From 0d6a64fa06ce6aae729fa05a539eadd88fa59007 Mon Sep 17 00:00:00 2001
From: Mole Shang <135e2@135e2.dev>
Date: Wed, 17 Jan 2024 11:33:39 +0800
Subject: lab util: finish

---
 user/pingpong.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 user/pingpong.c

(limited to 'user/pingpong.c')

diff --git a/user/pingpong.c b/user/pingpong.c
new file mode 100644
index 0000000..7b03a76
--- /dev/null
+++ b/user/pingpong.c
@@ -0,0 +1,44 @@
+#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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