Loop after input of NULL value in simple C shell - c

Question

I'm trying to write a simple C shell. My problem is that I have written the program so that when the user enters a NULL value I've got the shell to exit and stop running. However after using different shells i've realised that the shell continues to loop. Is there anyway to fix this without having to rewrite my code? I'm still quite a novice to C.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>
#define MAX_CMD_SIZE 512
int getPath(){
printf("PATH = %s\n", getenv("PATH"));
return 0;
}
int setPath(char* arg){
setenv("PATH", arg, 1);
return 0;
}
int setwd() {
char *arg;
arg = getenv("HOME");
chdir(arg);
return 0;
}
int main()
{
char buff[MAX_CMD_SIZE]; //buff used to hold commands the user will type in
char *defaultPath = getenv("PATH");
char *args[50] = {NULL};
char *arg;
int i;
pid_t pid;
setwd();
while(1){
printf(">");
if (fgets(buff, MAX_CMD_SIZE, stdin) == NULL) { //Will exit if no value is typed on pressing enter
setPath(defaultPath);
getPath();
exit(0);
}
arg = strtok(buff, " <|>\n\t");
i = 0;
if (arg == NULL) return -1;
while (arg != NULL){
printf("%s\n", arg);
args[i] = arg;
arg = strtok(NULL, " <|>\n\t");
i++;
}
if (strcmp(args[0], "exit") == 0 && !feof(stdin)){ //Will exit if input is equal to "exit" or ctrl + d
setPath(defaultPath);
getPath();
exit(0);
}
else {
pid = fork();
if (pid < 0){ //Error checking
fprintf(stderr, "Fork Failed\n");
} else if (pid == 0){ //This is the child procsess
execvp(args[0], args);
exit(-1);
} else { //Parent Process
wait(NULL); // Parent will wait for child to complete
}
}
}
return 0;
}