ncurses based mini game is printing the bullet twice - c

Question

I'm developing a micro-game in c using the ncurses library for the front-end.
I simplified the code to the minimum, the expected result should be a shuttle that periodically shoots one bomb.
The problem is that when the program runs, the first shoot is always duplicated then sometimes the problem occurs again.
There are 2 processes that communicate through a pipe.
Here is a minimal version of the program to highlight the error:
#include <curses.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#define ENEMYSPRITE "()"
#define BOMB "#"
typedef struct {
char * c;
int x;
int y;
int oldx;
int oldy;
}
pos;
void bombe(int pipeout, pos pos_enemy) {
pos pos_bomba;
pos_bomba.c = BOMB;
pos_bomba.x = pos_enemy.x;
pos_bomba.y = pos_enemy.y + 1;
write(pipeout, & pos_bomba, sizeof(pos_bomba));
while (1) {
pos_bomba.oldy = pos_bomba.y;
pos_bomba.oldx = pos_bomba.x;
pos_bomba.y++;
write(pipeout, & pos_bomba, sizeof(pos_bomba));
usleep(150000);
}
_exit(0);
}
void gameBoard(int pipein) {
pos pos_enemy, pos_bomba, readValue;
while (1) {
read(pipein, & readValue, sizeof(readValue));
if (strcmp(readValue.c, BOMB) == 0) {
mvaddstr(pos_bomba.oldy, pos_bomba.oldx, " "); // deleting the old bullet's position
pos_bomba = readValue;
}
mvaddstr(readValue.y, readValue.x, readValue.c);
refresh();
}
}
void enemy(int pipeout) {
pid_t pid_bomba;
pos pos_enemy;
pos_enemy.c = ENEMYSPRITE;
pos_enemy.x = 10;
pos_enemy.y = 5;
write(pipeout, & pos_enemy, sizeof(pos_enemy));
while (1) {
pid_bomba = fork();
if (pid_bomba == 0) {
bombe(pipeout, pos_enemy);
}
write(pipeout, & pos_enemy, sizeof(pos_enemy));
usleep(1000000);
}
}
int main(int argc, char ** argv) {
initscr();
noecho();
curs_set(0);
int fdescriptor[2];
pipe(fdescriptor);
pid_t pidEnemy = fork();
if (pidEnemy == 0) {
close(fdescriptor[0]);
enemy(fdescriptor[1]);
} else {
close(fdescriptor[1]);
gameBoard(fdescriptor[0]);
}
return 0;
}

Answer 1

I believe the problem with our code is inside function bombe(). Here is the revision that fixed the problem of initially it shoots twice.
void bombe(int pipeout, pos pos_enemy) {
pos pos_bomba = pos_enemy;
pos_bomba.c = BOMB;
pos_bomba.y = pos_enemy.y + 1;
while (1) {
pos_bomba.oldy = pos_bomba.y;
pos_bomba.oldx = pos_bomba.x;
write(pipeout, & pos_bomba, sizeof(pos_bomba));
++pos_bomba.y;
usleep(1155000);
}
_exit(0);
}
Note that now only one write() inside this function.