This code should take an integer, create pipes, spawn two children, wait until they are dead, and start all over again. However, around the third time around the loop I lose my prompt to enter a number and it no longer prints the number I've entered. Any ideas?
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#define WRITE 1
#define READ 0
int main (int argc, const char * argv[]) {
//Pipe file-descriptor array
unsigned int isChildA = 0;
int pipeA[2];
int pipeB[2];
int num = 0;
while(1){
fprintf(stderr,"Enter an integer: ");
scanf("%i", &num);
if(num == 0){
fprintf(stderr,"You entered zero, exiting...\n");
exit(0);
}
//Open Pipes
if(pipe(pipeA) < 0){
fprintf(stderr,"Could not create pipe A.\n");
exit(1);
}
if(pipe(pipeB) < 0){
fprintf(stderr,"Could not create pipe B.\n");
exit(1);
}
fprintf(stderr,"Value read: %i \n", num);
fprintf(stderr,"Parent PID: %i\n", getpid());
pid_t procID = fork();
switch (procID) {
case -1:
fprintf(stderr,"Fork error, quitting...\n");
exit(1);
break;
case 0:
isChildA = 1;
break;
default:
procID = fork();
if (procID<0) {
fprintf(stderr,"Fork error, quitting...\n");
exit(1);
}
else if(procID == 0){
isChildA = 0;
}
else {
write(pipeA[WRITE], &num, sizeof(int));
close(pipeA[WRITE]);
close(pipeA[READ]);
close(pipeB[WRITE]);
close(pipeB[READ]);
pid_t pid;
while (pid = waitpid(-1, NULL, 0)) {
if (errno == ECHILD) {
break;
}
}
}
break;
}
if (procID == 0) {
//We're a child, do kid-stuff.
ssize_t bytesRead = 0;
int response;
while (1) {
while (bytesRead == 0) {
bytesRead = read((isChildA?pipeA[READ]:pipeB[READ]), &response, sizeof(int));
}
if (response < 2) {
//Kill other child and self
fprintf(stderr, "Terminating PROCID: %i\n", getpid());
write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int));
close(pipeA[WRITE]);
close(pipeA[READ]);
close(pipeB[WRITE]);
close(pipeB[READ]);
return 0;
}
else if(!(response%2)){
//Even
response/=2;
fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response);
write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int));
bytesRead = 0;
}
else {
//Odd
response*=3;
response++;
fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response);
write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int));
bytesRead = 0;
}
}
}
}
return 0;
}
This is the output I am getting...
bash-3.00$ ./proj2
Enter an integer: 101
Value read: 101
Parent PID: 9379
PROCID: 9380, VALUE: 304
PROCID: 9381, VALUE: 152
PROCID: 9380, VALUE: 76
PROCID: 9381, VALUE: 38
PROCID: 9380, VALUE: 19
PROCID: 9381, VALUE: 58
PROCID: 9380, VALUE: 29
PROCID: 9381, VALUE: 88
PROCID: 9380, VALUE: 44
PROCID: 9381, VALUE: 22
PROCID: 9380, VALUE: 11
PROCID: 9381, VALUE: 34
PROCID: 9380, VALUE: 17
PROCID: 9381, VALUE: 52
PROCID: 9380, VALUE: 26
PROCID: 9381, VALUE: 13
PROCID: 9380, VALUE: 40
PROCID: 9381, VALUE: 20
PROCID: 9380, VALUE: 10
PROCID: 9381, VALUE: 5
PROCID: 9380, VALUE: 16
PROCID: 9381, VALUE: 8
PROCID: 9380, VALUE: 4
PROCID: 9381, VALUE: 2
PROCID: 9380, VALUE: 1
Terminating PROCID: 9381
Terminating PROCID: 9380
Enter an integer: 102
Value read: 102
Parent PID: 9379
PROCID: 9386, VALUE: 51
PROCID: 9387, VALUE: 154
PROCID: 9386, VALUE: 77
PROCID: 9387, VALUE: 232
PROCID: 9386, VALUE: 116
PROCID: 9387, VALUE: 58
PROCID: 9386, VALUE: 29
PROCID: 9387, VALUE: 88
PROCID: 9386, VALUE: 44
PROCID: 9387, VALUE: 22
PROCID: 9386, VALUE: 11
PROCID: 9387, VALUE: 34
PROCID: 9386, VALUE: 17
PROCID: 9387, VALUE: 52
PROCID: 9386, VALUE: 26
PROCID: 9387, VALUE: 13
PROCID: 9386, VALUE: 40
PROCID: 9387, VALUE: 20
PROCID: 9386, VALUE: 10
PROCID: 9387, VALUE: 5
PROCID: 9386, VALUE: 16
PROCID: 9387, VALUE: 8
PROCID: 9386, VALUE: 4
PROCID: 9387, VALUE: 2
PROCID: 9386, VALUE: 1
Terminating PROCID: 9387
Terminating PROCID: 9386
Enter an integer: 104
Value read: 104
Parent PID: 9379
Enter an integer: PROCID: 9388, VALUE: 52
PROCID: 9389, VALUE: 26
PROCID: 9388, VALUE: 13
PROCID: 9389, VALUE: 40
PROCID: 9388, VALUE: 20
PROCID: 9389, VALUE: 10
PROCID: 9388, VALUE: 5
PROCID: 9389, VALUE: 16
PROCID: 9388, VALUE: 8
PROCID: 9389, VALUE: 4
PROCID: 9388, VALUE: 2
PROCID: 9389, VALUE: 1
Terminating PROCID: 9388
Terminating PROCID: 9389
105
Value read: 105
Parent PID: 9379
Enter an integer: PROCID: 9395, VALUE: 316
PROCID: 9396, VALUE: 158
PROCID: 9395, VALUE: 79
PROCID: 9396, VALUE: 238
PROCID: 9395, VALUE: 119
PROCID: 9396, VALUE: 358
PROCID: 9395, VALUE: 179
PROCID: 9396, VALUE: 538
PROCID: 9395, VALUE: 269
PROCID: 9396, VALUE: 808
PROCID: 9395, VALUE: 404
PROCID: 9396, VALUE: 202
PROCID: 9395, VALUE: 101
PROCID: 9396, VALUE: 304
PROCID: 9395, VALUE: 152
PROCID: 9396, VALUE: 76
PROCID: 9395, VALUE: 38
PROCID: 9396, VALUE: 19
PROCID: 9395, VALUE: 58
PROCID: 9396, VALUE: 29
PROCID: 9395, VALUE: 88
PROCID: 9396, VALUE: 44
PROCID: 9395, VALUE: 22
PROCID: 9396, VALUE: 11
PROCID: 9395, VALUE: 34
PROCID: 9396, VALUE: 17
PROCID: 9395, VALUE: 52
PROCID: 9396, VALUE: 26
PROCID: 9395, VALUE: 13
PROCID: 9396, VALUE: 40
PROCID: 9395, VALUE: 20
PROCID: 9396, VALUE: 10
PROCID: 9395, VALUE: 5
PROCID: 9396, VALUE: 16
PROCID: 9395, VALUE: 8
PROCID: 9396, VALUE: 4
PROCID: 9395, VALUE: 2
PROCID: 9396, VALUE: 1
Terminating PROCID: 9395
Terminating PROCID: 9396
105
Value read: 105
Parent PID: 9379
Enter an integer: PROCID: 9397, VALUE: 316
PROCID: 9398, VALUE: 158
PROCID: 9397, VALUE: 79
PROCID: 9398, VALUE: 238
PROCID: 9397, VALUE: 119
PROCID: 9398, VALUE: 358
PROCID: 9397, VALUE: 179
PROCID: 9398, VALUE: 538
PROCID: 9397, VALUE: 269
PROCID: 9398, VALUE: 808
PROCID: 9397, VALUE: 404
PROCID: 9398, VALUE: 202
PROCID: 9397, VALUE: 101
PROCID: 9398, VALUE: 304
PROCID: 9397, VALUE: 152
PROCID: 9398, VALUE: 76
PROCID: 9397, VALUE: 38
PROCID: 9398, VALUE: 19
PROCID: 9397, VALUE: 58
PROCID: 9398, VALUE: 29
PROCID: 9397, VALUE: 88
PROCID: 9398, VALUE: 44
PROCID: 9397, VALUE: 22
PROCID: 9398, VALUE: 11
PROCID: 9397, VALUE: 34
PROCID: 9398, VALUE: 17
PROCID: 9397, VALUE: 52
PROCID: 9398, VALUE: 26
PROCID: 9397, VALUE: 13
PROCID: 9398, VALUE: 40
PROCID: 9397, VALUE: 20
PROCID: 9398, VALUE: 10
PROCID: 9397, VALUE: 5
PROCID: 9398, VALUE: 16
PROCID: 9397, VALUE: 8
PROCID: 9398, VALUE: 4
PROCID: 9397, VALUE: 2
PROCID: 9398, VALUE: 1
Terminating PROCID: 9397
Terminating PROCID: 9398
106
Value read: 106
Parent PID: 9379
Enter an integer: PROCID: 9399, VALUE: 53
PROCID: 9400, VALUE: 160
PROCID: 9399, VALUE: 80
PROCID: 9400, VALUE: 40
PROCID: 9399, VALUE: 20
PROCID: 9400, VALUE: 10
PROCID: 9399, VALUE: 5
PROCID: 9400, VALUE: 16
PROCID: 9399, VALUE: 8
PROCID: 9400, VALUE: 4
PROCID: 9399, VALUE: 2
PROCID: 9400, VALUE: 1
Terminating PROCID: 9399
Terminating PROCID: 9400
^C
Another thing that's strange, when ran from within XCode it behaves normally. However, when ran from bash on Solaris or OSX it acts up.
