path: root/sg_dd.c

#define _XOPEN_SOURCE 500

#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <ctype.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <sys/time.h> 
#include <linux/major.h>
typedef unsigned char u_char;	/* horrible, for scsi.h */
#include "sg_include.h"
#include "sg_err.h"
#include "llseek.h"

/* A utility program for the Linux OS SCSI generic ("sg") device driver.
*  Copyright (C) 1999 - 2002 D. Gilbert and P. Allworth
*  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, or (at your option)
*  any later version.

   This program is a specialization of the Unix "dd" command in which
   either the input or the output file is a scsi generic device or a
   raw device. The block size ('bs') is assumed to be 512 if not given. 
   This program complains if 'ibs' or 'obs' are given with a value
   that differs from 'bs' (or the default 512).
   If 'if' is not given or 'if=-' then stdin is assumed. If 'of' is
   not given or 'of=-' then stdout assumed. Multipliers:
     'c','C'  *1       'b','B' *512      'k' *1024      'K' *1000
     'm' *(1024^2)     'M' *(1000^2)     'g' *(1024^3)  'G' *(1000^3)

   A non-standard argument "bpt" (blocks per transfer) is added to control
   the maximum number of blocks in each transfer. The default value is 128.
   For example if "bs=512" and "bpt=32" then a maximum of 32 blocks (16KB
   in this case) is transferred to or from the sg device in a single SCSI
   command. The actual size of the SCSI READ or WRITE command block can be
   selected with the "cdbsz" argument.

   This version should compile with Linux sg drivers with version numbers
   >= 30000 .
*/

static char * version_str = "5.20 20020316";


#define DEF_BLOCK_SIZE 512
#define DEF_BLOCKS_PER_TRANSFER 128
#define DEF_SCSI_CDBSZ 10
#define MAX_SCSI_CDBSZ 16

#define ME "sg_dd: "

// #define SG_DEBUG

#define SENSE_BUFF_LEN 32       /* Arbitrary, could be larger */
#define READ_CAP_REPLY_LEN 8
#define DEF_TIMEOUT 40000       /* 40,000 millisecs == 40 seconds */

#ifndef RAW_MAJOR
#define RAW_MAJOR 255	/*unlikey value */
#endif 

#define FT_OTHER 0		/* filetype other than sg or raw device */
#define FT_SG 1			/* filetype is sg char device */
#define FT_RAW 2		/* filetype is raw char device */

static int sum_of_resids = 0;

static int dd_count = -1;
static int in_full = 0;
static int in_partial = 0;
static int out_full = 0;
static int out_partial = 0;

static const char * proc_allow_dio = "/proc/scsi/sg/allow_dio";

static void install_handler (int sig_num, void (*sig_handler) (int sig))
{
    struct sigaction sigact;
    sigaction (sig_num, NULL, &sigact);
    if (sigact.sa_handler != SIG_IGN)
    {
        sigact.sa_handler = sig_handler;
        sigemptyset (&sigact.sa_mask);
        sigact.sa_flags = 0;
        sigaction (sig_num, &sigact, NULL);
    }
}

void print_stats()
{
    if (0 != dd_count)
        fprintf(stderr, "  remaining block count=%d\n", dd_count);
    fprintf(stderr, "%d+%d records in\n", in_full - in_partial, in_partial);
    fprintf(stderr, "%d+%d records out\n", out_full - out_partial, 
    	    out_partial);
}

static void interrupt_handler(int sig)
{
    struct sigaction sigact;

    sigact.sa_handler = SIG_DFL;
    sigemptyset (&sigact.sa_mask);
    sigact.sa_flags = 0;
    sigaction (sig, &sigact, NULL);
    fprintf(stderr, "Interrupted by signal,");
    print_stats ();
    kill (getpid (), sig);
}

static void siginfo_handler(int sig)
{
    fprintf(stderr, "Progress report, continuing ...\n");
    print_stats ();
}

int dd_filetype(const char * filename)
{
    struct stat st;

    if (stat(filename, &st) < 0)
	return FT_OTHER;
    if (S_ISCHR(st.st_mode)) {
	if (RAW_MAJOR == major(st.st_rdev))
	    return FT_RAW;
	else if (SCSI_GENERIC_MAJOR == major(st.st_rdev))
	    return FT_SG;
    }
    return FT_OTHER;
}

void usage()
{
    fprintf(stderr, "Usage: "
           "sg_dd  [if=<infile>] [skip=<n>] [of=<ofile>] [seek=<n>] "
           "[bs=<num>]\n"
           "              [bpt=<num>] [count=<n>] [time=0|1]"
           " [dio=0|1] [sync=0|1]\n"
	   "              [cdbsz=<6|10|12|16>] [fua=0|1|2|3] [gen=0|1]"
	   " [--version]\n"
           " 'bpt' is blocks_per_transfer (default is 128)\n"
           " 'dio' is direct IO, 1->attempt, 0->indirect IO (def)\n"
           " 'gen' 0->either 'if' or 'of' must be sg or raw device(def)\n"
           " 'time' 0->no timing(def), 1->time plus calculate throughput\n"
           " 'fua' force unit access: 0->don't(def), 1->of, 2->if, 3->of+if\n"
           " 'sync' 0->no sync(def), 1->SYNCHRONIZE CACHE on of after xfer\n"
           " 'cdbsz' size of SCSI READ or WRITE command (default is 10)\n");
}

/* Return of 0 -> success, -1 -> failure, 2 -> try again */
int read_capacity(int sg_fd, int * num_sect, int * sect_sz)
{
    int res;
    unsigned char rcCmdBlk [10] = {READ_CAPACITY, 0, 0, 0, 0, 0, 0, 0, 0, 0};
    unsigned char rcBuff[READ_CAP_REPLY_LEN];
    unsigned char sense_b[64];
    sg_io_hdr_t io_hdr;

    memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
    io_hdr.interface_id = 'S';
    io_hdr.cmd_len = sizeof(rcCmdBlk);
    io_hdr.mx_sb_len = sizeof(sense_b);
    io_hdr.dxfer_direction = SG_DXFER_FROM_DEV;
    io_hdr.dxfer_len = sizeof(rcBuff);
    io_hdr.dxferp = rcBuff;
    io_hdr.cmdp = rcCmdBlk;
    io_hdr.sbp = sense_b;
    io_hdr.timeout = DEF_TIMEOUT;

    if (ioctl(sg_fd, SG_IO, &io_hdr) < 0) {
        perror("read_capacity (SG_IO) error");
        return -1;
    }
    res = sg_err_category3(&io_hdr);
    if (SG_ERR_CAT_MEDIA_CHANGED == res)
        return 2; /* probably have another go ... */
    else if (SG_ERR_CAT_CLEAN != res) {
        sg_chk_n_print3("read capacity", &io_hdr);
        return -1;
    }
    *num_sect = 1 + ((rcBuff[0] << 24) | (rcBuff[1] << 16) |
                (rcBuff[2] << 8) | rcBuff[3]);
    *sect_sz = (rcBuff[4] << 24) | (rcBuff[5] << 16) |
               (rcBuff[6] << 8) | rcBuff[7];
    return 0;
}

/* Return of 0 -> success, -1 -> failure, 2 -> try again */
int sync_cache(int sg_fd)
{
    int res;
    unsigned char scCmdBlk [10] = {SYNCHRONIZE_CACHE, 0, 0, 0, 0, 0, 0, 
    				   0, 0, 0};
    unsigned char sense_b[64];
    sg_io_hdr_t io_hdr;

    memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
    io_hdr.interface_id = 'S';
    io_hdr.cmd_len = sizeof(scCmdBlk);
    io_hdr.mx_sb_len = sizeof(sense_b);
    io_hdr.dxfer_direction = SG_DXFER_NONE;
    io_hdr.dxfer_len = 0;
    io_hdr.dxferp = NULL;
    io_hdr.cmdp = scCmdBlk;
    io_hdr.sbp = sense_b;
    io_hdr.timeout = DEF_TIMEOUT;

    if (ioctl(sg_fd, SG_IO, &io_hdr) < 0) {
        perror("synchronize_cache (SG_IO) error");
        return -1;
    }
    res = sg_err_category3(&io_hdr);
    if (SG_ERR_CAT_MEDIA_CHANGED == res)
        return 2; /* probably have another go ... */
    else if (SG_ERR_CAT_CLEAN != res) {
        sg_chk_n_print3("synchronize cache", &io_hdr);
        return -1;
    }
    return 0;
}

int sg_build_scsi_cdb(unsigned char * cdbp, int cdb_sz, unsigned int blocks,
		      unsigned int start_block, int write_true, int fua,
		      int dpo)
{
    int rd_opcode[] = {0x8, 0x28, 0xa8, 0x88};
    int wr_opcode[] = {0xa, 0x2a, 0xaa, 0x8a};
    int sz_ind;

    memset(cdbp, 0, cdb_sz);
    if (dpo)
	cdbp[1] |= 0x10;
    if (fua)
	cdbp[1] |= 0x8;
    switch (cdb_sz) {
    case 6:
    	sz_ind = 0;
	cdbp[0] = (unsigned char)(write_true ? wr_opcode[sz_ind] :
					       rd_opcode[sz_ind]);
	cdbp[1] = (unsigned char)((start_block >> 16) & 0x1f);
	cdbp[2] = (unsigned char)((start_block >> 8) & 0xff);
	cdbp[3] = (unsigned char)(start_block & 0xff);
	cdbp[4] = (256 == blocks) ? 0 : (unsigned char)blocks;
	if (blocks > 256) {
	    fprintf(stderr, ME "for 6 byte commands, maximum number of "
	    		    "blocks is 256\n");
	    return 1;
	}
	if ((start_block + blocks - 1) & (~0x1fffff)) {
	    fprintf(stderr, ME "for 6 byte commands, can't address blocks"
	    		    " beyond %d\n", 0x1fffff);
	    return 1;
	}
	if (dpo || fua) {
	    fprintf(stderr, ME "for 6 byte commands, neither dpo nor fua"
	    		    " bits supported\n");
	    return 1;
	}
    	break;
    case 10:
    	sz_ind = 1;
	cdbp[0] = (unsigned char)(write_true ? wr_opcode[sz_ind] :
					       rd_opcode[sz_ind]);
	cdbp[2] = (unsigned char)((start_block >> 24) & 0xff);
	cdbp[3] = (unsigned char)((start_block >> 16) & 0xff);
	cdbp[4] = (unsigned char)((start_block >> 8) & 0xff);
	cdbp[5] = (unsigned char)(start_block & 0xff);
	cdbp[7] = (unsigned char)((blocks >> 8) & 0xff);
	cdbp[8] = (unsigned char)(blocks & 0xff);
	if (blocks & (~0xffff)) {
	    fprintf(stderr, ME "for 10 byte commands, maximum number of "
	    		    "blocks is %d\n", 0xffff);
	    return 1;
	}
    	break;
    case 12:
    	sz_ind = 2;
	cdbp[0] = (unsigned char)(write_true ? wr_opcode[sz_ind] :
					       rd_opcode[sz_ind]);
	cdbp[2] = (unsigned char)((start_block >> 24) & 0xff);
	cdbp[3] = (unsigned char)((start_block >> 16) & 0xff);
	cdbp[4] = (unsigned char)((start_block >> 8) & 0xff);
	cdbp[5] = (unsigned char)(start_block & 0xff);
	cdbp[6] = (unsigned char)((blocks >> 24) & 0xff);
	cdbp[7] = (unsigned char)((blocks >> 16) & 0xff);
	cdbp[8] = (unsigned char)((blocks >> 8) & 0xff);
	cdbp[9] = (unsigned char)(blocks & 0xff);
    	break;
    case 16:
    	sz_ind = 3;
	cdbp[0] = (unsigned char)(write_true ? wr_opcode[sz_ind] :
					       rd_opcode[sz_ind]);
	/* can't cope with block number > 32 bits (yet) */
	cdbp[6] = (unsigned char)((start_block >> 24) & 0xff);
	cdbp[7] = (unsigned char)((start_block >> 16) & 0xff);
	cdbp[8] = (unsigned char)((start_block >> 8) & 0xff);
	cdbp[9] = (unsigned char)(start_block & 0xff);
	cdbp[10] = (unsigned char)((blocks >> 24) & 0xff);
	cdbp[11] = (unsigned char)((blocks >> 16) & 0xff);
	cdbp[12] = (unsigned char)((blocks >> 8) & 0xff);
	cdbp[13] = (unsigned char)(blocks & 0xff);
    	break;
    default:
    	fprintf(stderr, ME "expected cdb size of 6, 10, 12, or 16 but got"
			"=%d\n", cdb_sz);
    	return 1;
    }
    return 0;
}

/* -1 -> unrecoverable error, 0 -> successful, 1 -> recoverable (ENOMEM),
   2 -> try again */
int sg_read(int sg_fd, unsigned char * buff, int blocks, int from_block,
            int bs, int cdbsz, int fua, int * diop)
{
    unsigned char rdCmd[MAX_SCSI_CDBSZ];
    unsigned char senseBuff[SENSE_BUFF_LEN];
    sg_io_hdr_t io_hdr;
    int res;

    if (sg_build_scsi_cdb(rdCmd, cdbsz, blocks, from_block, 0, fua, 0)) {
    	fprintf(stderr, ME "bad rd cdb build, from_block=%d, blocks=%d\n",
		from_block, blocks);
    	return -1;
    }

    memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
    io_hdr.interface_id = 'S';
    io_hdr.cmd_len = cdbsz;
    io_hdr.cmdp = rdCmd;
    io_hdr.dxfer_direction = SG_DXFER_FROM_DEV;
    io_hdr.dxfer_len = bs * blocks;
    io_hdr.dxferp = buff;
    io_hdr.mx_sb_len = SENSE_BUFF_LEN;
    io_hdr.sbp = senseBuff;
    io_hdr.timeout = DEF_TIMEOUT;
    io_hdr.pack_id = from_block;
    if (diop && *diop)
        io_hdr.flags |= SG_FLAG_DIRECT_IO;

    while (((res = write(sg_fd, &io_hdr, sizeof(io_hdr))) < 0) &&
           (EINTR == errno))
        ;
    if (res < 0) {
        if (ENOMEM == errno)
            return 1;
        perror("reading (wr) on sg device, error");
        return -1;
    }

    while (((res = read(sg_fd, &io_hdr, sizeof(io_hdr))) < 0) &&
           (EINTR == errno))
        ;
    if (res < 0) {
        perror("reading (rd) on sg device, error");
        return -1;
    }
    switch (sg_err_category3(&io_hdr)) {
    case SG_ERR_CAT_CLEAN:
        break;
    case SG_ERR_CAT_RECOVERED:
        fprintf(stderr, "Recovered error while reading block=%d, num=%d\n",
               from_block, blocks);
        break;
    case SG_ERR_CAT_MEDIA_CHANGED:
        return 2;
    default:
        sg_chk_n_print3("reading", &io_hdr);
        return -1;
    }
    if (diop && *diop && 
        ((io_hdr.info & SG_INFO_DIRECT_IO_MASK) != SG_INFO_DIRECT_IO))
        *diop = 0;      /* flag that dio not done (completely) */
    sum_of_resids += io_hdr.resid;
#if SG_DEBUG
    fprintf(stderr, "duration=%u ms\n", io_hdr.duration);
#endif
    return 0;
}

/* -1 -> unrecoverable error, 0 -> successful, 1 -> recoverable (ENOMEM),
   2 -> try again */
int sg_write(int sg_fd, unsigned char * buff, int blocks, int to_block,
             int bs, int cdbsz, int fua, int * diop)
{
    unsigned char wrCmd[MAX_SCSI_CDBSZ];
    unsigned char senseBuff[SENSE_BUFF_LEN];
    sg_io_hdr_t io_hdr;
    int res;

    if (sg_build_scsi_cdb(wrCmd, cdbsz, blocks, to_block, 1, fua, 0)) {
    	fprintf(stderr, ME "bad wr cdb build, to_block=%d, blocks=%d\n",
		to_block, blocks);
    	return -1;
    }

    memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
    io_hdr.interface_id = 'S';
    io_hdr.cmd_len = cdbsz;
    io_hdr.cmdp = wrCmd;
    io_hdr.dxfer_direction = SG_DXFER_TO_DEV;
    io_hdr.dxfer_len = bs * blocks;
    io_hdr.dxferp = buff;
    io_hdr.mx_sb_len = SENSE_BUFF_LEN;
    io_hdr.sbp = senseBuff;
    io_hdr.timeout = DEF_TIMEOUT;
    io_hdr.pack_id = to_block;
    if (diop && *diop)
        io_hdr.flags |= SG_FLAG_DIRECT_IO;

    while (((res = write(sg_fd, &io_hdr, sizeof(io_hdr))) < 0) &&
           (EINTR == errno))
        ;
    if (res < 0) {
        if (ENOMEM == errno)
            return 1;
        perror("writing (wr) on sg device, error");
        return -1;
    }

    while (((res = read(sg_fd, &io_hdr, sizeof(io_hdr))) < 0) &&
           (EINTR == errno))
        ;
    if (res < 0) {
        perror("writing (rd) on sg device, error");
        return -1;
    }
    switch (sg_err_category3(&io_hdr)) {
    case SG_ERR_CAT_CLEAN:
        break;
    case SG_ERR_CAT_RECOVERED:
        fprintf(stderr, "Recovered error while writing block=%d, num=%d\n",
               to_block, blocks);
        break;
    case SG_ERR_CAT_MEDIA_CHANGED:
        return 2;
    default:
        sg_chk_n_print3("writing", &io_hdr);
        return -1;
    }
    if (diop && *diop && 
        ((io_hdr.info & SG_INFO_DIRECT_IO_MASK) != SG_INFO_DIRECT_IO))
        *diop = 0;      /* flag that dio not done (completely) */
    return 0;
}

int get_num(char * buf)
{
    int res, num;
    char c;

    res = sscanf(buf, "%d%c", &num, &c);
    if (0 == res)
        return -1;
    else if (1 == res)
        return num;
    else {
    	switch (c) {
	case 'c':
	case 'C':
            return num;
	case 'b':
	case 'B':
            return num * 512;
	case 'k':
            return num * 1024;
	case 'K':
            return num * 1000;
	case 'm':
            return num * 1024 * 1024;
	case 'M':
            return num * 1000000;
	case 'g':
            return num * 1024 * 1024 * 1024;
	case 'G':
            return num * 1000000000;
        default:
            fprintf(stderr, "unrecognized multiplier\n");
            return -1;
	}
    }
}

#define STR_SZ 1024
#define INOUTF_SZ 512
#define EBUFF_SZ 512


int main(int argc, char * argv[])
{
    int skip = 0;
    int seek = 0;
    int bs = 0;
    int ibs = 0;
    int obs = 0;
    int bpt = DEF_BLOCKS_PER_TRANSFER;
    char str[STR_SZ];
    char * key;
    char * buf;
    char inf[INOUTF_SZ];
    int in_type = FT_OTHER;
    char outf[INOUTF_SZ];
    int out_type = FT_OTHER;
    int dio = 0;
    int dio_incomplete = 0;
    int do_time = 0;
    int do_gen = 0;
    int scsi_cdbsz = DEF_SCSI_CDBSZ;
    int fua_mode = 0;
    int do_sync = 0;
    int res, k, t, buf_sz, dio_tmp;
    int infd, outfd, blocks;
    unsigned char * wrkBuff;
    unsigned char * wrkPos;
    int in_num_sect = 0;
    int out_num_sect = 0;
    int in_sect_sz, out_sect_sz;
    char ebuff[EBUFF_SZ];
    int blocks_per;
    int req_count;
    struct timeval start_tm, end_tm;

    inf[0] = '\0';
    outf[0] = '\0';
    if (argc < 2) {
        usage();
        return 1;
    }

    for(k = 1; k < argc; k++) {
        if (argv[k]) {
            strncpy(str, argv[k], STR_SZ);
	    str[STR_SZ - 1] = '\0';
	}
        else
            continue;
        for(key = str, buf = key; *buf && *buf != '=';)
            buf++;
        if (*buf)
            *buf++ = '\0';
        if (strcmp(key,"if") == 0)
            strncpy(inf, buf, INOUTF_SZ);
        else if (strcmp(key,"of") == 0)
            strncpy(outf, buf, INOUTF_SZ);
        else if (0 == strcmp(key,"ibs"))
            ibs = get_num(buf);
        else if (0 == strcmp(key,"obs"))
            obs = get_num(buf);
        else if (0 == strcmp(key,"bs"))
            bs = get_num(buf);
        else if (0 == strcmp(key,"bpt"))
            bpt = get_num(buf);
        else if (0 == strcmp(key,"skip"))
            skip = get_num(buf);
        else if (0 == strcmp(key,"seek"))
            seek = get_num(buf);
        else if (0 == strcmp(key,"count"))
            dd_count = get_num(buf);
        else if (0 == strcmp(key,"dio"))
            dio = get_num(buf);
        else if (0 == strcmp(key,"time"))
            do_time = get_num(buf);
        else if (0 == strcmp(key,"gen"))
            do_gen = get_num(buf);
        else if (0 == strcmp(key,"cdbsz"))
            scsi_cdbsz = get_num(buf);
        else if (0 == strcmp(key,"fua"))
            fua_mode = get_num(buf);
        else if (0 == strcmp(key,"sync"))
            do_sync = get_num(buf);
        else if (0 == strncmp(key, "--vers", 6)) {
            fprintf(stderr, ME "for Linux sg version 3 driver: %s\n",
                    version_str);
            return 0;
        }
        else {
            fprintf(stderr, "Unrecognized argument '%s'\n", key);
            usage();
            return 1;
        }
    }
    if (bs <= 0) {
        bs = DEF_BLOCK_SIZE;
        fprintf(stderr, "Assume default 'bs' (block size) of %d bytes\n", bs);
    }
    if ((ibs && (ibs != bs)) || (obs && (obs != bs))) {
        fprintf(stderr, "If 'ibs' or 'obs' given must be same as 'bs'\n");
        usage();
        return 1;
    }
    if ((skip < 0) || (seek < 0)) {
        fprintf(stderr, "skip and seek cannot be negative\n");
        return 1;
    }
#ifdef SG_DEBUG
    fprintf(stderr, ME "if=%s skip=%d of=%s seek=%d count=%d\n",
           inf, skip, outf, seek, dd_count);
#endif
    install_handler (SIGINT, interrupt_handler);
    install_handler (SIGQUIT, interrupt_handler);
    install_handler (SIGPIPE, interrupt_handler);
    install_handler (SIGUSR1, siginfo_handler);

    infd = STDIN_FILENO;
    outfd = STDOUT_FILENO;
    if (inf[0] && ('-' != inf[0])) {
	in_type = dd_filetype(inf);

	if (FT_SG == in_type) {
	    if ((infd = open(inf, O_RDWR)) < 0) {
                snprintf(ebuff, EBUFF_SZ,
			 ME "could not open %s for sg reading", inf);
                perror(ebuff);
                return 1;
            }
	    t = bs * bpt;
            res = ioctl(infd, SG_SET_RESERVED_SIZE, &t);
            if (res < 0)
                perror(ME "SG_SET_RESERVED_SIZE error");
            res = ioctl(infd, SG_GET_VERSION_NUM, &t);
            if ((res < 0) || (t < 30000)) {
                fprintf(stderr, ME "sg driver prior to 3.x.y\n");
                return 1;
            }
        }
        if (FT_SG != in_type) {
            if ((infd = open(inf, O_RDONLY)) < 0) {
                snprintf(ebuff, EBUFF_SZ,
			 ME "could not open %s for reading", inf);
                perror(ebuff);
                return 1;
            }
            else if (skip > 0) {
                llse_loff_t offset = skip;

                offset *= bs;       /* could exceed 32 bits here! */
                if (llse_llseek(infd, offset, SEEK_SET) < 0) {
                    snprintf(ebuff, EBUFF_SZ,
			ME "couldn't skip to required position on %s", inf);
                    perror(ebuff);
                    return 1;
                }
            }
        }
    }

    if (outf[0] && ('-' != outf[0])) {
	out_type = dd_filetype(outf);

	if (FT_SG == out_type) {
	    if ((outfd = open(outf, O_RDWR)) < 0) {
                snprintf(ebuff, EBUFF_SZ,
			 ME "could not open %s for sg writing", outf);
                perror(ebuff);
                return 1;
            }
            t = bs * bpt;
            res = ioctl(outfd, SG_SET_RESERVED_SIZE, &t);
            if (res < 0)
                perror(ME "SG_SET_RESERVED_SIZE error");
            res = ioctl(outfd, SG_GET_VERSION_NUM, &t);
            if ((res < 0) || (t < 30000)) {
                fprintf(stderr, ME "sg driver prior to 3.x.y\n");
                return 1;
            }
        }
	else {
	    if (FT_OTHER == out_type) {
		if ((outfd = open(outf, O_WRONLY | O_CREAT, 0666)) < 0) {
		    snprintf(ebuff, EBUFF_SZ,
			    ME "could not open %s for writing", outf);
		    perror(ebuff);
		    return 1;
		}
	    }
	    else {
		if ((outfd = open(outf, O_WRONLY)) < 0) {
		    snprintf(ebuff, EBUFF_SZ,
			    ME "could not open %s for raw writing", outf);
		    perror(ebuff);
		    return 1;
		}
	    }
            if (seek > 0) {
                llse_loff_t offset = seek;

                offset *= bs;       /* could exceed 32 bits here! */
                if (llse_llseek(outfd, offset, SEEK_SET) < 0) {
                    snprintf(ebuff, EBUFF_SZ,
			ME "couldn't seek to required position on %s", outf);
                    perror(ebuff);
                    return 1;
                }
            }
        }
    }
    if ((STDIN_FILENO == infd) && (STDOUT_FILENO == outfd)) {
        fprintf(stderr, 
		"Can't have both 'if' as stdin _and_ 'of' as stdout\n");
        return 1;
    }
    if ((FT_OTHER == in_type) && (FT_OTHER == out_type) && !do_gen) {
        fprintf(stderr, "Both 'if' and 'of' can't be ordinary files\n");
        fprintf(stderr, "If you really want this set 'gen=1'\n");
        return 1;
    }
    if (dd_count < 0) {
        if (FT_SG == in_type) {
            res = read_capacity(infd, &in_num_sect, &in_sect_sz);
            if (2 == res) {
                fprintf(stderr, 
			"Unit attention, media changed(in), continuing\n");
                res = read_capacity(infd, &in_num_sect, &in_sect_sz);
            }
            if (0 != res) {
                fprintf(stderr, "Unable to read capacity on %s\n", inf);
                in_num_sect = -1;
            }
            else {
#if 0
                if (0 == in_sect_sz)
                    in_sect_sz = bs;
                else if (in_sect_sz > bs)
                    in_num_sect *=  (in_sect_sz / bs);
                else if (in_sect_sz < bs)
                    in_num_sect /=  (bs / in_sect_sz);
#endif
                if (in_num_sect > skip)
                    in_num_sect -= skip;
            }
        }
        if (FT_SG == out_type) {
            res = read_capacity(outfd, &out_num_sect, &out_sect_sz);
            if (2 == res) {
                fprintf(stderr, 
			"Unit attention, media changed(out), continuing\n");
                res = read_capacity(outfd, &out_num_sect, &out_sect_sz);
            }
            if (0 != res) {
                fprintf(stderr, "Unable to read capacity on %s\n", outf);
                out_num_sect = -1;
            }
            else {
                if (out_num_sect > seek)
                    out_num_sect -= seek;
            }
        }
#ifdef SG_DEBUG
    fprintf(stderr, 
	    "Start of loop, count=%d, in_num_sect=%d, out_num_sect=%d\n", 
            dd_count, in_num_sect, out_num_sect);
#endif
        if (in_num_sect > 0) {
            if (out_num_sect > 0)
                dd_count = (in_num_sect > out_num_sect) ? out_num_sect :
                                                       in_num_sect;
            else
                dd_count = in_num_sect;
        }
        else
            dd_count = out_num_sect;
    }
    if (dd_count < 0) {
        fprintf(stderr, "Couldn't calculate count, please give one\n");
        return 1;
    }

    if (dio || (FT_RAW == in_type) || (FT_RAW == out_type)) {
	size_t psz = getpagesize();
	wrkBuff = malloc(bs * bpt + psz);
	if (0 == wrkBuff) {
            fprintf(stderr, "Not enough user memory for raw\n");
            return 1;
        }
	wrkPos = (unsigned char *)(((unsigned long)wrkBuff + psz - 1) &
		                   (~(psz - 1)));
    }
    else {
	wrkBuff = malloc(bs * bpt);
	if (0 == wrkBuff) {
            fprintf(stderr, "Not enough user memory\n");
            return 1;
        }
        wrkPos = wrkBuff;
    }

    blocks_per = bpt;
#ifdef SG_DEBUG
    fprintf(stderr, "Start of loop, count=%d, blocks_per=%d\n", 
	    dd_count, blocks_per);
#endif
    if (do_time) {
        start_tm.tv_sec = 0;
        start_tm.tv_usec = 0;
        gettimeofday(&start_tm, NULL);
    }
    req_count = dd_count;

    while (dd_count > 0) {
        blocks = (dd_count > blocks_per) ? blocks_per : dd_count;
        if (FT_SG == in_type) {
	    int fua = fua_mode & 2;

            dio_tmp = dio;
            res = sg_read(infd, wrkPos, blocks, skip, bs, scsi_cdbsz, fua, 
	    		  &dio_tmp);
            if (1 == res) {     /* ENOMEM, find what's available+try that */
                if (ioctl(infd, SG_GET_RESERVED_SIZE, &buf_sz) < 0) {
                    perror("RESERVED_SIZE ioctls failed");
                    break;
                }
                blocks_per = (buf_sz + bs - 1) / bs;
                blocks = blocks_per;
                fprintf(stderr, 
			"Reducing read to %d blocks per loop\n", blocks_per);
                res = sg_read(infd, wrkPos, blocks, skip, bs, scsi_cdbsz,
			      fua, &dio_tmp);
            }
            else if (2 == res) {
                fprintf(stderr, 
			"Unit attention, media changed, continuing (r)\n");
                res = sg_read(infd, wrkPos, blocks, skip, bs, scsi_cdbsz,
			      fua, &dio_tmp);
            }
            if (0 != res) {
                fprintf(stderr, "sg_read failed, skip=%d\n", skip);
                break;
            }
            else {
                in_full += blocks;
                if (dio && (0 == dio_tmp))
                    dio_incomplete++;
            }
        }
        else {
	    while (((res = read(infd, wrkPos, blocks * bs)) < 0) &&
		   (EINTR == errno))
		;
            if (res < 0) {
                snprintf(ebuff, EBUFF_SZ, ME "reading, skip=%d ", skip);
                perror(ebuff);
                break;
            }
            else if (res < blocks * bs) {
                dd_count = 0;
                blocks = res / bs;
                if ((res % bs) > 0) {
                    blocks++;
                    in_partial++;
                }
            }
            in_full += blocks;
        }

        if (FT_SG == out_type) {
	    int fua = fua_mode & 1;

            dio_tmp = dio;
            res = sg_write(outfd, wrkPos, blocks, seek, bs, scsi_cdbsz,
	    		   fua, &dio_tmp);
            if (1 == res) {     /* ENOMEM, find what's available+try that */
                if (ioctl(outfd, SG_GET_RESERVED_SIZE, &buf_sz) < 0) {
                    perror("RESERVED_SIZE ioctls failed");
                    break;
                }
                blocks_per = (buf_sz + bs - 1) / bs;
                blocks = blocks_per;
                fprintf(stderr, 
			"Reducing write to %d blocks per loop\n", blocks);
                res = sg_write(outfd, wrkPos, blocks, seek, bs, scsi_cdbsz,
			       fua, &dio_tmp);
            }
            else if (2 == res) {
                fprintf(stderr, 
			"Unit attention, media changed, continuing (w)\n");
                res = sg_write(outfd, wrkPos, blocks, seek, bs, scsi_cdbsz,
			       fua, &dio_tmp);
            }
            else if (0 != res) {
                fprintf(stderr, "sg_write failed, seek=%d\n", seek);
                break;
            }
            else {
                out_full += blocks;
                if (dio && (0 == dio_tmp))
                    dio_incomplete++;
            }
        }
        else {
	    while (((res = write(outfd, wrkPos, blocks * bs)) < 0)
		   && (EINTR == errno))
		;
            if (res < 0) {
                snprintf(ebuff, EBUFF_SZ, ME "writing, seek=%d ", seek);
                perror(ebuff);
                break;
            }
            else if (res < blocks * bs) {
                fprintf(stderr, "output file probably full, seek=%d ", seek);
                blocks = res / bs;
                out_full += blocks;
                if ((res % bs) > 0)
                    out_partial++;
                break;
            }
            else
                out_full += blocks;
        }
        if (dd_count > 0)
            dd_count -= blocks;
        skip += blocks;
        seek += blocks;
    }
    if ((do_time) && (start_tm.tv_sec || start_tm.tv_usec)) {
        struct timeval res_tm;
        double a, b;

        gettimeofday(&end_tm, NULL);
        res_tm.tv_sec = end_tm.tv_sec - start_tm.tv_sec;
        res_tm.tv_usec = end_tm.tv_usec - start_tm.tv_usec;
        if (res_tm.tv_usec < 0) {
            --res_tm.tv_sec;
            res_tm.tv_usec += 1000000;
        }
        a = res_tm.tv_sec;
        a += (0.000001 * res_tm.tv_usec);
        b = (double)bs * (req_count - dd_count);
        printf("time to transfer data was %d.%06d secs",
               (int)res_tm.tv_sec, (int)res_tm.tv_usec);
        if ((a > 0.00001) && (b > 511))
            printf(", %.2f MB/sec\n", b / (a * 1000000.0));
        else
            printf("\n");
    }
    if (do_sync) {
	if (FT_SG == out_type) {
	    fprintf(stderr, ">> Synchronizing cache on %s\n", outf);
            res = sync_cache(outfd);
            if (2 == res) {
                fprintf(stderr, 
			"Unit attention, media changed(in), continuing\n");
                res = sync_cache(outfd);
            }
            if (0 != res)
                fprintf(stderr, "Unable to synchronize cache\n");
	}
    }
    free(wrkBuff);
    if (STDIN_FILENO != infd)
        close(infd);
    if (STDOUT_FILENO != outfd)
        close(outfd);
    res = 0;
    if (0 != dd_count) {
        fprintf(stderr, "Some error occurred,");
	res = 2;
    }
    print_stats();
    if (dio_incomplete) {
    	int fd;
	char c;

        fprintf(stderr, ">> Direct IO requested but incomplete %d times\n", 
                dio_incomplete);
	if ((fd = open(proc_allow_dio, O_RDONLY)) >= 0) {
	    if (1 == read(fd, &c, 1)) {
	    	if ('0' == c)
		    fprintf(stderr, ">>> %s set to '0' but should be set "
		    	    "to '1' for direct IO\n", proc_allow_dio);
	    }
	    close(fd);
	}
    }
    if (sum_of_resids)
        fprintf(stderr, ">> Non-zero sum of residual counts=%d\n", 
		sum_of_resids);
    return res;
}