/* Remounting filesystems read-only is difficult when there are files
* opened for writing or pending deletes on the filesystem. There is
* no way to force the remount with the mount(2) syscall. The magic sysrq
* 'u' command does an emergency remount read-only on all writable filesystems
* that have a block device (i.e. not tmpfs filesystems) by calling
* emergency_remount(), which knows how to force the remount to read-only.
* Unfortunately, that is asynchronous, and just schedules the work and
* returns. The best way to determine if it is done is to read /proc/mounts
* repeatedly until there are no more writable filesystems mounted on
* block devices.
*/
void emergency_remount_ro(void)
{
int fd, cnt = 0;
sync();
/* Trigger the remount of the filesystems as read-only,
* which also marks them clean.
*/
fd = open("/proc/sysrq-trigger", O_WRONLY|O_CLOEXEC);
if (fd < 0) {
return;
}
write(fd, "u", 1);
close(fd);
/* Now poll /proc/mounts till it's done */
while (!remount_ro_done() && (cnt < 3600)) {
usleep(100000);
cnt++;
}
return;
}
/* Remounting filesystems read-only is difficult when there are files
* opened for writing or pending deletes on the filesystem. There is
* no way to force the remount with the mount(2) syscall. The magic sysrq
* 'u' command does an emergency remount read-only on all writable filesystems
* that have a block device (i.e. not tmpfs filesystems) by calling
* emergency_remount(), which knows how to force the remount to read-only.
* Unfortunately, that is asynchronous, and just schedules the work and
* returns. The best way to determine if it is done is to read /proc/mounts
* repeatedly until there are no more writable filesystems mounted on
* block devices.
*/
static void remount_ro(void)
{
int fd, cnt = 0;
/* Trigger the remount of the filesystems as read-only,
* which also marks them clean.
*/
fd = open("/proc/sysrq-trigger", O_WRONLY);
if (fd < 0) {
return;
}
write(fd, "u", 1);
close(fd);
/* Now poll /proc/mounts till it's done */
#ifdef STE_HARDWARE
while (!remount_ro_done() && (cnt < 50)) {
#else
while (!remount_ro_done() && (cnt < 3600)) {
#endif
usleep(100000);
cnt++;
}
return;
}
int android_reboot(int cmd, int flags, char *arg)
{
int ret = 0;
int reason = -1;
#ifdef RECOVERY_PRE_COMMAND
if (cmd == (int) ANDROID_RB_RESTART2) {
if (arg && strlen(arg) > 0) {
char cmd[PATH_MAX];
sprintf(cmd, RECOVERY_PRE_COMMAND " %s", arg);
system(cmd);
}
}
#endif
sync();
remount_ro();
switch (cmd) {
case ANDROID_RB_RESTART:
reason = RB_AUTOBOOT;
break;
case ANDROID_RB_POWEROFF:
ret = reboot(RB_POWER_OFF);
return ret;
case ANDROID_RB_RESTART2:
// REBOOT_MAGIC
break;
default:
return -1;
}
#ifdef RECOVERY_PRE_COMMAND_CLEAR_REASON
reason = RB_AUTOBOOT;
#endif
if (reason != -1)
ret = reboot(reason);
else
ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, arg);
return ret;
}