C - Last child never reached signal - c

Question

My code forks n processes. When the last process is reached, it sends a message to the top level process via a FIFO to kill all processes. My code works great, except the the last process never reaches my signal and never gets killed by the top process.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/signal.h>
#include <unistd.h>
#include <errno.h>
#include <stdbool.h>
#define MAX_BUF 1024
int *ptr;
int numprocs;
void signal_handler(int sig){
int currpid = getpid();
int lev;
int i;
for(i = 1; i < numprocs; i++){
if(ptr[i] == currpid){
lev = numprocs - i;
break;
}
}
fprintf(stdout,"EXITING: Level %d process with pid=%d, child of ppid=%d.\n", lev, ptr[i], ptr[i-1]);
exit(0);
}
int main(int argc, char **argv){
numprocs = atoi(argv[1]);
int lev = numprocs;
bool x = true;
//create shared memory
const int SIZE = numprocs * sizeof(int);
const char *name = "dleggio1OS";
int shm_fd;
shm_fd = shm_open(name, O_CREAT | O_RDWR, 0666);
ftruncate(shm_fd, SIZE);
ptr = mmap(0, SIZE, PROT_WRITE, MAP_SHARED, shm_fd, 0);
*ptr = getpid();
//create unnamed pipe
int pfds[2];
char buf[30];
if(pipe(pfds) == -1){
perror("pipe");
exit(1);
}
//create fifo
int fd;
char *myfifo = "/tmp/dleggio1fifo";
mkfifo(myfifo, 0666);
pid_t pid = fork();
if(pid == 0){ //first child ..... keep forking
//read unnamed pipe
close(pfds[1]);
if(read(pfds[0], buf, 3) <= 0){
perror("child");
exit(1);
}
int check = atoi(buf);
fprintf(stdout,"ALIVE: Level %d process with pid=%d, child of ppid=%d.\n", check, getpid(), getppid());
//write to shared memory
ptr[numprocs - check] = getpid();
signal(SIGUSR1,signal_handler);
int i;
lev--;
for(i = 2; i < numprocs; i++){
//create named pipe
int pfds[2];
char buf[30];
if(pipe(pfds) == -1){
perror("pipe");
exit(1);
}
lev--;
pid_t pid;
if((pid = fork()) < 0){
perror("fork");
exit(1);
}
else if(pid == 0){
//update shared memory
ptr[i] = getpid();
//read from named pipe
close(pfds[1]);
if(read(pfds[0], buf, 3) <= 0){
perror("child");
exit(1);
}
int check = atoi(buf);
fprintf(stdout,"ALIVE: Level %d process with pid=%d, child of ppid=%d.\n", check, getpid(), getppid());
if(check == 1){
//write to fifo
fd = open(myfifo, O_WRONLY);
write(fd,"leaf",sizeof("leaf"));
close(fd);
unlink(myfifo);
signal(SIGUSR1,signal_handler);
}
signal(SIGUSR1,signal_handler);
}
else{
//write to named pipe
close(pfds[0]);
char hold[3];
sprintf(hold,"%d",lev);
if(write(pfds[1], hold, 3) <= 0){
perror("parent");
exit(1);
}
wait(NULL);
}
}
}
else{ //top level
fprintf(stdout,"ALIVE: Level %d process with pid=%d, child of ppid=%d.\n", lev, getpid(), getppid());
//write to unnamed pipe
lev--;
close(pfds[0]);
char hold[3];
sprintf(hold,"%d",lev);
if(write(pfds[1], hold, 3) <= 0){
perror("parent");
exit(1);
}
//read from fifo
char buff[MAX_BUF];
fd = open(myfifo,O_RDONLY);
read(fd,buff,MAX_BUF);
close(fd);
unlink(myfifo);
char *comp = "leaf";
if(strcmp(buff,comp) == 0){
int j;
for(j = 0; j < numprocs; j++) printf("%d\n",ptr[j]);
for(j = 1; j < numprocs; j++) kill(ptr[j],SIGUSR1);
shm_unlink(name);
fprintf(stdout,"EXITING: Level %d process with pid=%d, child of ppid=%d.\n", numprocs, getpid(), getppid());
exit(0);
}
}
}
Output:
./prog1 4
ALIVE: Level 4 process with pid=5129, child of ppid=4692.
ALIVE: Level 3 process with pid=5130, child of ppid=5129.
ALIVE: Level 2 process with pid=5131, child of ppid=5130.
ALIVE: Level 1 process with pid=5132, child of ppid=5131.
5129
5130
5131
5132
EXITING: Level 4 process with pid=5129, child of ppid=4692.
EXITING: Level 3 process with pid=5130, child of ppid=5129.
EXITING: Level 2 process with pid=5131, child of ppid=5130.