view toys/mke2fs.c @ 565:44abf4d901f3

Rewrite dirtree so we don't need readdir, scandir, and fts.h. Rewrite ls (from scratch) to use new dirtree infrastructure. (This breaks everything else that currently uses dirtree.)
author Rob Landley <rob@landley.net>
date Sat, 14 Apr 2012 22:30:41 -0500
parents 7cb15eae1664
children
line wrap: on
line source

/* vi: set ts=4:
 *
 * mke2fs.c - Create an ext2 filesystem image.
 *
 * Copyright 2006, 2007 Rob Landley <rob@landley.net>
 *
 * Not in SUSv3.

// Still to go: "E:jJ:L:m:O:"
USE_MKE2FS(NEWTOY(mke2fs, "<1>2g:Fnqm#N#i#b#", TOYFLAG_SBIN))

config MKE2FS
	bool "mke2fs (unfinished and broken by dirtree changes)"
	default n
	help
	  usage: mke2fs [-Fnq] [-b ###] [-N|i ###] [-m ###] device

	  Create an ext2 filesystem on a block device or filesystem image.

	  -F         Force to run on a mounted device
	  -n         Don't write to device
	  -q         Quiet (no output)
	  -b size    Block size (1024, 2048, or 4096)
	  -N inodes  Allocate this many inodes
	  -i bytes   Allocate one inode for every XXX bytes of device
	  -m percent Reserve this percent of filesystem space for root user

config MKE2FS_JOURNAL
	bool "Journaling support (ext3)"
	default n
	depends on MKE2FS
	help
	  usage: [-j] [-J size=###,device=XXX]

	  -j         Create journal (ext3)
	  -J         Journal options
	             size: Number of blocks (1024-102400)
	             device: Specify an external journal

config MKE2FS_GEN
	bool "Generate (gene2fs)"
	default n
	depends on MKE2FS
	help
	  usage: gene2fs [options] device filename

	  The [options] are the same as mke2fs.

config MKE2FS_LABEL
	bool "Label support"
	default n
	depends on MKE2FS
	help
	  usage: mke2fs [-L label] [-M path] [-o string]

	  -L         Volume label
	  -M         Path to mount point
	  -o         Created by

config MKE2FS_EXTENDED
	bool "Extended options"
	default n
	depends on MKE2FS
	help
	  usage: mke2fs [-E stride=###] [-O option[,option]]

	  -E stride= Set RAID stripe size (in blocks)
	  -O [opts]  Specify fewer ext2 option flags (for old kernels)
	             All of these are on by default (as appropriate)
	     none         Clear default options (all but journaling)
	     dir_index    Use htree indexes for large directories
	     filetype     Store file type info in directory entry
	     has_journal  Set by -j
	     journal_dev  Set by -J device=XXX
	     sparse_super Don't allocate huge numbers of redundant superblocks
*/

#include "toys.h"

DEFINE_GLOBALS(
	// Command line arguments.
	long blocksize;
	long bytes_per_inode;
	long inodes;           // Total inodes in filesystem.
	long reserved_percent; // Integer precent of space to reserve for root.
	char *gendir;          // Where to read dirtree from.

	// Internal data.
	struct dirtree *dt;    // Tree of files to copy into the new filesystem.
	unsigned treeblocks;   // Blocks used by dt
	unsigned treeinodes;   // Inodes used by dt

	unsigned blocks;       // Total blocks in the filesystem.
	unsigned freeblocks;   // Free blocks in the filesystem.
	unsigned inodespg;     // Inodes per group
	unsigned groups;       // Total number of block groups.
	unsigned blockbits;    // Bits per block.  (Also blocks per group.)

	// For gene2fs
	unsigned nextblock;    // Next data block to allocate
	unsigned nextgroup;    // Next group we'll be allocating from
	int fsfd;              // File descriptor of filesystem (to output to).

	struct ext2_superblock sb;
)

// Shortcut to our global data structure, since we use it so much.
#define TT this.mke2fs

#define INODES_RESERVED 10

static uint32_t div_round_up(uint32_t a, uint32_t b)
{
	uint32_t c = a/b;

	if (a%b) c++;
	return c;
}

// Calculate data blocks plus index blocks needed to hold a file.

static uint32_t file_blocks_used(uint64_t size, uint32_t *blocklist)
{
	uint32_t dblocks = (uint32_t)((size+(TT.blocksize-1))/TT.blocksize);
	uint32_t idx=TT.blocksize/4, iblocks=0, diblocks=0, tiblocks=0;

	// Fill out index blocks in inode.

	if (blocklist) {
		int i;

		// Direct index blocks
		for (i=0; i<13 && i<dblocks; i++) blocklist[i] = i;
		// Singly indirect index blocks
		if (dblocks > 13+idx) blocklist[13] = 13+idx;
		// Doubly indirect index blocks
		idx = 13 + idx + (idx*idx);
		if (dblocks > idx) blocklist[14] = idx;

		return 0;
	}

	// Account for direct, singly, doubly, and triply indirect index blocks

	if (dblocks > 12) {
		iblocks = ((dblocks-13)/idx)+1;
		if (iblocks > 1) {
			diblocks = ((iblocks-2)/idx)+1;
			if (diblocks > 1)
				tiblocks = ((diblocks-2)/idx)+1;
		}
	}

	return dblocks + iblocks + diblocks + tiblocks;
}

// Use the parent pointer to iterate through the tree non-recursively.
static struct dirtree *treenext(struct dirtree *this)
{
	while (this && !this->next) this = this->parent;
	if (this) this = this->next;

	return this;
}

// Recursively calculate the number of blocks used by each inode in the tree.
// Returns blocks used by this directory, assigns bytes used to *size.
// Writes total block count to TT.treeblocks and inode count to TT.treeinodes.

static long check_treesize(struct dirtree *that, off_t *size)
{
	long blocks;

	while (that) {
		*size += sizeof(struct ext2_dentry) + strlen(that->name);

		if (that->child)
			that->st.st_blocks = check_treesize(that->child, &that->st.st_size);
		else if (S_ISREG(that->st.st_mode)) {
			 that->st.st_blocks = file_blocks_used(that->st.st_size, 0);
			 TT.treeblocks += that->st.st_blocks;
		}
		that = that->next;
	}
	TT.treeblocks += blocks = file_blocks_used(*size, 0);
	TT.treeinodes++;

	return blocks;
}

// Calculate inode numbers and link counts.
// 
// To do this right I need to copy the tree and sort it, but here's a really
// ugly n^2 way of dealing with the problem that doesn't scale well to large
// numbers of files (> 100,000) but can be done in very little code.
// This rewrites inode numbers to their final values, allocating depth first.

static void check_treelinks(struct dirtree *tree)
{
	struct dirtree *current=tree, *that;
	long inode = INODES_RESERVED;

	while (current) {
		++inode;
		// Since we can't hardlink to directories, we know their link count.
		if (S_ISDIR(current->st.st_mode)) current->st.st_nlink = 2;
		else {
			dev_t new = current->st.st_dev;

			if (!new) continue;

			// Look for other copies of current node
			current->st.st_nlink = 0;
			for (that = tree; that; that = treenext(that)) {
				if (current->st.st_ino == that->st.st_ino &&
					current->st.st_dev == that->st.st_dev)
				{
					current->st.st_nlink++;
					current->st.st_ino = inode;
				}
			}
		}
		current->st.st_ino = inode;
		current = treenext(current);
	}
}

// According to http://www.opengroup.org/onlinepubs/9629399/apdxa.htm
// we should generate a uuid structure by reading a clock with 100 nanosecond
// precision, normalizing it to the start of the gregorian calendar in 1582,
// and looking up our eth0 mac address.
//
// On the other hand, we have 128 bits to come up with a unique identifier, of
// which 6 have a defined value.  /dev/urandom it is.

static void create_uuid(char *uuid)
{
	// Read 128 random bits
	int fd = xopen("/dev/urandom", O_RDONLY);
	xreadall(fd, uuid, 16);
	close(fd);

	// Claim to be a DCE format UUID.
	uuid[6] = (uuid[6] & 0x0F) | 0x40;
	uuid[8] = (uuid[8] & 0x3F) | 0x80;

    // rfc2518 section 6.4.1 suggests if we're not using a macaddr, we should
	// set bit 1 of the node ID, which is the mac multicast bit.  This means we
	// should never collide with anybody actually using a macaddr.
	uuid[11] = uuid[11] | 128;
}

// Calculate inodes per group from total inodes.
static uint32_t get_inodespg(uint32_t inodes)
{
	uint32_t temp;

	// Round up to fill complete inode blocks.
	temp = (inodes + TT.groups - 1) / TT.groups;
	inodes = TT.blocksize/sizeof(struct ext2_inode);
	return ((temp + inodes - 1)/inodes)*inodes;
}

// Fill out superblock and TT structures.

static void init_superblock(struct ext2_superblock *sb)
{
	uint32_t temp;

	// Set log_block_size and log_frag_size.

	for (temp = 0; temp < 4; temp++) if (TT.blocksize == 1024<<temp) break;
	if (temp==4) error_exit("bad blocksize");
	sb->log_block_size = sb->log_frag_size = SWAP_LE32(temp);

	// Fill out blocks_count, r_blocks_count, first_data_block

	sb->blocks_count = SWAP_LE32(TT.blocks);
	sb->free_blocks_count = SWAP_LE32(TT.freeblocks);
	temp = (TT.blocks * (uint64_t)TT.reserved_percent) / 100;
	sb->r_blocks_count = SWAP_LE32(temp);

	sb->first_data_block = SWAP_LE32(TT.blocksize == 1024 ? 1 : 0);

	// Set blocks_per_group and frags_per_group, which is the size of an
	// allocation bitmap that fits in one block (I.E. how many bits per block)?

	sb->blocks_per_group = sb->frags_per_group = SWAP_LE32(TT.blockbits);

	// Set inodes_per_group and total inodes_count
	sb->inodes_per_group = SWAP_LE32(TT.inodespg);
	sb->inodes_count = SWAP_LE32(TT.inodespg * TT.groups);

	// Determine free inodes.
	temp = TT.inodespg*TT.groups - INODES_RESERVED;
	if (temp < TT.treeinodes) error_exit("Not enough inodes.\n");
	sb->free_inodes_count = SWAP_LE32(temp - TT.treeinodes);

	// Fill out the rest of the superblock.
	sb->max_mnt_count=0xFFFF;
	sb->wtime = sb->lastcheck = sb->mkfs_time = SWAP_LE32(time(NULL));
	sb->magic = SWAP_LE32(0xEF53);
	sb->state = sb->errors = SWAP_LE16(1);

	sb->rev_level = SWAP_LE32(1);
	sb->first_ino = SWAP_LE32(INODES_RESERVED+1);
	sb->inode_size = SWAP_LE16(sizeof(struct ext2_inode));
	sb->feature_incompat = SWAP_LE32(EXT2_FEATURE_INCOMPAT_FILETYPE);
	sb->feature_ro_compat = SWAP_LE32(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER);

	create_uuid(sb->uuid);
	
	// TODO If we're called as mke3fs or mkfs.ext3, do a journal.

	//if (strchr(toys.which->name,'3'))
	//	sb->feature_compat |= SWAP_LE32(EXT3_FEATURE_COMPAT_HAS_JOURNAL);
}

// Does this group contain a superblock backup (and group descriptor table)?
static int is_sb_group(uint32_t group)
{
	int i;

	// Superblock backups are on groups 0, 1, and powers of 3, 5, and 7.
	if(!group || group==1) return 1;
	for (i=3; i<9; i+=2) {
		int j = i;
		while (j<group) j*=i;
		if (j==group) return 1;
	}
	return 0;
}

	
// Number of blocks used in group by optional superblock/group list backup.
static int group_superblock_overhead(uint32_t group)
{
	int used;

	if (!is_sb_group(group)) return 0;

	// How many blocks does the group descriptor table take up?
	used = TT.groups * sizeof(struct ext2_group);
	used += TT.blocksize - 1;
	used /= TT.blocksize;
	// Plus the superblock itself.
	used++;
	// And a corner case.
	if (!group && TT.blocksize == 1024) used++;

	return used;
}

// Number of blocks used in group to store superblock/group/inode list
static int group_overhead(uint32_t group)
{
	// Return superblock backup overhead (if any), plus block/inode
	// allocation bitmaps, plus inode tables.
	return group_superblock_overhead(group) + 2 + get_inodespg(TT.inodespg)
				/ (TT.blocksize/sizeof(struct ext2_inode));
}

// In bitmap "array" set "len" bits starting at position "start" (from 0).
static void bits_set(char *array, int start, int len)
{
	while(len) {
		if ((start&7) || len<8) {
			array[start/8]|=(1<<(start&7));
			start++;
			len--;
		} else {
			array[start/8]=255;
			start+=8;
			len-=8;
		}
	}
}

// Seek past len bytes (to maintain sparse file), or write zeroes if output
// not seekable
static void put_zeroes(int len)
{
	if(-1 == lseek(TT.fsfd, len, SEEK_SET)) {
		memset(toybuf, 0, sizeof(toybuf));
		while (len) {
			int out = len > sizeof(toybuf) ? sizeof(toybuf) : len;
			xwrite(TT.fsfd, toybuf, out);
			len -= out;
		}
	}
}

// Fill out an inode structure from struct stat info in dirtree.
static void fill_inode(struct ext2_inode *in, struct dirtree *that)
{
	uint32_t fbu[15];
	int temp;

	file_blocks_used(that->st.st_size, fbu);

	// If that inode needs data blocks allocated to it.
	if (that->st.st_size) {
		int i, group = TT.nextblock/TT.blockbits;

		// TODO: teach this about indirect blocks.
		for (i=0; i<15; i++) {
			// If we just jumped into a new group, skip group overhead blocks.
			while (group >= TT.nextgroup)
				TT.nextblock += group_overhead(TT.nextgroup++);
		}
	}
	// TODO :  S_ISREG/DIR/CHR/BLK/FIFO/LNK/SOCK(m)
	in->mode = SWAP_LE32(that->st.st_mode);

	in->uid = SWAP_LE16(that->st.st_uid & 0xFFFF);
	in->uid_high = SWAP_LE16(that->st.st_uid >> 16);
	in->gid = SWAP_LE16(that->st.st_gid & 0xFFFF);
	in->gid_high = SWAP_LE16(that->st.st_gid >> 16);
	in->size = SWAP_LE32(that->st.st_size & 0xFFFFFFFF);

	// Contortions to make the compiler not generate a warning for x>>32
	// when x is 32 bits.  The optimizer should clean this up.
	if (sizeof(that->st.st_size) > 4) temp = 32;
	else temp = 0;
	if (temp) in->dir_acl = SWAP_LE32(that->st.st_size >> temp);
	
	in->atime = SWAP_LE32(that->st.st_atime);
	in->ctime = SWAP_LE32(that->st.st_ctime);
	in->mtime = SWAP_LE32(that->st.st_mtime);

	in->links_count = SWAP_LE16(that->st.st_nlink);
	in->blocks = SWAP_LE32(that->st.st_blocks);
	// in->faddr
}

// Works like an archiver.
// The first argument is the name of the file to create.  If it already
// exists, that size will be used.

void mke2fs_main(void)
{
	int i, temp;
	off_t length;
	uint32_t usedblocks, usedinodes, dtiblk, dtbblk;
	struct dirtree *dti, *dtb;

	// Handle command line arguments.

	if (toys.optargs[1]) {
		sscanf(toys.optargs[1], "%u", &TT.blocks);
		temp = O_RDWR|O_CREAT;
	} else temp = O_RDWR;
	if (!TT.reserved_percent) TT.reserved_percent = 5;

	// TODO: Check if filesystem is mounted here

	// For mke?fs, open file.  For gene?fs, create file.
	TT.fsfd = xcreate(*toys.optargs, temp, 0777);
	
	// Determine appropriate block size and block count from file length.
	// (If no length, default to 4k.  They can override it on the cmdline.)

	length = fdlength(TT.fsfd);
	if (!TT.blocksize) TT.blocksize = (length && length < 1<<29) ? 1024 : 4096;
	TT.blockbits = 8*TT.blocksize;
	if (!TT.blocks) TT.blocks = length/TT.blocksize;

	// Collect gene2fs list or lost+found, calculate requirements.

	if (TT.gendir) {
		strncpy(toybuf, TT.gendir, sizeof(toybuf));
		dti = dirtree_read(toybuf, NULL, NULL);
	} else {
		dti = xzalloc(sizeof(struct dirtree)+11);
		strcpy(dti->name, "lost+found");
		dti->st.st_mode = S_IFDIR|0755;
		dti->st.st_ctime = dti->st.st_mtime = time(NULL);
	}

	// Add root directory inode.  This is iterated through for when finding
	// blocks, but not when finding inodes.  The tree's parent pointers don't
	// point back into this.

	dtb = xzalloc(sizeof(struct dirtree)+1);
	dtb->st.st_mode = S_IFDIR|0755;
	dtb->st.st_ctime = dtb->st.st_mtime = time(NULL);
	dtb->child = dti;
	
	// Figure out how much space is used by preset files
	length = check_treesize(dtb, &(dtb->st.st_size));
	check_treelinks(dtb);

	// Figure out how many total inodes we need.

	if (!TT.inodes) {
		if (!TT.bytes_per_inode) TT.bytes_per_inode = 8192;
		TT.inodes = (TT.blocks * (uint64_t)TT.blocksize) / TT.bytes_per_inode;
	}

	// If we're generating a filesystem and have no idea how many blocks it
	// needs, start with a minimal guess, find the overhead of that many
	// groups, and loop until this is enough groups to store this many blocks.
	if (!TT.blocks) TT.groups = (TT.treeblocks/TT.blockbits)+1;
	else TT.groups = div_round_up(TT.blocks, TT.blockbits);

	for (;;) {
		temp = TT.treeblocks;

		for (i = 0; i<TT.groups; i++) temp += group_overhead(i);

		if (TT.blocks) {
			if (TT.blocks < temp) error_exit("Not enough space.\n");
			break;
		}
		if (temp <= TT.groups * TT.blockbits) {
			TT.blocks = temp;
			break;
		}
		TT.groups++;
	}
	TT.freeblocks = TT.blocks - temp;

	// Now we know all the TT data, initialize superblock structure.

	init_superblock(&TT.sb);

	// Start writing.  Skip the first 1k to avoid the boot sector (if any).
	put_zeroes(1024);

	// Loop through block groups, write out each one.
	dtiblk = dtbblk = usedblocks = usedinodes = 0;
	for (i=0; i<TT.groups; i++) {
		struct ext2_inode *in = (struct ext2_inode *)toybuf;
		uint32_t start, itable, used, end;
		int j, slot;

		// Where does this group end?
		end = TT.blockbits;
		if ((i+1)*TT.blockbits > TT.blocks) end = TT.blocks & (TT.blockbits-1);

		// Blocks used by inode table
		itable = (TT.inodespg*sizeof(struct ext2_inode))/TT.blocksize;

		// If a superblock goes here, write it out.
		start = group_superblock_overhead(i);
		if (start) {
			struct ext2_group *bg = (struct ext2_group *)toybuf;
			int treeblocks = TT.treeblocks, treeinodes = TT.treeinodes;

			TT.sb.block_group_nr = SWAP_LE16(i);

			// Write superblock and pad it up to block size
			xwrite(TT.fsfd, &TT.sb, sizeof(struct ext2_superblock));
			temp = TT.blocksize - sizeof(struct ext2_superblock);
			if (!i && TT.blocksize > 1024) temp -= 1024;
			memset(toybuf, 0, TT.blocksize);
			xwrite(TT.fsfd, toybuf, temp);

			// Loop through groups to write group descriptor table.
			for(j=0; j<TT.groups; j++) {

				// Figure out what sector this group starts in.
				used = group_superblock_overhead(j);

				// Find next array slot in this block (flush block if full).
				slot = j % (TT.blocksize/sizeof(struct ext2_group));
				if (!slot) {
					if (j) xwrite(TT.fsfd, bg, TT.blocksize);
					memset(bg, 0, TT.blocksize);
				}

				// How many free inodes in this group?
				temp = TT.inodespg;
				if (!i) temp -= INODES_RESERVED;
				if (temp > treeinodes) {
					treeinodes -= temp;
					temp = 0;
				} else {
					temp -= treeinodes;
					treeinodes = 0;
				}
				bg[slot].free_inodes_count = SWAP_LE16(temp);

				// How many free blocks in this group?
				temp = TT.inodespg/(TT.blocksize/sizeof(struct ext2_inode)) + 2;
				temp = end-used-temp;
				if (temp > treeblocks) {
					treeblocks -= temp;
					temp = 0;
				} else {
					temp -= treeblocks;
					treeblocks = 0;
				}
				bg[slot].free_blocks_count = SWAP_LE32(temp);

				// Fill out rest of group structure
				used += j*TT.blockbits;
				bg[slot].block_bitmap = SWAP_LE32(used++);
				bg[slot].inode_bitmap = SWAP_LE32(used++);
				bg[slot].inode_table = SWAP_LE32(used);
				bg[slot].used_dirs_count = 0;  // (TODO)
			}
			xwrite(TT.fsfd, bg, TT.blocksize);
		}

		// Now write out stuff that every block group has.

		// Write block usage bitmap

		start += 2 + itable;
		memset(toybuf, 0, TT.blocksize);
		bits_set(toybuf, 0, start);
		bits_set(toybuf, end, TT.blockbits-end);
		temp = TT.treeblocks - usedblocks;
		if (temp) {
			if (end-start > temp) temp = end-start;
			bits_set(toybuf, start, temp);
		}
		xwrite(TT.fsfd, toybuf, TT.blocksize);

		// Write inode bitmap
		memset(toybuf, 0, TT.blocksize);
		j = 0;
		if (!i) bits_set(toybuf, 0, j = INODES_RESERVED);
		bits_set(toybuf, TT.inodespg, slot = TT.blockbits-TT.inodespg);
		temp = TT.treeinodes - usedinodes;
		if (temp) {
			if (slot-j > temp) temp = slot-j;
			bits_set(toybuf, j, temp);
		}
		xwrite(TT.fsfd, toybuf, TT.blocksize);

		// Write inode table for this group (TODO)
		for (j = 0; j<TT.inodespg; j++) {
			slot = j % (TT.blocksize/sizeof(struct ext2_inode));
			if (!slot) {
				if (j) xwrite(TT.fsfd, in, TT.blocksize);
				memset(in, 0, TT.blocksize);
			}
			if (!i && j<INODES_RESERVED) {
				// Write root inode
				if (j == 2) fill_inode(in+slot, dtb);
			} else if (dti) {
				fill_inode(in+slot, dti);
				dti = treenext(dti);
			}
		}
		xwrite(TT.fsfd, in, TT.blocksize);

		while (dtb) {
			// TODO write index data block
			// TODO write root directory data block
			// TODO write directory data block
			// TODO write file data block
			put_zeroes(TT.blocksize);
			start++;
			if (start == end) break;
		}
		// Write data blocks (TODO)
		put_zeroes((end-start) * TT.blocksize);
	}
}