lvm2/tools/pvck.c

/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2007 Red Hat, Inc. All rights reserved.
 *
 * This file is part of LVM2.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "base/memory/zalloc.h"
#include "tools.h"
#include "lib/format_text/format-text.h"
#include "lib/format_text/layout.h"
#include "lib/mm/xlate.h"
#include "lib/misc/crc.h"

static char *_chars_to_str(void *in, void *out, int num, int max, const char *field)
{
	char *i = in;
	char *o = out;
	int n;

	memset(out, 0, max);

	if (num > max-1) {
		log_print("CHECK: abbreviating output for %s", field);
		num = max - 1;
	}

	for (n = 0; n < num; n++) {
		if (isprint((int)*i))
			*o = *i;
		else
			*o = '?';
		i++;
		o++;
	}

	return out;
}

/* 
 * This is used to print mda_header.magic as a series of hex values
 * since it only contains some printable chars.
 */
static char *_chars_to_hexstr(void *in, void *out, int num, int max, const char *field)
{
	char *tmp;
	char *i = in;
	int n;
	int off = 0;
	int ret;

	if (!(tmp = zalloc(max))) {
		log_print("CHECK: no mem for printing %s", field);
		return out;
	}

	memset(out, 0, max);
	memset(tmp, 0, max);

	if (num > max-1) {
		log_print("CHECK: abbreviating output for %s", field);
		num = max - 1;
	}

	for (n = 0; n < num; n++) {
		ret = sprintf(tmp+off, "%x", *i & 0xFF);
		off += ret;
		i++;
	}

	memcpy(out, tmp, 256);

	free(tmp);

	return out;
}

static int _check_label_header(struct label_header *lh, uint64_t labelsector,
			       int *found_label)
{
	uint32_t crc;
	int good_id = 1, good_type = 1;
	int bad = 0;

	if (memcmp(lh->id, LABEL_ID, sizeof(lh->id))) {
		log_print("CHECK: label_header.id expected %s", LABEL_ID);
		good_id = 0;
		bad++;
	}

	if (xlate64(lh->sector_xl) != labelsector) {
		log_print("CHECK: label_header.sector expected %d", (int)labelsector);
		bad++;
	}

	crc = calc_crc(INITIAL_CRC, (uint8_t *)&lh->offset_xl,
		       LABEL_SIZE - ((uint8_t *) &lh->offset_xl - (uint8_t *) lh));
		
	if (crc != xlate32(lh->crc_xl)) {
		log_print("CHECK: label_header.crc expected 0x%x", crc);
		bad++;
	}

	if (xlate32(lh->offset_xl) != 32) {
		log_print("CHECK: label_header.offset expected 32");
		bad++;
	}

	if (memcmp(lh->type, LVM2_LABEL, sizeof(lh->type))) {
		log_print("CHECK: label_header.type expected %s", LVM2_LABEL);
		good_type = 0;
		bad++;
	}

	/* Report a label is found if at least id and type are correct. */
	if (found_label && good_id && good_type)
		*found_label = 1;

	if (bad)
		return 0;
	return 1;
}

static int _check_pv_header(struct pv_header *ph)
{
	struct id id;
	int bad = 0;

	if (!id_read_format_try(&id, (char *)&ph->pv_uuid)) {
		log_print("CHECK: pv_header.pv_uuid invalid format");
		bad++;
	}

	if (bad)
		return 0;
	return 1;
}

/*
 * mda_offset/mda_size are from the pv_header/disk_locn and could
 * be incorrect.
 */
static int _check_mda_header(struct mda_header *mh, int mda_num, uint64_t mda_offset, uint64_t mda_size, int *found_header)
{
	char str[256];
	uint32_t crc;
	int good_magic = 1;
	int bad = 0;

	crc = calc_crc(INITIAL_CRC, (uint8_t *)mh->magic,
		       MDA_HEADER_SIZE - sizeof(mh->checksum_xl));

	if (crc != xlate32(mh->checksum_xl)) {
		log_print("CHECK: mda_header_%d.checksum expected 0x%x", mda_num, crc);
		bad++;
	}

	if (memcmp(mh->magic, FMTT_MAGIC, sizeof(mh->magic))) {
		log_print("CHECK: mda_header_%d.magic expected 0x%s", mda_num, _chars_to_hexstr((void *)&FMTT_MAGIC, str, 16, 256, "mda_header.magic"));
		good_magic = 0;
		bad++;
	}

	if (xlate32(mh->version) != FMTT_VERSION) {
		log_print("CHECK: mda_header_%d.version expected %u", mda_num, FMTT_VERSION);
		bad++;
	}

	if (xlate64(mh->start) != mda_offset) {
		log_print("CHECK: mda_header_%d.start does not match pv_header.disk_locn.offset %llu", mda_num, (unsigned long long)mda_offset);
		bad++;
	}

	if (xlate64(mh->size) != mda_size) {
		log_print("CHECK: mda_header_%d.size does not match pv_header.disk_locn.size %llu", mda_num, (unsigned long long)mda_size);
		bad++;
	}

	/* Report a header is found if at least magic is correct. */
	if (found_header && good_magic)
		*found_header = 1;

	if (bad)
		return 0;
	return 1;
}

/*
 *
 * mda_offset, mda_size are from pv_header.disk_locn
 * (the location of the metadata area.)
 *
 * meta_offset, meta_size, meta_checksum are from mda_header.raw_locn
 * (the location of the metadata text in the metadata area.)
 */

static int _dump_raw_locn(struct device *dev, int print_fields,
			  struct raw_locn *rlocn, int rlocn_index, uint64_t rlocn_offset,
			  int mda_num, uint64_t mda_offset, uint64_t mda_size,
			  uint64_t *meta_offset_ret,
			  uint64_t *meta_size_ret,
			  uint32_t *meta_checksum_ret)
{
	uint64_t meta_offset, meta_size;
	uint32_t meta_checksum;
	uint32_t meta_flags;
	int bad = 0;
	int mn = mda_num; /* 1 or 2 */
	int ri = rlocn_index; /* 0 or 1 */
	int wrapped = 0;

	meta_offset = xlate64(rlocn->offset);
	meta_size = xlate64(rlocn->size);
	meta_checksum = xlate32(rlocn->checksum);
	meta_flags = xlate32(rlocn->flags);

	if (meta_offset + meta_size > mda_size)
		wrapped = 1;

	if (print_fields) {
		log_print("mda_header_%d.raw_locn[%d] at %llu # %s%s", mn, ri, (unsigned long long)rlocn_offset, (ri == 0) ? "commit" : "precommit", wrapped ? " wrapped" : "");
		log_print("mda_header_%d.raw_locn[%d].offset %llu", mn, ri, (unsigned long long)meta_offset);
		log_print("mda_header_%d.raw_locn[%d].size %llu", mn, ri, (unsigned long long)meta_size);
		log_print("mda_header_%d.raw_locn[%d].checksum 0x%x", mn, ri, meta_checksum);

		if (meta_flags & RAW_LOCN_IGNORED)
			log_print("mda_header_%d.raw_locn[%d].flags 0x%x # RAW_LOCN_IGNORED", mn, ri, meta_flags);
		else
			log_print("mda_header_%d.raw_locn[%d].flags 0x%x", mn, ri, meta_flags);
	}

	/* The precommit pointer will usually be empty. */
	if ((rlocn_index == 1) && meta_offset)
		log_print("CHECK: mda_header_%d.raw_locn[%d] for precommit not empty", mn, ri);

	/* This metadata area is not being used to hold text metadata. */
	/* Old, out of date text metadata may exist if the area was once used. */
	if (meta_flags & RAW_LOCN_IGNORED)
		return 1;

	/*
	 * A valid meta_size can be no larger than the metadata area size minus
	 * the 512 bytes used by the mda_header sector.
	 */
	if (meta_size > (mda_size - 512)) {
		log_print("CHECK: mda_header_%d.raw_locn[%d].size larger than metadata area size", mn, ri);
		/* If meta_size is bad, try to continue using a reasonable value */
		meta_size = (mda_size - 512);
	}

	if (meta_offset_ret)
		*meta_offset_ret = meta_offset;
	if (meta_size_ret)
		*meta_size_ret = meta_size;
	if (meta_checksum_ret)
		*meta_checksum_ret = meta_checksum;

	/* No text metadata exists in this metadata area. */
	if (!meta_offset)
		return 1;

	if (bad)
		return 0;
	return 1;
}

static int _dump_meta_area(struct device *dev, const char *tofile,
			   uint64_t mda_offset, uint64_t mda_size)
{
	FILE *fp;
	char *meta_buf;

	if (!tofile)
		return_0;

	if (!(meta_buf = malloc(mda_size)))
		return_0;
	memset(meta_buf, 0, mda_size);

	if (!dev_read_bytes(dev, mda_offset, mda_size, meta_buf)) {
		log_print("CHECK: failed to read metadata area at offset %llu size %llu",
			  (unsigned long long)mda_offset, (unsigned long long)mda_size);
		return 0;
	}

	if (!(fp = fopen(tofile, "wx"))) {
		log_error("Failed to create file %s", tofile);
		return 0;
	}

	fwrite(meta_buf, mda_size - 512, 1, fp);

	if (fflush(fp))
		stack;
	if (fclose(fp))
		stack;
	return 1;
}

/*
 * Search for any instance of id_str[] in the metadata area,
 * where the id_str indicates the start of a metadata copy
 * (which could be complete or a fragment.)
 * id_str is an open brace followed by id = <uuid>.
 *
 * {\n
 *    id = "lL7Mnk-oCGn-Bde2-9B6S-44Z7-VrHa-wvfC3v"
 *
 * 1\23456789012345678901234567890123456789012345678
 *          10        20        30        40
 */
#define ID_STR_SIZE 48

#define SEARCH_VGNAME_LEN 512

static int _dump_meta_all(struct device *dev, const char *tofile,
			  uint64_t mda_offset, uint64_t mda_size,
			  uint64_t meta_offset, uint64_t meta_size,
			  char *meta_buf)
{
	FILE *fp = NULL;
	struct dm_config_tree *cft;
	char vgname[SEARCH_VGNAME_LEN];
	char id_str[ID_STR_SIZE];
	char *text_buf, *new_buf;
	char *p, *brace, *start, *buf_begin, *buf_end;
	uint64_t search_offset, start_offset;
	uint32_t brace_dist, new_len, len_a, len_b;
	uint32_t left_count, right_count;
	uint32_t seqno;
	int search_wrapped = 0;
	int p_wrapped;
	int save_bad;
	int i;

	/*
	 * metadata begins:
	 *
	 * <vgname> {
	 * id = "<uuid>"
	 *
	 * Search the metadata buffer for each instance
	 * of the string:
	 *
	 * {
	 * id = "<uuid>"
	 *
	 * Then reverse by the length of the <vgname> +1
	 * to get to the start of the metadata.  The
	 * vgname must come from the original/current copy
	 * of metadata found through the mda_header pointer.
	 *
	 * From the start of the metadata, find the end of
	 * the metadata by searching foward until \0 is found.
	 * Metadata ends with the three bytes:
	 * \n\n\0 (0x0a0a00)
	 */

	memset(vgname, 0, sizeof(vgname));
	memset(id_str, 0, sizeof(id_str));

	for (i = 0; i < SEARCH_VGNAME_LEN; i++) {
		if (meta_buf[i] == ' ')
			break;
		vgname[i] = meta_buf[i];
	}

	if (!(p = strchr(meta_buf, '{')))
		return_0;

	for (i = 0; i < ID_STR_SIZE; i++) {
		id_str[i] = *p;
		p++;
	}

	if (!(text_buf = malloc(mda_size)))
		return_0;
	memset(text_buf, 0, mda_size);

	if (!dev_read_bytes(dev, mda_offset, mda_size, text_buf)) {
		log_print("CHECK: failed to read metadata area at offset %llu size %llu",
			  (unsigned long long)mda_offset, (unsigned long long)mda_size);
		free(text_buf);
		return 0;
	}

	search_offset = meta_offset + meta_size;

 search_next:
	if (search_wrapped && (search_offset >= meta_offset + meta_size))
		goto done;

	if (search_offset > mda_size) {
		if (search_wrapped)
			goto done;
		search_offset = 512;
		search_wrapped = 1;
	}

	/*
	 * Search between buf_begin and buf_end for next open brace.
	 */
	buf_begin = text_buf + search_offset;
	buf_end = text_buf + mda_size;
	brace = NULL;

	for (p = buf_begin; p < buf_end; p++) {
		if (*p != '{')
			continue;
		brace = p;
		break;
	}

	if (!brace && search_wrapped)
		goto done;
	if (!brace) {
		search_offset = 512;
		search_wrapped = 1;
		goto search_next;
	}

	/*
	 * brace_dist is the distance from the last place we
	 * began searching to the brace we are testing for
	 * metadata.  If this brace is not the start of valid 
	 * metadata, then advance brace_dist and search for
	 * the next brace to check.
	 */
	brace_dist = (uint32_t)(brace - buf_begin);

	/*
	 * Found an open brace, check if it's the start of new metadata
	 * by checking if brace is followed by id = "<uuid>".
	 */

	if (memcmp(brace, id_str, ID_STR_SIZE)) {
		/* It's not, look for next open brace. */
		search_offset += (brace_dist + 1);
		goto search_next;
	}

	/*
	 * This looks like a new instance of metadata, check if it's complete.
	 * The start of the metadata is the vgname preceding the open brace,
	 * so step backward through the text_buf to find the start of vgname.
	 * There is no delimiter preceding the vgname, there can be any
	 * text or data in the byte immediately before vgname (this means
	 * we cannot handle extracting metadata prior to a vgrename.)
	 *
	 * <vgname> {
	 * id = "..."
	 */
	start = brace - (strlen(vgname) + 1);

	/* Offset from the begininng of device to the start of this metadata. */
	start_offset = (uint64_t)(start - text_buf) + mda_offset;

	/*
	 * The end of the metadata is found by searching forward in text_buf
	 * until \0, at which point open and close braces should match.
	 * This forward search may wrap around to the start of text_buf.
	 *
	 * Metadata ends with the three bytes \n\n\0: 0a 0a 00
	 */
	p = start;
	p_wrapped = 0;
	len_a = 0;
	len_b = 0;
	new_len = 0;
	new_buf = NULL;
	left_count = 0;
	right_count = 0;
	save_bad = 0;
	seqno = 0;

	while (1) {
		p++;

		if (p == (buf_end)) {
			p = text_buf + 512;
			p_wrapped = 1;
		}

		if (*p == '{')
			left_count++;
		else if (*p == '}')
			right_count++;
		else if (*p == '\0')
			break;
	}

	/* \0 should be preceded by \n\n (0x0a0a) */
	if ((*(p - 2) != 0x0a) || (*(p - 1) != 0x0a))
		log_print("Unexpected metadata end bytes.");

	if (p_wrapped) {
		len_a = (uint32_t)(buf_end - start);
		len_b = (uint32_t)(p - (text_buf + 512));
		new_len = len_a + len_b;
		search_wrapped = 1;
	} else {
		new_len = (uint32_t)(p - start);
	}

	/*
	 * A couple simple tests indicate if this could be valid metadata
	 * before attempting to parse it. (min length is probably greater
	 * than 256, so this could be increased.)
	 *
	 * If this is complete but corrupt, we should save it.
	 * TODO: If this is a fragment we should skip it.
	 */
	if ((left_count != right_count) || (new_len < 256)) {
		/*
		 * To skip this:
		 * search_offset += (brace_dist + 1);
		 * goto search_next;
		 */
		log_print("Found incorrect metadata at %llu length %u with braces %u %u",
			  (unsigned long long)start_offset, new_len, left_count, right_count);
		save_bad = 1;
	}

	/*
	 * Copy the potential metadata into a new buffer to parse.
	 */
	if (!(new_buf = malloc(new_len + 1))) {
		search_offset += (brace_dist + 1);
		log_print("No memory for metadata at %llu length %u with %u sections",
			  (unsigned long long)start_offset, new_len, right_count);
		goto search_next;
	}
	memset(new_buf, 0, new_len + 1);

	if (p_wrapped) {
		memcpy(new_buf, start, len_a);
		memcpy(new_buf + len_a, text_buf + 512, len_b);
	} else {
		memcpy(new_buf, start, new_len);
	}

	if (save_bad)
		goto save;

	/*
	 * Check the metadata is parsable.
	 * If this is complete but corrupt, we should save it.
	 * TODO: If this is a fragment we should skip it.
	 */
	if ((cft = config_open(CONFIG_FILE_SPECIAL, NULL, 0))) {
		if (!dm_config_parse(cft, new_buf, new_buf + new_len)) {
			/*
			 * To skip this:
			 * search_offset += (brace_dist + 1);
			 * goto search_next;
			 */
			log_print("Found unparsable metadata at %llu length %u with %u sections",
				  (unsigned long long)start_offset, new_len, right_count);
			config_destroy(cft);
			goto save;
		}

		if (cft->root && cft->root->child)
			dm_config_get_uint32(cft->root->child, "seqno", &seqno);
		config_destroy(cft);
	}

	log_print("Found metadata at %llu length %u seqno %u with %u sections",
		  (unsigned long long)start_offset, new_len, seqno, right_count);

 save:
	if (!fp && tofile) {
		if (!(fp = fopen(tofile, "a"))) {
			log_error("Failed to open file %s", tofile);
			goto out;
		}
	}

	if (fp) {
		fprintf(fp, "%s", new_buf);
		fprintf(fp, "\n--\n");
	}

 out:
	free(new_buf);

	/*
	 * Look for another id_str instance after the metadata
	 * that was just finished.
	 */

	if (p_wrapped)
		search_offset = len_b;
	else
		search_offset += new_len;
	goto search_next;

 done:
	if (fp) {
		if (fflush(fp))
			stack;
		if (fclose(fp))
			stack;
	}

	free(text_buf);
	return 1;
}

static int _dump_meta_text(struct device *dev,
			   int print_fields, int print_metadata, const char *tofile,
			   int mda_num, int rlocn_index,
			   uint64_t mda_offset, uint64_t mda_size,
			   uint64_t meta_offset, uint64_t meta_size,
			   uint32_t meta_checksum,
			   char **meta_buf_out)
{
	char *meta_buf;
	struct dm_config_tree *cft;
	const char *vgname = NULL;
	uint32_t crc;
	uint32_t seqno = 0;
	int mn = mda_num; /* 1 or 2 */
	int ri = rlocn_index; /* 0 or 1 */
	int bad = 0;

	if (!(meta_buf = malloc(meta_size))) {
		log_print("CHECK: mda_header_%d.raw_locn[%d] no mem for metadata text size %llu", mn, ri,
			  (unsigned long long)meta_size);
		return 0;
	}
	memset(meta_buf, 0, meta_size);

	/*
	 * Read the metadata text specified by the raw_locn so we can
	 * check the raw_locn values.
	 *
	 * meta_offset is the offset from the start of the mda_header,
	 * so the text location from the start of the disk is
	 * mda_offset + meta_offset.
	 */
	if (meta_offset + meta_size > mda_size) {
	 	/* text metadata wraps to start of text metadata area */
		uint32_t wrap = (uint32_t) ((meta_offset + meta_size) - mda_size);
		off_t offset_a = mda_offset + meta_offset;
		uint32_t size_a = meta_size - wrap;
		off_t offset_b = mda_offset + 512; /* continues after mda_header sector */
		uint32_t size_b = wrap;

		if (!dev_read_bytes(dev, offset_a, size_a, meta_buf)) {
			log_print("CHECK: failed to read metadata text at mda_header_%d.raw_locn[%d].offset %llu size %llu part_a %llu %llu", mn, ri,
				  (unsigned long long)meta_offset, (unsigned long long)meta_size,
				  (unsigned long long)offset_a, (unsigned long long)size_a);
			return 0;
		}

		if (!dev_read_bytes(dev, offset_b, size_b, meta_buf + size_a)) {
			log_print("CHECK: failed to read metadata text at mda_header_%d.raw_locn[%d].offset %llu size %llu part_b %llu %llu", mn, ri,
				  (unsigned long long)meta_offset, (unsigned long long)meta_size,
				  (unsigned long long)offset_b, (unsigned long long)size_b);
			return 0;
		}
	} else {
		if (!dev_read_bytes(dev, mda_offset + meta_offset, meta_size, meta_buf)) {
			log_print("CHECK: failed to read metadata text at mda_header_%d.raw_locn[%d].offset %llu size %llu", mn, ri,
				  (unsigned long long)meta_offset, (unsigned long long)meta_size);
			return 0;
		}
	}

	crc = calc_crc(INITIAL_CRC, (uint8_t *)meta_buf, meta_size);
	if (crc != meta_checksum) {
		log_print("CHECK: metadata text at %llu crc does not match mda_header_%d.raw_locn[%d].checksum",
			  (unsigned long long)(mda_offset + meta_offset), mn, ri);
		bad++;
	}

	if (!(cft = config_open(CONFIG_FILE_SPECIAL, NULL, 0))) {
		log_print("CHECK: failed to set up metadata parsing");
		bad++;
	} else {
		if (!dm_config_parse(cft, meta_buf, meta_buf + meta_size)) {
			log_print("CHECK: failed to parse metadata text at %llu size %llu",
				  (unsigned long long)(mda_offset + meta_offset),
				   (unsigned long long)meta_size);
			bad++;
		} else {
			if (cft->root && cft->root->key)
				vgname = strdup(cft->root->key);
			if (cft->root && cft->root->child)
				dm_config_get_uint32(cft->root->child, "seqno", &seqno);
		}
		config_destroy(cft);
	}

	if (print_fields || print_metadata)
		log_print("metadata text at %llu crc 0x%x # vgname %s seqno %u",
			  (unsigned long long)(mda_offset + meta_offset), crc,
			  vgname ? vgname : "?", seqno);

	if (!print_metadata)
		goto out;

	if (!tofile) {
		log_print("---");
		printf("%s\n", meta_buf);
		log_print("---");
	} else {
		FILE *fp;
		if (!(fp = fopen(tofile, "wx"))) {
			log_error("Failed to create file %s", tofile);
			goto out;
		}

		fprintf(fp, "%s", meta_buf);

		if (fflush(fp))
			stack;
		if (fclose(fp))
			stack;
	}

 out:
	*meta_buf_out = meta_buf;

	if (bad)
		return 0;
	return 1;
}

static int _dump_label_and_pv_header(struct cmd_context *cmd, int print_fields,
				     struct device *dev,
				     int *found_label,
				     uint64_t *mda1_offset, uint64_t *mda1_size,
				     uint64_t *mda2_offset, uint64_t *mda2_size)
{
	char str[256];
	struct label_header *lh;
	struct pv_header *pvh;
	struct pv_header_extension *pvhe;
	struct disk_locn *dlocn;
	uint64_t lh_offset;
	uint64_t pvh_offset;
	uint64_t pvhe_offset;
	uint64_t dlocn_offset;
	char *buf;
	uint64_t labelsector;
	uint64_t tmp;
	int mda_count = 0;
	int bad = 0;
	int di;

	/*
	 * By default LVM skips the first sector (sector 0), and writes
	 * the label_header in the second sector (sector 1).
	 * (sector size 512 bytes)
	 */
	if (arg_is_set(cmd, labelsector_ARG))
		labelsector = arg_uint64_value(cmd, labelsector_ARG, UINT64_C(0));
	else
		labelsector = 1;

	lh_offset = labelsector * 512; /* from start of disk */

	if (!(buf = zalloc(512)))
		return_0;

	if (!dev_read_bytes(dev, lh_offset, 512, buf)) {
		log_print("CHECK: failed to read label_header at %llu",
			  (unsigned long long)lh_offset);
		return 0;
	}

	lh = (struct label_header *)buf;

	if (print_fields) {
		log_print("label_header at %llu", (unsigned long long)lh_offset);
		log_print("label_header.id %s", _chars_to_str(lh->id, str, 8, 256, "label_header.id"));
		log_print("label_header.sector %llu", (unsigned long long)xlate64(lh->sector_xl));
		log_print("label_header.crc 0x%x", xlate32(lh->crc_xl));
		log_print("label_header.offset %u", xlate32(lh->offset_xl));
		log_print("label_header.type %s", _chars_to_str(lh->type, str, 8, 256, "label_header.type"));
	}

	if (!_check_label_header(lh, labelsector, found_label))
		bad++;

	/*
	 * The label_header is 32 bytes in size (size of struct label_header).
	 * The pv_header should begin immediately after the label_header.
	 * The label_header.offset gives the offset of pv_header from the
	 * start of the label_header, which should always be 32.
	 *
	 * If label_header.offset is corrupted, then we should print a
	 * warning about the bad value, and read the pv_header from the
	 * correct location instead of the bogus location.
	 */

	pvh = (struct pv_header *)(buf + 32);
	pvh_offset = lh_offset + 32; /* from start of disk */

	/* sanity check */
	if ((void *)pvh != (void *)(buf + pvh_offset - lh_offset))
		log_print("CHECK: problem with pv_header offset calculation");

	if (print_fields) {
		log_print("pv_header at %llu", (unsigned long long)pvh_offset);
		log_print("pv_header.pv_uuid %s", _chars_to_str(pvh->pv_uuid, str, ID_LEN, 256, "pv_header.pv_uuid"));
		log_print("pv_header.device_size %llu", (unsigned long long)xlate64(pvh->device_size_xl));
	}

	if (!_check_pv_header(pvh))
		bad++;

	/*
	 * The pv_header is 40 bytes, excluding disk_locn's.
	 * disk_locn structs immediately follow the pv_header.
	 * Each disk_locn is 16 bytes.
	 */
	di = 0;
	dlocn = pvh->disk_areas_xl;
	dlocn_offset = pvh_offset + 40; /* from start of disk */

	/* sanity check */
	if ((void *)dlocn != (void *)(buf + dlocn_offset - lh_offset))
		log_print("CHECK: problem with pv_header.disk_locn[%d] offset calculation", di);

	while ((tmp = xlate64(dlocn->offset))) {
		if (print_fields) {
			log_print("pv_header.disk_locn[%d] at %llu # location of data area", di,
				  (unsigned long long)dlocn_offset);
			log_print("pv_header.disk_locn[%d].offset %llu", di,
				  (unsigned long long)xlate64(dlocn->offset));
			log_print("pv_header.disk_locn[%d].size %llu", di,
				  (unsigned long long)xlate64(dlocn->size));
		}
		di++;
		dlocn++;
		dlocn_offset += 16;
	}

	/* all-zero dlocn struct is area list end */
	if (print_fields) {
		log_print("pv_header.disk_locn[%d] at %llu # location list end", di,
			  (unsigned long long) dlocn_offset);
		log_print("pv_header.disk_locn[%d].offset %llu", di,
			  (unsigned long long)xlate64(dlocn->offset));
		log_print("pv_header.disk_locn[%d].size %llu", di,
			  (unsigned long long)xlate64(dlocn->size));
	}

	/* advance past the all-zero dlocn struct */
	di++;
	dlocn++;
	dlocn_offset += 16;

	/* sanity check */
	if ((void *)dlocn != (void *)(buf + dlocn_offset - lh_offset))
		log_print("CHECK: problem with pv_header.disk_locn[%d] offset calculation", di);

	while ((tmp = xlate64(dlocn->offset))) {
		if (print_fields) {
			log_print("pv_header.disk_locn[%d] at %llu # location of metadata area", di,
				  (unsigned long long)dlocn_offset);
			log_print("pv_header.disk_locn[%d].offset %llu", di,
				  (unsigned long long)xlate64(dlocn->offset));
			log_print("pv_header.disk_locn[%d].size %llu", di,
				  (unsigned long long)xlate64(dlocn->size));
		}

		if (!mda_count) {
			*mda1_offset = xlate64(dlocn->offset);
			*mda1_size = xlate64(dlocn->size);

			if (*mda1_offset != 4096) {
				log_print("CHECK: pv_header.disk_locn[%d].offset expected 4096 # for first mda", di);
				bad++;
			}
		} else {
			*mda2_offset = xlate64(dlocn->offset);
			*mda2_size = xlate64(dlocn->size);

			/*
			 * No fixed location for second mda, so we have to look for
			 * mda_header at this offset to see if it's correct.
			 */
		}

		di++;
		dlocn++;
		dlocn_offset += 16;
		mda_count++;
	}

	/* all-zero dlocn struct is area list end */
	if (print_fields) {
		log_print("pv_header.disk_locn[%d] at %llu # location list end", di,
			  (unsigned long long) dlocn_offset);
		log_print("pv_header.disk_locn[%d].offset %llu", di,
			  (unsigned long long)xlate64(dlocn->offset));
		log_print("pv_header.disk_locn[%d].size %llu", di,
			  (unsigned long long)xlate64(dlocn->size));
	}

	/* advance past the all-zero dlocn struct */
	di++;
	dlocn++;
	dlocn_offset += 16;

	/*
	 * pv_header_extension follows the last disk_locn
	 * terminating struct, so it's not always at the
	 * same location.
	 */

	pvhe = (struct pv_header_extension *)dlocn;
	pvhe_offset = dlocn_offset; /* from start of disk */

	/* sanity check */
	if ((void *)pvhe != (void *)(buf + pvhe_offset - lh_offset))
		log_print("CHECK: problem with pv_header_extension offset calculation");

	if (print_fields) {
		log_print("pv_header_extension at %llu", (unsigned long long)pvhe_offset);
		log_print("pv_header_extension.version %u", xlate32(pvhe->version));
		log_print("pv_header_extension.flags %u", xlate32(pvhe->flags));
	}

	/*
	 * The pv_header_extension is 8 bytes, excluding disk_locn's.
	 * disk_locn structs immediately follow the pv_header_extension.
	 * Each disk_locn is 16 bytes.
	 */
	di = 0;
	dlocn = pvhe->bootloader_areas_xl;
	dlocn_offset = pvhe_offset + 8;

	while ((tmp = xlate64(dlocn->offset))) {
		if (print_fields) {
			log_print("pv_header_extension.disk_locn[%d] at %llu # bootloader area", di,
				  (unsigned long long)dlocn_offset);
			log_print("pv_header_extension.disk_locn[%d].offset %llu", di,
				  (unsigned long long)xlate64(dlocn->offset));
			log_print("pv_header_extension.disk_locn[%d].size %llu", di,
				  (unsigned long long)xlate64(dlocn->size));
		}

		di++;
		dlocn++;
		dlocn_offset += 16;
	}

	/* all-zero dlocn struct is area list end */
	if (print_fields) {
		log_print("pv_header_extension.disk_locn[%d] at %llu # location list end", di,
			  (unsigned long long) dlocn_offset);
		log_print("pv_header_extension.disk_locn[%d].offset %llu", di,
			  (unsigned long long)xlate64(dlocn->offset));
		log_print("pv_header_extension.disk_locn[%d].size %llu", di,
			  (unsigned long long)xlate64(dlocn->size));
	}

	if (bad)
		return 0;
	return 1;
}

/*
 * mda_offset and mda_size are the location/size of the metadata area,
 * which starts with the mda_header and continues through the circular
 * buffer of text.
 *
 * mda_offset and mda_size values come from the pv_header/disk_locn,
 * which could be incorrect.
 *
 * We know that the first mda_offset will always be 4096, so we use
 * that value regardless of what the first mda_offset value in the
 * pv_header is.
 */

static int _dump_mda_header(struct cmd_context *cmd,
			    int print_fields, int print_metadata, int print_area,
			    const char *tofile,
			    struct device *dev,
			    uint64_t mda_offset, uint64_t mda_size,
			    uint32_t *checksum0_ret,
			    int *found_header)
{
	char str[256];
	char *buf;
	char *meta_buf = NULL;
	struct mda_header *mh;
	struct raw_locn *rlocn0, *rlocn1;
	uint64_t rlocn0_offset, rlocn1_offset;
	uint64_t meta_offset = 0;
	uint64_t meta_size = 0;
	uint32_t meta_checksum = 0;
	int mda_num = (mda_offset == 4096) ? 1 : 2;
	int bad = 0;

	*checksum0_ret = 0; /* checksum from raw_locn[0] */

	if (!(buf = zalloc(512)))
		return_0;

	/*
	 * The first mda_header is 4096 bytes from the start
	 * of the device.  Each mda_header is 512 bytes.
	 *
	 * The start/size values in the mda_header should
	 * match the mda_offset/mda_size values that came
	 * from the pv_header/disk_locn.
	 *
	 * (Why was mda_header magic made only partially printable?)
	 */

	if (!dev_read_bytes(dev, mda_offset, 512, buf)) {
		log_print("CHECK: failed to read mda_header at %llu", (unsigned long long)mda_offset);
		return 0;
	}

	mh = (struct mda_header *)buf;

	if (print_fields) {
		log_print("mda_header_%d at %llu # metadata area", mda_num, (unsigned long long)mda_offset);
		log_print("mda_header_%d.checksum 0x%x", mda_num, xlate32(mh->checksum_xl));
		log_print("mda_header_%d.magic 0x%s", mda_num, _chars_to_hexstr(mh->magic, str, 16, 256, "mda_header.magic"));
		log_print("mda_header_%d.version %u", mda_num, xlate32(mh->version));
		log_print("mda_header_%d.start %llu", mda_num, (unsigned long long)xlate64(mh->start));
		log_print("mda_header_%d.size %llu", mda_num, (unsigned long long)xlate64(mh->size));
	}

	if (!_check_mda_header(mh, mda_num, mda_offset, mda_size, found_header))
		bad++;

	if (print_area) {
		if (!_dump_meta_area(dev, tofile, mda_offset, mda_size))
			bad++;
		goto out;
	}

	/*
	 * mda_header is 40 bytes, the raw_locn structs
	 * follow immediately after, each raw_locn struct
	 * is 24 bytes.
	 */

	rlocn0 = mh->raw_locns;
	rlocn0_offset = mda_offset + 40; /* from start of disk */

	/* sanity check */
	if ((void *)rlocn0 != (void *)(buf + rlocn0_offset - mda_offset))
		log_print("CHECK: problem with rlocn0 offset calculation");

	meta_offset = 0;
	meta_size = 0;
	meta_checksum = 0;

	if (!_dump_raw_locn(dev, print_fields, rlocn0, 0, rlocn0_offset, mda_num, mda_offset, mda_size,
			    &meta_offset, &meta_size, &meta_checksum))
		bad++;

	*checksum0_ret = meta_checksum;

	rlocn1 = (struct raw_locn *)((char *)mh->raw_locns + 24);
	rlocn1_offset = rlocn0_offset + 24;

	/* sanity check */
	if ((void *)rlocn1 != (void *)(buf + rlocn1_offset - mda_offset))
		log_print("CHECK: problem with rlocn1 offset calculation");

	if (!_dump_raw_locn(dev, print_fields, rlocn1, 1, rlocn1_offset, mda_num, mda_offset, mda_size,
			   NULL, NULL, NULL))
		bad++;

	if (!meta_offset)
		goto out;

	/*
	 * looking at the current copy of metadata referenced by raw_locn
	 */
	if (print_metadata < 2) {
		if (!_dump_meta_text(dev, print_fields, print_metadata, tofile, mda_num, 0, mda_offset, mda_size, meta_offset, meta_size, meta_checksum, &meta_buf))
			bad++;
	}

	/*
	 * looking at all copies of the metadata in the area
	 */
	if (print_metadata == 2) {
		if (!_dump_meta_text(dev, 0, 0, NULL, mda_num, 0, mda_offset, mda_size, meta_offset, meta_size, meta_checksum, &meta_buf))
			bad++;

		if (!_dump_meta_all(dev, tofile, mda_offset, mda_size, meta_offset, meta_size, meta_buf))
			bad++;
	}

	/* Should we also check text metadata if it exists in rlocn1? */
 out:
	if (bad)
		return 0;
	return 1;
}

static int _dump_headers(struct cmd_context *cmd,
			 int argc, char **argv)
{
	struct device *dev;
	const char *pv_name;
	uint64_t mda1_offset = 0, mda1_size = 0, mda2_offset = 0, mda2_size = 0;
	uint32_t mda1_checksum, mda2_checksum;
	int bad = 0;

	pv_name = argv[0];

	if (!(dev = dev_cache_get(cmd, pv_name, cmd->filter))) {
		log_error("No device found for %s %s.", pv_name, dev_cache_filtered_reason(pv_name));
		return ECMD_FAILED;
	}

	label_scan_setup_bcache();

	if (!_dump_label_and_pv_header(cmd, 1, dev, NULL,
			&mda1_offset, &mda1_size, &mda2_offset, &mda2_size))
		bad++;

	/* N.B. mda1_size and mda2_size may be different */

	/*
	 * The first mda is always 4096 bytes from the start of the device.
	 *
	 * TODO: A second mda may not exist.  If the pv_header says there
	 * is no second mda, we may still want to check for a second mda
	 * in case it's the pv_header that is wrong.  Try looking for
	 * an mda_header at 1MB prior to the end of the device, if
	 * mda2_offset is 0 or if we don't find an mda_header at mda2_offset
	 * which may have been corrupted.
	 */

	if (!_dump_mda_header(cmd, 1, 0, 0, NULL, dev, 4096, mda1_size, &mda1_checksum, NULL))
		bad++;

	/*
	 * mda2_offset may be incorrect.  Probe for a valid mda_header at
	 * mda2_offset and at other possible/expected locations, e.g.
	 * 1MB before end of device.  Call dump_mda_header with a different
	 * offset than mda2_offset if there's no valid header at mda2_offset 
	 * but there is a valid header elsewhere.
	 */
	if (mda2_offset) {
		if (!_dump_mda_header(cmd, 1, 0, 0, NULL, dev, mda2_offset, mda2_size, &mda2_checksum, NULL))
			bad++;

		/* This probably indicates that one was committed and the other not. */
		if (mda1_checksum && mda2_checksum && (mda1_checksum != mda2_checksum))
			log_print("CHECK: mdas have different raw_locn[0].checksum values");
	}

	if (bad) {
		log_error("Found bad header or metadata values.");
		return ECMD_FAILED;
	}
	return ECMD_PROCESSED;
}

static int _dump_metadata(struct cmd_context *cmd,
			 int argc, char **argv,
			 int print_metadata, int print_area)
{
	struct device *dev;
	const char *pv_name;
	const char *tofile = NULL;
	uint64_t mda1_offset = 0, mda1_size = 0, mda2_offset = 0, mda2_size = 0;
	uint32_t mda1_checksum, mda2_checksum;
	int mda_num = 1;
	int bad = 0;

	if (arg_is_set(cmd, file_ARG)) {
		if (!(tofile = arg_str_value(cmd, file_ARG, NULL)))
			return ECMD_FAILED;
	}

	/* 1: dump metadata from first mda, 2: dump metadata from second mda */
	if (arg_is_set(cmd, pvmetadatacopies_ARG))
		mda_num = arg_int_value(cmd, pvmetadatacopies_ARG, 1);

	pv_name = argv[0];

	if (!(dev = dev_cache_get(cmd, pv_name, cmd->filter))) {
		log_error("No device found for %s %s.", pv_name, dev_cache_filtered_reason(pv_name));
		return ECMD_FAILED;
	}

	label_scan_setup_bcache();

	if (!_dump_label_and_pv_header(cmd, 0, dev, NULL,
			&mda1_offset, &mda1_size, &mda2_offset, &mda2_size))
		bad++;


	/*
	 * The first mda is always 4096 bytes from the start of the device.
	 *
	 * TODO: A second mda may not exist.  If the pv_header says there
	 * is no second mda, we may still want to check for a second mda
	 * in case it's the pv_header that is wrong.  Try looking for
	 * an mda_header at 1MB prior to the end of the device, if
	 * mda2_offset is 0 or if we don't find an mda_header at mda2_offset
	 * which may have been corrupted.
	 *
	 * mda2_offset may be incorrect.  Probe for a valid mda_header at
	 * mda2_offset and at other possible/expected locations, e.g.
	 * 1MB before end of device.  Call dump_mda_header with a different
	 * offset than mda2_offset if there's no valid header at mda2_offset 
	 * but there is a valid header elsewhere.
	 */

	if (mda_num == 1) {
		if (!_dump_mda_header(cmd, 0, print_metadata, print_area, tofile, dev, 4096, mda1_size, &mda1_checksum, NULL))
			bad++;
	} else if (mda_num == 2) {
		if (!mda2_offset) {
			log_print("CHECK: second mda not found");
			bad++;
		} else {
			if (!_dump_mda_header(cmd, 0, print_metadata, print_area, tofile, dev, mda2_offset, mda2_size, &mda2_checksum, NULL))
				bad++;
		}
	}

	if (bad) {
		log_error("Found bad header or metadata values.");
		return ECMD_FAILED;
	}
	return ECMD_PROCESSED;
}

static int _dump_found(struct cmd_context *cmd, struct device *dev,
		       uint64_t labelsector)
{
	uint64_t mda1_offset = 0, mda1_size = 0, mda2_offset = 0, mda2_size = 0;
	uint32_t mda1_checksum = 0, mda2_checksum = 0;
	int found_label = 0, found_header1 = 0, found_header2 = 0;
	int bad = 0;

	if (!_dump_label_and_pv_header(cmd, 0, dev, &found_label,
			&mda1_offset, &mda1_size, &mda2_offset, &mda2_size))
		bad++;

	if (found_label && mda1_offset) {
		if (!_dump_mda_header(cmd, 0, 0, 0, NULL, dev, 4096, mda1_size, &mda1_checksum, &found_header1))
			bad++;
	}

	if (found_label && mda2_offset) {
		if (!_dump_mda_header(cmd, 0, 0, 0, NULL, dev, mda2_offset, mda2_size, &mda2_checksum, &found_header2))
			bad++;
	}

	if (found_label)
		log_print("Found label on %s, sector %llu, type=LVM2 001",
			  dev_name(dev), (unsigned long long)labelsector);
	else {
		log_error("Could not find LVM label on %s", dev_name(dev));
		return 0;
	}

	if (found_header1)
		log_print("Found text metadata area: offset=%llu, size=%llu",
			  (unsigned long long)mda1_offset,
			  (unsigned long long)mda1_size);

	if (found_header2)
		log_print("Found text metadata area: offset=%llu, size=%llu",
			  (unsigned long long)mda2_offset,
			  (unsigned long long)mda2_size);

	if (bad)
		return 0;
	return 1;
}

int pvck(struct cmd_context *cmd, int argc, char **argv)
{
	struct device *dev;
	const char *dump;
	const char *pv_name;
	uint64_t labelsector = 1;
	int bad = 0;
	int i;

	if (arg_is_set(cmd, dump_ARG)) {
		dump = arg_str_value(cmd, dump_ARG, NULL);

		if (!strcmp(dump, "metadata"))
			return _dump_metadata(cmd, argc, argv, 1, 0);

		if (!strcmp(dump, "metadata_all"))
			return _dump_metadata(cmd, argc, argv, 2, 0);

		if (!strcmp(dump, "metadata_area"))
			return _dump_metadata(cmd, argc, argv, 0, 1);

		if (!strcmp(dump, "headers"))
			return _dump_headers(cmd, argc, argv);

		log_error("Unknown dump value.");
		return ECMD_FAILED;
	}

	/*
	 * The old/original form of pvck, which did not do much,
	 * but this is here to preserve the historical output.
	 */

	if (arg_is_set(cmd, labelsector_ARG))
		labelsector = arg_uint64_value(cmd, labelsector_ARG, UINT64_C(0));

	label_scan_setup_bcache();

	for (i = 0; i < argc; i++) {
		pv_name = argv[i];

		if (!(dev = dev_cache_get(cmd, argv[i], cmd->filter))) {
			log_error("Device %s %s.", pv_name, dev_cache_filtered_reason(pv_name));
			continue;
		}

		if (!_dump_found(cmd, dev, labelsector))
			bad++;
	}

	if (bad)
		return ECMD_FAILED;
	return ECMD_PROCESSED;
}