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/* A utility program originally written for the Linux OS SCSI subsystem.
* Copyright (C) 2021 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.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*
* This program is experimental. It allows the SG_CTL_FLAGM_SNAP_DEV
* variant of ioctl(SG_SET_GET_EXTENDED) to be called. This assumes
* a Linux sg driver whose version number > 4.00.30 .
*/
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stdbool.h>
#include <string.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <getopt.h>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifndef HAVE_LINUX_SG_V4_HDR
/* Kernel uapi header contain __user decorations on user space pointers
* to indicate they are unsafe in the kernel space. However glibc takes
* all those __user decorations out from headers in /usr/include/linux .
* So to stop compile errors when directly importing include/uapi/scsi/sg.h
* undef __user before doing that include. */
#define __user
/* Want to block the original sg.h header from also being included. That
* causes lots of multiple definition errors. This will only work if this
* header is included _before_ the original sg.h header. */
#define _SCSI_GENERIC_H /* original kernel header guard */
#define _SCSI_SG_H /* glibc header guard */
#include "uapi_sg.h" /* local copy of include/uapi/scsi/sg.h */
#else
#define __user
#endif /* end of: ifndef HAVE_LINUX_SG_V4_HDR */
#include "sg_lib.h"
#include "sg_pr2serr.h"
#define ME "sg_take_snap: "
static const char * version_str = "1.01 20210403";
#define SG_TAKE_MAX_DEVS 16
static const char *dev_arr[SG_TAKE_MAX_DEVS];
static int next_vacant_dev_idx = 0;
static struct option long_options[] = {
{"clear", no_argument, 0, 'c'},
{"help", no_argument, 0, 'h'},
{"verbose", no_argument, 0, 'v'},
{"version", no_argument, 0, 'V'},
{0, 0, 0, 0},
};
static void
usage(void)
{
pr2serr("Usage: sg_take_snap [--clear] [--help] [--verbose] [--version] "
"DEVICE*\n"
" where:\n"
" --clear|-c set 'clear_first' flag; otherwise appends\n"
" --help|-h print usage information then exit\n"
" --verbose|-v increase the level of verbosity\n"
" --version|-V print version number then exit\n\n"
"Use ioctl(SG_SET_GET_EXTENDED(SG_CTL_FLAGM_SNAP_DEV)) to take "
"snap .\nThe output is placed in /sys/kernel/debug/scsi_generic/"
"snapped and needs\nroot permissions to read. Requires a Linux "
"sg driver version > 4.00.30 .\nOne or more DEVICEs can be "
"given. Note: sending the ioctl to do this\ncreates some "
"'noise' in the output\n"
);
}
int main(int argc, char * argv[])
{
bool clear_first = false;
int c, k, sg_fd, res;
int ret = 0;
int verbose = 0;
const char * device_name = NULL;
struct sg_extended_info sei;
struct sg_extended_info * seip;
while (1) {
int option_index = 0;
c = getopt_long(argc, argv, "chvV", long_options, &option_index);
if (c == -1)
break;
switch (c) {
case 'c':
clear_first = true;
break;
case 'h':
usage();
return 0;
case 'v':
++verbose;
break;
case 'V':
pr2serr(ME "version: %s\n", version_str);
return 0;
default:
pr2serr("unrecognised option code 0x%x ??\n", c);
usage();
return SG_LIB_SYNTAX_ERROR;
}
}
if (optind < argc) {
for (; optind < argc; ++optind) {
if (next_vacant_dev_idx < SG_TAKE_MAX_DEVS) {
dev_arr[next_vacant_dev_idx] = argv[optind];
++next_vacant_dev_idx;
} else if (next_vacant_dev_idx == SG_TAKE_MAX_DEVS) {
pr2serr("Maximum of %d DEVICEs on command line\n",
next_vacant_dev_idx);
usage();
return SG_LIB_SYNTAX_ERROR;
} else {
pr2serr("something is wrong ...\n");
return SG_LIB_SYNTAX_ERROR;
}
}
}
if (NULL == dev_arr[0]) {
pr2serr("Need at least one DEVICE name. Use '--help' to see "
"usage.\n");
return SG_LIB_SYNTAX_ERROR;
}
for (k = 0; k < next_vacant_dev_idx; ++k) {
device_name = dev_arr[k];
sg_fd = open(device_name, O_RDWR | O_NONBLOCK);
if (sg_fd < 0) {
int err = errno;
ret = sg_convert_errno(err);
pr2serr(ME "open error: %s: ", device_name);
perror("");
sg_fd = -1;
goto fini;
}
if (0 == k) {
int t;
res = ioctl(sg_fd, SG_GET_VERSION_NUM, &t);
if ((res < 0) || (t < 30000)) {
pr2serr("sg driver prior to 3.0.00\n");
ret = SG_LIB_FILE_ERROR;
goto fini;
}
if (verbose) {
pr2serr("sg driver version: %d.%02d.%02d\n",
t / 10000, (t % 10000) / 100, t % 100);
}
if (t < 40000) {
pr2serr("Warning: sg driver prior to 4.0.00\n");
ret = SG_LIB_FILE_ERROR;
goto fini;
} else if (t < 40045) {
pr2serr("Warning: sg driver prior to 4.0.45\n");
ret = SG_LIB_FILE_ERROR;
goto fini;
}
}
seip = &sei;
memset(seip, 0, sizeof(*seip));
seip->sei_wr_mask |= SG_SEIM_CTL_FLAGS;
seip->sei_rd_mask |= SG_SEIM_CTL_FLAGS;
seip->ctl_flags_wr_mask |= SG_CTL_FLAGM_SNAP_DEV;
if (clear_first) /* ... else 0 (due to memset) --> append */
seip->ctl_flags |= SG_CTL_FLAGM_SNAP_DEV;
if (ioctl(sg_fd, SG_SET_GET_EXTENDED, seip) < 0) {
pr2serr("ioctl(SG_SET_GET_EXTENDED(SG_CTL_FLAGM_SNAP_DEV)), %s "
"failed errno=%d %s\n", device_name, errno,
strerror(errno));
ret = SG_LIB_FILE_ERROR;
goto fini;
}
if (verbose)
pr2serr("ioctl(%s, SG_SET_GET_EXTENDED(SG_CTL_FLAGM_SNAP_DEV)) "
"ok\n", device_name);
res = close(sg_fd);
sg_fd = -1;
if (res < 0) {
pr2serr("close errno=%d on %s\n", errno, device_name);
ret = res;
goto fini;
}
}
fini:
if (sg_fd >= 0) {
res = close(sg_fd);
if (res < 0) {
res = sg_convert_errno(errno);
perror(ME "close error");
if (0 == ret)
ret = res;
}
}
return (ret >= 0) ? ret : SG_LIB_CAT_OTHER;
}
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