此附录包含一个示例程序。它是 sg3_utils 包中 sg_simple2.c 的简化版本。它向指定的 sg 设备发送 SCSI INQUIRY 命令，并打印出一些响应或输出错误信息。 希望显示错误处理不会掩盖所要说明的内容。
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <scsi/sg.h> /* take care: fetches glibc's /usr/include/scsi/sg.h */
/* This is a simple program executing a SCSI INQUIRY command using the
sg_io_hdr interface of the SCSI generic (sg) driver.
* Copyright (C) 2001 D. Gilbert
* This program is free software. Version 1.01 (20020226)
*/
#define INQ_REPLY_LEN 96
#define INQ_CMD_CODE 0x12
#define INQ_CMD_LEN 6
int main(int argc, char * argv[])
{
int sg_fd, k;
unsigned char inqCmdBlk[INQ_CMD_LEN] =
{INQ_CMD_CODE, 0, 0, 0, INQ_REPLY_LEN, 0};
/* This is a "standard" SCSI INQUIRY command. It is standard because the
* CMDDT and EVPD bits (in the second byte) are zero. All SCSI targets
* should respond promptly to a standard INQUIRY */
unsigned char inqBuff[INQ_REPLY_LEN];
unsigned char sense_buffer[32];
sg_io_hdr_t io_hdr;
if (2 != argc) {
printf("Usage: 'sg_simple0 <sg_device>'\n");
return 1;
}
if ((sg_fd = open(argv[1], O_RDONLY)) < 0) {
/* Note that most SCSI commands require the O_RDWR flag to be set */
perror("error opening given file name");
return 1;
}
/* It is prudent to check we have a sg device by trying an ioctl */
if ((ioctl(sg_fd, SG_GET_VERSION_NUM, &k) < 0) || (k < 30000)) {
printf("%s is not an sg device, or old sg driver\n", argv[1]);
return 1;
}
/* Prepare INQUIRY command */
memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
io_hdr.interface_id = 'S';
io_hdr.cmd_len = sizeof(inqCmdBlk);
/* 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;
io_hdr.cmdp = inqCmdBlk;
io_hdr.sbp = sense_buffer;
io_hdr.timeout = 20000; /* 20000 millisecs == 20 seconds */
/* io_hdr.flags = 0; */ /* take defaults: indirect IO, etc */
/* io_hdr.pack_id = 0; */
/* io_hdr.usr_ptr = NULL; */
if (ioctl(sg_fd, SG_IO, &io_hdr) < 0) {
perror("sg_simple0: Inquiry SG_IO ioctl error");
return 1;
}
/* now for the error processing */
if ((io_hdr.info & SG_INFO_OK_MASK) != SG_INFO_OK) {
if (io_hdr.sb_len_wr > 0) {
printf("INQUIRY sense data: ");
for (k = 0; k < io_hdr.sb_len_wr; ++k) {
if ((k > 0) && (0 == (k % 10)))
printf("\n ");
printf("0x%02x ", sense_buffer[k]);
}
printf("\n");
}
if (io_hdr.masked_status)
printf("INQUIRY SCSI status=0x%x\n", io_hdr.status);
if (io_hdr.host_status)
printf("INQUIRY host_status=0x%x\n", io_hdr.host_status);
if (io_hdr.driver_status)
printf("INQUIRY driver_status=0x%x\n", io_hdr.driver_status);
}
else { /* assume INQUIRY response is present */
char * p = (char *)inqBuff;
printf("Some of the INQUIRY command's response:\n");
printf(" %.8s %.16s %.4s\n", p + 8, p + 16, p + 32);
printf("INQUIRY duration=%u millisecs, resid=%d\n",
io_hdr.duration, io_hdr.resid);
}
close(sg_fd);
return 0;
}
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sg_simple4.c 程序是 sg3_utils 包中使用 mmap-ed IO 的示例。 在同一个包的 sg_rbuf.c 中可以找到使用直接 IO 的示例。