Add JDK detection

build.gradle.kts

@@ -38,6 +38,13 @@ buildScan {
     setLicenseAgree("yes")
 }
 
+val configuredJdks: List<JdkId> =
+        getConfiguredJdks().also {
+            it.forEach {
+                logger.info("Using ${it.majorVersion} home: ${it.homeDir}")
+            }
+        }
+
 val buildNumber = "1.1-SNAPSHOT"
 extra["build.number"] = buildNumber
 
@@ -288,8 +295,10 @@ tasks {
 }
 
 fun jdkPath(version: String): String {
-    val varName = "JDK_${version.replace(".", "")}"
+    val jdkName = "JDK_${version.replace(".", "")}"
-    return System.getenv(varName) ?: throw GradleException ("Please set environment variable $varName to point to JDK $version installation")
+    val jdkMajorVersion = JdkMajorVersion.valueOf(jdkName)
+    return configuredJdks.find { it.majorVersion == jdkMajorVersion }?.homeDir?.canonicalPath
+        ?: throw GradleException ("Please set environment variable $jdkName to point to JDK $version installation")
 }
 
 fun Project.configureJvmProject(javaHome: String, javaVersion: String) {

buildSrc/build.gradle.kts

@@ -29,9 +29,12 @@ repositories {
     System.getProperty("bootstrap.kotlin.repo")?.let {
         maven { setUrl(it) }
     }
+//    maven { setUrl("https://repo.gradle.org/gradle/libs-releases-local") }
 }
 
 dependencies {
+    compile(files("../dependencies/native-platform-uberjar.jar"))
+//    compile("net.rubygrapefruit:native-platform:0.14")
     // TODO: adding the dep to the plugin breaks the build unexpectedly, resolve and uncomment
 //    compile("org.jetbrains.kotlin:kotlin-gradle-plugin:${rootProject.extra["bootstrap_kotlin_version"]}")
 }

buildSrc/src/main/kotlin/jdksFinder.kt

@@ -0,0 +1,183 @@
+@file:Suppress("unused") // usages in build scripts are not tracked properly
+
+import net.rubygrapefruit.platform.Native
+import net.rubygrapefruit.platform.WindowsRegistry
+import org.gradle.api.GradleException
+import org.gradle.api.Project
+import java.io.File
+import net.rubygrapefruit.platform.WindowsRegistry.Key.HKEY_LOCAL_MACHINE
+import org.gradle.internal.os.OperatingSystem
+
+enum class JdkMajorVersion {
+    JDK_16, JDK_17, JDK_18, JDK_9
+}
+
+val jdkAlternativeVarNames = mapOf(JdkMajorVersion.JDK_9 to listOf("JDK_19"))
+
+data class JdkId(val explicit: Boolean, val majorVersion: JdkMajorVersion, var version: String, var homeDir: File)
+
+fun Project.getConfiguredJdks(): List<JdkId> {
+    val res = arrayListOf<JdkId>()
+    for (jdkMajorVersion in JdkMajorVersion.values()) {
+        val explicitJdkEnvVal = System.getenv(jdkMajorVersion.name)
+                ?: jdkAlternativeVarNames[jdkMajorVersion]?.mapNotNull { System.getenv(it) }?.firstOrNull()
+                ?: continue
+        val explicitJdk = File(explicitJdkEnvVal)
+        if (!explicitJdk.isDirectory) {
+            throw GradleException("Invalid environment value $jdkMajorVersion: $explicitJdkEnvVal, expecting JDK home path")
+        }
+        res.add(JdkId(true, jdkMajorVersion, "X", explicitJdk))
+    }
+    if (res.size < JdkMajorVersion.values().size) {
+        res.discoverJdks(this)
+    }
+    return res
+}
+
+// see JEP 223
+private val javaMajorVersionRegex = Regex("""(?:1\.)?(\d+).*""")
+private val javaVersionRegex = Regex("""(?:1\.)?(\d+)(\.\d+)?([+-_]\w+){0,3}""")
+
+fun MutableCollection<JdkId>.addIfBetter(project: Project, version: String, id: String, homeDir: File): Boolean {
+    val matchString = javaMajorVersionRegex.matchEntire(version)?.groupValues?.get(1)
+    val majorJersion = when (matchString) {
+        "6" -> JdkMajorVersion.JDK_16
+        "7" -> JdkMajorVersion.JDK_17
+        "8" -> JdkMajorVersion.JDK_18
+        "9" -> JdkMajorVersion.JDK_9
+        else -> {
+            project.logger.info("Cannot recognize version string '$version' (found version '$matchString')")
+            return false
+        }
+    }
+    val prev = find { it.majorVersion == majorJersion }
+    if (prev == null) {
+        add(JdkId(false, majorJersion, version, homeDir))
+        return true
+    }
+    if (prev.explicit) return false
+    val versionsComparisonRes = compareVersions(prev.version, version)
+    if (versionsComparisonRes < 0 || (versionsComparisonRes == 0 && id.contains("64"))) { // prefer 64-bit
+        prev.version = version
+        prev.homeDir = homeDir
+        return true
+    }
+    return false
+}
+
+private fun compareVersions(left: String, right: String): Int {
+    if (left == right) return 0
+    fun MatchResult.extractNumVer(): List<Int> =
+            groups.drop(2).map {
+                it?.value?.filter { it in '0'..'9' }?.toIntOrNull() ?: 0
+            }
+    val lmi = (javaVersionRegex.matchEntire(left)?.extractNumVer() ?: emptyList()).iterator()
+    val rmi = (javaVersionRegex.matchEntire(right)?.extractNumVer() ?: emptyList()).iterator()
+    while (lmi.hasNext() && rmi.hasNext()) {
+        val l = lmi.next()
+        val r = rmi.next()
+        when {
+            l < r -> return -1
+            l > r -> return 1
+        }
+    }
+    return when {
+        rmi.hasNext() -> -1
+        lmi.hasNext() -> 1
+        else -> 0
+    }
+}
+
+fun MutableCollection<JdkId>.discoverJdks(project: Project) {
+    val os = OperatingSystem.current()
+    when {
+        os.isWindows -> discoverJdksOnWindows(project)
+        os.isMacOsX -> discoverJdksOnMacOS(project)
+        else -> discoverJdksOnUnix(project)
+    }
+}
+
+private val macOsJavaHomeOutRegexes = listOf(Regex("""\s+(\S+),\s+(\S+):\s+".*?"\s+(.+)"""),
+                                             Regex("""\s+(\S+)\s+\((.*?)\):\s+(.+)"""))
+
+fun MutableCollection<JdkId>.discoverJdksOnMacOS(project: Project) {
+    val procBuilder = ProcessBuilder("/usr/libexec/java_home", "-V").redirectErrorStream(true)
+    val process = procBuilder.start()
+    val retCode = process.waitFor()
+    if (retCode != 0) throw GradleException("Unable to run 'java_home', return code $retCode")
+    process.inputStream.bufferedReader().forEachLine { line ->
+        for (rex in macOsJavaHomeOutRegexes) {
+            val matchResult = rex.matchEntire(line)
+            if (matchResult != null) {
+                addIfBetter(project, matchResult.groupValues[1], matchResult.groupValues[0], File(matchResult.groupValues[3]))
+                break
+            }
+        }
+    }
+}
+
+private val unixConventionalJdkLocations = listOf(
+        "/usr/lib/jvm",       // *deb, Arch
+        "/opt",               // *rpm, Gentoo, HP/UX
+        "/usr/lib",           // Slackware 32
+        "/usr/lib64",         // Slackware 64
+        "/usr/local",         // OpenBSD, FreeBSD
+        "/usr/pkg/java",      // NetBSD
+        "/usr/jdk/instances") // Solaris
+
+private val unixConventionalJdkDirRex = Regex("jdk|jre|java|zulu")
+
+fun MutableCollection<JdkId>.discoverJdksOnUnix(project: Project) {
+    for (loc in unixConventionalJdkLocations) {
+        val installedJdks = File(loc).listFiles { dir ->
+            dir.isDirectory &&
+            unixConventionalJdkDirRex.containsMatchIn(dir.name) &&
+            File(dir, "bin", "java").isFile
+        } ?: continue
+        for (dir in installedJdks) {
+            val versionMatch = javaVersionRegex.find(dir.name)
+            if (versionMatch == null) {
+                project.logger.info("Unable to extract version from possible JDK dir: $dir")
+            }
+            else {
+                addIfBetter(project, versionMatch.value, dir.name, dir)
+            }
+        }
+    }
+}
+
+private val windowsConventionalJdkRegistryPaths = listOf(
+        "SOFTWARE\\JavaSoft\\Java Development Kit",
+        "SOFTWARE\\Wow6432Node\\JavaSoft\\Java Development Kit")
+
+fun MutableCollection<JdkId>.discoverJdksOnWindows(project: Project) {
+    val registry = Native.get(WindowsRegistry::class.java)
+    for (regPath in windowsConventionalJdkRegistryPaths) {
+        val jdkKeys = try {
+            registry.getSubkeys(HKEY_LOCAL_MACHINE, regPath)
+        } catch (e: RuntimeException) {
+            // ignore missing nodes
+            continue
+        }
+        for (jdkKey in jdkKeys) {
+            try {
+                val javaHome = registry.getStringValue(HKEY_LOCAL_MACHINE, regPath + "\\" + jdkKey, "JavaHome")
+                val versionMatch = javaVersionRegex.find(jdkKey)
+                if (versionMatch == null) {
+                    project.logger.info("Unable to extract version from possible JDK location: $javaHome ($jdkKey)")
+                }
+                else {
+                    javaHome.takeIf { it.isNotEmpty() }
+                            ?.let { File(it) }
+                            ?.takeIf { it.isDirectory && File(it, "bin", "java.exe").isFile }
+                            ?.let {
+                                addIfBetter(project, versionMatch.value, jdkKey, it)
+                            }
+                }
+            }
+            catch (e: RuntimeException) {
+                // Ignore
+            }
+        }
+    }
+}