From 258ccc09b0dd066808f51e93bb34c944ebf08c63 Mon Sep 17 00:00:00 2001
From: Jake Hillion <jake@hillion.co.uk>
Date: Fri, 20 May 2022 17:48:39 +0100
Subject: [PATCH 1/2] return correct exit code

---
 examples/fib/main.rs            |  1 +
 examples/fib/specification.json | 12 ++++++++++++
 src/main.rs                     |  2 +-
 3 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 examples/fib/main.rs
 create mode 100644 examples/fib/specification.json

diff --git a/examples/fib/main.rs b/examples/fib/main.rs
new file mode 100644
index 0000000..f328e4d
--- /dev/null
+++ b/examples/fib/main.rs
@@ -0,0 +1 @@
+fn main() {}
diff --git a/examples/fib/specification.json b/examples/fib/specification.json
new file mode 100644
index 0000000..3e339bf
--- /dev/null
+++ b/examples/fib/specification.json
@@ -0,0 +1,12 @@
+{
+    "entrypoints": {
+        "main1": {
+            "args": [
+                "BinaryName"
+            ],
+            "environment": [
+                "Stdout"
+            ]
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 5dbb0ae..62c853e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -98,7 +98,7 @@ fn main() {
         };
 
         match run(&args) {
-            Ok(_) => exitcode::OK,
+            Ok(code) => code,
             Err(e) => {
                 error!("error: {}", e);
                 -1
-- 
2.47.0


From 9fe48a7749d2919e14b522877455846587f6a5a7 Mon Sep 17 00:00:00 2001
From: Jake Hillion <jake@hillion.co.uk>
Date: Fri, 20 May 2022 17:48:51 +0100
Subject: [PATCH 2/2] fib example

---
 README.md                       | 10 ++++++++++
 examples/fib/main.rs            | 17 ++++++++++++++++-
 examples/fib/spec.json          | 30 ++++++++++++++++++++++++++++++
 examples/fib/specification.json | 12 ------------
 4 files changed, 56 insertions(+), 13 deletions(-)
 create mode 100644 examples/fib/spec.json
 delete mode 100644 examples/fib/specification.json

diff --git a/README.md b/README.md
index 35ce8de..c29320e 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,16 @@
 
 ## Running the examples
 
+### examples/fib
+
+The fib example performs fibonacci trivially on a fixed number. It is the most basic example of a process that requires no privilege, excluding `Stdout` to print the result.
+
+To run this example:
+
+    cargo build
+    cargo build --example fib
+    target/debug/clone-shim -s examples/fib/spec.json target/debug/examples/fib
+
 ### examples/basic
 
 The basic example instructs the shim to spawn two processes, each of which writes "hello from main{1,2}!" to stdout.
diff --git a/examples/fib/main.rs b/examples/fib/main.rs
index f328e4d..e364deb 100644
--- a/examples/fib/main.rs
+++ b/examples/fib/main.rs
@@ -1 +1,16 @@
-fn main() {}
+fn main() {
+    println!("fib(1) = {}", fib(1));
+    println!("fib(7) = {}", fib(7));
+    println!("fib(19) = {}", fib(19));
+}
+
+fn fib(i: u64) -> u64 {
+    let mut a = 0;
+    let mut b = 1;
+
+    for _ in 0..i {
+        (a, b) = (b, a + b);
+    }
+
+    a
+}
diff --git a/examples/fib/spec.json b/examples/fib/spec.json
new file mode 100644
index 0000000..a1ff278
--- /dev/null
+++ b/examples/fib/spec.json
@@ -0,0 +1,30 @@
+{
+    "entrypoints": {
+        "fib": {
+            "args": [
+                "BinaryName"
+            ],
+            "environment": [
+                "Stdout",
+                {
+                    "Filesystem": {
+                        "host_path": "/lib/x86_64-linux-gnu/libgcc_s.so.1",
+                        "environment_path": "/lib/libgcc_s.so.1"
+                    }
+                },
+                {
+                    "Filesystem": {
+                        "host_path": "/lib/x86_64-linux-gnu/libc.so.6",
+                        "environment_path": "/lib/libc.so.6"
+                    }
+                },
+                {
+                    "Filesystem": {
+                        "host_path": "/lib64/ld-linux-x86-64.so.2",
+                        "environment_path": "/lib64/ld-linux-x86-64.so.2"
+                    }
+                }
+            ]
+        }
+    }
+}
\ No newline at end of file
diff --git a/examples/fib/specification.json b/examples/fib/specification.json
deleted file mode 100644
index 3e339bf..0000000
--- a/examples/fib/specification.json
+++ /dev/null
@@ -1,12 +0,0 @@
-{
-    "entrypoints": {
-        "main1": {
-            "args": [
-                "BinaryName"
-            ],
-            "environment": [
-                "Stdout"
-            ]
-        }
-    }
-}
\ No newline at end of file
-- 
2.47.0