mkfs.cramfs.c

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/*
 * mkcramfs - make a cramfs file system
 *
 * Copyright (C) 1999-2001 Transmeta Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * Old version would die on largish filesystems. Change to mmap the
 * files one by one instaed of all simultaneously. - aeb, 2002-11-01
 */

#include <sys/types.h>
#include <stdio.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/fcntl.h>
#include <dirent.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <assert.h>
#include <getopt.h>
#include <zlib.h>

#include "cramfs.h"
#include "md5.h"
#include "nls.h"

#define PAD_SIZE 512		/* only 0 and 512 supported by kernel */

static const char *progname = "mkcramfs";
static int verbose = 0;

#ifdef __ia64__
#define PAGE_CACHE_SIZE (16384)
#elif defined __alpha__
#define PAGE_CACHE_SIZE (8192)
#else
#define PAGE_CACHE_SIZE (4096)
#endif

/* The kernel assumes PAGE_CACHE_SIZE as block size. */
static unsigned int blksize = PAGE_CACHE_SIZE; /* settable via -b option */
static long total_blocks = 0, total_nodes = 1; /* pre-count the root node */
static int image_length = 0;

/*
 * If opt_holes is set, then mkcramfs can create explicit holes in the
 * data, which saves 26 bytes per hole (which is a lot smaller a
 * saving than for most filesystems).
 *
 * Note that kernels up to at least 2.3.39 don't support cramfs holes,
 * which is why this is turned off by default.
 */
static int opt_edition = 0;
static int opt_errors = 0;
static int opt_holes = 0;
static int opt_pad = 0;
static char *opt_image = NULL;
static char *opt_name = NULL;

static int warn_dev = 0;
static int warn_gid = 0;
static int warn_namelen = 0;
static int warn_skip = 0;
static int warn_size = 0;
static int warn_uid = 0;

#ifndef MIN
# define MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
#endif

/* In-core version of inode / directory entry. */
struct entry {
	/* stats */
	char *name;
	unsigned int mode, size, uid, gid;
	unsigned char md5sum[16];
	unsigned char flags;
#define HAVE_MD5	1
#define	INVALID		2

	/* FS data */
	char *path;
        struct entry *same;	    /* points to other identical file */
        unsigned int offset;        /* pointer to compressed data in archive */
	unsigned int dir_offset;    /* offset of directory entry in archive */

	/* organization */
	struct entry *child;	    /* NULL for non-directory and empty dir */
	struct entry *next;
};

/*
 * Width of various bitfields in struct cramfs_inode.
 * Used only to generate warnings.
 */
#define CRAMFS_SIZE_WIDTH 24
#define CRAMFS_UID_WIDTH 16
#define CRAMFS_GID_WIDTH 8
#define CRAMFS_OFFSET_WIDTH 26

/* Input status of 0 to print help and exit without an error. */
static void
usage(int status) {
	FILE *stream = status ? stderr : stdout;

	fprintf(stream,
		_("usage: %s [-v] [-b blksz] [-e edition] [-i file] [-n name] "
		    "dirname outfile\n"
		  " -h         print this help\n"
		  " -v         be verbose\n"
		  " -E         make all warnings errors "
		    "(non-zero exit status)\n"
		  " -b blksz   use this blocksize, must equal page size\n"
		  " -e edition set edition number (part of fsid)\n"
		  " -i file    insert a file image into the filesystem "
		    "(requires >= 2.4.0)\n"
		  " -n name    set name of cramfs filesystem\n"
		  " -p         pad by %d bytes for boot code\n"
		  " -s         sort directory entries (old option, ignored)\n"
		  " -z         make explicit holes (requires >= 2.3.39)\n"
		  " dirname    root of the filesystem to be compressed\n"
		  " outfile    output file\n"),
		progname, PAD_SIZE);

	exit(status);
}

/* malloc or die */
static void *
xmalloc (size_t size) {
	void *t = malloc(size);
	if (t == NULL) {
		perror(NULL);
		exit(8);	/* out of memory */
	}
	return t;
}

static char *
do_mmap(char *path, unsigned int size, unsigned int mode){
	int fd;
	char *start;

	if (!size)
		return NULL;

	if (S_ISLNK(mode)) {
		start = xmalloc(size);
		if (readlink(path, start, size) < 0) {
			perror(path);
			warn_skip = 1;
			start = NULL;
		}
		return start;
	}

	fd = open(path, O_RDONLY);
	if (fd < 0) {
		perror(path);
		warn_skip = 1;
		return NULL;
	}

	start = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	if (-1 == (int) (long) start) {
		perror("mmap");
		exit(8);
	}
	close(fd);

	return start;
}

static void
do_munmap(char *start, unsigned int size, unsigned int mode){
	if (S_ISLNK(mode))
		free(start);
	else
		munmap(start, size);
}

/* compute md5sums, so that we do not have to compare every pair of files */
static void
mdfile(struct entry *e) {
	MD5_CTX ctx;
	char *start;

	start = do_mmap(e->path, e->size, e->mode);
	if (start == NULL) {
		e->flags |= INVALID;
	} else {
		MD5Init(&ctx);
		MD5Update(&ctx, start, e->size);
		MD5Final(e->md5sum, &ctx);

		do_munmap(start, e->size, e->mode);

		e->flags |= HAVE_MD5;
	}
}

/* md5 digests are equal; files are almost certainly the same,
   but just to be sure, do the comparison */
static int
identical_file(struct entry *e1, struct entry *e2){
	char *start1, *start2;
	int equal;

	start1 = do_mmap(e1->path, e1->size, e1->mode);
	if (!start1)
		return 0;
	start2 = do_mmap(e2->path, e2->size, e2->mode);
	if (!start2)
		return 0;
	equal = !memcmp(start1, start2, e1->size);
	do_munmap(start1, e1->size, e1->mode);
	do_munmap(start2, e2->size, e2->mode);
	return equal;
}

/*
 * The longest file name component to allow for in the input directory tree.
 * Ext2fs (and many others) allow up to 255 bytes.  A couple of filesystems
 * allow longer (e.g. smbfs 1024), but there isn't much use in supporting
 * >255-byte names in the input directory tree given that such names get
 * truncated to 255 bytes when written to cramfs.
 */
#define MAX_INPUT_NAMELEN 255

static int find_identical_file(struct entry *orig, struct entry *new)
{
        if (orig == new)
		return 1;
        if (!orig)
		return 0;
        if (orig->size == new->size && orig->path) {
		if (!orig->flags)
			mdfile(orig);
		if (!new->flags)
			mdfile(new);

		if ((orig->flags & HAVE_MD5) && (new->flags & HAVE_MD5) &&
		    !memcmp(orig->md5sum, new->md5sum, 16) &&
		    identical_file(orig, new)) {
			new->same = orig;
			return 1;
		}
        }
        return find_identical_file(orig->child, new) ||
                   find_identical_file(orig->next, new);
}

static void eliminate_doubles(struct entry *root, struct entry *orig) {
        if (orig) {
                if (orig->size && orig->path)
			find_identical_file(root,orig);
                eliminate_doubles(root,orig->child);
                eliminate_doubles(root,orig->next);
        }
}

/*
 * We define our own sorting function instead of using alphasort which
 * uses strcoll and changes ordering based on locale information.
 */
static int cramsort (const void *a, const void *b)
{
	return strcmp ((*(const struct dirent **) a)->d_name,
		       (*(const struct dirent **) b)->d_name);
}

static unsigned int parse_directory(struct entry *root_entry, const char *name, struct entry **prev, loff_t *fslen_ub)
{
	struct dirent **dirlist;
	int totalsize = 0, dircount, dirindex;
	char *path, *endpath;
	size_t len = strlen(name);

	/* Set up the path. */
	/* TODO: Reuse the parent's buffer to save memcpy'ing and duplication. */
	path = xmalloc(len + 1 + MAX_INPUT_NAMELEN + 1);
	memcpy(path, name, len);
	endpath = path + len;
	*endpath = '/';
	endpath++;

        /* read in the directory and sort */
        dircount = scandir(name, &dirlist, 0, cramsort);

	if (dircount < 0) {
		perror(name);
		exit(8);
	}

	/* process directory */
	for (dirindex = 0; dirindex < dircount; dirindex++) {
		struct dirent *dirent;
		struct entry *entry;
		struct stat st;
		int size;
		size_t namelen;

		dirent = dirlist[dirindex];

		/* Ignore "." and ".." - we won't be adding them
		   to the archive */
		if (dirent->d_name[0] == '.') {
			if (dirent->d_name[1] == '\0')
				continue;
			if (dirent->d_name[1] == '.') {
				if (dirent->d_name[2] == '\0')
					continue;
			}
		}
		namelen = strlen(dirent->d_name);
		if (namelen > MAX_INPUT_NAMELEN) {
			fprintf(stderr,
				_("Very long (%u bytes) filename `%s' found.\n"
				  " Please increase MAX_INPUT_NAMELEN in "
				  "mkcramfs.c and recompile.  Exiting.\n"),
				namelen, dirent->d_name);
			exit(8);
		}
		memcpy(endpath, dirent->d_name, namelen + 1);

		if (lstat(path, &st) < 0) {
			perror(endpath);
			warn_skip = 1;
			continue;
		}
		entry = calloc(1, sizeof(struct entry));
		if (!entry) {
			perror(NULL);
			exit(8);
		}
		entry->name = strdup(dirent->d_name);
		if (!entry->name) {
			perror(NULL);
			exit(8);
		}
		if (namelen > 255) {
			/* Can't happen when reading from ext2fs. */

			/* TODO: we ought to avoid chopping in half
			   multi-byte UTF8 characters. */
			entry->name[namelen = 255] = '\0';
			warn_namelen = 1;
		}
		entry->mode = st.st_mode;
		entry->size = st.st_size;
		entry->uid = st.st_uid;
		if (entry->uid >= 1 << CRAMFS_UID_WIDTH)
			warn_uid = 1;
		entry->gid = st.st_gid;
		if (entry->gid >= 1 << CRAMFS_GID_WIDTH)
			/* TODO: We ought to replace with a default
                           gid instead of truncating; otherwise there
                           are security problems.  Maybe mode should
                           be &= ~070.  Same goes for uid once Linux
                           supports >16-bit uids. */
			warn_gid = 1;
		size = sizeof(struct cramfs_inode) + ((namelen + 3) & ~3);
		*fslen_ub += size;
		if (S_ISDIR(st.st_mode)) {
			entry->size = parse_directory(root_entry, path, &entry->child, fslen_ub);
		} else if (S_ISREG(st.st_mode)) {
			entry->path = strdup(path);
			if (entry->size) {
				if (entry->size >= (1 << CRAMFS_SIZE_WIDTH)) {
					warn_size = 1;
					entry->size = (1 << CRAMFS_SIZE_WIDTH) - 1;
				}
			}
		} else if (S_ISLNK(st.st_mode)) {
			entry->path = strdup(path);
		} else if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode)) {
			/* maybe we should skip sockets */
			entry->size = 0;
		} else {
			entry->size = st.st_rdev;
			if (entry->size & -(1<<CRAMFS_SIZE_WIDTH))
				warn_dev = 1;
		}

		if (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)) {
			int blocks = ((entry->size - 1) / blksize + 1);

			/* block pointers & data expansion allowance + data */
			if (entry->size)
				*fslen_ub += (4+26)*blocks + entry->size + 3;
                }

		/* Link it into the list */
		*prev = entry;
		prev = &entry->next;
		totalsize += size;
	}
	free(path);
	free(dirlist);		/* allocated by scandir() with malloc() */
	return totalsize;
}

/* Returns sizeof(struct cramfs_super), which includes the root inode. */
static unsigned int write_superblock(struct entry *root, char *base, int size)
{
	struct cramfs_super *super = (struct cramfs_super *) base;
	unsigned int offset = sizeof(struct cramfs_super) + image_length;

	if (opt_pad) {
		offset += opt_pad;
	}

	super->magic = CRAMFS_MAGIC;
	super->flags = CRAMFS_FLAG_FSID_VERSION_2 | CRAMFS_FLAG_SORTED_DIRS;
	if (opt_holes)
		super->flags |= CRAMFS_FLAG_HOLES;
	if (image_length > 0)
		super->flags |= CRAMFS_FLAG_SHIFTED_ROOT_OFFSET;
	super->size = size;
	memcpy(super->signature, CRAMFS_SIGNATURE, sizeof(super->signature));

	super->fsid.crc = crc32(0L, Z_NULL, 0);
	super->fsid.edition = opt_edition;
	super->fsid.blocks = total_blocks;
	super->fsid.files = total_nodes;

	memset(super->name, 0x00, sizeof(super->name));
	if (opt_name)
		strncpy(super->name, opt_name, sizeof(super->name));
	else
		strncpy(super->name, "Compressed", sizeof(super->name));

	super->root.mode = root->mode;
	super->root.uid = root->uid;
	super->root.gid = root->gid;
	super->root.size = root->size;
	super->root.offset = offset >> 2;

	return offset;
}

static void set_data_offset(struct entry *entry, char *base, unsigned long offset)
{
	struct cramfs_inode *inode = (struct cramfs_inode *) (base + entry->dir_offset);
	if (offset >= (1 << (2 + CRAMFS_OFFSET_WIDTH))) {
		fprintf(stderr, _("filesystem too big.  Exiting.\n"));
		exit(8);
	}
	inode->offset = (offset >> 2);
}


/*
 * We do a width-first printout of the directory