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/*
* Copyright (c) 2017 Denys Vlasenko <vda.linux@googlemail.com>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config RESUME
//config: bool "resume"
//config: default y
//config: help
//config: Resume from saved "suspend-to-disk" image
//applet:IF_RESUME(APPLET_NOEXEC(resume, resume, BB_DIR_BIN, BB_SUID_DROP, resume))
//kbuild:lib-$(CONFIG_RESUME) += resume.o
#include "libbb.h"
/* This is a NOEXEC applet. Be very careful! */
/* name_to_dev_t() in klibc-utils supports extended device name formats,
* apart from the usual case where /dev/NAME already exists.
*
* - device number in hexadecimal represents itself (in dev_t layout).
* - device number in major:minor decimal represents itself.
* - if block device (or partition) with this name is found in sysfs.
* - if /dev/ prefix is not given, it is assumed.
*
* klibc-utils also recognizes these, but they don't work
* for "resume" tool purposes (thus we don't support them (yet?)):
* - /dev/nfs
* - /dev/ram (alias to /dev/ram0)
* - /dev/mtd
*/
static dev_t name_to_dev_t(const char *devname)
{
char devfile[sizeof(int)*3 * 2 + 4];
char *sysname;
unsigned major_num, minor_num;
struct stat st;
int r;
if (strncmp(devname, "/dev/", 5) != 0) {
char *cptr;
cptr = strchr(devname, ':');
if (cptr) {
/* Colon-separated decimal device number? */
*cptr = '\0';
major_num = bb_strtou(devname, NULL, 10);
if (!errno)
minor_num = bb_strtou(cptr + 1, NULL, 10);
*cptr = ':';
if (!errno)
return makedev(major_num, minor_num);
} else {
/* Hexadecimal device number? */
dev_t res = (dev_t) bb_strtoul(devname, NULL, 16);
if (!errno)
return res;
}
devname = xasprintf("/dev/%s", devname);
}
/* Now devname is always "/dev/FOO" */
if (stat(devname, &st) == 0 && S_ISBLK(st.st_mode))
return st.st_rdev;
/* Full blockdevs as well as partitions may be visible
* in /sys/class/block/ even if /dev is not populated.
*/
sysname = xasprintf("/sys/class/block/%s/dev", devname + 5);
r = open_read_close(sysname, devfile, sizeof(devfile) - 1);
//free(sysname);
if (r > 0) {
devfile[r] = '\0';
if (sscanf(devfile, "%u:%u", &major_num, &minor_num) == 2) {
return makedev(major_num, minor_num);
}
}
return (dev_t) 0;
}
//usage:#define resume_trivial_usage
//usage: "BLOCKDEV [OFFSET]"
//usage:#define resume_full_usage "\n"
//usage: "\n""Restore system state from 'suspend-to-disk' data in BLOCKDEV"
int resume_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int resume_main(int argc UNUSED_PARAM, char **argv)
{
unsigned long long ofs;
dev_t resume_device;
char *s;
int fd;
argv++;
if (!argv[0])
bb_show_usage();
resume_device = name_to_dev_t(argv[0]);
if (major(resume_device) == 0) {
bb_error_msg_and_die("invalid resume device: %s", argv[0]);
}
ofs = (argv[1] ? xstrtoull(argv[1], 0) : 0);
fd = xopen("/sys/power/resume", O_WRONLY);
s = xasprintf("%u:%u:%llu", major(resume_device), minor(resume_device), ofs);
xwrite_str(fd, s);
/* if write() returns, resume did not succeed */
return EXIT_FAILURE; /* klibc-utils exits -1 aka 255 */
}
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