Added VFS driver and initramfs disk creator

fs_generator.c

@@ -0,0 +1,55 @@
+/* This program comes from James Molloy tutorial 
+ * on how to create an UNIX clone You can find the original code at:
+ * http://www.jamesmolloy.co.uk/tutorial_html/8.-The%20VFS%20and%20the%20initrd.html */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+struct initrd_header {
+    unsigned char magic; // Magic number for consistency
+    char name[64];
+    unsigned int offset; // Offset of the file start
+    unsigned int length;
+};
+
+int main(int argc, char **argv) {
+    int heads = (argc - 1) / 2;
+    struct initrd_header headers[64];
+    printf("Size of header(in bytes): %ld\n", sizeof(struct initrd_header));
+    unsigned int off = sizeof(struct initrd_header) * 64 + sizeof(int);
+    for(int i = 0; i < heads; i++) {
+        printf("Writing file %s->%s at 0x%d\n", argv[i*2+1], argv[i*2+2], off);
+        strcpy(headers[i].name, argv[i*2+2]);
+        headers[i].offset = off;
+        FILE *stream = fopen(argv[i*2+1], "r");
+        if(stream == 0) {
+            puts("Error, file not found!");
+            return 1;
+        }
+        fseek(stream, 0, SEEK_END);
+        headers[i].length = ftell(stream);
+        off += headers[i].length;
+        fclose(stream);
+        headers[i].magic = 0xBF;
+    }
+
+    FILE *wstream = fopen("./initrd.img", "w");
+    unsigned char *data = (unsigned char*)malloc(off);
+    fwrite(&heads, sizeof(int), 1, wstream);
+    fwrite(&heads, sizeof(struct initrd_header), 64, wstream);
+
+    for(int i = 0; i < heads; i++) {
+        FILE *stream = fopen(argv[i*2+1], "r");
+        unsigned char *buf = (unsigned char*)malloc(headers[i].length);
+        fread(buf, 1, headers[i].length, stream);
+        fread(buf, 1, headers[i].length, wstream);
+        fclose(stream);
+        free(buf);
+    }
+
+    fclose(wstream);
+    free(data);
+
+    return 0;
+}

isodir/boot/grub/grub.cfg

@@ -0,0 +1,7 @@
+set timeout = 0
+set default = 0
+
+menuentry "iceOS" {
+	multiboot2 /boot/iceOS.bin
+	boot
+}

kernel/drivers/fs.c

@@ -0,0 +1,51 @@
+#include "fs.h"
+
+fs_node_t *fs_root = 0; // Initialize the root of the filesystem
+
+uint32_t read_fs(fs_node_t *node, uint32_t offset, uint32_t size, uint8_t *buffer) {
+    // Check if inode got a read callback from the kernel
+    if(node->read != 0)
+        return node->read(node, offset, size, buffer);
+    else
+        return 0;
+}
+
+uint32_t write_fs(fs_node_t *node, uint32_t offset, uint32_t size, uint8_t *buffer) {
+    // Check if inode got a write callback from the kernel
+    if(node->write != 0)
+        return node->write(node, offset, size, buffer);
+    else
+        return 0;
+}
+
+void open_fs(fs_node_t *node, uint8_t read, uint8_t write) {
+    // Check if inode got a open callback from the kernel
+    if(node->open != 0)
+        return node->open(node);
+    else
+        return 0;
+}
+
+void close_fs(fs_node_t *node) {
+    // Check if inode got a close callback from the kernel
+    if(node->close =! 0)
+        return node->close(node);
+    else
+        return 0;
+}
+
+struct dirent *readdir_fs(fs_node_t *node, uint32_t index) {
+    // Read dir content(only if file descriptor is FS_DIRECTORY)
+    if((node->flags&0x7) == FS_DIRECTORY && node->readdir != 0)
+        return node->readdir(node, index);
+    else
+        return 0;
+}
+
+fs_node_t *finddir_fs(fs_node_t *node, char *name) {
+    // Check if an inode is a directory
+    if((node->flags&0x7) == FS_DIRECTORY && node->finddir != 0) 
+        return node->finddir(node, name);
+    else
+        return 0;
+}

kernel/drivers/fs.h

@@ -0,0 +1,84 @@
+/**************************************
+ *          iceOS Kernel              *
+ * Developed by Marco 'icebit' Cetica * 
+ *            (c) 2019                *
+ *       Released under GPLv3         *
+ * https://github.com/ice-bit/iceOS   *
+ ***************************************/
+#ifndef FS_H
+#define FS_H
+
+#include <stdint.h>
+/* This Virtual File System(VFS) is a simplified version of 
+ * standard UNIX VFS where all files comes organized in a graph
+ * of nodes. Keeping in mind the concept of "everything is a file" we can
+ * store a file, a directory, a serial device or anything else just by adding
+ * a new node to the data structure. 
+ * And this is a list of common operations: 
+ * - Open: Initialize a new node as a file descriptor
+ * - Close: CLose a node 
+ * - Read: return the content of a node
+ * - Write: set content to node
+ * - Readdir: Return directory content
+ * - Finddir: Given a specific name find the corresponding child node.*/
+
+// Define some standard node types
+#define FS_FILE 0x01
+#define FS_DIRECTORY 0x02
+#define FS_CHARDEVICE 0x03
+#define FS_BLOCKDEVICE 0x04
+#define FS_PIPE 0x05
+#define FS_SYMLINK 0x06
+#define FS_MOUNTPOINT 0x08
+
+struct fs_node;
+
+/* Define some callbacks to be called when read/write/open/close
+ * operations are called */
+typedef uint32_t (*read_type_t)(struct fs_node*, uint32_t, uint32_t, uint8_t*);
+typedef uint32_t (*write_type_t)(struct fs_node*, uint32_t, uint32_t, uint8_t*);
+typedef void (*open_type_t)(struct fs_node*);
+typedef void (*close_type_t)(struct fs_node*);
+typedef struct dirent*(*readdir_type_t)(struct fs_node*, uint32_t);
+typedef struct fs_node*(*finddir_type_t)(struct fs_node*, char *name);
+
+// This define the structure of a node
+typedef struct fs_node {
+    uint8_t name[128]; // File name
+    uint32_t mask; // Permission mask
+    uint32_t uid; // Owning user
+    uint32_t gid; // Owning group
+    uint32_t flags; // Node type
+    uint32_t inode; // used by file systems to identify files
+    uint32_t length; // Length of the file, in bytes.
+    uint32_t impl;
+    // Callback section
+    read_type_t read;
+    write_type_t write;
+    open_type_t open;
+    close_type_t close;
+    readdir_type_t readdir;
+    finddir_type_t finddir;
+    struct fs_node *ptr; // Used by mountpoints and symlinks
+} fs_node_t;
+
+struct dirent {
+    uint8_t name[120]; // File name
+    uint32_t ino; // POSIX standard requires inode number;
+};
+
+// Filesystem root
+extern fs_node_t *fs_root;
+
+/* Write/Read/Open/Close operations
+ * NOTE: those functions are NOT like the Callback
+ * functions; the first one deals with inodes while
+ * the second one deals with file descriptors. */
+uint32_t read_fs(fs_node_t *node, uint32_t offset, uint32_t size, uint8_t *buffer);
+uint32_t write_fs(fs_node_t *node, uint32_t offset, uint32_t size, uint8_t *buffer);
+void open_fs(fs_node_t *node, uint8_t read, uint8_t write);
+void close_fs(fs_node_t *node);
+struct dirent *readdir_fs(fs_node_t *node, uint32_t index);
+fs_node_t *finddir_fs(fs_node_t *node, char *name);
+
+#endif

kernel/drivers/gdt.h

@@ -136,5 +136,4 @@ typedef struct gdt_ptr gdt_ptr_t;
 /* GDT Kernel API */
 void gdt_setup();
 
-
 #endif