How to execute a different binary on run-time in Contiki OS? - c

Question

I am trying to make a sensor that runs on Contiki OS to execute a new binary and replace the current one, if an event occurs.
I am using Cooja simulator and sky note and I uploaded the binary into the coffee file system of the node(using cooja script) and I want to execute the hello-world.ce
To compile my current program(reboot.c) that i will dynamicaly load a module from I used the following commands:
make TARGET=sky clean CLEAN=symbols.?
make reboot.sky TARGET=sky
make CORE=reboot.sky TARGET=sky reboot.sky
And for the hello-world that will be loaded I used:
make TARGET=sky hello-world.ce
Here is part of my code (reboot.c) from where i am trying to execute hello-world
#include "contiki.h"
#include "core/loader/elfloader.h"
#include "cfs/cfs.h"
PROCESS(hello_world_process, "Reboot process");
AUTOSTART_PROCESSES(&hello_world_process);
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(hello_world_process, ev, data)
{
PROCESS_BEGIN();
int i;
int binFile,ret;
elfloader_init();
binFile=cfs_open("hello-world.ce",CFS_READ);
printf("cfs_open:%d\n",binFile); //returns 0 so the file is opened
ret=elfloader_load(binFile);
cfs_close(binFile);
printf("loader returned: %d\n",ret); //returns 0 ->meaning everything is ok
if(ret == ELFLOADER_OK){
printf("elf OK\n");
for(i=0; elfloader_autostart_processes[i] != NULL; i++) {
printf("exec: starting process %s. \n", elfloader_autostart_processes[i]->name);
}
autostart_start(elfloader_autostart_processes);
}
printf("end of rebooting program\n”);
PROCESS_END();
}
It seems that the elfloader_autostart_processes is set to null since the print statement is not executed in the for loop. The program continues and prints "end of rebooting program" and I was expecting it to print hello-world as an indicator that the binary has been loaded and started.
Can you provide any help?

Answer 1

I manage to achieve it using another build in library of Contiki. Specifically I used shell-exec.c that is responsible to execute files and I gave it as an argument the file that I wanted to be executed on run-time. I used a Cooja script to upload the file on the sensor in Cooja simulator.
#include "contiki.h"
#include "shell-exec.c"
#include "serial-shell.h"
#include "cfs/cfs.h"
#include <stdio.h> /* For printf() */
/*---------------------------------------------------------------------------*/
PROCESS(rebooting, "Reboot process");
AUTOSTART_PROCESSES(&rebooting);
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(rebooting, ev, data)
{
PROCESS_BEGIN();
static struct etimer et;
/* Allow some time for the file to upload using cooja. */
etimer_set(&et, 10 * CLOCK_SECOND);
PROCESS_WAIT_UNTIL(etimer_expired(&et));
process_start(&shell_exec_process,"hello-world.ce\0");
PROCESS_END();
}
Cooja Script
WAIT_UNTIL(msg.startsWith('Starting'));
log.log("Mote started\n");
mymote = mote; /* store mote reference */
fs = mote.getFilesystem();
DIR="~/hello-world"; /* Directory that the binary is stored in the host machine running cooja */
mote_file=DIR+ "hello-world.ce";
ret=fs.insertFile(mote_file);
log.log("inserted");