fix: Show Java version from OpenJ9 Java runtimes (#507)

This PR tries to improve the version detection across multiple Java VM vendors. The module captures both STDOUT and STDERR outputs of the java -Xinternalversion call.

Eclipse OpenJ9, Azul Zulu, SapMachine, Amazon Corretto and GraalVM outputs are unit tested now.

2 files changed, 66 insertions, 0 deletions

diff --git a/src/modules/utils/java_version_parser.rs b/src/modules/utils/java_version_parser.rs
new file mode 100644
index 000000000..cf9445dfe
--- /dev/null
+++ b/src/modules/utils/java_version_parser.rs
@@ -0,0 +1,65 @@
+use nom::{
+    branch::alt,
+    bytes::complete::{tag, take_until, take_while1},
+    combinator::rest,
+    sequence::{preceded, tuple},
+    IResult,
+};
+
+fn is_version(c: char) -> bool {
+    c >= '0' && c <= '9' || c == '.'
+}
+
+fn version(input: &str) -> IResult<&str, &str> {
+    take_while1(&is_version)(input)
+}
+
+fn zulu(input: &str) -> IResult<&str, &str> {
+    let zulu_prefix_value = preceded(take_until("("), tag("("));
+    preceded(zulu_prefix_value, version)(input)
+}
+
+fn jre_prefix(input: &str) -> IResult<&str, &str> {
+    preceded(take_until("JRE ("), tag("JRE ("))(input)
+}
+
+fn j9_prefix(input: &str) -> IResult<&str, &str> {
+    preceded(take_until("VM ("), tag("VM ("))(input)
+}
+
+fn suffix(input: &str) -> IResult<&str, &str> {
+    rest(input)
+}
+
+fn parse(input: &str) -> IResult<&str, &str> {
+    let prefix = alt((jre_prefix, j9_prefix));
+    let version_or_zulu = alt((version, zulu));
+    let (input, (_, version, _)) = tuple((prefix, version_or_zulu, suffix))(input)?;
+
+    Ok((input, version))
+}
+
+/// Parse the java version from `java -Xinternalversion` format.
+///
+/// The expected format is similar to:
+///     "JRE (1.8.0_222-b10)"
+///     "JRE (Zulu 8.40.0.25-CA-linux64) (1.8.0_222-b10)"
+///     "VM (1.8.0_222-b10)".
+///
+/// Some Java vendors might not follow this format.
+pub fn parse_jre_version(input: &str) -> Option<&str> {
+    parse(input).map(|result| result.1).ok()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_eclipse_openj9() {
+        let java_8 = "Eclipse OpenJ9 OpenJDK 64-bit Server VM (1.8.0_222-b10) from linux-amd64 JRE with Extensions for OpenJDK for Eclipse OpenJ9 8.0.222.0, built on Jul 17 2019 21:29:18 by jenkins with g++ (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)";
+        let java_11 = "Eclipse OpenJ9 OpenJDK 64-bit Server VM (11.0.4+11) from linux-amd64 JRE with Extensions for OpenJDK for Eclipse OpenJ9 11.0.4.0, built on Jul 17 2019 21:51:37 by jenkins with g++ (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)";
+        assert_eq!(parse(java_8), Ok(("", "1.8.0")));
+        assert_eq!(parse(java_11), Ok(("", "11.0.4")));
+    }
+}
diff --git a/src/modules/utils/mod.rs b/src/modules/utils/mod.rs
new file mode 100644
index 000000000..9e69310b2
--- /dev/null
+++ b/src/modules/utils/mod.rs
@@ -0,0 +1 @@
+pub mod java_version_parser;