Rust and BTF CO-RE for userspace (#103)

* add rust examples

* update btf

* update btf

* update docs

src/37-uprobe-rust/args/.gitignore

@@ -0,0 +1,2 @@
+target
+Cargo.lock

src/37-uprobe-rust/args/Cargo.toml

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+[package]
+name = "helloworld"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/37-uprobe-rust/args/src/main.rs

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+use std::env;
+
+pub fn hello(i: i32, len: usize) -> i32 {
+    println!("Hello, world! {} in {}", i, len);
+    i + len as i32
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+
+    // Skip the first argument, which is the path to the binary, and iterate over the rest
+    for arg in args.iter().skip(1) {
+        match arg.parse::<i32>() {
+            Ok(i) => {
+                let ret = hello(i, args.len());
+                println!("return value: {}", ret);
+            }
+            Err(_) => {
+                eprintln!("Error: Argument '{}' is not a valid integer", arg);
+            }
+        }
+    }
+}