Process tree (fork) Linux - c

Question

i need to create a process tree using fork() in linux.
The tree must be like that :
Moreover, each process has a random ID. So in each process, we must compare his ID and his son(s) ID(s) and keep the minimal ID.
So, i've tried to do the left part of the tree with a recursive function but it doesn't work... (many issues with pipes...)
(i'm sorry, my English is bad because i'm French :( )
int creerArbreGauche(int n,int m)
{
if(m>0){
if(fork()==0){
printf("pid : %d m : %d \n",getpid(),m);
if(m==(n-1)) //si on est au dernier proc
{
printf("Premiere condition %d \n",id[0][m]);
close(tube_G_FP[0]);
write(tube_G_FP[1],&id[0][m],sizeof(int));
creerArbreGauche(n,m-1);
//read(tube_G_FP[0],&var,sizeof(int));
}
else{
printf("Je rentre ici\n");
close(tube_G_FP[1]);
read(tube_G_FP[0],&var,sizeof(int));
printf("Var = %d\n",var);
if(var<id[0][m]){
close(tube_G_FP[0]);
write(tube_G_FP[1],&var,sizeof(int));
printf("Var gagne et l'envoie au pere: %d \n",var);
creerArbreGauche(n,m-1);
//close(tube_G_FP[1]);
}
else{
close(tube_G_FP[0]);
write(tube_G_FP[1],&id[0][m],sizeof(int));
printf("id[0][%d] gagne et envoie au pere son id : %d \n",m,id[0][m]);
creerArbreGauche(n,m-1);
}
}
exit(0);
}
wait(NULL);
}
else{
return 0;
}
}

Answer 1

This is clearly wrong:
close(tube_G_FP[1]); // we close tube_G_FP[1]
read(tube_G_FP[0],&var,sizeof(int));
printf("Var = %d\n",var);
if(var<id[0][m]){
close(tube_G_FP[0]);
write(tube_G_FP[1],&var,sizeof(int)); // we write to tube_G_FP[1]

Answer 2

I've found a solution and made this in a single function here it is:
//some of these variables can be declared in the main function
int var;
int var2;
int **id; //tableau d'id
int count;
int creerArbreGauche(int n,int m,int** tab_tube_G,int** tab_tube_D)
{
printf("m : %d\n",m);
if(m>0){
if(fork()==0){
if(m==(n-1)) //si on est au dernier proc
{
printf("Premiere condition, processus : [%d][%d] avec id : %d \n",count,m,id[count][m]);
write(tab_tube_G[m][1],&id[count ][m],sizeof(int));
creerArbreGauche(n,m-1,tab_tube_G,tab_tube_D);
}
else{
printf("Je rentre ici\n");
read(tab_tube_G[m+1][0],&var,sizeof(int));
printf("Var = %d\n",var);
if(var<id[count][m]){
write(tab_tube_G[m][1],&var,sizeof(int));
printf("Var gagne et l'envoie au pere: %d \n",var);
creerArbreGauche(n,m-1,tab_tube_G,tab_tube_D);
}
else{
write(tab_tube_G[m][1],&id[count][m],sizeof(int));
printf("id[%d][%d] gagne et envoie au pere son id : %d \n", count, m, id[count][m]);
creerArbreGauche(n,m-1,tab_tube_G,tab_tube_D);
}
}
exit(0);
}
wait(NULL);
}
else{
if(n==1){
if(fork()==0){
write(tab_tube_D[count][1],&id[count][m],sizeof(int));
printf("on est au processus [%d] [%d]\n",count,m);
exit(0);
}
wait(NULL);
}
else{ //on est dans le vrai pere
printf("On est dans le pere des peres\n");
read(tab_tube_G[m+1][0],&var,sizeof(int));
close(tab_tube_D[count+1][1]);
read(tab_tube_D[count+1][0],&var2,sizeof(int));
printf("id processus [%d][0] : %d \n",(count+1),var2);
printf("VarFinal = %d\n",var);
printf("id du padré %d\n",id[count][m]);
if((var<=id[count][m])&&(var<=var2)){
printf("Var a gagné : %d \n",var);
write(tab_tube_D[count][1],&var,sizeof(int));
return var;
}
else if((var2<=id[count][m])&&(var2<=var)){
printf("Var2 a gagné : %d \n",var2);
write(tab_tube_D[count][1],&var2,sizeof(int));
return var2;
}
else{
printf("id[%d][%d] (Racine) gagne : %d \n", count, m, id[count][m]);
write(tab_tube_D[count][1],&id[count][m],sizeof(int));
return id[count][0];
}
}
}
printf("\n");
}
int main(){
srand(time(NULL));
int n=4, m=n-1;
int i,j;
int res;
//GENERATION DES IDs
id = (int**)malloc(n*sizeof(int*)); //tableau 2D de n ligne id
for(i=0;i<n;i++){
id[i] = (int*)malloc((n-1)*sizeof(int));
}
for(i=0;i<n;i++){
for(j=0;j<(n-i);j++){
id[i][j] = rand()%(n*n);
printf("ceci est l'id : [%d][%d] = %d \n",i,j,id[i][j]);
}
}
//GENERATION DE MES TUBES GAUCHE
int** tab_tube_G =(int**)malloc(n*sizeof(int));
for(int i=0;i<n;i++){
tab_tube_G[i] =(int*)malloc(2*sizeof(int));
pipe(&tab_tube_G[i][0]);
}
//GENERATION DE TUBES DROIT
int** tab_tube_D =(int**)malloc(n*sizeof(int));
for(int i=0;i<n;i++){
tab_tube_D[i] =(int*)malloc(2*sizeof(int));
pipe(&tab_tube_D[i][0]);
}
count = n-1;
//GENERATION COMPLETE DE TOUT MON ARBRE
for(i=1; i<=n; i++){
m=i-1;
printf(" i = %d \t\n",i);
res = creerArbreGauche(i, m, tab_tube_G, tab_tube_D);
count--;
}
printf("res : %d\n",res);
return 0;
}