From: Fredrik Tolf <fredrik@dolda2000.com>
Date: Thu, 10 Feb 2022 16:48:46 +0000 (+0100)
Subject: Initial commit.
X-Git-Url: http://dolda2000.com/gitweb/?p=jagi.git;a=commitdiff_plain;h=49ccd711f15e0fbb64afdef0e6698aca14ecbc79

Initial commit.
---

49ccd711f15e0fbb64afdef0e6698aca14ecbc79
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..796b96d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/build.xml b/build.xml
new file mode 100644
index 0000000..e805cd6
--- /dev/null
+++ b/build.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0"?>
+
+<project name="jagi" default="jar">
+  
+  <property environment="env" />
+  
+  <target name="build-env">
+    <mkdir dir="build" />
+    <mkdir dir="build/bin" />
+  </target>
+
+  <target name="classes" depends="build-env">
+    <javac srcdir="src" destdir="build/bin" debug="on"
+	   source="1.8" target="1.8" includeantruntime="no">
+      <compilerarg value="-Xlint:unchecked" />
+    </javac>
+  </target>
+  
+  <target name="jar" depends="build-env, classes">
+    <jar destfile="build/jagi.jar" basedir="build/bin">
+      <manifest>
+	<attribute name="Main-Class" value="jagi.scgi.Bootstrap" />
+      </manifest>
+    </jar>
+  </target>
+  
+  <target name="clean">
+    <delete dir="build" />
+  </target>
+</project>
diff --git a/src/jagi/PosixArgs.java b/src/jagi/PosixArgs.java
new file mode 100644
index 0000000..fa6d28b
--- /dev/null
+++ b/src/jagi/PosixArgs.java
@@ -0,0 +1,100 @@
+package jagi;
+
+import java.util.*;
+
+public class PosixArgs {
+    private List<Arg> parsed;
+    public String[] rest;
+    public String arg = null;
+    
+    private static class Arg {
+	private char ch;
+	private String arg;
+	
+	private Arg(char ch, String arg) {
+	    this.ch = ch;
+	    this.arg = arg;
+	}
+    }
+    
+    private PosixArgs() {
+	parsed = new ArrayList<Arg>();
+    }
+
+    public static PosixArgs getopt(String[] argv, int start, String desc) {
+	PosixArgs ret = new PosixArgs();
+	List<Character> fl = new ArrayList<Character>(), fla = new ArrayList<Character>();
+	List<String> rest = new ArrayList<String>();
+	for(int i = 0; i < desc.length();) {
+	    char ch = desc.charAt(i++);
+	    if((i < desc.length()) && (desc.charAt(i) == ':')) {
+		i++;
+		fla.add(ch);
+	    } else {
+		fl.add(ch);
+	    }
+	}
+	boolean acc = true;
+	for(int i = start; i < argv.length;) {
+	    String arg = argv[i++];
+	    if(acc && arg.equals("--")) {
+		acc = false;
+	    } else if(acc && (arg.charAt(0) == '-') && (arg.length() > 1)) {
+		for(int o = 1; o < arg.length();) {
+		    char ch = arg.charAt(o++);
+		    if(fl.contains(ch)) {
+			ret.parsed.add(new Arg(ch, null));
+		    } else if(fla.contains(ch)) {
+			if(o < arg.length()) {
+			    ret.parsed.add(new Arg(ch, arg.substring(o)));
+			    break;
+			} else if(i < argv.length) {
+			    ret.parsed.add(new Arg(ch, argv[i++]));
+			    break;
+			} else {
+			    System.err.println("option requires an argument -- '" + ch + "'");
+			    return(null);
+			}
+		    } else {
+			System.err.println("invalid option -- '" + ch + "'");
+			return(null);
+		    }
+		}
+	    } else {
+		rest.add(arg);
+	    }
+	}
+	ret.rest = rest.toArray(new String[0]);
+	return(ret);
+    }
+    
+    public static PosixArgs getopt(String[] argv, String desc) {
+	return(getopt(argv, 0, desc));
+    }
+    
+    public Iterable<Character> parsed() {
+	return(new Iterable<Character>() {
+		public Iterator<Character> iterator() {
+		    return(new Iterator<Character>() {
+			    private int i = 0;
+			    
+			    public boolean hasNext() {
+				return(i < parsed.size());
+			    }
+			    
+			    public Character next() {
+				if(i >= parsed.size())
+				    throw(new NoSuchElementException());
+				Arg a = parsed.get(i++);
+				arg = a.arg;
+				return(a.ch);
+			    }
+			    
+			    public void remove() {
+				throw(new UnsupportedOperationException());
+			    }
+			});
+		}
+	    });
+    }
+}
diff --git a/src/jagi/Utils.java b/src/jagi/Utils.java
new file mode 100644
index 0000000..ef4e02a
--- /dev/null
+++ b/src/jagi/Utils.java
@@ -0,0 +1,85 @@
+package jagi;
+
+import java.util.*;
+import java.io.*;
+import java.nio.*;
+import java.nio.channels.*;
+
+public class Utils {
+    public static final java.nio.charset.Charset UTF8 = java.nio.charset.Charset.forName("UTF-8");
+    public static final java.nio.charset.Charset LATIN1 = java.nio.charset.Charset.forName("ISO-8859-1");
+    public static final java.nio.charset.Charset ASCII = java.nio.charset.Charset.forName("US-ASCII");
+
+    public static int read(ReadableByteChannel ch) throws IOException {
+	ByteBuffer buf = ByteBuffer.allocate(1);
+	while(true) {
+	    int rv = ch.read(buf);
+	    if(rv < 0)
+		return(-1);
+	    else if(rv == 1)
+		return(buf.get(0) & 0xff);
+	    else if(rv > 1)
+		throw(new AssertionError());
+	}
+    }
+
+    public static ByteBuffer readall(ReadableByteChannel ch, ByteBuffer dst) throws IOException {
+	while(dst.remaining() > 0)
+	    ch.read(dst);
+	return(dst);
+    }
+
+    public static void writeall(WritableByteChannel ch, ByteBuffer src) throws IOException {
+	while(src.remaining() > 0)
+	    ch.write(src);
+    }
+
+    public static void transfer(WritableByteChannel dst, ReadableByteChannel src) throws IOException {
+	ByteBuffer buf = ByteBuffer.allocate(65536);
+	while(true) {
+	    buf.clear();
+	    if(src.read(buf) < 0)
+		break;
+	    buf.flip();
+	    while(buf.remaining() > 0)
+		dst.write(buf);
+	}
+    }
+
+    public static String htmlquote(CharSequence text) {
+	StringBuilder buf = new StringBuilder();
+	for(int i = 0; i < text.length(); i++) {
+	    char c = text.charAt(i);
+	    switch(c) {
+	    case '&': buf.append("&amp;"); break;
+	    case '<': buf.append("&lt;"); break;
+	    case '>': buf.append("&gt;"); break;
+	    case '"': buf.append("&quot;"); break;
+	    default: buf.append(c); break;
+	    }
+	}
+	return(buf.toString());
+    }
+
+    public static Map<Object, Object> simpleerror(int code, CharSequence title, CharSequence msg) {
+	StringBuilder buf = new StringBuilder();
+	buf.append("<?xml version=\"1.0\" encoding=\"US-ASCII\"?>\n");
+	buf.append("<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.1//EN\" \"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd\">\n");
+	buf.append("<html xmlns=\"http://www.w3.org/1999/xhtml\" xml:lang=\"en-US\">\n");
+	buf.append("<head>\n");
+	buf.append("<title>" + title + "</title>\n");
+	buf.append("</head>\n");
+	buf.append("<body>\n");
+	buf.append("<h1>" + title + "</h1>\n");
+	buf.append("<p>" + htmlquote(msg) + "</p>\n");
+	buf.append("</body>\n");
+	buf.append("</html>\n");
+	ByteBuffer out = ASCII.encode(CharBuffer.wrap(buf));
+	Map<Object, Object> resp = new HashMap<>();
+	resp.put("http.status", code + " " + title);
+	resp.put("http.Content-Type", "text/html; charset=us-ascii");
+	resp.put("http.Content-Length", Integer.toString(out.remaining()));
+	resp.put("jagi.output", out);
+	return(resp);
+    }
+}
diff --git a/src/jagi/fs/Bootstrap.java b/src/jagi/fs/Bootstrap.java
new file mode 100644
index 0000000..d24a258
--- /dev/null
+++ b/src/jagi/fs/Bootstrap.java
@@ -0,0 +1,29 @@
+package jagi.fs;
+
+import java.util.function.*;
+import java.io.*;
+import jagi.*;
+
+public class Bootstrap {
+    private static void usage(PrintStream out) {
+	out.println("usage: jagi-fs [-h]");
+    }
+
+    public static Function wmain(String[] argv) {
+	PosixArgs opt = PosixArgs.getopt(argv, "h");
+	if(opt == null) {
+	    usage(System.err);
+	    System.exit(1);
+	    return(null);
+	}
+	for(char c : opt.parsed()) {
+	    switch(c) {
+	    case 'h':
+		usage(System.out);
+		System.exit(0);
+		break;
+	    }
+	}
+	return(new Handler());
+    }
+}
diff --git a/src/jagi/fs/Compiler.java b/src/jagi/fs/Compiler.java
new file mode 100644
index 0000000..dcfee03
--- /dev/null
+++ b/src/jagi/fs/Compiler.java
@@ -0,0 +1,195 @@
+package jagi.fs;
+
+import java.util.*;
+import java.util.regex.*;
+import java.nio.file.*;
+import java.nio.file.attribute.*;
+import java.io.*;
+import java.net.*;
+import javax.tools.*;
+
+public class Compiler {
+    private final Map<Path, Module> modules = new HashMap<>();
+
+    public static class FilePart extends SimpleJavaFileObject {
+	public final Path file;
+	public final String clnm;
+	public final CharSequence src;
+
+	private static URI dummyuri(Path file, String clnm) {
+	    String clp = clnm.replace('.', '/') + Kind.SOURCE.extension;
+	    return(URI.create(file.toUri().toString() + "!/" + clp));
+	}
+
+	public FilePart(Path file, String clnm, CharSequence src) {
+	    super(dummyuri(file, clnm), Kind.SOURCE);
+	    this.file = file;
+	    this.clnm = clnm;
+	    this.src = src;
+	}
+
+	public CharSequence getCharContent(boolean ice) {
+	    return(src);
+	}
+
+	private static final Pattern classpat = Pattern.compile("^((public|abstract)\\s+)*(class|interface)\\s+(\\S+)");
+	public static Collection<FilePart> split(Path file) throws IOException {
+	    Collection<FilePart> ret = new ArrayList<>();
+	    StringBuilder head = new StringBuilder();
+	    StringBuilder cur = null;
+	    String clnm = null;
+	    try(BufferedReader fp = Files.newBufferedReader(file)) {
+		for(String ln = fp.readLine(); ln != null; ln = fp.readLine()) {
+		    Matcher m = classpat.matcher(ln);
+		    if(m.find()) {
+			if(cur != null)
+			    ret.add(new FilePart(file, clnm, cur));
+			clnm = m.group(4);
+			cur = new StringBuilder();
+			cur.append(head);
+		    }
+		    if(cur != null) {
+			cur.append(ln); cur.append('\n');
+		    } else {
+			head.append(ln); head.append('\n');
+		    }
+		}
+		if(cur != null)
+		    ret.add(new FilePart(file, clnm, cur));
+	    }
+	    return(ret);
+	}
+    }
+
+    public static class ClassOutput extends SimpleJavaFileObject {
+	public final String name;
+	private final ByteArrayOutputStream buf = new ByteArrayOutputStream();
+
+	public ClassOutput(String name) {
+	    super(URI.create("mem://" + name), Kind.CLASS);
+	    this.name = name;
+	}
+
+	public OutputStream openOutputStream() {
+	    return(buf);
+	}
+    }
+
+    public static class FileContext extends ForwardingJavaFileManager<JavaFileManager> {
+	public final Collection<ClassOutput> output = new ArrayList<>();
+
+	public FileContext(JavaCompiler javac) {
+	    super(javac.getStandardFileManager(null, null, null));
+	}
+
+	public JavaFileObject getJavaFileForOutput(Location location, String name, JavaFileObject.Kind kind, FileObject sibling) {
+	    ClassOutput cl = new ClassOutput(name);
+	    output.add(cl);
+	    return(cl);
+	}
+    }
+
+    public static class CompilationException extends RuntimeException {
+	public final Path file;
+	private final List<Diagnostic<? extends JavaFileObject>> messages;
+
+	public CompilationException(Path file, List<Diagnostic<? extends JavaFileObject>> messages) {
+	    this.file = file;
+	    this.messages = messages;
+	}
+
+	public String getMessage() {
+	    return(file + ": compilation failed");
+	}
+
+	public String messages() {
+	    StringBuilder buf = new StringBuilder();
+	    for(Diagnostic msg : messages)
+		buf.append(msg.toString() + "\n");
+	    return(buf.toString());
+	}
+
+	public void printStackTrace(PrintStream out) {
+	    out.print(messages());
+	    super.printStackTrace(out);
+	}
+    }
+
+    public static Collection<ClassOutput> compile(Path file) throws IOException {
+	List<String> opt = Arrays.asList();
+	JavaCompiler javac = ToolProvider.getSystemJavaCompiler();
+	if(javac == null)
+	    throw(new RuntimeException("no javac present"));
+	Collection<FilePart> files;
+	files = FilePart.split(file);
+	DiagnosticCollector<JavaFileObject> out = new DiagnosticCollector<>();
+	FileContext fs = new FileContext(javac);
+	JavaCompiler.CompilationTask job = javac.getTask(null, fs, out, opt, null, files);
+	if(!job.call())
+	    throw(new CompilationException(file, out.getDiagnostics()));
+	return(fs.output);
+    }
+
+    public static class BufferedClassLoader extends ClassLoader {
+	public final Map<String, byte[]> contents;
+
+	public BufferedClassLoader(Collection<ClassOutput> contents) {
+	    this.contents = new HashMap<>();
+	    for(ClassOutput clc : contents)
+		this.contents.put(clc.name, clc.buf.toByteArray());
+	}
+
+	public Class<?> findClass(String name) throws ClassNotFoundException {
+	    byte[] c = contents.get(name);
+	    if(c == null)
+		throw(new ClassNotFoundException(name));
+	    return(defineClass(name, c, 0, c.length));
+	}
+    }
+
+    public static class Module {
+	public final Path file;
+	private FileTime mtime = null;
+	private ClassLoader code = null;
+
+	private Module(Path file) {
+	    this.file = file;
+	}
+
+	public void update() throws IOException {
+	    synchronized(this) {
+		FileTime mtime = Files.getLastModifiedTime(file);
+		if((this.mtime == null) || (this.mtime.compareTo(mtime) < 0)) {
+		    code = new BufferedClassLoader(compile(file));
+		    this.mtime = mtime;
+		}
+	    }
+	}
+
+	public ClassLoader code() {
+	    if(code == null)
+		throw(new RuntimeException("module has not yet been updated"));
+	    return(code);
+	}
+    }
+
+    public Module module(Path file) {
+	synchronized(modules) {
+	    Module ret = modules.get(file);
+	    if(ret == null)
+		modules.put(file, ret = new Module(file));
+	    return(ret);
+	}
+    }
+
+    private static Compiler global = null;
+    public static Compiler get() {
+	if(global == null) {
+	    synchronized(Compiler.class) {
+		if(global == null)
+		    global = new Compiler();
+	    }
+	}
+	return(global);
+    }
+}
diff --git a/src/jagi/fs/Handler.java b/src/jagi/fs/Handler.java
new file mode 100644
index 0000000..0f61ecd
--- /dev/null
+++ b/src/jagi/fs/Handler.java
@@ -0,0 +1,112 @@
+package jagi.fs;
+
+import java.util.*;
+import java.util.function.*;
+import java.util.logging.*;
+import java.lang.reflect.*;
+import java.io.*;
+import java.nio.file.*;
+import jagi.*;
+
+public class Handler implements Function<Map<Object, Object>, Map<Object, Object>> {
+    private static final Logger log = Logger.getLogger("jagi-fs");
+    private Map<String, Function<Map<Object, Object>, Map<Object, Object>>> handlers = new HashMap<>();
+    private Map<String, Function<Map<Object, Object>, Map<Object, Object>>> exts = new HashMap<>();
+
+    @SuppressWarnings("unchecked")
+    private static Function<Map<Object, Object>, Map<Object, Object>> resolve(ClassLoader loader, String nm) {
+	Class<?> cl;
+	try {
+	    cl = loader.loadClass(nm);
+	} catch(ClassNotFoundException e) {
+	    try {
+		cl = loader.loadClass(nm + ".Bootstrap");
+	    } catch(ClassNotFoundException e2) {
+		throw(new RuntimeException("could not find handler class or package: " + nm, e2));
+	    }
+	}
+	Method wmain;
+	try {
+	    wmain = cl.getDeclaredMethod("wmain", String[].class);
+	    int mod = wmain.getModifiers();
+	    if(((mod & Modifier.STATIC) == 0) || ((mod & Modifier.PUBLIC) == 0))
+		throw(new NoSuchMethodException());
+	} catch(NoSuchMethodException e) {
+	    throw(new RuntimeException("could not find wmain method in " + cl.getName(), e));
+	}
+	Object handler;
+	try {
+	    handler = wmain.invoke(null, new Object[] {new String[] {}});
+	} catch(IllegalAccessException e) {
+	    throw(new RuntimeException("could not call wmain in " + cl.getName(), e));
+	} catch(InvocationTargetException e) {
+	    throw(new RuntimeException("wmain in " + cl.getName() + " failed", e.getCause()));
+	}
+	if(!(handler instanceof Function))
+	    throw(new RuntimeException("wmain in " + cl.getName() + " returned " + ((handler == null) ? "null" : ("a " + handler.getClass()))));
+	return((Function<Map<Object, Object>, Map<Object, Object>>)handler);
+    }
+
+    public Function<Map<Object, Object>, Map<Object, Object>> resolve(String nm) {
+	synchronized(handlers) {
+	    Function<Map<Object, Object>, Map<Object, Object>> handler = handlers.get(nm);
+	    if(handler == null)
+		handlers.put(nm, handler = resolve(Thread.currentThread().getContextClassLoader(), nm));
+	    return(handler);
+	}
+    }
+
+    public void addext(String ext, String name) {
+	addext(ext, resolve(name));
+    }
+
+    public void addext(String ext, Function<Map<Object, Object>, Map<Object, Object>> handler) {
+	Map<String, Function<Map<Object, Object>, Map<Object, Object>>> exts = new HashMap<>(this.exts);
+	synchronized(exts) {
+	    exts.put(ext, handler);
+	}
+	this.exts = exts;
+    }
+
+    {
+	addext("jagi", new JavaHandler());
+    }
+
+    public Map<Object, Object> apply(Map<Object, Object> req) {
+	String filename = (String)req.get("SCRIPT_FILENAME");
+	if(filename == null) {
+	    log.warning("jagi-fs called without SCRIPT_FILENAME set");
+	    return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
+	}
+	Path path = Paths.get(filename);
+	if(!Files.isReadable(path)) {
+	    log.warning(path + ": not readable");
+	    return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
+	}
+	String hname = (String)req.get("HTTP_X_ASH_JAVA_HANDLER");
+	if(hname != null) {
+	    Function<Map<Object, Object>, Map<Object, Object>> handler;
+	    try {
+		handler = resolve(hname);
+	    } catch(Exception e) {
+		log.log(Level.WARNING, "could not load handler " + hname, e);
+		return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
+	    }
+	    return(handler.apply(req));
+	} else {
+	    String base = path.getFileName().toString();
+	    int p = base.lastIndexOf('.');
+	    if(p < 0) {
+		log.warning(path + ": no file extension");
+		return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
+	    }
+	    String ext = base.substring(p + 1);
+	    Function<Map<Object, Object>, Map<Object, Object>> handler = exts.get(ext);
+	    if(handler == null) {
+		log.warning("non-registered file extension: " + ext);
+		return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
+	    }
+	    return(handler.apply(req));
+	}
+    }
+}
diff --git a/src/jagi/fs/JavaHandler.java b/src/jagi/fs/JavaHandler.java
new file mode 100644
index 0000000..111264f
--- /dev/null
+++ b/src/jagi/fs/JavaHandler.java
@@ -0,0 +1,102 @@
+package jagi.fs;
+
+import jagi.*;
+import java.util.*;
+import java.util.function.*;
+import java.util.logging.*;
+import java.lang.reflect.*;
+import java.nio.file.*;
+
+public class JavaHandler implements Function<Map<Object, Object>, Map<Object, Object>> {
+    private static final Logger log = Logger.getLogger("jagi-fs");
+    private final Map<ClassLoader, Function<Map<Object, Object>, Map<Object, Object>>> handlers = new WeakHashMap<>();
+
+    public static class HandlerException extends RuntimeException {
+	public final Path file;
+
+	public HandlerException(Path file, String msg, Throwable cause) {
+	    super(msg, cause);
+	    this.file = file;
+	}
+	public HandlerException(Path file, String msg) {
+	    this(file, msg, null);
+	}
+
+	public String getMessage() {
+	    return(file + ": " + super.getMessage());
+	}
+    }
+
+    @SuppressWarnings("unchecked")
+    private static Function<Map<Object, Object>, Map<Object, Object>> makehandler(Compiler.Module mod) {
+	Class<?> main;
+	try {
+	    main = mod.code().loadClass("Main");
+	} catch(ClassNotFoundException e) {
+	    throw(new HandlerException(mod.file, "no Main class"));
+	}
+	try {
+	    Method wmain = main.getDeclaredMethod("wmain", String[].class);
+	    int attr = wmain.getModifiers();
+	    if(((attr & Modifier.STATIC) == 0) || ((attr & Modifier.PUBLIC) == 0))
+		throw(new NoSuchMethodException());
+	    Object handler = wmain.invoke(null, new Object[] {new String[] {}});
+	    if(!(handler instanceof Function))
+		throw(new HandlerException(mod.file, "wmain in " + main.getName() + " returned " + ((handler == null) ? "null" : ("a " + handler.getClass()))));
+	    return((Function<Map<Object, Object>, Map<Object, Object>>)handler);
+	} catch(IllegalAccessException e) {
+	    throw(new HandlerException(mod.file, "could not call wmain", e));
+	} catch(InvocationTargetException e) {
+	    throw(new HandlerException(mod.file, "wmain failed", e.getCause()));
+	} catch(NoSuchMethodException e) {
+	}
+	if(Function.class.isAssignableFrom(main)) {
+	    try {
+		Constructor<? extends Function> cons = main.asSubclass(Function.class).getConstructor();
+		Function handler = cons.newInstance();
+		return((Function<Map<Object, Object>, Map<Object, Object>>)handler);
+	    } catch(NoSuchMethodException e) {
+	    } catch(InvocationTargetException e) {
+		throw(new HandlerException(mod.file, "constructor failed", e.getCause()));
+	    } catch(ReflectiveOperationException e) {
+		throw(new HandlerException(mod.file, "could not construct Main", e));
+	    }
+	}
+	throw(new HandlerException(mod.file, "no wmain and not directly applicable"));
+    }
+
+    private Function<Map<Object, Object>, Map<Object, Object>> gethandler(Compiler.Module mod) {
+	ClassLoader code = mod.code();
+	synchronized(handlers) {
+	    Function<Map<Object, Object>, Map<Object, Object>> ret = handlers.get(code);
+	    if(ret == null)
+		handlers.put(code, ret = makehandler(mod));
+	    return(ret);
+	}
+    }
+
+    public Map<Object, Object> apply(Map<Object, Object> req) {
+	Compiler.Module mod = Compiler.get().module(Paths.get((String)req.get("SCRIPT_FILENAME")));
+	try {
+	    mod.update();
+	} catch(Compiler.CompilationException e) {
+	    log.warning(String.format("Could not compile %s:\n%s", mod.file, e.messages()));
+	    return(Utils.simpleerror(500, "Internal Error", "Could not load JAGI handler"));
+	} catch(Exception e) {
+	    log.log(Level.WARNING, String.format("Error occurred when loading %s", mod.file), e);
+	    return(Utils.simpleerror(500, "Internal Error", "Could not load JAGI handler"));
+	}
+	Function<Map<Object, Object>, Map<Object, Object>> handler;
+	try {
+	    handler = gethandler(mod);
+	} catch(HandlerException e) {
+	    Throwable cause = e.getCause();
+	    if(cause != null)
+		log.log(Level.WARNING, cause, e::getMessage);
+	    else
+		log.log(Level.WARNING, e::getMessage);
+	    return(Utils.simpleerror(500, "Internal Error", "Invalid JAGI handler"));
+	}
+	return(handler.apply(req));
+    }
+}
diff --git a/src/jagi/scgi/Bootstrap.java b/src/jagi/scgi/Bootstrap.java
new file mode 100644
index 0000000..accac96
--- /dev/null
+++ b/src/jagi/scgi/Bootstrap.java
@@ -0,0 +1,172 @@
+package jagi.scgi;
+
+import jagi.*;
+import java.lang.reflect.*;
+import java.util.*;
+import java.util.function.*;
+import java.io.*;
+import java.net.*;
+import java.nio.channels.*;
+
+public class Bootstrap {
+    private static InetSocketAddress resolveinaddr(String spec) {
+	int p = spec.indexOf(':');
+	SocketAddress bind;
+	if(p >= 0) {
+	    InetAddress host;
+	    try {
+		if(spec.charAt(0) == '[') {
+		    p = spec.indexOf(']');
+		    if((p < 0) || (spec.charAt(p + 1) != ':'))
+			throw(new IllegalArgumentException("invalid address syntax: " + spec));
+		    host = InetAddress.getByName(spec.substring(1, p));
+		    p++;
+		} else {
+		    host = InetAddress.getByName(spec.substring(0, p));
+		}
+	    } catch(UnknownHostException e) {
+		throw(new IllegalArgumentException("could not resolve inet host: " + spec, e));
+	    }
+	    try {
+		return(new InetSocketAddress(host, Integer.parseInt(spec.substring(p + 1))));
+	    } catch(NumberFormatException e) {
+		throw(new IllegalArgumentException("not a valid port number: " + spec.substring(p + 1), e));
+	    }
+	} else {
+	    try {
+		return(new InetSocketAddress(Integer.parseInt(spec)));
+	    } catch(NumberFormatException e) {
+		throw(new IllegalArgumentException("not a valid port number: " + spec, e));
+	    }
+	}
+    }
+
+    private static ServerSocketChannel tcplisten(String spec) {
+	SocketAddress bind;
+	try {
+	    bind = resolveinaddr(spec);
+	} catch(IllegalArgumentException e) {
+	    System.err.println("scgi-jagi: " + e.getMessage());
+	    System.exit(1);
+	    return(null);
+	}
+	try {
+	    ServerSocketChannel sk = ServerSocketChannel.open();
+	    sk.bind(bind);
+	    return(sk);
+	} catch(IOException e) {
+	    System.err.println("scgi-jagi: could not create TCP socket: " + e.getMessage());
+	    System.exit(1);
+	    return(null);
+	}
+    }
+
+    private static ServerSocketChannel getstdin() {
+	Channel stdin;
+	try {
+	    stdin = System.inheritedChannel();
+	} catch(IOException e) {
+	    System.err.println("scgi-jagi: could not get stdin channel: " + e.getMessage());
+	    System.exit(1);
+	    return(null);
+	}
+	if(!(stdin instanceof ServerSocketChannel)) {
+	    System.err.println("scgi-jagi: stdin is not a listening socket");
+	    System.exit(1);
+	    return(null);
+	}
+	return((ServerSocketChannel)stdin);
+    }
+
+    private static Function gethandler(ClassLoader loader, String nm, String... args) {
+	Class<?> cl;
+	try {
+	    cl = loader.loadClass(nm);
+	} catch(ClassNotFoundException e) {
+	    try {
+		cl = loader.loadClass(nm + ".Bootstrap");
+	    } catch(ClassNotFoundException e2) {
+		System.err.println("scgi-jagi: could not find handler class or package: " + nm);
+		System.exit(1);
+		return(null);
+	    }
+	}
+	Method wmain;
+	try {
+	    wmain = cl.getDeclaredMethod("wmain", String[].class);
+	    int mod = wmain.getModifiers();
+	    if(((mod & Modifier.STATIC) == 0) || ((mod & Modifier.PUBLIC) == 0))
+		throw(new NoSuchMethodException());
+	} catch(NoSuchMethodException e) {
+	    System.err.println("scgi-jagi: could not find wmain method in " + cl.getName());
+	    System.exit(1);
+	    return(null);
+	}
+	Object handler;
+	try {
+	    handler = wmain.invoke(null, new Object[] {args});
+	} catch(IllegalAccessException e) {
+	    System.err.println("scgi-jagi: could not call wmain in " + cl.getName());
+	    System.exit(1);
+	    return(null);
+	} catch(InvocationTargetException e) {
+	    System.err.println("scgi-jagi: wmain in " + cl.getName() + " failed");
+	    e.printStackTrace(System.err);
+	    System.exit(1);
+	    return(null);
+	}
+	if(!(handler instanceof Function)) {
+	    System.err.println("scgi-jagi: wmain in " + cl.getName() + " returned " + ((handler == null) ? "null" : ("a " + handler.getClass())));
+	    System.exit(1);
+	    return(null);
+	}
+	return((Function)handler);
+    }
+
+    private static void usage(PrintStream out) {
+	out.println("usage: jagi.jar [-h] [-T [HOST:]PORT] HANDLER-CLASS [ARGS...]");
+    }
+
+    public static void main(String[] args) {
+	PosixArgs opt = PosixArgs.getopt(args, "hT:");
+	if(opt == null) {
+	    usage(System.err);
+	    System.exit(1);
+	    return;
+	}
+	String tcpspec = null;
+	ClassLoader loader = Bootstrap.class.getClassLoader();
+	for(char c : opt.parsed()) {
+	    switch(c) {
+	    case 'h':
+		usage(System.out);
+		System.exit(0);
+		break;
+	    case 'T':
+		tcpspec = opt.arg;
+		break;
+	    }
+	}
+	if(opt.rest.length < 1) {
+	    usage(System.err);
+	    System.exit(1);
+	    return;
+	}
+	Function handler = gethandler(loader, opt.rest[0], Arrays.copyOfRange(opt.rest, 1, opt.rest.length));
+	ServerSocketChannel sk;
+	if(tcpspec != null) {
+	    sk = tcplisten(tcpspec);
+	} else {
+	    sk = getstdin();
+	}
+	Runnable server = new SimpleServer(sk, handler);
+	try {
+	    server.run();
+	} catch(Throwable e) {
+	    System.err.println("scgi-jagi: server exited abnormally");
+	    e.printStackTrace();
+	    System.exit(1);
+	}
+	System.exit(0);
+    }
+}
diff --git a/src/jagi/scgi/Jagi.java b/src/jagi/scgi/Jagi.java
new file mode 100644
index 0000000..758afdc
--- /dev/null
+++ b/src/jagi/scgi/Jagi.java
@@ -0,0 +1,44 @@
+package jagi.scgi;
+
+import jagi.*;
+import java.util.*;
+import java.io.*;
+import java.nio.*;
+import java.nio.channels.*;
+import java.nio.charset.*;
+
+public class Jagi {
+    public static void decodehead(Map<? super String, ? super String> into, Map<ByteBuffer, ByteBuffer> head, Charset coding) throws CharacterCodingException {
+	for(Map.Entry<ByteBuffer, ByteBuffer> h : head.entrySet())
+	    into.put(coding.newDecoder().decode(h.getKey()).toString(), coding.decode(h.getValue()).toString());
+    }
+
+    public static Map<Object, Object> mkenv(ReadableByteChannel sk) throws IOException {
+	Map<ByteBuffer, ByteBuffer> rawhead = Scgi.readhead(sk);
+	Map<Object, Object> env;
+	try {
+	    env = new HashMap<>();
+	    decodehead(env, rawhead, Utils.UTF8);
+	    env.put("jagi.uri_encoding", "utf-8");
+	} catch(CharacterCodingException e) {
+	    env = new HashMap<>();
+	    decodehead(env, rawhead, Utils.LATIN1);
+	    env.put("jagi.uri_encoding", "latin-1");
+	}
+	env.put("jagi.version.major", 1);
+	env.put("jagi.version.minor", 0);
+	if(env.containsKey("HTTP_X_ASH_PROTOCOL"))
+	    env.put("jagi.url_scheme", env.get("HTTP_X_ASH_PROTOCOL"));
+	else if(env.containsKey("HTTPS"))
+	    env.put("jagi.url_scheme", "https");
+	else
+	    env.put("jagi.url_scheme", "http");
+	env.put("jagi.input", sk);
+	env.put("jagi.errors", System.err);
+	env.put("jagi.multithread", true);
+	env.put("jagi.multiprocess", false);
+	env.put("jagi.run_once", false);
+	env.put("jagi.cleanup", new HashSet<>());
+	return(env);
+    }
+}
diff --git a/src/jagi/scgi/Scgi.java b/src/jagi/scgi/Scgi.java
new file mode 100644
index 0000000..5e219b0
--- /dev/null
+++ b/src/jagi/scgi/Scgi.java
@@ -0,0 +1,48 @@
+package jagi.scgi;
+
+import jagi.*;
+import java.util.*;
+import java.io.*;
+import java.nio.*;
+import java.nio.channels.*;
+
+public class Scgi {
+    public static ByteBuffer readns(ReadableByteChannel sk) throws IOException {
+	int hln = 0;
+	while(true) {
+	    int c = Utils.read(sk);
+	    if(c == ':')
+		break;
+	    else if((c >= '0') && (c <= '9'))
+		hln = (hln * 10) + (c - '0');
+	    else if(c < 0)
+		throw(new IOException("unexpected eof in netstring header"));
+	    else
+		throw(new IOException("invalid netstring length byte: " + (c & 0xff)));
+	}
+	ByteBuffer data = Utils.readall(sk, ByteBuffer.allocate(hln));
+	if(Utils.read(sk) != ',')
+	    throw(new IOException("non-terminated netstring"));
+	return(data);
+    }
+
+    public static Map<ByteBuffer, ByteBuffer> readhead(ReadableByteChannel sk) throws IOException {
+	Map<ByteBuffer, ByteBuffer> ret = new HashMap<>();
+	ByteBuffer ns = readns(sk);
+	ByteBuffer k = null;
+	for(int i = 0, p = 0; i < ns.limit(); i++) {
+	    if(ns.get(i) == 0) {
+		ByteBuffer s = ns.duplicate();
+		s.position(p).limit(i);
+		if(k == null) {
+		    k = s;
+		} else {
+		    ret.put(k, s);
+		    k = null;
+		}
+		p = i + 1;
+	    }
+	}
+	return(ret);
+    }
+}
diff --git a/src/jagi/scgi/SimpleServer.java b/src/jagi/scgi/SimpleServer.java
new file mode 100644
index 0000000..7e6dec1
--- /dev/null
+++ b/src/jagi/scgi/SimpleServer.java
@@ -0,0 +1,157 @@
+package jagi.scgi;
+
+import jagi.*;
+import java.util.*;
+import java.util.function.*;
+import java.io.*;
+import java.nio.*;
+import java.nio.channels.*;
+
+public class SimpleServer implements Runnable {
+    private final ServerSocketChannel sk;
+    private final Function handler;
+
+    public SimpleServer(ServerSocketChannel sk, Function handler) {
+	this.sk = sk;
+	this.handler = handler;
+    }
+
+    private void respond(SocketChannel cl, String status, Map resp) throws IOException {
+	Object output = resp.get("jagi.output");
+	try {
+	    BufferedWriter fm = new BufferedWriter(Channels.newWriter(cl, Utils.UTF8.newEncoder(), -1));
+	    fm.write("Status: ");
+	    fm.write(status);
+	    fm.write("\n");
+	    for(Iterator it = resp.entrySet().iterator(); it.hasNext();) {
+		Map.Entry ent = (Map.Entry)it.next();
+		Object val = ent.getValue();
+		if((ent.getKey() instanceof String) && (val != null)) {
+		    String key = (String)ent.getKey();
+		    if(key.startsWith("http.")) {
+			String head = key.substring(5);
+			if(head.equalsIgnoreCase("status"))
+			    continue;
+			if(val instanceof Collection) {
+			    for(Object part : (Collection)val) {
+				fm.write(head);
+				fm.write(": ");
+				fm.write(part.toString());
+				fm.write("\n");
+			    }
+			} else {
+			    fm.write(head);
+			    fm.write(": ");
+			    fm.write(val.toString());
+			    fm.write("\n");
+			}
+		    }
+		}
+	    }
+	    fm.write("\n");
+	    fm.flush();
+	    if(output == null) {
+	    } else if(output instanceof byte[]) {
+		Utils.writeall(cl, ByteBuffer.wrap((byte[])output));
+	    } else if(output instanceof ByteBuffer) {
+		Utils.writeall(cl, (ByteBuffer)output);
+	    } else if(output instanceof String) {
+		Utils.writeall(cl, ByteBuffer.wrap(((String)output).getBytes(Utils.UTF8)));
+	    } else if(output instanceof CharSequence) {
+		Utils.writeall(cl, Utils.UTF8.encode(CharBuffer.wrap((CharSequence)output)));
+	    } else if(output instanceof InputStream) {
+		Utils.transfer(cl, Channels.newChannel((InputStream)output));
+	    } else if(output instanceof ReadableByteChannel) {
+		Utils.transfer(cl, (ReadableByteChannel)output);
+	    } else {
+		throw(new  IllegalArgumentException("response-body: " + String.valueOf(output)));
+	    }
+	} finally {
+	    if(output instanceof Closeable)
+		((Closeable)output).close();
+	}
+    }
+
+    private void feedinput(SocketChannel cl, Map resp) throws IOException {
+	Object sink = resp.get("jagi.input-sink");
+	try {
+	    if(sink instanceof OutputStream) {
+		Utils.transfer(Channels.newChannel((OutputStream)sink), cl);
+	    } else if(sink instanceof WritableByteChannel) {
+		Utils.transfer((WritableByteChannel)sink, cl);
+	    } else {
+		throw(new IllegalArgumentException("input-sink: " + String.valueOf(sink)));
+	    }
+	} finally {
+	    if(sink instanceof Closeable)
+		((Closeable)sink).close();
+	}
+    }
+
+    @SuppressWarnings("unchecked")
+    private void serve(SocketChannel cl) throws IOException {
+	Function handler = this.handler;
+	Map<Object, Object> env = Jagi.mkenv(cl);
+	Throwable error = null;
+	try {
+	    while(true) {
+		Map resp = (Map)handler.apply(env);
+		String st;
+		if((st = (String)resp.get("jagi.status")) != null) {
+		    handler = (Function)resp.get("jagi.next");
+		    switch(st) {
+		    case "feed-input":
+			feedinput(cl, resp);
+			break;
+		    default:
+			throw(new IllegalArgumentException(st));
+		    }
+		} else if((st = (String)resp.get("http.status")) != null) {
+		    respond(cl, st, resp);
+		    break;
+		}
+	    }
+	} catch(Throwable t) {
+	    error = t;
+	    throw(t);
+	} finally {
+	    Collection cleanup = (Collection)env.get("jagi.cleanup");
+	    RuntimeException ce = null;
+	    for(Object obj : cleanup) {
+		if(obj instanceof AutoCloseable) {
+		    try {
+			((AutoCloseable)obj).close();
+		    } catch(Exception e) {
+			if(error == null)
+			    error = ce = new RuntimeException("error(s) occurred during cleanup");
+			error.addSuppressed(e);
+		    }
+		}
+	    }
+	    if(ce != null)
+		throw(ce);
+	}
+    }
+
+    public void run() {
+	while(true) {
+	    SocketChannel cl;
+	    try {
+		cl = sk.accept();
+	    } catch(IOException e) {
+		throw(new RuntimeException(e));
+	    }
+	    try {
+		serve(cl);
+	    } catch(Exception e) {
+		e.printStackTrace();
+	    } finally {
+		try {
+		    cl.close();
+		} catch(IOException e) {
+		    e.printStackTrace();
+		}
+	    }
+	}
+    }
+}