systemd/extras/scsi_id/scsi_serial.c

/*
 * scsi_serial.c
 *
 * Code related to requesting and getting an id from a scsi device
 *
 * Copyright (C) IBM Corp. 2003
 *
 * Author:
 *	Patrick Mansfield<patmans@us.ibm.com>
 *
 *	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 version 2 of the License.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <syslog.h>
#include <scsi/sg.h>

#include "../../udev.h"
#include "scsi.h"
#include "scsi_id.h"
#include "scsi_id_version.h"

/*
 * A priority based list of id, naa, and binary/ascii for the identifier
 * descriptor in VPD page 0x83.
 *
 * Brute force search for a match starting with the first value in the
 * following id_search_list. This is not a performance issue, since there
 * is normally one or some small number of descriptors.
 */
static const struct scsi_id_search_values id_search_list[] = {
	{ SCSI_ID_NAA,	SCSI_ID_NAA_IEEE_REG_EXTENDED,	SCSI_ID_BINARY },
	{ SCSI_ID_NAA,	SCSI_ID_NAA_IEEE_REG_EXTENDED,	SCSI_ID_ASCII },
	{ SCSI_ID_NAA,	SCSI_ID_NAA_IEEE_REG,	SCSI_ID_BINARY },
	{ SCSI_ID_NAA,	SCSI_ID_NAA_IEEE_REG,	SCSI_ID_ASCII },
	/*
	 * Devices already exist using NAA values that are now marked
	 * reserved. These should not conflict with other values, or it is
	 * a bug in the device. As long as we find the IEEE extended one
	 * first, we really don't care what other ones are used. Using
	 * don't care here means that a device that returns multiple
	 * non-IEEE descriptors in a random order will get different
	 * names.
	 */
	{ SCSI_ID_NAA,	SCSI_ID_NAA_DONT_CARE,	SCSI_ID_BINARY },
	{ SCSI_ID_NAA,	SCSI_ID_NAA_DONT_CARE,	SCSI_ID_ASCII },
	{ SCSI_ID_EUI_64,	SCSI_ID_NAA_DONT_CARE,	SCSI_ID_BINARY },
	{ SCSI_ID_EUI_64,	SCSI_ID_NAA_DONT_CARE,	SCSI_ID_ASCII },
	{ SCSI_ID_T10_VENDOR,	SCSI_ID_NAA_DONT_CARE,	SCSI_ID_BINARY },
	{ SCSI_ID_T10_VENDOR,	SCSI_ID_NAA_DONT_CARE,	SCSI_ID_ASCII },
	{ SCSI_ID_VENDOR_SPECIFIC,	SCSI_ID_NAA_DONT_CARE,	SCSI_ID_BINARY },
	{ SCSI_ID_VENDOR_SPECIFIC,	SCSI_ID_NAA_DONT_CARE,	SCSI_ID_ASCII },
};

static const char hex_str[]="0123456789abcdef";

/*
 * Values returned in the result/status, only the ones used by the code
 * are used here.
 */

#define DID_NO_CONNECT			0x01	/* Unable to connect before timeout */
#define DID_BUS_BUSY			0x02	/* Bus remain busy until timeout */
#define DID_TIME_OUT			0x03	/* Timed out for some other reason */
#define DRIVER_TIMEOUT			0x06
#define DRIVER_SENSE			0x08	/* Sense_buffer has been set */

/* The following "category" function returns one of the following */
#define SG_ERR_CAT_CLEAN		0	/* No errors or other information */
#define SG_ERR_CAT_MEDIA_CHANGED	1	/* interpreted from sense buffer */
#define SG_ERR_CAT_RESET		2	/* interpreted from sense buffer */
#define SG_ERR_CAT_TIMEOUT		3
#define SG_ERR_CAT_RECOVERED		4 	/* Successful command after recovered err */
#define SG_ERR_CAT_NOTSUPPORTED 	5	/* Illegal / unsupported command */
#define SG_ERR_CAT_SENSE		98	/* Something else in the sense buffer */
#define SG_ERR_CAT_OTHER		99	/* Some other error/warning */

static int sg_err_category_new(int scsi_status, int msg_status, int
			       host_status, int driver_status, const
			       unsigned char *sense_buffer, int sb_len)
{
	scsi_status &= 0x7e;

	/*
	 * XXX change to return only two values - failed or OK.
	 */

	/*
	 * checks msg_status
	 */
	if (!scsi_status && !msg_status && !host_status && !driver_status)
		return SG_ERR_CAT_CLEAN;

	if ((scsi_status == SCSI_CHECK_CONDITION) ||
	    (scsi_status == SCSI_COMMAND_TERMINATED) ||
	    ((driver_status & 0xf) == DRIVER_SENSE)) {
		if (sense_buffer && (sb_len > 2)) {
			int sense_key;
			unsigned char asc;

			if (sense_buffer[0] & 0x2) {
				sense_key = sense_buffer[1] & 0xf;
				asc = sense_buffer[2];
			} else {
				sense_key = sense_buffer[2] & 0xf;
				asc = (sb_len > 12) ? sense_buffer[12] : 0;
			}

			if (sense_key == RECOVERED_ERROR)
				return SG_ERR_CAT_RECOVERED;
			else if (sense_key == UNIT_ATTENTION) {
				if (0x28 == asc)
					return SG_ERR_CAT_MEDIA_CHANGED;
				if (0x29 == asc)
					return SG_ERR_CAT_RESET;
			} else if (sense_key == ILLEGAL_REQUEST) {
				return SG_ERR_CAT_NOTSUPPORTED;
			}
		}
		return SG_ERR_CAT_SENSE;
	}
	if (!host_status) {
		if ((host_status == DID_NO_CONNECT) ||
		    (host_status == DID_BUS_BUSY) ||
		    (host_status == DID_TIME_OUT))
			return SG_ERR_CAT_TIMEOUT;
	}
	if (!driver_status) {
		if (driver_status == DRIVER_TIMEOUT)
			return SG_ERR_CAT_TIMEOUT;
	}
	return SG_ERR_CAT_OTHER;
}

static int sg_err_category3(struct sg_io_hdr *hp)
{
	return sg_err_category_new(hp->status, hp->msg_status,
				   hp->host_status, hp->driver_status,
				   hp->sbp, hp->sb_len_wr);
}

static int scsi_dump_sense(struct sysfs_device *dev_scsi, struct sg_io_hdr *io)
{
	unsigned char *sense_buffer;
	int s;
	int sb_len;
	int code;
	int sense_class;
	int sense_key;
	int descriptor_format;
	int asc, ascq;
#ifdef DUMP_SENSE
	char out_buffer[256];
	int i, j;
#endif

	/*
	 * Figure out and print the sense key, asc and ascq.
	 *
	 * If you want to suppress these for a particular drive model, add
	 * a black list entry in the scsi_id config file.
	 *
	 * XXX We probably need to: lookup the sense/asc/ascq in a retry
	 * table, and if found return 1 (after dumping the sense, asc, and
	 * ascq). So, if/when we get something like a power on/reset,
	 * we'll retry the command.
	 */

	dbg("got check condition\n");

	sb_len = io->sb_len_wr;
	if (sb_len < 1) {
		info("%s: sense buffer empty", dev_scsi->kernel);
		return -1;
	}

	sense_buffer = io->sbp;
	sense_class = (sense_buffer[0] >> 4) & 0x07;
	code = sense_buffer[0] & 0xf;

	if (sense_class == 7) {
		/*
		 * extended sense data.
		 */
		s = sense_buffer[7] + 8;
		if (sb_len < s) {
			info("%s: sense buffer too small %d bytes, %d bytes too short",
			    dev_scsi->kernel, sb_len, s - sb_len);
			return -1;
		}
		if ((code == 0x0) || (code == 0x1)) {
			descriptor_format = 0;
			sense_key = sense_buffer[2] & 0xf;
			if (s < 14) {
				/*
				 * Possible?
				 */
				info("%s: sense result too" " small %d bytes",
				    dev_scsi->kernel, s);
				return -1;
			}
			asc = sense_buffer[12];
			ascq = sense_buffer[13];
		} else if ((code == 0x2) || (code == 0x3)) {
			descriptor_format = 1;
			sense_key = sense_buffer[1] & 0xf;
			asc = sense_buffer[2];
			ascq = sense_buffer[3];
		} else {
			info("%s: invalid sense code 0x%x",
			    dev_scsi->kernel, code);
			return -1;
		}
		info("%s: sense key 0x%x ASC 0x%x ASCQ 0x%x",
		    dev_scsi->kernel, sense_key, asc, ascq);
	} else {
		if (sb_len < 4) {
			info("%s: sense buffer too small %d bytes, %d bytes too short",
			    dev_scsi->kernel, sb_len, 4 - sb_len);
			return -1;
		}

		if (sense_buffer[0] < 15)
			info("%s: old sense key: 0x%x", dev_scsi->kernel, sense_buffer[0] & 0x0f);
		else
			info("%s: sense = %2x %2x",
			    dev_scsi->kernel, sense_buffer[0], sense_buffer[2]);
		info("%s: non-extended sense class %d code 0x%0x",
		    dev_scsi->kernel, sense_class, code);

	}

#ifdef DUMP_SENSE
	for (i = 0, j = 0; (i < s) && (j < 254); i++) {
		dbg("i %d, j %d\n", i, j);
		out_buffer[j++] = hex_str[(sense_buffer[i] & 0xf0) >> 4];
		out_buffer[j++] = hex_str[sense_buffer[i] & 0x0f];
		out_buffer[j++] = ' ';
	}
	out_buffer[j] = '\0';
	info("%s: sense dump:", dev_scsi->kernel);
	info("%s: %s", dev_scsi->kernel, out_buffer);

#endif
	return -1;
}

static int scsi_dump(struct sysfs_device *dev_scsi, struct sg_io_hdr *io)
{
	if (!io->status && !io->host_status && !io->msg_status &&
	    !io->driver_status) {
		/*
		 * Impossible, should not be called.
		 */
		info("%s: called with no error", __FUNCTION__);
		return -1;
	}

	info("%s: sg_io failed status 0x%x 0x%x 0x%x 0x%x",
	    dev_scsi->kernel, io->driver_status, io->host_status, io->msg_status, io->status);
	if (io->status == SCSI_CHECK_CONDITION)
		return scsi_dump_sense(dev_scsi, io);
	else
		return -1;
}

static int scsi_inquiry(struct sysfs_device *dev_scsi, int fd,
			unsigned char evpd, unsigned char page,
			unsigned char *buf, unsigned int buflen)
{
	unsigned char inq_cmd[INQUIRY_CMDLEN] =
		{ INQUIRY_CMD, evpd, page, 0, buflen, 0 };
	unsigned char sense[SENSE_BUFF_LEN];
	struct sg_io_hdr io_hdr;
	int retval;
	int retry = 3; /* rather random */

	if (buflen > SCSI_INQ_BUFF_LEN) {
		info("buflen %d too long", buflen);
		return -1;
	}

resend:
	dbg("%s evpd %d, page 0x%x\n", dev_scsi->kernel, evpd, page);

	memset(&io_hdr, 0, sizeof(struct sg_io_hdr));
	io_hdr.interface_id = 'S';
	io_hdr.cmd_len = sizeof(inq_cmd);
	io_hdr.mx_sb_len = sizeof(sense);
	io_hdr.dxfer_direction = SG_DXFER_FROM_DEV;
	io_hdr.dxfer_len = buflen;
	io_hdr.dxferp = buf;
	io_hdr.cmdp = inq_cmd;
	io_hdr.sbp = sense;
	io_hdr.timeout = DEF_TIMEOUT;

	if (ioctl(fd, SG_IO, &io_hdr) < 0) {
		info("%s: ioctl failed: %s", dev_scsi->kernel, strerror(errno));
		retval = -1;
		goto error;
	}

	retval = sg_err_category3(&io_hdr);

	switch (retval) {
		case SG_ERR_CAT_NOTSUPPORTED:
			buf[1] = 0;
			/* Fallthrough */
		case SG_ERR_CAT_CLEAN:
		case SG_ERR_CAT_RECOVERED:
			retval = 0;
			break;

		default:
			retval = scsi_dump(dev_scsi, &io_hdr);
	}

	if (!retval) {
		retval = buflen;
	} else if (retval > 0) {
		if (--retry > 0) {
			dbg("%s: Retrying ...\n", dev_scsi->kernel);
			goto resend;
		}
		retval = -1;
	}

error:
	if (retval < 0)
		info("%s: Unable to get INQUIRY vpd %d page 0x%x.",
		    dev_scsi->kernel, evpd, page);

	return retval;
}

/* Get list of supported EVPD pages */
static int do_scsi_page0_inquiry(struct sysfs_device *dev_scsi, int fd,
				 unsigned char *buffer, unsigned int len)
{
	int retval;
	const char *vendor;

	memset(buffer, 0, len);
	retval = scsi_inquiry(dev_scsi, fd, 1, 0x0, buffer, len);
	if (retval < 0)
		return 1;

	if (buffer[1] != 0) {
		info("%s: page 0 not available.", dev_scsi->kernel);
		return 1;
	}
	if (buffer[3] > len) {
		info("%s: page 0 buffer too long %d", dev_scsi->kernel,  buffer[3]);
		return 1;
	}

	/*
	 * Following check is based on code once included in the 2.5.x
	 * kernel.
	 *
	 * Some ill behaved devices return the standard inquiry here
	 * rather than the evpd data, snoop the data to verify.
	 */
	if (buffer[3] > MODEL_LENGTH) {
		/*
		 * If the vendor id appears in the page assume the page is
		 * invalid.
		 */
		vendor = sysfs_attr_get_value(dev_scsi->devpath, "vendor");
		if (!vendor) {
			info("%s: cannot get model attribute", dev_scsi->kernel);
			return 1;
		}
		if (!strncmp((char *)&buffer[VENDOR_LENGTH], vendor, VENDOR_LENGTH)) {
			info("%s: invalid page0 data", dev_scsi->kernel);
			return 1;
		}
	}
	return 0;
}

/*
 * The caller checks that serial is long enough to include the vendor +
 * model.
 */
static int prepend_vendor_model(struct sysfs_device *dev_scsi, char *serial)
{
	const char *attr;
	int ind;

	attr = sysfs_attr_get_value(dev_scsi->devpath, "vendor");
	if (!attr) {
		info("%s: cannot get vendor attribute", dev_scsi->kernel);
		return 1;
	}
	strncpy(serial, attr, VENDOR_LENGTH);
	ind = strlen(serial) - 1;

	attr = sysfs_attr_get_value(dev_scsi->devpath, "model");
	if (!attr) {
		info("%s: cannot get model attribute", dev_scsi->kernel);
		return 1;
	}
	strncat(serial, attr, MODEL_LENGTH);
	ind = strlen(serial) - 1;
	ind++;

	/*
	 * This is not a complete check, since we are using strncat/cpy
	 * above, ind will never be too large.
	 */
	if (ind != (VENDOR_LENGTH + MODEL_LENGTH)) {
		info("%s: expected length %d, got length %d",
		     dev_scsi->kernel, (VENDOR_LENGTH + MODEL_LENGTH), ind);
		return 1;
	}
	return ind;
}

/**
 * check_fill_0x83_id - check the page 0x83 id, if OK allocate and fill
 * serial number.
 **/
static int check_fill_0x83_id(struct sysfs_device *dev_scsi,
			      unsigned char *page_83,
			      const struct scsi_id_search_values
			      *id_search, char *serial, int max_len)
{
	int i, j, len;

	/*
	 * ASSOCIATION must be with the device (value 0)
	 */
	if ((page_83[1] & 0x30) != 0)
		return 1;

	if ((page_83[1] & 0x0f) != id_search->id_type)
		return 1;

	/*
	 * Possibly check NAA sub-type.
	 */
	if ((id_search->naa_type != SCSI_ID_NAA_DONT_CARE) &&
	    (id_search->naa_type != (page_83[4] & 0xf0) >> 4))
		return 1;

	/*
	 * Check for matching code set - ASCII or BINARY.
	 */
	if ((page_83[0] & 0x0f) != id_search->code_set)
		return 1;

	/*
	 * page_83[3]: identifier length
	 */
	len = page_83[3];
	if ((page_83[0] & 0x0f) != SCSI_ID_ASCII)
		/*
		 * If not ASCII, use two bytes for each binary value.
		 */
		len *= 2;

       	/*
	 * Add one byte for the NUL termination, and one for the id_type.
	 */
	len += 2;
	if (id_search->id_type == SCSI_ID_VENDOR_SPECIFIC)
		len += VENDOR_LENGTH + MODEL_LENGTH;

	if (max_len < len) {
		info("%s: length %d too short - need %d",
		    dev_scsi->kernel, max_len, len);
		return 1;
	}

	serial[0] = hex_str[id_search->id_type];

	/*
	 * For SCSI_ID_VENDOR_SPECIFIC prepend the vendor and model before
	 * the id since it is not unique across all vendors and models,
	 * this differs from SCSI_ID_T10_VENDOR, where the vendor is
	 * included in the identifier.
	 */
	if (id_search->id_type == SCSI_ID_VENDOR_SPECIFIC)
		if (prepend_vendor_model(dev_scsi, &serial[1]) < 0) {
			dbg("prepend failed\n");
			return 1;
		}

	i = 4; /* offset to the start of the identifier */
	j = strlen(serial);
	if ((page_83[0] & 0x0f) == SCSI_ID_ASCII) {
		/*
		 * ASCII descriptor.
		 */
		while (i < (4 + page_83[3]))
			serial[j++] = page_83[i++];
	} else {
		/*
		 * Binary descriptor, convert to ASCII, using two bytes of
		 * ASCII for each byte in the page_83.
		 */
		while (i < (4 + page_83[3])) {
			serial[j++] = hex_str[(page_83[i] & 0xf0) >> 4];
			serial[j++] = hex_str[page_83[i] & 0x0f];
			i++;
		}
	}
	return 0;
}

/* Extract the raw binary from VPD 0x83 pre-SPC devices */
static int check_fill_0x83_prespc3(struct sysfs_device *dev_scsi,
			           unsigned char *page_83,
			           const struct scsi_id_search_values
			           *id_search, char *serial, int max_len)
{
	int i, j;
	
	serial[0] = hex_str[id_search->id_type];
	/* serial has been memset to zero before */
	j = strlen(serial);	/* j = 1; */

	for (i = 0; i < page_83[3]; ++i) {
		serial[j++] = hex_str[(page_83[4+i] & 0xf0) >> 4];
		serial[j++] = hex_str[ page_83[4+i] & 0x0f];
	}
	dbg("using pre-spc3-83 for %s.\n", dev_scsi->kernel);
	return 0;
}


/* Get device identification VPD page */
static int do_scsi_page83_inquiry(struct sysfs_device *dev_scsi, int fd,
				  char *serial, int len)
{
	int retval;
	unsigned int id_ind, j;
	unsigned char page_83[SCSI_INQ_BUFF_LEN];

	memset(page_83, 0, SCSI_INQ_BUFF_LEN);
	retval = scsi_inquiry(dev_scsi, fd, 1, PAGE_83, page_83,
			      SCSI_INQ_BUFF_LEN);
	if (retval < 0)
		return 1;

	if (page_83[1] != PAGE_83) {
		info("%s: Invalid page 0x83", dev_scsi->kernel);
		return 1;
	}
	
	/*
	 * XXX Some devices (IBM 3542) return all spaces for an identifier if
	 * the LUN is not actually configured. This leads to identifers of
	 * the form: "1            ".
	 */

	/*
	 * Model 4, 5, and (some) model 6 EMC Symmetrix devices return
	 * a page 83 reply according to SCSI-2 format instead of SPC-2/3.
	 *
	 * The SCSI-2 page 83 format returns an IEEE WWN in binary
	 * encoded hexi-decimal in the 16 bytes following the initial
	 * 4-byte page 83 reply header.
	 *
	 * Both the SPC-2 and SPC-3 formats return an IEEE WWN as part
	 * of an Identification descriptor.  The 3rd byte of the first
	 * Identification descriptor is a reserved (BSZ) byte field.
	 *
	 * Reference the 7th byte of the page 83 reply to determine
	 * whether the reply is compliant with SCSI-2 or SPC-2/3
	 * specifications.  A zero value in the 7th byte indicates
	 * an SPC-2/3 conformant reply, (i.e., the reserved field of the
	 * first Identification descriptor).  This byte will be non-zero
	 * for a SCSI-2 conformant page 83 reply from these EMC
	 * Symmetrix models since the 7th byte of the reply corresponds
	 * to the 4th and 5th nibbles of the 6-byte OUI for EMC, that is,
	 * 0x006048.
	 */
	
	if (page_83[6] != 0) 
		return check_fill_0x83_prespc3(dev_scsi, page_83, 
					       id_search_list, serial, len);

	/*
	 * Search for a match in the prioritized id_search_list.
	 */
	for (id_ind = 0;
	     id_ind < sizeof(id_search_list)/sizeof(id_search_list[0]);
	     id_ind++) {
		/*
		 * Examine each descriptor returned. There is normally only
		 * one or a small number of descriptors.
		 */
		for (j = 4; j <= (unsigned int)page_83[3] + 3; j += page_83[j + 3] + 4) {
			retval = check_fill_0x83_id(dev_scsi, &page_83[j],
						    &id_search_list[id_ind],
						    serial, len);
			dbg("%s id desc %d/%d/%d\n", dev_scsi->kernel,
				id_search_list[id_ind].id_type,
				id_search_list[id_ind].naa_type,
				id_search_list[id_ind].code_set);
			if (!retval) {
				dbg("	used\n");
				return retval;
			} else if (retval < 0) {
				dbg("	failed\n");
				return retval;
			} else {
				dbg("	not used\n");
			}
		}
	}
	return 1;
}

/*
 * Get device identification VPD page for older SCSI-2 device which is not
 * compliant with either SPC-2 or SPC-3 format.
 *
 * Return the hard coded error code value 2 if the page 83 reply is not
 * conformant to the SCSI-2 format.
 */
static int do_scsi_page83_prespc3_inquiry(struct sysfs_device *dev_scsi, int fd,
				          char *serial, int len)
{
	int retval;
	int i, j;
	unsigned char page_83[SCSI_INQ_BUFF_LEN];

	memset(page_83, 0, SCSI_INQ_BUFF_LEN);
	retval = scsi_inquiry(dev_scsi, fd, 1, PAGE_83, page_83, SCSI_INQ_BUFF_LEN);
	if (retval < 0)
		return 1;

	if (page_83[1] != PAGE_83) {
		info("%s: Invalid page 0x83", dev_scsi->kernel);
		return 1;
	}
	/*
	 * Model 4, 5, and (some) model 6 EMC Symmetrix devices return
	 * a page 83 reply according to SCSI-2 format instead of SPC-2/3.
	 *
	 * The SCSI-2 page 83 format returns an IEEE WWN in binary
	 * encoded hexi-decimal in the 16 bytes following the initial
	 * 4-byte page 83 reply header.
	 *
	 * Both the SPC-2 and SPC-3 formats return an IEEE WWN as part
	 * of an Identification descriptor.  The 3rd byte of the first
	 * Identification descriptor is a reserved (BSZ) byte field.
	 *
	 * Reference the 7th byte of the page 83 reply to determine
	 * whether the reply is compliant with SCSI-2 or SPC-2/3
	 * specifications.  A zero value in the 7th byte indicates
	 * an SPC-2/3 conformant reply, (i.e., the reserved field of the
	 * first Identification descriptor).  This byte will be non-zero
	 * for a SCSI-2 conformant page 83 reply from these EMC
	 * Symmetrix models since the 7th byte of the reply corresponds
	 * to the 4th and 5th nibbles of the 6-byte OUI for EMC, that is,
	 * 0x006048.
	 */
	if (page_83[6] == 0)
		return 2;

	serial[0] = hex_str[id_search_list[0].id_type];
	/*
	 * The first four bytes contain data, not a descriptor.
	 */
	i = 4;
	j = strlen(serial);
	/*
	 * Binary descriptor, convert to ASCII,
	 * using two bytes of ASCII for each byte
	 * in the page_83.
	 */
	while (i < (page_83[3]+4)) {
		serial[j++] = hex_str[(page_83[i] & 0xf0) >> 4];
		serial[j++] = hex_str[page_83[i] & 0x0f];
		i++;
	}
	dbg("using pre-spc3-83 for %s.\n", dev_scsi->kernel);
	return 0;
}

/* Get unit serial number VPD page */
static int do_scsi_page80_inquiry(struct sysfs_device *dev_scsi, int fd,
				  char *serial, int max_len)
{
	int retval;
	int ser_ind;
	int i;
	int len;
	unsigned char buf[SCSI_INQ_BUFF_LEN];

	memset(buf, 0, SCSI_INQ_BUFF_LEN);
	retval = scsi_inquiry(dev_scsi, fd, 1, PAGE_80, buf, SCSI_INQ_BUFF_LEN);
	if (retval < 0)
		return retval;

	if (buf[1] != PAGE_80) {
		info("%s: Invalid page 0x80", dev_scsi->kernel);
		return 1;
	}

	len = 1 + VENDOR_LENGTH + MODEL_LENGTH + buf[3];
	if (max_len < len) {
		info("%s: length %d too short - need %d",
		    dev_scsi->kernel, max_len, len);
		return 1;
	}
	/*
	 * Prepend 'S' to avoid unlikely collision with page 0x83 vendor
	 * specific type where we prepend '0' + vendor + model.
	 */
	serial[0] = 'S';
	ser_ind = prepend_vendor_model(dev_scsi, &serial[1]);
	if (ser_ind < 0)
		return 1;
	len = buf[3];
	for (i = 4; i < len + 4; i++, ser_ind++)
		serial[ser_ind] = buf[i];
	return 0;
}

int scsi_get_serial (struct sysfs_device *dev_scsi, const char *devname,
		     int page_code, char *serial, int len)
{
	unsigned char page0[SCSI_INQ_BUFF_LEN];
	int fd;
	int ind;
	int retval;

	memset(serial, 0, len);
	dbg("opening %s\n", devname);
	fd = open(devname, O_RDONLY | O_NONBLOCK);
	if (fd < 0) {
		info("%s: cannot open %s: %s",
		    dev_scsi->kernel, devname, strerror(errno));
		return 1;
	}

	if (page_code == PAGE_80) {
		if (do_scsi_page80_inquiry(dev_scsi, fd, serial, len)) {
			retval = 1;
			goto completed;
		} else  {
			retval = 0;
			goto completed;
		}
	} else if (page_code == PAGE_83) {
		if (do_scsi_page83_inquiry(dev_scsi, fd, serial, len)) {
			retval = 1;
			goto completed;
		} else  {
			retval = 0;
			goto completed;
		}
	} else if (page_code == PAGE_83_PRE_SPC3) {
		retval = do_scsi_page83_prespc3_inquiry(dev_scsi, fd, serial, len);
		if (retval) {
			/*
			 * Fallback to servicing a SPC-2/3 compliant page 83
			 * inquiry if the page 83 reply format does not
			 * conform to pre-SPC3 expectations.
			 */
			if (retval == 2) {
				if (do_scsi_page83_inquiry(dev_scsi, fd, serial, len)) {
					retval = 1;
					goto completed;
				} else  {
					retval = 0;
					goto completed;
				}
			}
			else {
				retval = 1;
				goto completed;
			}
		} else  {
			retval = 0;
			goto completed;
		}
	} else if (page_code != 0x00) {
		info("%s: unsupported page code 0x%d", dev_scsi->kernel, page_code);
		return 1;
	}

	/*
	 * Get page 0, the page of the pages. By default, try from best to
	 * worst of supported pages: 0x83 then 0x80.
	 */
	if (do_scsi_page0_inquiry(dev_scsi, fd, page0, SCSI_INQ_BUFF_LEN)) {
		/*
		 * Don't try anything else. Black list if a specific page
		 * should be used for this vendor+model, or maybe have an
		 * optional fall-back to page 0x80 or page 0x83.
		 */
		retval = 1;
		goto completed;
	}

	dbg("%s: Checking page0\n", dev_scsi->kernel);

	for (ind = 4; ind <= page0[3] + 3; ind++)
		if (page0[ind] == PAGE_83)
			if (!do_scsi_page83_inquiry(dev_scsi, fd, serial,
						    len)) {
				/*
				 * Success
				 */
				retval = 0;
				goto completed;
			}

	for (ind = 4; ind <= page0[3] + 3; ind++)
		if (page0[ind] == PAGE_80)
			if (!do_scsi_page80_inquiry(dev_scsi, fd, serial,
						    len)) {
				/*
				 * Success
				 */
				retval = 0;
				goto completed;
			}
	retval = 1;
completed:
	if (close(fd) < 0)
		info("%s: close failed: %s", dev_scsi->kernel, strerror(errno));
	return retval;
}