disasm: move out and implement on asm/rt

1 files changed, 51 insertions, 0 deletions

diff --git a/src/disasm.rs b/src/disasm.rs
new file mode 100644
index 0000000..d8e6058
--- /dev/null
+++ b/src/disasm.rs
@@ -0,0 +1,51 @@
+use std::io::{ErrorKind, Write};
+use std::process::{Command, Stdio};
+
+/// Disassemble the code currently added to the runtime, using
+/// [`ndisasm`](https://nasm.us/index.php) and print it to _stdout_. If
+/// `ndisasm` is not available on the system this prints a warning and
+/// becomes a nop.
+///
+/// # Panics
+///
+/// Panics if anything goes wrong with spawning, writing to or reading from
+/// the `ndisasm` child process.
+pub(crate) fn disasm<T: AsRef<[u8]>>(code: T) {
+    let code = code.as_ref();
+
+    // Create ndisasm process, which expects input on stdin.
+    let mut child = match Command::new("ndisasm")
+        .args(["-b64", "-"])
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .spawn()
+    {
+        Ok(child) => child,
+        Err(err) if err.kind() == ErrorKind::NotFound => {
+            println!("disasm: skipping, ndisasm not found");
+            return;
+        }
+        Err(err) => {
+            panic!("{:?}", err);
+        }
+    };
+
+    // Write code to stdin of ndisasm.
+    child
+        .stdin
+        .take()
+        .expect("failed to take stdin")
+        .write_all(code)
+        .expect("failed to write bytes to stdin");
+
+    // Wait for output from ndisasm and print to stdout.
+    println!(
+        "{}",
+        String::from_utf8_lossy(
+            &child
+                .wait_with_output()
+                .expect("failed to get stdout")
+                .stdout
+        )
+    );
+}