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/*
* mts-wait-for-cell-reset
*
* Block signal
* If not in reset, exit
* Register with mts-io for reset
* If not in reset, exit
* Suspend process for signal
* If signal occurs, exit
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>
const char *name = "mts-wait-for-cell-reset";
const int RST_SIG=SIGUSR2; // Wait for this signal
const char *MONITOR="/sys/devices/platform/mts-io/radio-reset-monitor";
const char *RADIO_DISCOVERY="/sys/devices/platform/mts-io/radio-udev-discovery";
/* Return 0 if Cellular modem is being reset
* Return 1 if Cellular modem is not being reset
*/
int
not_reset(const char *attr_name)
{
int not_in_reset, result;
char buf[256];
int discovery;
discovery = open(attr_name,O_RDONLY);
if (discovery == -1) {
fprintf(stderr,"FAILED: %s cannot open attribute %s: %s\n",name,attr_name,strerror(errno));
exit(1);
}
result = read(discovery,buf,sizeof buf);
if (result > 0)
not_in_reset = atoi(buf);
else if (result == 0) {
fprintf(stderr,"FAILED: %s attribute %s has no state\n",name,attr_name);
exit(1);
} else {
fprintf(stderr,"FAILED: %s attribute %s error: %s\n",name,attr_name,strerror(errno));
exit(1);
}
close(discovery);
return not_in_reset;
}
void
handler(int sig)
{
/* Normal way out of this program
* exit not safe from signal handler so
* use _exit()
*/
_exit(0);
}
int
main(int argc, char *argv[])
{
sigset_t blockedset,nullset;
int monitor;
int result;
char buf[128];
struct sigaction action;
memset(&action,0,sizeof action);
action.sa_handler = handler;
memset(&blockedset,0,sizeof blockedset);
sigaddset(&blockedset,RST_SIG);
memset(&nullset,0,sizeof nullset);
sigprocmask(SIG_BLOCK,&blockedset,NULL); // Blocked RST_SIG
sigaction(RST_SIG,&action,NULL);
if (not_reset(RADIO_DISCOVERY))
exit(0); // Not in reset
sprintf(buf,"%d %d",getpid(),RST_SIG);
monitor = open(MONITOR,O_WRONLY);
if (monitor == -1) {
fprintf(stderr,"FAILED: %s cannot open attribute %s: %s\n",name,MONITOR,strerror(errno));
exit(2);
}
result = write(monitor,buf,strlen(buf));
if(result != strlen(buf)) {
if (result == -1) {
fprintf(stderr,"FAILED: %s attribute %s write error: %s\n",name,MONITOR,strerror(errno));
exit(3);
}
fprintf(stderr,"FAILED: %s attribute %s incomplete write error: %d/%d\n",name,MONITOR,result,(int)strlen(buf));
exit(4);
}
close(monitor);
if (not_reset(RADIO_DISCOVERY))
exit(0);
sigsuspend(&nullset); // Allow all signals
/* NOTREACHED */
}
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