Add listing to EXT2
diff --git a/README.md b/README.md
index 774e14f..0db66bc 100644
--- a/README.md
+++ b/README.md
@@ -37,6 +37,9 @@
- [x] Initial ramdisk
- [ ] Filesystem drivers
- [ ] EXT2 (in progress)
+ - [x] Read
+ - [ ] Write
+ - [ ] Consistency check (`fsck`)
- [ ] FAT32
- [ ] System call API
- [ ] Filesystem API
diff --git a/include/kernel/dri/fs/ext2/ext2.h b/include/kernel/dri/fs/ext2/ext2.h
index 4205c4b..0ffeaac 100644
--- a/include/kernel/dri/fs/ext2/ext2.h
+++ b/include/kernel/dri/fs/ext2/ext2.h
@@ -4,55 +4,79 @@
struct ext2_superblock
{
- // Total number of inodes
+ /// Total number of inodes
uint total_inodes;
- // Total number of blocks
+
+ /// Total number of blocks
uint total_blocks;
- // Number of blocks reserved for superuser
+
+ /// Number of blocks reserved for superuser
uint blocks_reserved_for_superuser;
- // Number of unallocated blocks
+
+ /// Number of unallocated blocks
uint unallocated_blocks;
- // Number of unallocated inodes
+
+ /// Number of unallocated inodes
uint unallocated_inodes;
- // Block number containing the superblock
+
+ /// Block number containing the superblock
uint superblock_block_number;
- // the number to shift 1024 to the left by to get the block size
+
+ /// the number to shift 1024 to the left by to get the block size
uint block_size_shift;
- // the number to shift 1024 to the left by to get the fragment size
+
+ /// the number to shift 1024 to the left by to get the fragment size
uint fragment_size_shift;
- // Number of blocks in one block group
+
+ /// Number of blocks in one block group
uint blocks_per_block_group;
- // Number of fragments in one block group
+
+ /// Number of fragments in one block group
uint fragments_per_block_group;
- // Number of inodse in one block group
+
+ /// Number of inodse in one block group
uint inodes_per_block_group;
- // UNIX time of last mount
+
+ /// UNIX time of last mount
uint last_mount_time;
- // UNIX time of last write
+
+ /// UNIX time of last write
uint last_write_time;
- // Number of mounts since last consistency check
+
+ /// Number of mounts since last consistency check
ushort mounts_since_last_fsck;
- // Number of mounts allowed between consistency checks
+
+ /// Number of mounts allowed between consistency checks
ushort mounts_allowed_before_fsck;
- // EXT2 signature, should be 0xef53
+
+ /// EXT2 signature, should be 0xef53
ushort signature;
- // File system state, see enum ext2_fs_state
+
+ /// File system state, see enum ext2_fs_state
ushort state;
- // What to do in case of an error, see enum ext2_error_case
+
+ /// What to do in case of an error, see enum ext2_error_case
ushort error_case;
- // Minor portion of version
+
+ /// Minor portion of version
ushort version_minor;
- // UNIX time of last consistency check
+
+ /// UNIX time of last consistency check
uint last_fsck_time;
- // Max time between consistency checks
+
+ /// Max time between consistency checks
uint fsck_time_interval;
- // Operating system ID of creator
+
+ /// Operating system ID of creator
uint creator_os_id;
- // Major portion of version
+
+ /// Major portion of version
uint version_major;
- // User ID that can use reserved blocks
+
+ /// User ID that can use reserved blocks
ushort reserved_blocks_uid;
- // Group ID that can use reserved blocks
+
+ /// Group ID that can use reserved blocks
ushort reserved_blocks_gid;
};
@@ -80,6 +104,177 @@
#define EXT2_SIGNATURE 0xef53
+struct ext2_block_group_descriptor
+{
+ /// Address of block usage bitmap
+ uint block_bitmap; // 4
+
+ /// Address of inode usage bitmap
+ uint inode_bitmap; // 8
+
+ /// Starting block address of inode table
+ uint inode_table_start_block; // 12
+
+ /// Number of unallocated blocks in this group
+ ushort unallocated_blocks; // 14
+
+ /// Number of unallocated inodes in this group
+ ushort unallocated_inodes; // 16
+
+ /// Number of directories in this group
+ ushort num_dirs; // 18
+
+ ushort padding;
+
+ uchar reserved[12]; // 32
+};
+
+struct ext2_inode
+{
+ /// The format and permissions of the file, see EXT2_S_*
+ ushort mode;
+
+ /// The user id of the owner
+ ushort uid;
+
+ /// The lower 32 bits of the file size
+ uint size;
+
+ /// Last time this was accessed in UNIX time
+ uint access_time;
+
+ /// Time this was created in UNIX time
+ uint created_time;
+
+ /// Time this was last modified in UNIX time
+ uint modified_time;
+
+ /// Time this was deleted in UNIX time
+ uint deleted_time;
+
+ /// Owner group id
+ ushort gid;
+
+ /// Reference count for hard links
+ ushort links_count;
+
+ /// Number of 512 byte blocks storing this files data, NOT EXT2 blocks!
+ uint num_blocks;
+
+ /// Flags describing how this file can be accessed
+ uint flags;
+
+ /// First field reserved for the operating system
+ uint os_reserved_1;
+
+ union
+ {
+ /// The blocks of this file
+ uint blocks[15];
+
+ struct
+ {
+ /// The direct blocks
+ uint direct_blocks[12];
+
+ /// The single indirect block
+ uint ind_block;
+
+ /// The double indirect block
+ uint ind2_block;
+
+ /// The triple indirect block
+ uint ind3_block;
+ };
+ };
+
+ /// Used by NFS to version files
+ uint generation;
+
+ /// File attributes, unused
+ uint file_acl;
+
+ /// Directory attributes, unused
+ uint dir_acl;
+
+ /// Location of file fragment, unused
+ uint faddr;
+
+ /// Second field reserved for the operating system
+ uchar os_reserved_2[12];
+};
+
+enum
+{
+ // File types
+ EXT2_S_IFSOCK = 0xc000,
+ EXT2_S_IFLINK = 0xa000,
+ EXT2_S_IFREG = 0x8000,
+ EXT2_S_IFBLK = 0x6000,
+ EXT2_S_IFDIR = 0x4000,
+ EXT2_S_IFCHR = 0x2000,
+ EXT2_S_IFIFO = 0x1000,
+
+ /// Set UID
+ EXT2_S_ISUID = 0x0800,
+ /// Set GUID
+ EXT2_S_ISGID = 0x0400,
+ /// Sticky
+ EXT2_S_ISVTX = 0x0200,
+
+ // Normal UNIX file permissions
+ EXT2_S_IRUSR = 0x0100,
+ EXT2_S_IWUSR = 0x0080,
+ EXT2_S_IXUSR = 0x0040,
+ EXT2_S_IRGRP = 0x0020,
+ EXT2_S_IWGRP = 0x0010,
+ EXT2_S_IXGRP = 0x0008,
+ EXT2_S_IROTH = 0x0004,
+ EXT2_S_IWOTH = 0x0002,
+ EXT2_S_IXOTH = 0x0001,
+};
+
+struct ext2_dirent
+{
+ uint inode;
+ ushort rec_len;
+ uchar name_len;
+ uchar file_type;
+ char name[];
+};
+
+/// Read a file system block (0-indexed), if necessary multiple disk blocks
+/// will be read automatically
+void ext2_read_block(struct ext2_superblock *sb, void *buffer, uint block);
+
struct ext2_superblock ext2_read_superblock();
+
+void ext2_write_superblock(struct ext2_superblock *sb);
+
+// Just for fun, corrupt the superblock (obviously don't actually do this)
+void ext2_corrupt_superblock_for_fun();
+
void ext2_mount(struct fs_node *where);
+
bool ext2_valid_filesystem();
+
+bool ext2_find_inode(struct ext2_superblock *sb, uint number, struct ext2_inode *inode);
+
+/// Load a block group descriptor for a certain block group
+struct ext2_block_group_descriptor ext2_load_block_group_descriptor(
+ struct ext2_superblock *sb, uint block_group);
+
+/// List the contents of a directory dir. Calls `cb` for each item. If `dir` is
+/// not a directory, returns false. Otherwise returns true.
+bool ext2_dir_ls(struct ext2_superblock *sb,
+ struct ext2_inode *dir,
+ void (*cb)(uint inode,
+ const char *name,
+ void *data),
+ void *data);
+
+/// Read a data block for the inode, 0 being the first block of the file.
+bool ext2_read_inode_block(struct ext2_superblock *sb,
+ struct ext2_inode *inode,
+ void *buffer,
+ uint block);
diff --git a/include/kernel/log.h b/include/kernel/log.h
index 3365474..a4ae42b 100644
--- a/include/kernel/log.h
+++ b/include/kernel/log.h
@@ -5,6 +5,7 @@
#define RESET "\033[0m"
#define INFO "[\033[96m INFO " RESET "] "
#define OKAY "[\033[92m OK " RESET "] "
+#define WARN "[\033[93m WARN " RESET "] "
#define ERROR "[\033[91m ERROR " RESET "] "
#define DEBUG "[\033[93m DEBUG " RESET "] "
diff --git a/src/kernel/Jmk b/src/kernel/Jmk
index cbce0a2..05e2b8e 100644
--- a/src/kernel/Jmk
+++ b/src/kernel/Jmk
@@ -1,7 +1,8 @@
init(kernel, kernel.elf)
preset(freestanding)
-preset(optimize)
+# This makes debugging hard :(
+# preset(optimize)
preset(debug)
preset(32)
preset(warn)
@@ -60,7 +61,7 @@
type(custom_link)
debug-wait: kernel.elf
- qemu-system-i386 -s -S -kernel kernel.elf
+ qemu-system-i386 -s -S $(QEMUFLAGS) -kernel kernel.elf
debug: kernel.elf
qemu-system-i386 -s -S $(QEMUFLAGS) -kernel kernel.elf &
diff --git a/src/kernel/dri/fs/ext2/ext2.c b/src/kernel/dri/fs/ext2/ext2.c
index 31d3b26..3a1e183 100644
--- a/src/kernel/dri/fs/ext2/ext2.c
+++ b/src/kernel/dri/fs/ext2/ext2.c
@@ -2,6 +2,20 @@
#include <dri/fs/ext2/ext2.h>
#include <kint.h>
#include <log.h>
+#include <io.h>
+
+inline uint ext2_block_size(struct ext2_superblock *sb)
+{
+ return 1024 << sb->block_size_shift;
+}
+
+void ext2_read_block(struct ext2_superblock *sb, void *buffer, uint block)
+{
+ uint block_size = ext2_block_size(sb) / 512;
+ uint block_start = block_size * block;
+
+ ata_pio_read_sectors(buffer, block_start, block_size);
+}
struct ext2_superblock ext2_read_superblock()
{
@@ -31,13 +45,8 @@
}
}
-uint ext2_block_size(struct ext2_superblock *sb)
-{
- return 1024 << sb->block_size_shift;
-}
-
-void ext2_load_block_group_descriptor_table(struct ext2_superblock *sb,
- uint num_block_groups)
+struct ext2_block_group_descriptor ext2_load_block_group_descriptor(
+ struct ext2_superblock *sb, uint block_group)
{
/**
* The BGDT (not to be confused with the GDT) is located the block after the
@@ -51,7 +60,26 @@
if (block_size == 1024)
bgdt_block = 2;
- kprintf(DEBUG "BGDT block = %d block size = %d\n", bgdt_block, block_size);
+ const uint bgd_size = sizeof(struct ext2_block_group_descriptor);
+
+ // Disk page that the BGD is on relative to the initial FILE SYSTEM block
+ uint hd_page = block_group / (512 / bgd_size);
+ // The offset from the beginning of that page the BGD is at
+ uint bgd_offset = block_group % (512 / bgd_size);
+
+ struct ext2_block_group_descriptor descriptors[512 / bgd_size];
+ kassert(sizeof(descriptors) == 512, "Wrong BGD size");
+
+ uint lba = (block_size / 512) * bgdt_block + hd_page;
+
+ ata_pio_read_sectors(&descriptors, lba, 1);
+
+ return descriptors[bgd_offset];
+}
+
+static void print_entry(uint inode, const char *name, void *data)
+{
+ kprintf("%d\t %s\n", inode, name);
}
void ext2_mount(struct fs_node *where)
@@ -59,9 +87,25 @@
struct ext2_superblock sb = ext2_read_superblock();
kprintf(DEBUG "EXT2 magic = 0x%x\n", sb.signature);
+
+ // Read the root inode 2
+ struct ext2_inode root;
- uint num_block_groups = ext2_num_block_groups(&sb);
- ext2_load_block_group_descriptor_table(&sb, num_block_groups);
+ if (ext2_find_inode(&sb, 2, &root))
+ {
+ kprintf(OKAY "Found root inode 2 (size=0x%x, num_blocks=0x%x)\n", root.size, root.num_blocks);
+ // kprintf(DEBUG "Root.mode = 0x%x\n", root.mode & 0xf000);
+ kassert((root.mode & 0xf000) == EXT2_S_IFDIR, "Root (inode 2) is not a directory.");
+
+ kprintf("ls /\n");
+ kprintf("inode\t name\n");
+ kprintf("--------------------\n");
+ ext2_dir_ls(&sb, &root, print_entry, NULL);
+ }
+ else
+ {
+ kprintf(WARN "Failed to find root inode 2\n");
+ }
}
bool ext2_valid_filesystem()
@@ -72,3 +116,111 @@
return sb.signature == EXT2_SIGNATURE;
}
+
+void ext2_write_superblock(struct ext2_superblock *sb)
+{
+ ushort *wp = (ushort *)sb;
+
+ ata_pio_write_sectors(2, 2, wp);
+}
+
+void ext2_corrupt_superblock_for_fun()
+{
+ struct ext2_superblock sb = ext2_read_superblock();
+ sb.signature = 0xDEAD;
+ ext2_write_superblock(&sb);
+}
+
+bool ext2_find_inode(struct ext2_superblock *sb, uint number, struct ext2_inode *inode)
+{
+ if (number == 0)
+ return false;
+
+ uint block_group = (number - 1) / sb->inodes_per_block_group;
+ uint local_index = (number - 1) % sb->inodes_per_block_group;
+
+ // Load this from the block group descriptor table
+ struct ext2_block_group_descriptor descriptor =
+ ext2_load_block_group_descriptor(sb, block_group);
+
+ kprintf(DEBUG "Descriptor inode_table = 0x%x\n", descriptor.inode_table_start_block);
+
+ // We need to figure out what FS block the inode is on, we know how many
+ // inodes there are total in this BGD and the number per page, so this is
+ // simple.
+
+ const uint block_size = ext2_block_size(sb);
+
+ const uint inodes_per_block = block_size / sizeof(struct ext2_inode);
+
+ uint inode_block = local_index / inodes_per_block;
+ uint inode_index = local_index % inodes_per_block;
+
+ struct ext2_inode inodes[block_size / sizeof(struct ext2_inode)];
+
+ ext2_read_block(sb, inodes, descriptor.inode_table_start_block +
+ inode_block);
+
+ *inode = inodes[inode_index];
+
+ return true;
+}
+
+bool ext2_dir_ls(struct ext2_superblock *sb,
+ struct ext2_inode *dir,
+ void (*cb)(uint inode,
+ const char *name,
+ void *data),
+ void *data)
+{
+ if ((dir->mode & 0xf000) != EXT2_S_IFDIR)
+ return false;
+
+ for (int i = 0; i < dir->num_blocks; i++)
+ {
+ uchar buffer[ext2_block_size(sb)];
+ ext2_read_inode_block(sb, dir, buffer, i);
+
+ struct ext2_dirent *ent = (void *)buffer;
+
+ // While there are files in this block
+ while (ent < buffer + ext2_block_size(sb))
+ {
+ if (ent->inode == 0)
+ return true;
+
+ if (cb)
+ {
+ char name[257];
+
+ memcpy(name, ent->name, ent->name_len);
+ name[ent->name_len] = '\0';
+
+ cb(ent->inode, name, data);
+ }
+
+ ent = (void *)(((uint)(void *)ent) + ent->rec_len);
+ }
+ // We ran out of files in this block, continue to the next one. This
+ // works because files cannot span blocks
+ }
+
+ return true;
+}
+
+bool ext2_read_inode_block(struct ext2_superblock *sb,
+ struct ext2_inode *inode,
+ void *buffer,
+ uint block)
+{
+ if (block >= 12)
+ {
+ kprintf(ERROR "Sorry, EXT2 can only access the first 12 (direct) blocks "
+ "of an inode for now. Indirect look-up will be added later\n");
+ kpanic("Invalid inode block");
+ }
+
+ uint block_address = inode->blocks[block];
+
+ ext2_read_block(sb, buffer, block_address);
+}
diff --git a/src/kernel/main.c b/src/kernel/main.c
index 53fb71e..59fc111 100644
--- a/src/kernel/main.c
+++ b/src/kernel/main.c
@@ -101,19 +101,15 @@
test_ata_pio();
#endif
-#if 1 // ifdef TEST_EXT2
if (ext2_valid_filesystem())
{
- kprintf(OKAY "EXT2 filesystem is valid, again = %b\n", ext2_valid_filesystem());
-
- //kprintf(INFO "Mounting EXT2 to /\n");
- //ext2_mount(&root);
+ kprintf(OKAY "EXT2 filesystem is valid\n");
+ ext2_mount(&root);
}
-
- // Try reading the regions that the ext2 needs
- // uchar buffer[1024];
- // ata_pio_read_sectors(buffer, 2, 2);
-#endif
+ else
+ {
+ kprintf(WARN "Filesystem is not a valid EXT2 format, only EXT2 is supported\n");
+ }
while (true)
asm("hlt");