Get the process name of pid

Question

Related:
Process name from its pid in linux
Get pid of the process which has triggered some signal

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>

const char* get_process_name_by_pid(const int pid)
{
    char* name = (char*)calloc(1024,sizeof(char));
    if(name){
        sprintf(name, "/proc/%d/cmdline",pid);
        FILE* f = fopen(name,"r");
        if(f){
            size_t size;
            size = fread(name, sizeof(char), 1024, f);
            if(size>0){
                if('\n'==name[size-1])
                    name[size-1]='\0';
            }
            fclose(f);
        }
    }
    return name;
}



static void my_handler(int signum, siginfo_t *siginfo, void *context) {
    printf("Got signal '%d' from process '%d' of user '%d' (%s)\n",
        signum, siginfo->si_pid, siginfo->si_uid, get_process_name_by_pid(siginfo->si_uid));
}

int main(void) {
    struct sigaction act;
    memset(&act, '\0', sizeof(act));
    act.sa_sigaction = &my_handler;
    act.sa_flags = SA_SIGINFO;
    sigaction(SIGUSR1, &act, NULL);
    printf("Hi, my pid is %d\ntalk to me with 'kill -SIGUSR1 %d'\n", getpid(), getpid());
    while(1)
        sleep(1000);
    return 0;
}

I am trying to catch who sent the signal to a program.

This successfully shows the pid of the signal sender but I would also like to know the process name.

I've tried with the function get_process_name_by_pid() but it doesn seem to work
QUESTION: What can i do to see the process name?

Im running oh RHEL6.6

Answer 1

You are passing in the wrong argument to your get_process_name_by_pid() function. That functions needs a process id, you're passing it the user id. You want:

get_process_name_by_pid(siginfo->si_pid)