t i = 0; i < BYTES2BLOCKS(diskSize) - writtenBlocks; i++) {
         assert(fwrite(nullBlock, FS_BLOCK_SIZE, 1, imagePtr) == 1);
     }
     
@@ -98,10 +98,10 @@ int main(int argc, char** argv) {
 }
 
 void writeBootblock() {
-    bootBlock_t bootBlock = { 0 };
+    bootblock_t bootBlock = { 0 };
     assert(fread(bootBlock.sectors[0], FS_SECTOR_SIZE, 1, files[0].fp) == 1); // File 0 - Stage 1
 
-    for (uint8_t i = 1; i < bytesToSectors(files[i].size); i++) {
+    for (uint8_t i = 1; i < BYTES2SECTORS(files[i].size); i++) {
         if (i > 7) {
             fprintf(stderr, "%s is too large, maximum size of bootblock is 7 sectors (%d Bytes)\n", files[1].name, 7 * FS_SECTOR_SIZE);
             exit(1);
@@ -117,33 +117,39 @@ void writeBootblock() {
 }
 
 void writeSuperblock() {
-    superblock.inodeCount = fileCount;  // 2 reserved INodes (0 - Invalid, 1 - Root)
+    /* Block Layout
-    superblock.firstINodeBitmapBlock = 2;   // Block 0 - Boot, Block 1 - Superblock
+     * 0 - Boot
-    superblock.inodeBitmapBlockCount = superblock.inodeCount / (FS_BLOCK_SIZE * 8) + ((superblock.inodeCount % (FS_BLOCK_SIZE * 8) > 0) ? 1 : 0);
+     * 1 - Super
-    superblock.firstDataBitmapBlock = superblock.firstINodeBitmapBlock + superblock.inodeBitmapBlockCount;
+     * 2 - INode Bitmap
-    superblock.inodeBlockCount = bytesToBlocks(superblock.inodeCount * sizeof(inode_t));
+     * 3 - Data Bitmap
+     * 4 - First INode Block
+     */
 
-    dataBlocks = bytesToBlocks(diskSize);
+    // Constant
-    dataBitCount = (dataBlocks - superblock.firstDataBitmapBlock - superblock.inodeBlockCount);
+    superblock.deviceId = 0x01;
+    superblock.extentsPerIndirect = FS_BLOCK_SIZE / sizeof(extent_t);
+    superblock.maxFileSize = 0xffffffff;
+    superblock.inodesPerSector = (FS_SECTOR_SIZE / sizeof(inode_t));
 
-    superblock.dataBitmapBlockCount = dataBitCount / (FS_BLOCK_SIZE * 8) + ((dataBitCount % (FS_BLOCK_SIZE * 8) > 0) ? 1 : 0);
+    // INode
-    superblock.firstINodeBlock = superblock.firstDataBitmapBlock + superblock.dataBitmapBlockCount;
+    superblock.inodeCount = fileCount + 2; // 2 reserved INodes (0 - Invalid, 1 - Root)
-    superblock.firstDataBlock = superblock.firstINodeBlock + superblock.inodeBlockCount;
+    superblock.inodeBitmapBlock = 2;
-    superblock.dataBlockCount = (fileBlocks - 2) + 1; // 1 Block for root dir (-1 for boot block)
+    superblock.inodesStart = 4;
-    superblock.maxFileSize = 0xffffffff; 
+    superblock.inodeBlockCount = BYTES2BLOCKS(superblock.inodeCount * sizeof(inode_t));
-    superblock.blockSize = FS_BLOCK_SIZE;
+
-    superblock.inodeSize = sizeof(inode_t);
+    // Data
-    superblock.rootINodePtr = 0; // Gets setup at runtime
+    dataBlocks = BYTES2BLOCKS(diskSize);
-    superblock.inodesPerBlock = FS_BLOCK_SIZE / sizeof(inode_t);
+
-    superblock.directExtentsPerINode = 4;
+    superblock.dataBitmapBlock = 3;
-    superblock.extentsPerIndirectBlock = FS_BLOCK_SIZE / sizeof(extent_t);
+    superblock.dataStart = superblock.inodesStart + superblock.inodeBlockCount;
-    superblock.firstFreeINodeBit = superblock.inodeCount;
+    superblock.dataBlockCount = fileBlocks; // +1 for Root, -1 for Boot
-    superblock.firstFreeDataBit = (fileBlocks - 2) + 1; // +1 for root dir
+
-    superblock.deviceNumber = 0x01;
+    // Other
-    superblock.firstUnreservedINode = 3; // 0 - Invalid; 1 - Root dir; 2 - Bootloader INode
+    superblock.rootInodePtr = 0; // Will be filled at runtime
-    
+    superblock.firstUnreservedInode = 3; // 0 - Invalid, 1 - Root, 2 - Bootloader
-    assert(fwrite(&superblock, sizeof(superBlock_t), 1, imagePtr) == 1);
+
-    assert(fwrite(nullBlock, paddingBytes(sizeof(superBlock_t), FS_BLOCK_SIZE), 1, imagePtr) == 1); // Padding
+    assert(fwrite(&superblock, sizeof(superblock_t), 1, imagePtr) == 1);
+    assert(fwrite(nullBlock, paddingBytes(sizeof(superblock_t), FS_BLOCK_SIZE), 1, imagePtr) == 1); // Padding
 }
 
 void writeINodeBitmapBlocks() {
@@ -178,50 +184,33 @@ void writeDataBitmapBlocks() {
 
 void writeINodeBlocks() {
     inode_t inode = { 0 };
-    fsDatetime_t defaultTimestamp = {
-        .second = 12,
-        .minute = 12,
-        .hour   = 12,
-        .day    = 20,
-        .month  = 4,
-        .year   = 2024,
-    };
 
     // INode 0 - Invalid
     assert(fwrite(&inode, sizeof(inode), 1, imagePtr) == 1);
 
     // INode 1 - Root directory
-    inode = (inode_t) { // OOP In C???
+    inode.id = 1;
-        .id = 1,
+    inode.type = FT_DIR;
-        .filetype = FILETYPE_DIR,
+    inode.sizeBytes = sizeof(dirEntry_t) * fileCount;
-        .sizeBytes = sizeof(dirEntry_t) * fileCount,
+    inode.sizeSectors = BYTES2SECTORS(inode.sizeBytes);
-        // .sizeSectors = bytesToSectors(inode.sizeBytes), Set below
+    // TODO: Mode
-        .timestamp = defaultTimestamp,
-        .extent[0] = (extent_t) {
-            .firstBlock = superblock.firstDataBlock,
-            // .length = bytesToBlocks(inode.sizeBytes), Set below
-        },
-    };
 
-    inode.sizeSectors = bytesToSectors(inode.sizeBytes);
+    inode.extent[0].block = superblock.dataStart;
-    inode.extent[0].length = bytesToBlocks(inode.sizeBytes);
+    inode.extent[0].length = BYTES2BLOCKS(inode.sizeBytes);
         
     assert(fwrite(&inode, sizeof(inode), 1, imagePtr) == 1);
 
     // INode 2 - Bootloader (stage 3) followed by other INodes
-    uint32_t block = superblock.firstDataBlock + inode.extent[0].length;
+    uint32_t block = superblock.dataStart + inode.extent[0].length;
     for (uint32_t i = 2; i < fileCount; i++) {
         memset(&inode, 0, sizeof(inode));
         inode.id = i;
-        inode.filetype = FILETYPE_FILE;
+        inode.type = FT_FILE;
         inode.sizeBytes = files[i].size;
-        inode.sizeSectors = bytesToSectors(inode.sizeBytes);
+        inode.sizeSectors = BYTES2SECTORS(inode.sizeBytes);
-        inode.timestamp = defaultTimestamp;
+
-        inode.extent[0] = (extent_t) {
+        inode.extent[0].block = block,
-            .firstBlock = block,
+        inode.extent[0].length = BYTES2BLOCKS(inode.sizeBytes);
-            // .length = bytesToBlocks(inode.sizeBytes),
-        };
-        inode.extent[0].length = bytesToBlocks(inode.sizeBytes);
 
         assert(fwrite(&inode, sizeof(inode), 1, imagePtr) == 1);
         
@@ -248,12 +237,12 @@ void writeDataBlocks() {
         assert(fwrite(&dirEntry, sizeof(dirEntry), 1, imagePtr) == 1);
     }
 
-    // Padd out
+    // Pad out
     assert(fwrite(nullBlock, paddingBytes(fileCount * sizeof(dirEntry_t), FS_BLOCK_SIZE), 1, imagePtr) == 1);
 
     // Write actual file data
     for (uint32_t i = 2; i < fileCount; i++) {
-        uint32_t blockCount = bytesToBlocks(files[i].size);
+        uint32_t blockCount = BYTES2BLOCKS(files[i].size);
         uint32_t bytesWritten = 0;
 
         printf("%s, %d Bytes -> %d Blocks\n", files[i].name, files[i].size, blockCount);

src/stage1.asm

@@ -2,9 +2,9 @@
 [org 0x7c00]
 
 %define SUPERBLOCK 0x8c00
-%define FIRST_INODE_BLOCK (SUPERBLOCK) + 12
+%define FIRST_INODE_BLOCK (SUPERBLOCK) + 18
-%define STAGE3_INODE 0xb000 + 128
+%define STAGE3_INODE 0xb000 + (2 * 64)
-%define EXTENT0 (STAGE3_INODE) + 21      ; Offset of extent[0] in inode_t
+%define EXTENT0 (STAGE3_INODE) + 14      ; Offset of extent[0] in inode_t
 
 start:
     xor ax, ax

src/stage3.c

@@ -27,16 +27,16 @@ void main() {
     deinitMemoryRegion(MEMMAP_AREA, maxBlocks / BLOCKS_PER_BYTE);
 
     // Load root dir, find kernel INode and parse it
-    superBlock_t* superblock = (superBlock_t*)SUPERBLOCK_LOC;
+    superblock_t* superblock = (superblock_t*)SUPERBLOCK_LOC;
-    superblock->rootINodePtr = BOOT_FIRST_INODE_LOC + sizeof(inode_t);
+    superblock->rootInodePtr = BOOT_FIRST_INODE_LOC + sizeof(inode_t);
-    diskRead(superblock->firstDataBlock * 8, 8, (void*)SCRATCH_BLOCK_LOC);
+    diskRead(superblock->dataStart * 8, 8, (void*)SCRATCH_BLOCK_LOC);
 
     inode_t* inode;
-    if ((inode = getINode("kernel.bin")) == NULL) {
+    if ((inode = getInode("kernel.bin")) == NULL) {
         __asm__ volatile ("cli; hlt" : : "a"(0xDeadBeef));
     } else { loadFile(inode, (void*)KERNEL_LOC); }
 
-    if ((inode = getINode("term16n.fnt")) == NULL) {
+    if ((inode = getInode("term16n.fnt")) == NULL) {
         __asm__ volatile ("cli; hlt" : : "a"(0xDeadBeef));
     } else { loadFile(inode, (void*)FONT_LOC); }