ext2 as multiboot2 module

1 files changed, 237 insertions, 0 deletions

diff --git a/kernel/src/fs/ext2.c b/kernel/src/fs/ext2.c
new file mode 100644
index 0000000..11f26fc
--- /dev/null
+++ b/kernel/src/fs/ext2.c
@@ -0,0 +1,237 @@
+#include <libk/string.h>
+#include <libk/stdio.h>
+#include <libk/math.h>
+#include <heap.h>
+#include <disc.h>
+#include <ext2.h>
+
+ext2_superblock_t* ext2_superblock;
+
+void read_block(uint32_t block_num, void* block_ptr)
+{
+	uint32_t sectors_per_block = BLOCK_SIZE / SECTOR_SIZE;
+
+	for (size_t i = 0; i < sectors_per_block; i++) {
+		read_sector(block_num * sectors_per_block + i, (disc_sector_t*)block_ptr + i);
+	}
+}
+
+void read_superblock(ext2_superblock_t* superblock)
+{
+	char block[1024];
+	read_sector(2, (disc_sector_t*)block);
+	read_sector(3, (disc_sector_t*)block + 1);
+	memcpy(superblock, block, sizeof(ext2_superblock_t));
+}
+
+void read_bg_desc(uint32_t bg_desc, ext2_bg_desc_t* ext2_bg_desc)
+{
+	uint32_t starting_block_num = BLOCK_SIZE == 1024 ? 2 : 1;
+	uint32_t bg_descs_per_block = BLOCK_SIZE / BG_DESC_SIZE;
+	uint32_t block_num = starting_block_num + bg_desc / bg_descs_per_block;
+	uint32_t block_index = bg_desc % bg_descs_per_block;
+
+	char block[BLOCK_SIZE];
+	read_block(block_num, block);
+	memcpy(ext2_bg_desc, (char*)block + BG_DESC_SIZE * block_index, sizeof(ext2_bg_desc_t));
+}
+
+void read_inode(uint32_t starting_block_num, uint32_t inode_index, ext2_inode_t* ext2_inode)
+{
+	uint32_t block_num = starting_block_num + inode_index / INODES_PER_BLOCK;
+	uint32_t block_index = inode_index % INODES_PER_BLOCK;
+
+	char block[BLOCK_SIZE];
+	read_block(block_num, block);
+	memcpy(ext2_inode, (char*)block + block_index * INODE_SIZE, sizeof(ext2_inode_t));
+}
+
+list_t* directory_to_entries(uint32_t inode)
+{
+	list_t* list = NULL;
+
+	uint32_t bg_desc = (inode - 1) / ext2_superblock->inodes_per_group;
+	uint32_t inode_index = (inode - 1) % ext2_superblock->inodes_per_group;
+
+	// block group descriptor
+	ext2_bg_desc_t* ext2_bg_desc;
+	ext2_bg_desc = (ext2_bg_desc_t*)kalloc(sizeof(ext2_bg_desc_t));
+	read_bg_desc(bg_desc, ext2_bg_desc);
+
+	// inode table
+	ext2_inode_t* ext2_inode;
+	ext2_inode = (ext2_inode_t*)kalloc(sizeof(ext2_inode_t));
+	read_inode(ext2_bg_desc->inode_block_address, inode_index, ext2_inode);
+
+	// if it is not directory
+	if (!(ext2_inode->type_perms & TYPE_DIR))
+		return list;
+
+	// read inode contents
+	for (size_t i = 0; i < 12; i++) {
+		if (ext2_inode->dbp[i] == 0)
+			break;
+
+		// get block
+		char block[BLOCK_SIZE];
+		read_block(ext2_inode->dbp[i], block);
+
+		// parse block
+		for (size_t block_offset = 0; block_offset < BLOCK_SIZE;) {
+			// get dentry header
+			ext2_dentry_t* ext2_dentry;
+			ext2_dentry = (ext2_dentry_t*)kalloc(sizeof(ext2_dentry_t));
+			memcpy(ext2_dentry, (char*)block + block_offset, sizeof(ext2_dentry_t) - sizeof(char*));
+
+			// get dentry name
+			ext2_dentry->name = (char*)kalloc(ext2_dentry->name_length_lower);
+			memcpy(ext2_dentry->name, (char*)block + block_offset + sizeof(ext2_dentry_t) - sizeof(char*), ext2_dentry->name_length_lower);
+
+			if (inode == 0) {
+				kfree(ext2_dentry->name);
+				kfree(ext2_dentry);
+				break;
+			}
+
+			// put dentry in list
+			add_to_list_head(&list, ext2_dentry);
+
+			// offset
+			block_offset += ext2_dentry->size;
+		}
+	}
+
+
+	kfree(ext2_bg_desc);
+	kfree(ext2_inode);
+
+	return list;
+}
+
+char* files_to_buffer(uint32_t inode)
+{
+	uint32_t bg_desc = (inode - 1) / ext2_superblock->inodes_per_group;
+	uint32_t inode_index = (inode - 1) % ext2_superblock->inodes_per_group;
+
+	// block group descriptor
+	ext2_bg_desc_t* ext2_bg_desc;
+	ext2_bg_desc = (ext2_bg_desc_t*)kalloc(sizeof(ext2_bg_desc_t));
+	read_bg_desc(bg_desc, ext2_bg_desc);
+
+	// inode table
+	ext2_inode_t* ext2_inode;
+	ext2_inode = (ext2_inode_t*)kalloc(sizeof(ext2_inode_t));
+	read_inode(ext2_bg_desc->inode_block_address, inode_index, ext2_inode);
+
+	char* data;
+
+	uint32_t size = ext2_inode->size_lower;
+	data = (char*)kalloc(size);
+
+	uint32_t block_num = upper_div(size, BLOCK_SIZE);
+	for (size_t i = 0; i < min(block_num, 12); i++) {
+		char block[BLOCK_SIZE];
+		read_block(ext2_inode->dbp[i], block);
+		memcpy(data + i * BLOCK_SIZE, block, size >= (i + 1) * BLOCK_SIZE ? BLOCK_SIZE : size % BLOCK_SIZE);
+	}
+
+	return data;
+}
+
+list_t* path_to_list(const char* path)
+{
+	size_t i, j;
+	list_t* divided_path = NULL;
+
+	size_t n = strlen(path);
+	for (i = 0, j = 0; i <= n; i++) {
+		if (i == n || path[i] == '/') {
+			// add data before slash
+			if (i != j) {
+				char* ptr = (char*)kalloc(sizeof(char) * (uint32_t)(i - j + 1));
+				memcpy(ptr, path + j, i - j);
+				ptr[i - j] = '\0';
+				add_to_list_tail(&divided_path, ptr);
+			}
+			// add slash
+			if (i != n) {
+				char* ptr = (char*)kalloc(sizeof(char) * 2);
+				ptr[0] = '/';
+				ptr[1] = '\0';
+				add_to_list_tail(&divided_path, ptr);
+				j = i + 1;
+			}
+		}
+	}
+
+	return divided_path;
+}
+
+// only supports absolute path for now
+uint32_t path_to_inode(const char* path)
+{
+	uint32_t inode = 0;
+	list_t* divided_path = path_to_list(path);
+
+	list_t* curr_dir = divided_path;
+
+	// first entry is /
+	curr_dir = curr_dir->next;
+	inode = 2;
+
+	while (curr_dir != NULL) {
+		// list of dentry
+		list_t* list = directory_to_entries(inode);
+
+		// check if inode is actually a dir
+		if (list == NULL) {
+			printf("not a directory\n");
+			return 0;
+		}
+
+		// iterate through all direntries
+		uint8_t ind = 1;
+		for (list_t* curr_list = list; curr_list != NULL; curr_list = curr_list->next) {
+			ext2_dentry_t* ext2_dentry;
+			ext2_dentry = curr_list->data;
+
+			if (!memcmp(curr_dir->data, ext2_dentry->name)) {
+				ind = 0;
+				inode = ext2_dentry->inode;
+				break;
+			}
+		}
+
+		// if dir not found error
+		if (ind) {
+			printf("file/dir not found\n");
+			return 0;
+		}
+
+		// next dir
+		curr_dir = curr_dir->next;
+		if (curr_dir != NULL)
+			curr_dir = curr_dir->next;
+	}
+
+	return inode;
+}
+
+void ls(uint32_t inode)
+{
+	list_t* dir = directory_to_entries(inode);
+
+	printf("ls dir with inode %d:\n", inode);
+	for (list_t* tmp = dir; tmp != NULL; tmp = tmp->next) {
+		ext2_dentry_t* ext2_dentry;
+		ext2_dentry = tmp->data;
+		printf("inode: %d, name: %s\n", ext2_dentry->inode, ext2_dentry->name);
+	}
+}
+
+void print(uint32_t inode)
+{
+	printf("contents of inode %d:\n", inode);
+	char *p = files_to_buffer(inode);
+	printf("%s", p);
+}