basic example application

.vscode/settings.json

@@ -1,4 +1,3 @@
 {
-    "editor.formatOnSave": true,
-    "editor.defaultFormatter": "rust-lang.rust"
+    "editor.formatOnSave": true
 }

README.md

@@ -1,2 +1,12 @@
 # clone-shim
 
+## Running the examples
+
+### examples/basic
+
+The basic example instructs the shim to spawn two processes, each of which writes "hello from main{1,2}!" to stdout.
+
+To run this example:
+
+    cargo build --example basic
+    cargo run -- -s examples/basic/spec.json target/debug/examples/basic

examples/basic/main.rs

@@ -0,0 +1,22 @@
+fn main() {
+    let mut args = std::env::args();
+
+    let _bin = args.next();
+
+    match args.next() {
+        Some(s) => match s.as_str() {
+            "main1" => main1(),
+            "main2" => main2(),
+            _ => unimplemented!(),
+        },
+        None => unimplemented!(),
+    }
+}
+
+fn main1() {
+    println!("hello from main1!");
+}
+
+fn main2() {
+    println!("hello from main2!");
+}

examples/basic/spec.json

@@ -0,0 +1,16 @@
+{
+    "entrypoints": {
+        "main1": {
+            "args": [
+                "BinaryName",
+                "Entrypoint"
+            ]
+        },
+        "main2": {
+            "args": [
+                "BinaryName",
+                "Entrypoint"
+            ]
+        }
+    }
+}

src/main.rs

@@ -6,7 +6,7 @@ mod specification;
 
 use clone::{clone3, CloneArgs, CloneFlags};
 use error::Error;
-use specification::{Arg, Entrypoint, Pipe, Specification, Trigger};
+use specification::{Arg, Pipe, Specification, Trigger};
 
 use std::collections::HashMap;
 use std::ffi::CString;
@@ -132,11 +132,11 @@ fn run() -> Result<(), Error> {
                     })?;
                 }
             }
-            Trigger::Pipe(s) => {}
+            Trigger::Pipe(_s) => {
+                todo!()
+            }
         }
     }
 
     Ok(())
 }
-
-pub fn pipe_trigger(pipe: File, entry: &Entrypoint) {}

src/specification.rs

@@ -13,8 +13,13 @@ pub struct Specification {
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Entrypoint {
+    #[serde(default)]
     pub trigger: Trigger,
+
+    #[serde(default = "Arg::default_vec")]
     pub args: Vec<Arg>,
+
+    #[serde(default)]
     pub permissions: HashSet<Permissions>,
 }
 
@@ -25,8 +30,14 @@ pub enum Trigger {
     Pipe(String),
 }
 
+impl Default for Trigger {
+    fn default() -> Self {
+        Self::Startup
+    }
+}
+
 #[derive(Serialize, Deserialize, Debug)]
-#[serde(tag = "type")]
+// #[serde(tag = "type")]
 pub enum Arg {
     /// The binary name, or argv[0], of the original program start
     BinaryName,
@@ -41,6 +52,12 @@ pub enum Arg {
     Trailing,
 }
 
+impl Arg {
+    fn default_vec() -> Vec<Arg> {
+        vec![Arg::BinaryName]
+    }
+}
+
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(tag = "type")]
 pub enum Pipe {
@@ -74,7 +91,7 @@ impl Specification {
         let mut read = Vec::new();
         let mut write = Vec::new();
 
-        for (_, entry) in &self.entrypoints {
+        for entry in self.entrypoints.values() {
             match &entry.trigger {
                 Trigger::Startup => {}
                 Trigger::Pipe(s) => read.push(s.as_str()),
@@ -120,7 +137,7 @@ impl Specification {
             }
         }
 
-        for pipe in write_set {
+        if let Some(pipe) = write_set.into_iter().next() {
             return Err(Error::WriteOnlyPipe(pipe.to_string()));
         }