Downloading launcher files

theseus/src/launcher/java.rs

@@ -0,0 +1,31 @@
+use lazy_static::lazy_static;
+use regex::Regex;
+use std::process::Command;
+
+#[derive(thiserror::Error, Debug)]
+pub enum JavaError {
+    #[error("System Error")]
+    SystemError(#[from] std::io::Error),
+}
+
+lazy_static! {
+    static ref JAVA_VERSION_REGEX: Regex = Regex::new(r#""(.*?)""#).unwrap();
+}
+
+pub fn check_java() -> Result<Option<String>, JavaError> {
+    let child = Command::new("/usr/lib/jvm/java-8-openjdk/jre/bin/java")
+        .arg("-version")
+        .output()?;
+
+    let output = &*String::from_utf8_lossy(&*child.stderr);
+
+    if let Some(version_raw) = JAVA_VERSION_REGEX.find(output) {
+        let mut raw = version_raw.as_str().chars();
+        raw.next();
+        raw.next_back();
+
+        return Ok(Some(raw.as_str().to_string()));
+    }
+
+    Ok(None)
+}