Add Windows execution model

Author: mearvk

src/windows/WindowsExecution.java

@@ -0,0 +1,59 @@
+package windows;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.Map;
+
+/** A controlled Windows process execution request and result. */
+public final class WindowsExecution {
+    private final WindowsProgram program;
+    private final WindowsDirective directive;
+    private final WindowsCitizen citizen;
+    private final List<String> arguments;
+    private final Map<String, String> environment;
+
+    public WindowsExecution(
+            WindowsProgram program,
+            WindowsDirective directive,
+            WindowsCitizen citizen,
+            List<String> arguments,
+            Map<String, String> environment) {
+        this.program = program;
+        this.directive = directive;
+        this.citizen = citizen;
+        this.arguments = List.copyOf(arguments);
+        this.environment = Map.copyOf(environment);
+    }
+
+    public WindowsProgram program() { return program; }
+    public WindowsDirective directive() { return directive; }
+    public WindowsCitizen citizen() { return citizen; }
+    public List<String> arguments() { return arguments; }
+    public Map<String, String> environment() { return environment; }
+
+    public WindowsExecutionResult execute() throws Exception {
+        if (!directive.allowsExecution()) {
+            throw new SecurityException("Windows directive does not permit execution: " + directive.name());
+        }
+
+        ProcessBuilder builder = new ProcessBuilder(program.command(arguments));
+        builder.environment().putAll(environment);
+        builder.redirectErrorStream(true);
+
+        Instant started = Instant.now();
+        Process process = builder.start();
+        String output = new String(process.getInputStream().readAllBytes());
+        int exitCode = process.waitFor();
+        Instant finished = Instant.now();
+
+        return new WindowsExecutionResult(exitCode, output, started, finished);
+    }
+
+    public record WindowsExecutionResult(
+            int exitCode,
+            String output,
+            Instant started,
+            Instant finished) {
+        public boolean successful() { return exitCode == 0; }
+    }
+}