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#include "kernel/types.h"
#include "user/user.h"
int
main(int argc, char* argv[])
{
int p[2];
if (argc > 1) {
fprintf(2, "usage: pingpong\n");
exit(1);
}
pipe(p);
int pid = fork();
if (pid == 0) {
short n;
read(p[0], &n, sizeof(n));
if (n == 42) {
fprintf(1, "%d: received ping\n", getpid());
}
n++;
write(p[1], &n, sizeof(n));
close(p[0]);
close(p[1]);
exit(0);
}
short n = 42;
write(p[1], &n, sizeof(n));
read(p[0], &n, sizeof(n));
if (n == 43) {
fprintf(1, "%d: received pong\n", getpid());
}
close(p[0]);
close(p[1]);
wait(0);
exit(0);
}
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