Improve JAVA_HOME detection with SDKMAN and PATH Fallback

Benchmarks/Package.swift

@@ -1,9 +1,7 @@
 // swift-tools-version: 6.0
 
 import PackageDescription
-
-import class Foundation.FileManager
-import class Foundation.ProcessInfo
+import Foundation
 
 // Note: the JAVA_HOME environment variable must be set to point to where
 // Java is installed, e.g.,
@@ -24,8 +22,56 @@ func findJavaHome() -> String {
     return home
   }
 
+  if let home = getJavaHomeFromSDKMAN() {
+    return home
+  }
+
+  if let home = getJavaHomeFromPath() {
+    return home
+  }
+
   fatalError("Please set the JAVA_HOME environment variable to point to where Java is installed.")
 }
+
+func getJavaHomeFromSDKMAN() -> String? {
+  let home = FileManager.default.homeDirectoryForCurrentUser
+    .appendingPathComponent(".sdkman/candidates/java/current")
+
+  let javaBin = home.appendingPathComponent("bin/java").path
+  if FileManager.default.isExecutableFile(atPath: javaBin) {
+    return home.path
+  }
+  return nil
+}
+
+func getJavaHomeFromPath() -> String? {
+  let task = Process()
+  task.executableURL = URL(fileURLWithPath: "/usr/bin/which")
+  task.arguments = ["java"]
+
+  let pipe = Pipe()
+  task.standardOutput = pipe
+
+  do {
+    try task.run()
+    task.waitUntilExit()
+    guard task.terminationStatus == 0 else { return nil }
+
+    let data = pipe.fileHandleForReading.readDataToEndOfFile()
+    guard let javaPath = String(data: data, encoding: .utf8)?
+      .trimmingCharacters(in: .whitespacesAndNewlines),
+      !javaPath.isEmpty
+    else { return nil }
+
+    let resolved = URL(fileURLWithPath: javaPath).resolvingSymlinksInPath()
+    return resolved
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .path
+  } catch {
+    return nil
+  }
+}
 let javaHome = findJavaHome()
 
 let javaIncludePath = "\(javaHome)/include"

Package.swift

@@ -34,6 +34,14 @@ func findJavaHome() -> String {
     return home
   }
 
+  if let home = getJavaHomeFromSDKMAN() {
+    return home
+  }
+
+  if let home = getJavaHomeFromPath() {
+    return home
+  }
+
 
   if ProcessInfo.processInfo.environment["SPI_PROCESSING"] == "1" && ProcessInfo.processInfo.environment["SPI_BUILD"] == nil {
     // Just ignore that we're missing a JAVA_HOME when building in Swift Package Index during general processing where no Java is needed. However, do _not_ suppress the error during SPI's compatibility build stage where Java is required.
@@ -80,6 +88,46 @@ func getJavaHomeFromLibexecJavaHome() -> String? {
     }
 }
 
+func getJavaHomeFromSDKMAN() -> String? {
+  let home = FileManager.default.homeDirectoryForCurrentUser
+    .appendingPathComponent(".sdkman/candidates/java/current")
+
+  let javaBin = home.appendingPathComponent("bin/java").path
+  if FileManager.default.isExecutableFile(atPath: javaBin) {
+    return home.path
+  }
+  return nil
+}
+
+func getJavaHomeFromPath() -> String? {
+  let task = Process()
+  task.executableURL = URL(fileURLWithPath: "/usr/bin/which")
+  task.arguments = ["java"]
+
+  let pipe = Pipe()
+  task.standardOutput = pipe
+
+  do {
+    try task.run()
+    task.waitUntilExit()
+    guard task.terminationStatus == 0 else { return nil }
+
+    let data = pipe.fileHandleForReading.readDataToEndOfFile()
+    guard let javaPath = String(data: data, encoding: .utf8)?
+      .trimmingCharacters(in: .whitespacesAndNewlines),
+      !javaPath.isEmpty
+    else { return nil }
+
+    let resolved = URL(fileURLWithPath: javaPath).resolvingSymlinksInPath()
+    return resolved
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .path
+  } catch {
+    return nil
+  }
+}
+
 let javaHome = findJavaHome()
 
 let javaIncludePath = "\(javaHome)/include"

Plugins/PluginsShared/PluginUtils.swift

@@ -34,6 +34,14 @@ func findJavaHome() -> String {
     return home
   }
 
+  if let home = getJavaHomeFromSDKMAN() {
+    return home
+  }
+
+  if let home = getJavaHomeFromPath() {
+    return home
+  }
+
   fatalError("Please set the JAVA_HOME environment variable to point to where Java is installed.")
 }
 
@@ -77,3 +85,43 @@ extension PluginContext {
       .appending(path: "\(swiftModule)", directoryHint: .notDirectory)
   }
 }
+
+func getJavaHomeFromSDKMAN() -> String? {
+  let home = FileManager.default.homeDirectoryForCurrentUser
+    .appendingPathComponent(".sdkman/candidates/java/current")
+
+  let javaBin = home.appendingPathComponent("bin/java").path
+  if FileManager.default.isExecutableFile(atPath: javaBin) {
+    return home.path
+  }
+  return nil
+}
+
+func getJavaHomeFromPath() -> String? {
+  let task = Process()
+  task.executableURL = URL(fileURLWithPath: "/usr/bin/which")
+  task.arguments = ["java"]
+
+  let pipe = Pipe()
+  task.standardOutput = pipe
+
+  do {
+    try task.run()
+    task.waitUntilExit()
+    guard task.terminationStatus == 0 else { return nil }
+
+    let data = pipe.fileHandleForReading.readDataToEndOfFile()
+    guard let javaPath = String(data: data, encoding: .utf8)?
+      .trimmingCharacters(in: .whitespacesAndNewlines),
+      !javaPath.isEmpty
+    else { return nil }
+
+    let resolved = URL(fileURLWithPath: javaPath).resolvingSymlinksInPath()
+    return resolved
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .path
+  } catch {
+    return nil
+  }
+}

Samples/JavaDependencySampleApp/Package.swift

@@ -3,9 +3,7 @@
 
 import CompilerPluginSupport
 import PackageDescription
-
-import class Foundation.FileManager
-import class Foundation.ProcessInfo
+import Foundation
 
 // Note: the JAVA_HOME environment variable must be set to point to where
 // Java is installed, e.g.,
@@ -26,8 +24,56 @@ func findJavaHome() -> String {
     return home
   }
 
+  if let home = getJavaHomeFromSDKMAN() {
+    return home
+  }
+
+  if let home = getJavaHomeFromPath() {
+    return home
+  }
+
   fatalError("Please set the JAVA_HOME environment variable to point to where Java is installed.")
 }
+
+func getJavaHomeFromSDKMAN() -> String? {
+  let home = FileManager.default.homeDirectoryForCurrentUser
+    .appendingPathComponent(".sdkman/candidates/java/current")
+
+  let javaBin = home.appendingPathComponent("bin/java").path
+  if FileManager.default.isExecutableFile(atPath: javaBin) {
+    return home.path
+  }
+  return nil
+}
+
+func getJavaHomeFromPath() -> String? {
+  let task = Process()
+  task.executableURL = URL(fileURLWithPath: "/usr/bin/which")
+  task.arguments = ["java"]
+
+  let pipe = Pipe()
+  task.standardOutput = pipe
+
+  do {
+    try task.run()
+    task.waitUntilExit()
+    guard task.terminationStatus == 0 else { return nil }
+
+    let data = pipe.fileHandleForReading.readDataToEndOfFile()
+    guard let javaPath = String(data: data, encoding: .utf8)?
+      .trimmingCharacters(in: .whitespacesAndNewlines),
+      !javaPath.isEmpty
+    else { return nil }
+
+    let resolved = URL(fileURLWithPath: javaPath).resolvingSymlinksInPath()
+    return resolved
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .path
+  } catch {
+    return nil
+  }
+}
 let javaHome = findJavaHome()
 
 let javaIncludePath = "\(javaHome)/include"

Samples/JavaKitSampleApp/Package.swift

@@ -3,9 +3,7 @@
 
 import CompilerPluginSupport
 import PackageDescription
-
-import class Foundation.FileManager
-import class Foundation.ProcessInfo
+import Foundation
 
 // Note: the JAVA_HOME environment variable must be set to point to where
 // Java is installed, e.g.,
@@ -26,8 +24,56 @@ func findJavaHome() -> String {
     return home
   }
 
+  if let home = getJavaHomeFromSDKMAN() {
+    return home
+  }
+
+  if let home = getJavaHomeFromPath() {
+    return home
+  }
+
   fatalError("Please set the JAVA_HOME environment variable to point to where Java is installed.")
 }
+
+func getJavaHomeFromSDKMAN() -> String? {
+  let home = FileManager.default.homeDirectoryForCurrentUser
+    .appendingPathComponent(".sdkman/candidates/java/current")
+
+  let javaBin = home.appendingPathComponent("bin/java").path
+  if FileManager.default.isExecutableFile(atPath: javaBin) {
+    return home.path
+  }
+  return nil
+}
+
+func getJavaHomeFromPath() -> String? {
+  let task = Process()
+  task.executableURL = URL(fileURLWithPath: "/usr/bin/which")
+  task.arguments = ["java"]
+
+  let pipe = Pipe()
+  task.standardOutput = pipe
+
+  do {
+    try task.run()
+    task.waitUntilExit()
+    guard task.terminationStatus == 0 else { return nil }
+
+    let data = pipe.fileHandleForReading.readDataToEndOfFile()
+    guard let javaPath = String(data: data, encoding: .utf8)?
+      .trimmingCharacters(in: .whitespacesAndNewlines),
+      !javaPath.isEmpty
+    else { return nil }
+
+    let resolved = URL(fileURLWithPath: javaPath).resolvingSymlinksInPath()
+    return resolved
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .path
+  } catch {
+    return nil
+  }
+}
 let javaHome = findJavaHome()
 
 let javaIncludePath = "\(javaHome)/include"

Samples/JavaSieve/Package.swift

@@ -2,9 +2,7 @@
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
-
-import class Foundation.FileManager
-import class Foundation.ProcessInfo
+import Foundation
 
 // Note: the JAVA_HOME environment variable must be set to point to where
 // Java is installed, e.g.,
@@ -25,8 +23,56 @@ func findJavaHome() -> String {
     return home
   }
 
+  if let home = getJavaHomeFromSDKMAN() {
+    return home
+  }
+
+  if let home = getJavaHomeFromPath() {
+    return home
+  }
+
   fatalError("Please set the JAVA_HOME environment variable to point to where Java is installed.")
 }
+
+func getJavaHomeFromSDKMAN() -> String? {
+  let home = FileManager.default.homeDirectoryForCurrentUser
+    .appendingPathComponent(".sdkman/candidates/java/current")
+
+  let javaBin = home.appendingPathComponent("bin/java").path
+  if FileManager.default.isExecutableFile(atPath: javaBin) {
+    return home.path
+  }
+  return nil
+}
+
+func getJavaHomeFromPath() -> String? {
+  let task = Process()
+  task.executableURL = URL(fileURLWithPath: "/usr/bin/which")
+  task.arguments = ["java"]
+
+  let pipe = Pipe()
+  task.standardOutput = pipe
+
+  do {
+    try task.run()
+    task.waitUntilExit()
+    guard task.terminationStatus == 0 else { return nil }
+
+    let data = pipe.fileHandleForReading.readDataToEndOfFile()
+    guard let javaPath = String(data: data, encoding: .utf8)?
+      .trimmingCharacters(in: .whitespacesAndNewlines),
+      !javaPath.isEmpty
+    else { return nil }
+
+    let resolved = URL(fileURLWithPath: javaPath).resolvingSymlinksInPath()
+    return resolved
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .path
+  } catch {
+    return nil
+  }
+}
 let javaHome = findJavaHome()
 
 let javaIncludePath = "\(javaHome)/include"