i386/ucla/src/lab5/user/forktree.c

   1 // Fork a binary tree of processes and display their structure.
   2
   3 #include <inc/lib.h>
   4
   5 #define DEPTH 3
   6
   7 void forktree(const char *cur);
   8
   9 void
  10 forkchild(const char *cur, char branch)
  11 {
  12         char nxt[DEPTH+1];
  13
  14         if (strlen(cur) >= DEPTH)
  15                 return;
  16
  17         snprintf(nxt, DEPTH+1, "%s%c", cur, branch);
  18         if (fork() == 0) {
  19                 forktree(nxt);
  20                 exit();
  21         }
  22 }
  23
  24 void
  25 forktree(const char *cur)
  26 {
  27         cprintf("%04x: I am '%s'\n", sys_getenvid(), cur);
  28
  29         forkchild(cur, '0');
  30         // Yield to give the child a chance to run.
  31         // This will make child environment IDs slightly more predictable.
  32         sys_yield();
  33         forkchild(cur, '1');
  34 }
  35
  36 asmlinkage void
  37 umain(int argc, char **argv)
  38 {
  39         forktree("");
  40 }