org.graalvm.polyglot.io

Interface ProcessHandler

public interface ProcessHandler

Service-provider for guest languages process builder. This interface allows embedder to intercept subprocess creation done by guest languages.

Since:

19.1.0

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ProcessHandler.ProcessCommand Subprocess attributes passed to start method.
static class	ProcessHandler.Redirect Represents a source of subprocess input or a destination of subprocess output.

Method Summary

Modifier and Type	Method and Description
Process	start(ProcessHandler.ProcessCommand command) A request to start a new subprocess with given attributes.

Method Detail

start

Process start(ProcessHandler.ProcessCommand command)
       throws IOException

A request to start a new subprocess with given attributes.

The default implementation uses ProcessBuilder to create the new subprocess. The subprocess current working directory is set to ProcessHandler.ProcessCommand.getDirectory(). The ProcessHandler.ProcessCommand.getDirectory() value was either explicitely set by the guest language or the FileSystem's current working directory is used. The subprocess environment is set to ProcessHandler.ProcessCommand.getEnvironment(), the initial value of ProcessBuilder.environment() is cleaned. The ProcessHandler.ProcessCommand.getEnvironment() contains the environment variables set by guest language and possibly also the JVM process environment depending on value of Context.Builder.allowEnvironmentAccess(org.graalvm.polyglot.EnvironmentAccess).

Implementation example:

public Process start(ProcessCommand command) throws IOException {
    ProcessBuilder builder = new ProcessBuilder(command.getCommand())
        .redirectErrorStream(command.isRedirectErrorStream())
        .redirectInput(asProcessBuilderRedirect(command.getInputRedirect()))
        .redirectOutput(asProcessBuilderRedirect(command.getOutputRedirect()))
        .redirectError(asProcessBuilderRedirect(command.getErrorRedirect()));
    Map<String, String> env = builder.environment();
    env.clear();
    env.putAll(command.getEnvironment());
    String cwd = command.getDirectory();
    if (cwd != null) {
        builder.directory(Paths.get(cwd).toFile());
    }
    return builder.start();
}

Parameters:

command - the subprocess attributes

Throws:

SecurityException - if the process creation was forbidden by this handler

IOException - if the process fails to execute

Since:

19.1.0