feat(wpcarro/rust): Define stdin example

Pipe Rust strings to shell commands.

Change-Id: Id8afeed642d30c79e193fa9b353de081a5843eb5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6197
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI

users/wpcarro/scratch/rust/src/main.rs

@@ -3,16 +3,12 @@ use serde_json::{json, Value};
 
 mod display;
 mod json;
+mod stdin;
 
 ////////////////////////////////////////////////////////////////////////////////
 // Main
 ////////////////////////////////////////////////////////////////////////////////
 
 fn main() {
-    let john: display::Person = display::Person {
+    stdin::example();
-        fname: "John".to_string(),
-        lname: "Cleese".to_string(),
-        age: 82,
-    };
-    println!("Person: {}", john)
 }

users/wpcarro/scratch/rust/src/stdin/mod.rs

@@ -0,0 +1,22 @@
+use std::io::Write;
+use std::process::{Command, Stdio};
+
+// Example of piping-in a string defined in Rust to a shell command.
+pub fn example() {
+    let input = "Hello, world!";
+
+    let mut cat = Command::new("cat")
+        .stdin(Stdio::piped())
+        .spawn()
+        .ok()
+        .unwrap();
+
+    cat.stdin
+        .take()
+        .unwrap()
+        .write_all(&input.as_bytes())
+        .unwrap();
+
+    let output = cat.wait_with_output().unwrap();
+    println!("{}", String::from_utf8_lossy(&output.stdout));
+}