examples/sg_simple4.c

#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include "sg_lib.h"
#include "sg_io_linux.h"

/* This is a simple program executing a SCSI INQUIRY command and a
   TEST UNIT READY command using the SCSI generic (sg) driver
   This variant shows mmap-ed IO being used to read the data returned
   by the INQUIRY command.

*  Copyright (C) 2001-2016 D. Gilbert
*  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.

   Invocation: sg_simple4 [-x] <sg_device>

   Version 1.02 (20160528)

6 byte INQUIRY command:
[0x12][   |lu][pg cde][res   ][al len][cntrl ]

6 byte TEST UNIT READY command:
[0x00][   |lu][res   ][res   ][res   ][res   ]

*/

#ifndef SG_FLAG_MMAP_IO
#define SG_FLAG_MMAP_IO 4
#endif  /* since /usr/include/scsi/sg.h doesn't know about this yet */

#define INQ_REPLY_LEN 96
#define INQ_CMD_LEN 6
#define TUR_CMD_LEN 6

#define EBUFF_SZ 256

int main(int argc, char * argv[])
{
    int sg_fd, k, ok;
    unsigned char inq_cdb[INQ_CMD_LEN] =
                                {0x12, 0, 0, 0, INQ_REPLY_LEN, 0};
    unsigned char tur_cdb[TUR_CMD_LEN] =
                                {0x00, 0, 0, 0, 0, 0};
    unsigned char * inqBuff;
    unsigned char * inqBuff2;
    sg_io_hdr_t io_hdr;
    char * file_name = 0;
    char ebuff[EBUFF_SZ];
    unsigned char sense_buffer[32];
    int do_extra = 0;

    for (k = 1; k < argc; ++k) {
        if (0 == memcmp("-x", argv[k], 2))
            do_extra = 1;
        else if (*argv[k] == '-') {
            printf("Unrecognized switch: %s\n", argv[k]);
            file_name = 0;
            break;
        }
        else if (0 == file_name)
            file_name = argv[k];
        else {
            printf("too many arguments\n");
            file_name = 0;
            break;
        }
    }
    if (0 == file_name) {
        printf("Usage: 'sg_simple4 [-x] <sg_device>'\n");
        return 1;
    }

    /* N.B. An access mode of O_RDWR is required for some SCSI commands */
    if ((sg_fd = open(file_name, O_RDWR)) < 0) {
        snprintf(ebuff, EBUFF_SZ,
                 "sg_simple4: error opening file: %s", file_name);
        perror(ebuff);
        return 1;
    }
    /* Just to be safe, check we have a new sg device by trying an ioctl */
    if ((ioctl(sg_fd, SG_GET_VERSION_NUM, &k) < 0) || (k < 30122)) {
        printf("sg_simple4: %s needs sg driver version >= 3.1.22\n",
               file_name);
        close(sg_fd);
        return 1;
    }

    /* since I know this program will only read from inqBuff then I use
       PROT_READ rather than PROT_READ | PROT_WRITE */
    inqBuff = (unsigned char *)mmap(NULL, 8000, PROT_READ | PROT_WRITE,
                                    MAP_SHARED, sg_fd, 0);
    if (MAP_FAILED == inqBuff) {
        snprintf(ebuff, EBUFF_SZ, "sg_simple4: error using mmap() on "
                 "file: %s", file_name);
        perror(ebuff);
        return 1;
    }
    if (inqBuff[0])
        printf("non-null char at inqBuff[0]\n");
    if (inqBuff[5000])
        printf("non-null char at inqBuff[5000]\n");

    /* Prepare INQUIRY command */
    memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
    io_hdr.interface_id = 'S';
    io_hdr.cmd_len = sizeof(inq_cdb);
    /* io_hdr.iovec_count = 0; */  /* memset takes care of this */
    io_hdr.mx_sb_len = sizeof(sense_buffer);
    io_hdr.dxfer_direction = SG_DXFER_FROM_DEV;
    io_hdr.dxfer_len = INQ_REPLY_LEN;
    /* io_hdr.dxferp = inqBuff; // ignored in mmap-ed IO */
    io_hdr.cmdp = inq_cdb;
    io_hdr.sbp = sense_buffer;
    io_hdr.timeout = 20000;     /* 20000 millisecs == 20 seconds */
    io_hdr.flags = SG_FLAG_MMAP_IO;
    /* io_hdr.pack_id = 0; */
    /* io_hdr.usr_ptr = NULL; */

    if (ioctl(sg_fd, SG_IO, &io_hdr) < 0) {
        perror("sg_simple4: Inquiry SG_IO ioctl error");
        close(sg_fd);
        return 1;
    }

    /* now for the error processing */
    ok = 0;
    switch (sg_err_category3(&io_hdr)) {
    case SG_LIB_CAT_CLEAN:
        ok = 1;
        break;
    case SG_LIB_CAT_RECOVERED:
        printf("Recovered error on INQUIRY, continuing\n");
        ok = 1;
        break;
    default: /* won't bother decoding other categories */
        sg_chk_n_print3("INQUIRY command error", &io_hdr, 1);
        break;
    }

    if (ok) { /* output result if it is available */
        char * p = (char *)inqBuff;
        int f = (int)*(p + 7);
        printf("Some of the INQUIRY command's results:\n");
        printf("    %.8s  %.16s  %.4s  ", p + 8, p + 16, p + 32);
        printf("[wide=%d sync=%d cmdque=%d sftre=%d]\n",
               !!(f & 0x20), !!(f & 0x10), !!(f & 2), !!(f & 1));
        /* Extra info, not necessary to look at */
        if (do_extra)
            printf("INQUIRY duration=%u millisecs, resid=%d, msg_status=%d\n",
                   io_hdr.duration, io_hdr.resid, (int)io_hdr.msg_status);
    }


    /* Prepare TEST UNIT READY command */
    memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
    io_hdr.interface_id = 'S';
    io_hdr.cmd_len = sizeof(tur_cdb);
    io_hdr.mx_sb_len = sizeof(sense_buffer);
    io_hdr.dxfer_direction = SG_DXFER_NONE;
    io_hdr.cmdp = tur_cdb;
    io_hdr.sbp = sense_buffer;
    io_hdr.timeout = 20000;     /* 20000 millisecs == 20 seconds */

    if (ioctl(sg_fd, SG_IO, &io_hdr) < 0) {
        perror("sg_simple4: Test Unit Ready SG_IO ioctl error");
        close(sg_fd);
        return 1;
    }

    /* now for the error processing */
    ok = 0;
    switch (sg_err_category3(&io_hdr)) {
    case SG_LIB_CAT_CLEAN:
        ok = 1;
        break;
    case SG_LIB_CAT_RECOVERED:
        printf("Recovered error on Test Unit Ready, continuing\n");
        ok = 1;
        break;
    default: /* won't bother decoding other categories */
        sg_chk_n_print3("Test Unit Ready command error", &io_hdr, 1);
        break;
    }

    if (ok)
        printf("Test Unit Ready successful so unit is ready!\n");
    else
        printf("Test Unit Ready failed so unit may _not_ be ready!\n");

    if (do_extra)
        printf("TEST UNIT READY duration=%u millisecs, resid=%d, "
               "msg_status=%d\n",
               io_hdr.duration, io_hdr.resid, (int)io_hdr.msg_status);

    /* munmap(inqBuff, 8000); */
    /* could call munmap(inqBuff, INQ_REPLY_LEN) here but following close()
       causes this too happen anyway */
#if 1
    inqBuff2 = (unsigned char *)mmap(NULL, 8000, PROT_READ | PROT_WRITE,
                                     MAP_SHARED, sg_fd, 0);
    if (MAP_FAILED == inqBuff2) {
        snprintf(ebuff, EBUFF_SZ, "sg_simple4: error using mmap() 2 on "
                 "file: %s", file_name);
        perror(ebuff);
        return 1;
    }
    if (inqBuff2[0])
        printf("non-null char at inqBuff2[0]\n");
    if (inqBuff2[5000])
        printf("non-null char at inqBuff2[5000]\n");
    {
        pid_t pid;
        pid = fork();
        if (pid) {
            inqBuff2[5000] = 33;
            munmap(inqBuff, 8000);
            sleep(3);
        }
        else {
            inqBuff[5000] = 0xaa;
            munmap(inqBuff, 8000);
            sleep(1);
        }
    }
#endif
    close(sg_fd);
    return 0;
}