probe.c

busybox最新版的源码:学习和应用的好东东,多的不说了,大家看后再说吧

/* vi: set sw=4 ts=4: */
/*
 * probe.c - identify a block device by its contents, and return a dev
 *           struct with the details
 *
 * Copyright (C) 1999 by Andries Brouwer
 * Copyright (C) 1999, 2000, 2003 by Theodore Ts'o
 * Copyright (C) 2001 by Andreas Dilger
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the
 * GNU Lesser General Public License.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_SYS_MKDEV_H
#include <sys/mkdev.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#include "blkidP.h"
#include "../uuid/uuid.h"
#include "probe.h"

/*
 * This is a special case code to check for an MDRAID device.  We do
 * this special since it requires checking for a superblock at the end
 * of the device.
 */
static int check_mdraid(int fd, unsigned char *ret_uuid)
{
	struct mdp_superblock_s *md;
	blkid_loff_t		offset;
	char			buf[4096];

	if (fd < 0)
		return -BLKID_ERR_PARAM;

	offset = (blkid_get_dev_size(fd) & ~((blkid_loff_t)65535)) - 65536;

	if (blkid_llseek(fd, offset, 0) < 0 ||
	    read(fd, buf, 4096) != 4096)
		return -BLKID_ERR_IO;

	/* Check for magic number */
	if (memcmp("\251+N\374", buf, 4))
		return -BLKID_ERR_PARAM;

	if (!ret_uuid)
		return 0;
	*ret_uuid = 0;

	/* The MD UUID is not contiguous in the superblock, make it so */
	md = (struct mdp_superblock_s *)buf;
	if (md->set_uuid0 || md->set_uuid1 || md->set_uuid2 || md->set_uuid3) {
		memcpy(ret_uuid, &md->set_uuid0, 4);
		memcpy(ret_uuid, &md->set_uuid1, 12);
	}
	return 0;
}

static void set_uuid(blkid_dev dev, uuid_t uuid)
{
	char	str[37];

	if (!uuid_is_null(uuid)) {
		uuid_unparse(uuid, str);
		blkid_set_tag(dev, "UUID", str, sizeof(str));
	}
}

static void get_ext2_info(blkid_dev dev, unsigned char *buf)
{
	struct ext2_super_block *es = (struct ext2_super_block *) buf;
	const char *label = 0;

	DBG(DEBUG_PROBE, printf("ext2_sb.compat = %08X:%08X:%08X\n",
		   blkid_le32(es->s_feature_compat),
		   blkid_le32(es->s_feature_incompat),
		   blkid_le32(es->s_feature_ro_compat)));

	if (strlen(es->s_volume_name))
		label = es->s_volume_name;
	blkid_set_tag(dev, "LABEL", label, sizeof(es->s_volume_name));

	set_uuid(dev, es->s_uuid);
}

static int probe_ext3(int fd __BLKID_ATTR((unused)),
		      blkid_cache cache __BLKID_ATTR((unused)),
		      blkid_dev dev,
		      const struct blkid_magic *id __BLKID_ATTR((unused)),
		      unsigned char *buf)
{
	struct ext2_super_block *es;

	es = (struct ext2_super_block *)buf;

	/* Distinguish between jbd and ext2/3 fs */
	if (blkid_le32(es->s_feature_incompat) &
	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
		return -BLKID_ERR_PARAM;

	/* Distinguish between ext3 and ext2 */
	if (!(blkid_le32(es->s_feature_compat) &
	      EXT3_FEATURE_COMPAT_HAS_JOURNAL))
		return -BLKID_ERR_PARAM;

	get_ext2_info(dev, buf);

	blkid_set_tag(dev, "SEC_TYPE", "ext2", sizeof("ext2"));

	return 0;
}

static int probe_ext2(int fd __BLKID_ATTR((unused)),
		      blkid_cache cache __BLKID_ATTR((unused)),
		      blkid_dev dev,
		      const struct blkid_magic *id __BLKID_ATTR((unused)),
		      unsigned char *buf)
{
	struct ext2_super_block *es;

	es = (struct ext2_super_block *)buf;

	/* Distinguish between jbd and ext2/3 fs */
	if (blkid_le32(es->s_feature_incompat) &
	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
		return -BLKID_ERR_PARAM;

	get_ext2_info(dev, buf);

	return 0;
}

static int probe_jbd(int fd __BLKID_ATTR((unused)),
		     blkid_cache cache __BLKID_ATTR((unused)),
		     blkid_dev dev,
		     const struct blkid_magic *id __BLKID_ATTR((unused)),
		     unsigned char *buf)
{
	struct ext2_super_block *es = (struct ext2_super_block *) buf;

	if (!(blkid_le32(es->s_feature_incompat) &
	      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV))
		return -BLKID_ERR_PARAM;

	get_ext2_info(dev, buf);

	return 0;
}

static int probe_vfat(int fd __BLKID_ATTR((unused)),
		      blkid_cache cache __BLKID_ATTR((unused)),
		      blkid_dev dev,
		      const struct blkid_magic *id __BLKID_ATTR((unused)),
		      unsigned char *buf)
{
	struct vfat_super_block *vs;
	char serno[10];
	const char *label = 0;
	int label_len = 0;

	vs = (struct vfat_super_block *)buf;

	if (strncmp(vs->vs_label, "NO NAME", 7)) {
		char *end = vs->vs_label + sizeof(vs->vs_label) - 1;

		while (*end == ' ' && end >= vs->vs_label)
			--end;
		if (end >= vs->vs_label) {
			label = vs->vs_label;
			label_len = end - vs->vs_label + 1;
		}
	}

	/* We can't just print them as %04X, because they are unaligned */
	sprintf(serno, "%02X%02X-%02X%02X", vs->vs_serno[3], vs->vs_serno[2],
		vs->vs_serno[1], vs->vs_serno[0]);
	blkid_set_tag(dev, "LABEL", label, label_len);
	blkid_set_tag(dev, "UUID", serno, sizeof(serno));

	return 0;
}

static int probe_msdos(int fd __BLKID_ATTR((unused)),
		       blkid_cache cache __BLKID_ATTR((unused)),
		       blkid_dev dev,
		       const struct blkid_magic *id __BLKID_ATTR((unused)),
		       unsigned char *buf)
{
	struct msdos_super_block *ms = (struct msdos_super_block *) buf;
	char serno[10];
	const char *label = 0;
	int label_len = 0;

	if (strncmp(ms->ms_label, "NO NAME", 7)) {
		char *end = ms->ms_label + sizeof(ms->ms_label) - 1;

		while (*end == ' ' && end >= ms->ms_label)
			--end;
		if (end >= ms->ms_label) {
			label = ms->ms_label;
			label_len = end - ms->ms_label + 1;
		}
	}

	/* We can't just print them as %04X, because they are unaligned */
	sprintf(serno, "%02X%02X-%02X%02X", ms->ms_serno[3], ms->ms_serno[2],
		ms->ms_serno[1], ms->ms_serno[0]);
	blkid_set_tag(dev, "UUID", serno, 0);
	blkid_set_tag(dev, "LABEL", label, label_len);
	blkid_set_tag(dev, "SEC_TYPE", "msdos", sizeof("msdos"));

	return 0;
}

static int probe_xfs(int fd __BLKID_ATTR((unused)),
		     blkid_cache cache __BLKID_ATTR((unused)),
		     blkid_dev dev,
		     const struct blkid_magic *id __BLKID_ATTR((unused)),
		     unsigned char *buf)
{
	struct xfs_super_block *xs;
	const char *label = 0;

	xs = (struct xfs_super_block *)buf;

	if (strlen(xs->xs_fname))
		label = xs->xs_fname;
	blkid_set_tag(dev, "LABEL", label, sizeof(xs->xs_fname));
	set_uuid(dev, xs->xs_uuid);
	return 0;
}

static int probe_reiserfs(int fd __BLKID_ATTR((unused)),
			  blkid_cache cache __BLKID_ATTR((unused)),
			  blkid_dev dev,
			  const struct blkid_magic *id, unsigned char *buf)
{
	struct reiserfs_super_block *rs = (struct reiserfs_super_block *) buf;
	unsigned int blocksize;
	const char *label = 0;

	blocksize = blkid_le16(rs->rs_blocksize);

	/* If the superblock is inside the journal, we have the wrong one */
	if (id->bim_kboff/(blocksize>>10) > blkid_le32(rs->rs_journal_block))
		return -BLKID_ERR_BIG;

	/* LABEL/UUID are only valid for later versions of Reiserfs v3.6. */
	if (!strcmp(id->bim_magic, "ReIsEr2Fs") ||
	    !strcmp(id->bim_magic, "ReIsEr3Fs")) {
		if (strlen(rs->rs_label))
			label = rs->rs_label;
		set_uuid(dev, rs->rs_uuid);
	}
	blkid_set_tag(dev, "LABEL", label, sizeof(rs->rs_label));

	return 0;
}

static int probe_jfs(int fd __BLKID_ATTR((unused)),
		     blkid_cache cache __BLKID_ATTR((unused)),
		     blkid_dev dev,
		     const struct blkid_magic *id __BLKID_ATTR((unused)),
		     unsigned char *buf)
{
	struct jfs_super_block *js;
	const char *label = 0;

	js = (struct jfs_super_block *)buf;

	if (strlen((char *) js->js_label))
		label = (char *) js->js_label;
	blkid_set_tag(dev, "LABEL", label, sizeof(js->js_label));
	set_uuid(dev, js->js_uuid);
	return 0;
}

static int probe_romfs(int fd __BLKID_ATTR((unused)),
		       blkid_cache cache __BLKID_ATTR((unused)),
		       blkid_dev dev,
		       const struct blkid_magic *id __BLKID_ATTR((unused)),
		       unsigned char *buf)
{
	struct romfs_super_block *ros;
	const char *label = 0;

	ros = (struct romfs_super_block *)buf;

	if (strlen((char *) ros->ros_volume))
		label = (char *) ros->ros_volume;
	blkid_set_tag(dev, "LABEL", label, 0);
	return 0;
}

static int probe_cramfs(int fd __BLKID_ATTR((unused)),
		       blkid_cache cache __BLKID_ATTR((unused)),
		       blkid_dev dev,
		       const struct blkid_magic *id __BLKID_ATTR((unused)),
		       unsigned char *buf)
{
	struct cramfs_super_block *csb;
	const char *label = 0;

	csb = (struct cramfs_super_block *)buf;

	if (strlen((char *) csb->name))
		label = (char *) csb->name;
	blkid_set_tag(dev, "LABEL", label, 0);
	return 0;
}

static int probe_swap0(int fd __BLKID_ATTR((unused)),
		       blkid_cache cache __BLKID_ATTR((unused)),
		       blkid_dev dev,
		       const struct blkid_magic *id __BLKID_ATTR((unused)),
		       unsigned char *buf __BLKID_ATTR((unused)))
{
	blkid_set_tag(dev, "UUID", 0, 0);
	blkid_set_tag(dev, "LABEL", 0, 0);
	return 0;
}

static int probe_swap1(int fd,
		       blkid_cache cache __BLKID_ATTR((unused)),
		       blkid_dev dev,
		       const struct blkid_magic *id __BLKID_ATTR((unused)),
		       unsigned char *buf __BLKID_ATTR((unused)))
{
	struct swap_id_block *sws;

	probe_swap0(fd, cache, dev, id, buf);
	/*
	 * Version 1 swap headers are always located at offset of 1024
	 * bytes, although the swap signature itself is located at the
	 * end of the page (which may vary depending on hardware
	 * pagesize).
	 */
	if (lseek(fd, 1024, SEEK_SET) < 0) return 1;
	sws = xmalloc(1024);
	if (read(fd, sws, 1024) != 1024) {
		free(sws);
		return 1;
	}

	/* arbitrary sanity check.. is there any garbage down there? */
	if (sws->sws_pad[32] == 0 && sws->sws_pad[33] == 0)  {
		if (sws->sws_volume[0])
			blkid_set_tag(dev, "LABEL", (const char*)sws->sws_volume,