[starter] Add a process starter for use by the installer for launching tools (#4931)

processstarter/src/main/native/osx/main.mm

@@ -0,0 +1,80 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#import <Foundation/Foundation.h>
+#include <string>
+#include <filesystem>
+
+int main(int argc, char* argv[]) {
+  (void)argc;
+  (void)argv;
+  NSString* exePathPlat = [[NSBundle mainBundle] bundlePath];
+  NSString* identifier = [[NSBundle mainBundle] bundleIdentifier];
+  if (identifier == nil) {
+    exePathPlat = [[NSBundle mainBundle] executablePath];
+  }
+
+  std::filesystem::path exePath{[exePathPlat UTF8String]};
+  if (exePath.empty()) {
+    return 1;
+  }
+
+  if (!exePath.has_stem()) {
+    return 1;
+  }
+
+  if (!exePath.has_parent_path()) {
+    return 1;
+  }
+
+  std::filesystem::path jarPath{exePath};
+  jarPath.replace_extension("jar");
+  std::filesystem::path parentPath{exePath.parent_path()};
+
+  if (!parentPath.has_parent_path()) {
+    return 1;
+  }
+  std::filesystem::path toolsFolder{parentPath.parent_path()};
+
+  std::filesystem::path java = toolsFolder / "jdk" / "bin" / "java";
+
+  NSArray<NSString*>* Arguments =
+      @[ @"-jar", [NSString stringWithFormat:@"%s", jarPath.c_str()] ];
+
+  NSTask* task = [[NSTask alloc] init];
+  task.launchPath = [NSString stringWithFormat:@"%s", java.c_str()];
+  task.arguments = Arguments;
+  task.terminationHandler = ^(NSTask* t) {
+    (void)t;
+    CFRunLoopStop(CFRunLoopGetMain());
+  };
+
+  if (![task launchAndReturnError:nil]) {
+    task.terminationHandler = nil;
+
+    NSString* javaHome =
+        [[[NSProcessInfo processInfo] environment] objectForKey:@"JAVA_HOME"];
+    task = [[NSTask alloc] init];
+    task.launchPath = @"java";
+    if (javaHome != nil) {
+      std::filesystem::path javaHomePath{[javaHome UTF8String]};
+      javaHomePath /= "bin";
+      javaHomePath /= "java";
+      task.launchPath = [NSString stringWithFormat:@"%s", javaHomePath.c_str()];
+    }
+    task.arguments = Arguments;
+    task.terminationHandler = ^(NSTask* t) {
+      (void)t;
+      CFRunLoopStop(CFRunLoopGetMain());
+    };
+
+    if (![task launchAndReturnError:nil]) {
+      return 1;
+    }
+  }
+
+  CFRunLoopRunInMode(kCFRunLoopDefaultMode, 3, false);
+
+  return task.running ? 0 : 1;
+}