# HG changeset patch
# User wenzelm
# Date 1625079458 -7200
# Node ID f627ffab387b6fcddf211504e8d4ce503cdfad5d
# Parent  0dd54d6c974ab569cf53aed892de957fe5e039d6
support for Isabelle setup in pure Java;

diff -r 0dd54d6c974a -r f627ffab387b Admin/components/components.sha1
--- a/Admin/components/components.sha1	Wed Jun 30 16:53:33 2021 +0200
+++ b/Admin/components/components.sha1	Wed Jun 30 20:57:38 2021 +0200
@@ -121,6 +121,7 @@
 b166b4bd583b6442a5d75eab06f7adbb66919d6d  isabelle_fonts-20210319.tar.gz
 9467ad54a9ac10a6e7e8db5458d8d2a5516eba96  isabelle_fonts-20210321.tar.gz
 1f7a0b9829ecac6552b21e995ad0f0ac168634f3  isabelle_fonts-20210322.tar.gz
+916adccd2f40c55116b68b92ce1eccb24d4dd9a2  isabelle_setup-20210630.tar.gz
 0b2206f914336dec4923dd0479d8cee4b904f544  jdk-11+28.tar.gz
 e12574d838ed55ef2845acf1152329572ab0cc56  jdk-11.0.10+9.tar.gz
 3e05213cad47dbef52804fe329395db9b4e57f39  jdk-11.0.2+9.tar.gz
diff -r 0dd54d6c974a -r f627ffab387b Admin/components/main
--- a/Admin/components/main	Wed Jun 30 16:53:33 2021 +0200
+++ b/Admin/components/main	Wed Jun 30 20:57:38 2021 +0200
@@ -8,6 +8,7 @@
 flatlaf-1.2
 idea-icons-20210508
 isabelle_fonts-20210322
+isabelle_setup-20210630
 jdk-15.0.2+7
 jedit_build-20210510-1
 jfreechart-1.5.1
diff -r 0dd54d6c974a -r f627ffab387b Admin/lib/Tools/build_setup
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Admin/lib/Tools/build_setup	Wed Jun 30 20:57:38 2021 +0200
@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+#
+# Author: Makarius
+#
+# DESCRIPTION: build component for Isabelle/Java setup tool
+
+## sources
+
+declare -a SOURCES=(
+  "Environment.java"
+  "Setup.java"
+)
+
+
+## usage
+
+PRG=$(basename "$0")
+
+function usage()
+{
+  echo
+  echo "Usage: isabelle $PRG [OPTIONS] COMPONENT_DIR"
+  echo
+  echo "  Build component for Isabelle/Java setup tool."
+  echo
+  exit 1
+}
+
+function fail()
+{
+  echo "$1" >&2
+  exit 2
+}
+
+
+## process command line
+
+[ "$#" -ge 1 ] && { COMPONENT_DIR="$1"; shift; }
+[ "$#" -ne 0 -o -z "$COMPONENT_DIR" ] && usage
+
+
+
+## main
+
+[ -d "$COMPONENT_DIR" ] && fail "Directory already exists: \"$COMPONENT_DIR\""
+
+
+# build jar
+
+TARGET_DIR="$COMPONENT_DIR/lib"
+mkdir -p "$TARGET_DIR/isabelle/setup"
+
+declare -a ARGS=("-Xlint:unchecked")
+for SRC in "${SOURCES[@]}"
+do
+  ARGS["${#ARGS[@]}"]="$(platform_path "$ISABELLE_HOME/src/Tools/Setup/src/isabelle/setup/$SRC")"
+done
+
+isabelle_jdk javac -d "$TARGET_DIR" "${ARGS[@]}" || \
+  fail "Failed to compile sources"
+
+isabelle_jdk jar -c -f "$(platform_path "$TARGET_DIR/isabelle_setup.jar")" \
+  -e "isabelle.setup.Setup" -C "$TARGET_DIR" isabelle || fail "Failed to produce jar"
+
+rm -rf "$TARGET_DIR/isabelle"
+
+
+# etc/settings
+
+mkdir -p "$COMPONENT_DIR/etc"
+cat > "$COMPONENT_DIR/etc/settings" <<EOF
+# -*- shell-script -*- :mode=shellscript:
+
+ISABELLE_SETUP_JAR="\$COMPONENT/lib/isabelle_setup.jar"
+classpath "\$ISABELLE_SETUP_JAR"
+EOF
+
+
+# README
+
+cat > "$COMPONENT_DIR/README" <<EOF
+Isabelle setup in pure Java, see also \$ISABELLE_HOME/src/Tools/Setup/.
+EOF
diff -r 0dd54d6c974a -r f627ffab387b src/Pure/General/file.scala
--- a/src/Pure/General/file.scala	Wed Jun 30 16:53:33 2021 +0200
+++ b/src/Pure/General/file.scala	Wed Jun 30 20:57:38 2021 +0200
@@ -29,7 +29,7 @@
   def standard_path(path: Path): String = path.expand.implode
 
   def standard_path(platform_path: String): String =
-    isabelle.setup.Isabelle_Env.standard_path(Isabelle_System.cygwin_root(), platform_path)
+    isabelle.setup.Environment.standard_path(Isabelle_System.cygwin_root(), platform_path)
 
   def standard_path(file: JFile): String = standard_path(file.getPath)
 
@@ -46,7 +46,7 @@
   /* platform path (Windows or Posix) */
 
   def platform_path(standard_path: String): String =
-    isabelle.setup.Isabelle_Env.platform_path(Isabelle_System.cygwin_root(), standard_path)
+    isabelle.setup.Environment.platform_path(Isabelle_System.cygwin_root(), standard_path)
 
   def platform_path(path: Path): String = platform_path(standard_path(path))
   def platform_file(path: Path): JFile = new JFile(platform_path(path))
diff -r 0dd54d6c974a -r f627ffab387b src/Pure/System/bash.scala
--- a/src/Pure/System/bash.scala	Wed Jun 30 16:53:33 2021 +0200
+++ b/src/Pure/System/bash.scala	Wed Jun 30 20:57:38 2021 +0200
@@ -59,7 +59,7 @@
     }
     cmd.add("-c")
     cmd.add("kill -" + signal + " -" + group_pid)
-    isabelle.setup.Isabelle_Env.exec_process(cmd).ok
+    isabelle.setup.Environment.exec_process(cmd, null, null, false).ok
   }
 
   def process(script: String,
@@ -94,10 +94,10 @@
     File.write(script_file, winpid_script)
 
     private val proc =
-      isabelle.setup.Isabelle_Env.process_builder(
+      isabelle.setup.Environment.process_builder(
         JList.of(File.platform_path(Path.variable("ISABELLE_BASH_PROCESS")),
           File.standard_path(timing_file), "bash", File.standard_path(script_file)),
-        cwd = cwd, env = env, redirect = redirect).start()
+        cwd, env, redirect).start()
 
 
     // channels
diff -r 0dd54d6c974a -r f627ffab387b src/Pure/System/isabelle_env.scala
--- a/src/Pure/System/isabelle_env.scala	Wed Jun 30 16:53:33 2021 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,308 +0,0 @@
-/*  Title:      Pure/System/isabelle_env.scala
-    Author:     Makarius
-
-Fundamental Isabelle system environment: quasi-static module with
-optional init operation.
-*/
-
-package isabelle.setup
-
-
-import java.util.Locale
-import java.util.regex.Pattern
-import java.util.{HashMap, LinkedList, List => JList, Map => JMap}
-import java.io.{File => JFile}
-import java.nio.file.Files
-
-
-object Isabelle_Env
-{
-  val is_windows: Boolean = System.getProperty("os.name", "").startsWith("Windows")
-
-  def runtime_exception(message: String): Nothing = throw new RuntimeException(message)
-
-  def quote(s: String): String = "\"" + s + "\""
-
-
-
-  /** bootstrap information **/
-
-  def bootstrap_directory(
-    preference: String, variable: String, property: String, description: String): String =
-  {
-    val a = preference  // explicit argument
-    val b = System.getenv(variable)  // e.g. inherited from running isabelle tool
-    val c = System.getProperty(property)  // e.g. via JVM application boot process
-    val dir =
-      if (a != null && a.nonEmpty) a
-      else if (b != null && b.nonEmpty) b
-      else if (c != null && c.nonEmpty) c
-      else runtime_exception("Unknown " + description + " directory")
-
-    if ((new JFile(dir)).isDirectory) dir
-    else runtime_exception("Bad " + description + " directory " + quote(dir))
-  }
-
-
-
-  /** Support for Cygwin as POSIX emulation on Windows **/
-
-  /* system path representations */
-
-  def standard_path(cygwin_root: String, platform_path: String): String =
-    if (is_windows) {
-      val backslashes = platform_path.replace('/', '\\')
-      def slashes(s: String): String = s.replace('\\', '/')
-
-      val root_pattern = Pattern.compile("(?i)" + Pattern.quote(cygwin_root) + """(?:\\+|\z)(.*)""")
-      val root_matcher = root_pattern.matcher(backslashes)
-
-      val drive_pattern = Pattern.compile("""([a-zA-Z]):\\*(.*)""")
-      val drive_matcher = drive_pattern.matcher(backslashes)
-
-      if (root_matcher.matches) {
-        val rest = root_matcher.group(1)
-        "/" + slashes(rest)
-      }
-      else if (drive_matcher.matches) {
-        val letter = drive_matcher.group(1).toLowerCase(Locale.ROOT)
-        val rest = drive_matcher.group(2)
-        "/cygdrive/" + letter + (if (rest == "") "" else "/" + slashes(rest))
-      }
-      else slashes(backslashes)
-    }
-    else platform_path
-
-  def platform_path(cygwin_root: String, standard_path: String): String =
-    if (is_windows) {
-      val result_path = new StringBuilder
-
-      val cygdrive_pattern = Pattern.compile("/cygdrive/([a-zA-Z])($|/.*)")
-      val cygdrive_matcher = cygdrive_pattern.matcher(standard_path)
-
-      val named_root_pattern = Pattern.compile("//+([^/]*)(.*)")
-      val named_root_matcher = named_root_pattern.matcher(standard_path)
-
-      val rest =
-        if (cygdrive_matcher.matches) {
-          val drive = cygdrive_matcher.group(1).toUpperCase(Locale.ROOT)
-          val rest = cygdrive_matcher.group(2)
-          result_path ++= drive
-          result_path ++= ":"
-          result_path ++= JFile.separator
-          rest
-        }
-        else if (named_root_matcher.matches) {
-          val root = named_root_matcher.group(1)
-          val rest = named_root_matcher.group(2)
-          result_path ++= JFile.separator
-          result_path ++= JFile.separator
-          result_path ++= root
-          rest
-        }
-        else {
-          if (standard_path.startsWith("/")) result_path ++= cygwin_root
-          standard_path
-        }
-      for (p <- rest.split("/", -1) if p != "") {
-        val len = result_path.length
-        if (len > 0 && result_path(len - 1) != JFile.separatorChar)
-          result_path += JFile.separatorChar
-        result_path ++= p
-      }
-      result_path.toString
-    }
-    else standard_path
-
-
-  /* symlink emulation */
-
-  def cygwin_link(content: String, target: JFile): Unit =
-  {
-    val target_path = target.toPath
-    Files.writeString(target_path, "!<symlink>" + content + "\u0000")
-    Files.setAttribute(target_path, "dos:system", true)
-  }
-
-
-  /* init (e.g. after extraction via 7zip) */
-
-  def cygwin_init(isabelle_root: String, cygwin_root: String): Unit =
-  {
-    if (is_windows) {
-      def cygwin_exec(cmd: JList[String]): Unit =
-      {
-        val cwd = new JFile(isabelle_root)
-        val env = new HashMap(System.getenv())
-        env.put("CYGWIN", "nodosfilewarning")
-        val res = exec_process(cmd, cwd = cwd, env = env, redirect = true)
-        if (!res.ok) runtime_exception(res.out)
-      }
-
-      val uninitialized_file = new JFile(cygwin_root, "isabelle\\uninitialized")
-      val uninitialized = uninitialized_file.isFile && uninitialized_file.delete
-
-      if (uninitialized) {
-        val symlinks_path = (new JFile(cygwin_root + "\\isabelle\\symlinks")).toPath
-        val symlinks = Files.readAllLines(symlinks_path).toArray(new Array[String](0))
-
-        // recover symlinks
-        var i = 0
-        val m = symlinks.length
-        val n = if (m > 0 && symlinks(m - 1).isEmpty) m - 1 else m
-        while (i < n) {
-          if (i + 1 < n) {
-            val target = symlinks(i)
-            val content = symlinks(i + 1)
-            cygwin_link(content, new JFile(isabelle_root, target))
-            i += 2
-          }
-          else runtime_exception("Unbalanced symlinks list")
-        }
-
-        cygwin_exec(JList.of(cygwin_root + "\\bin\\dash.exe", "/isabelle/rebaseall"))
-        cygwin_exec(JList.of(cygwin_root + "\\bin\\bash.exe", "/isabelle/postinstall"))
-      }
-    }
-  }
-
-
-
-  /** raw process **/
-
-  /* raw process */
-
-  def process_builder(cmd: JList[String],
-    cwd: JFile = null,
-    env: JMap[String, String] = settings(),
-    redirect: Boolean = false): ProcessBuilder =
-  {
-    val builder = new ProcessBuilder
-
-    // fragile on Windows:
-    // see https://docs.microsoft.com/en-us/cpp/cpp/main-function-command-line-args?view=msvc-160
-    builder.command(cmd)
-
-    if (cwd != null) builder.directory(cwd)
-    if (env != null) {
-      builder.environment.clear()
-      builder.environment().putAll(env)
-    }
-    builder.redirectErrorStream(redirect)
-  }
-
-  class Exec_Result(val rc: Int, val out: String, val err: String)
-  {
-    def ok: Boolean = rc == 0
-  }
-
-  def exec_process(command_line: JList[String],
-    cwd: JFile = null,
-    env: JMap[String, String] = settings(),
-    redirect: Boolean = false): Exec_Result =
-  {
-    val out_file = Files.createTempFile(null, null)
-    val err_file = Files.createTempFile(null, null)
-    try {
-      val proc =
-      {
-        val builder = process_builder(command_line, cwd = cwd, env = env, redirect = redirect)
-        builder.redirectOutput(out_file.toFile)
-        builder.redirectError(err_file.toFile)
-        builder.start()
-      }
-      proc.getOutputStream.close()
-      try { proc.waitFor() }
-      finally {
-        proc.getInputStream.close()
-        proc.getErrorStream.close()
-        proc.destroy()
-        Thread.interrupted()
-      }
-
-      val rc = proc.exitValue()
-      val out = Files.readString(out_file)
-      val err = Files.readString(err_file)
-      new Exec_Result(rc, out, err)
-    }
-    finally {
-      Files.deleteIfExists(out_file)
-      Files.deleteIfExists(err_file)
-    }
-  }
-
-
-
-  /** implicit settings environment **/
-
-  @volatile private var _settings: JMap[String, String] = null
-
-  def settings(): JMap[String, String] =
-  {
-    if (_settings == null) init("", "")  // unsynchronized check
-    _settings
-  }
-
-  def init(_isabelle_root: String, _cygwin_root: String): Unit = synchronized
-  {
-    if (_settings == null) {
-      val isabelle_root =
-        bootstrap_directory(_isabelle_root, "ISABELLE_ROOT", "isabelle.root", "Isabelle root")
-
-      val cygwin_root =
-        if (is_windows) {
-          val root = bootstrap_directory(_cygwin_root, "CYGWIN_ROOT", "cygwin.root", "Cygwin root")
-          cygwin_init(isabelle_root, root)
-          root
-        }
-        else ""
-
-      val env = new HashMap(System.getenv())
-      def env_default(a: String, b: String): Unit = if (b != "") env.putIfAbsent(a, b)
-
-      env_default("CYGWIN_ROOT", cygwin_root)
-      env_default("TEMP_WINDOWS",
-        {
-          val temp = if (is_windows) System.getenv("TEMP") else null
-          if (temp != null && temp.contains('\\')) temp else ""
-        })
-      env_default("ISABELLE_JDK_HOME",
-        standard_path(cygwin_root, System.getProperty("java.home", "")))
-      env_default("HOME", System.getProperty("user.home", ""))
-      env_default("ISABELLE_APP", System.getProperty("isabelle.app", ""))
-
-      val settings = new HashMap[String, String]
-      val settings_file = Files.createTempFile(null, null)
-      try {
-        val cmd = new LinkedList[String]
-        if (is_windows) {
-          cmd.add(cygwin_root + "\\bin\\bash")
-          cmd.add("-l")
-          cmd.add(standard_path(cygwin_root, isabelle_root + "\\bin\\isabelle"))
-        } else {
-          cmd.add(isabelle_root + "/bin/isabelle")
-        }
-        cmd.add("getenv")
-        cmd.add("-d")
-        cmd.add(settings_file.toString)
-
-        val res = exec_process(cmd, env = env, redirect = true)
-        if (!res.ok) runtime_exception(res.out)
-
-        for (s <- Files.readString(settings_file).split("\u0000", -1)) {
-          val i = s.indexOf('=')
-          if (i > 0) settings.put(s.substring(0, i), s.substring(i + 1))
-          else if (i < 0 && s.nonEmpty) settings.put(s, "")
-        }
-      }
-      finally { Files.delete(settings_file) }
-
-      if (is_windows) settings.put("CYGWIN_ROOT", cygwin_root)
-
-      settings.put("PATH", settings.get("PATH_JVM"))
-      settings.remove("PATH_JVM")
-
-      _settings = JMap.copyOf(settings)
-    }
-  }
-}
diff -r 0dd54d6c974a -r f627ffab387b src/Pure/System/isabelle_system.scala
--- a/src/Pure/System/isabelle_system.scala	Wed Jun 30 16:53:33 2021 +0200
+++ b/src/Pure/System/isabelle_system.scala	Wed Jun 30 20:57:38 2021 +0200
@@ -18,7 +18,7 @@
 {
   /* settings */
 
-  def settings(): JMap[String, String] = isabelle.setup.Isabelle_Env.settings()
+  def settings(): JMap[String, String] = isabelle.setup.Environment.settings()
 
   def getenv(name: String, env: JMap[String, String] = settings()): String =
     Option(env.get(name)).getOrElse("")
@@ -51,7 +51,7 @@
 
   def init(isabelle_root: String = "", cygwin_root: String = ""): Unit =
   {
-    isabelle.setup.Isabelle_Env.init(isabelle_root, cygwin_root)
+    isabelle.setup.Environment.init(isabelle_root, cygwin_root)
     synchronized {
       if (_services.isEmpty) {
         val variable = "ISABELLE_SCALA_SERVICES"
@@ -253,7 +253,7 @@
     if (force) target.delete
 
     def cygwin_link(): Unit =
-      isabelle.setup.Isabelle_Env.cygwin_link(File.standard_path(src), target)
+      isabelle.setup.Environment.cygwin_link(File.standard_path(src), target)
 
     try { Files.createSymbolicLink(target.toPath, src_file.toPath) }
     catch {
diff -r 0dd54d6c974a -r f627ffab387b src/Pure/System/platform.scala
--- a/src/Pure/System/platform.scala	Wed Jun 30 16:53:33 2021 +0200
+++ b/src/Pure/System/platform.scala	Wed Jun 30 20:57:38 2021 +0200
@@ -11,7 +11,7 @@
 {
   /* platform family */
 
-  def is_windows: Boolean = isabelle.setup.Isabelle_Env.is_windows
+  val is_windows: Boolean = isabelle.setup.Environment.is_windows()
   val is_linux: Boolean = System.getProperty("os.name", "") == "Linux"
   val is_macos: Boolean = System.getProperty("os.name", "") == "Mac OS X"
   val is_unix: Boolean = is_linux || is_macos
diff -r 0dd54d6c974a -r f627ffab387b src/Pure/build-jars
--- a/src/Pure/build-jars	Wed Jun 30 16:53:33 2021 +0200
+++ b/src/Pure/build-jars	Wed Jun 30 20:57:38 2021 +0200
@@ -136,7 +136,6 @@
   src/Pure/System/executable.scala
   src/Pure/System/getopts.scala
   src/Pure/System/isabelle_charset.scala
-  src/Pure/System/isabelle_env.scala
   src/Pure/System/isabelle_fonts.scala
   src/Pure/System/isabelle_platform.scala
   src/Pure/System/isabelle_process.scala
diff -r 0dd54d6c974a -r f627ffab387b src/Tools/Setup/src/isabelle/setup/Environment.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Tools/Setup/src/isabelle/setup/Environment.java	Wed Jun 30 20:57:38 2021 +0200
@@ -0,0 +1,336 @@
+/*  Title:      Pure/System/isabelle_env.scala
+    Author:     Makarius
+
+Fundamental Isabelle system environment: quasi-static module with
+optional init operation.
+*/
+
+package isabelle.setup;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.function.BiFunction;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+
+public class Environment
+{
+    /** Support for Cygwin as POSIX emulation on Windows **/
+
+    public static Boolean is_windows()
+    {
+        return System.getProperty("os.name", "").startsWith("Windows");
+    }
+
+    public static String quote(String s)
+    {
+        return "\"" + s + "\"";
+    }
+
+
+
+    /* system path representations */
+
+    private static String slashes(String s) { return s.replace('\\', '/'); }
+
+    public static String standard_path(String cygwin_root, String platform_path)
+    {
+        if (is_windows()) {
+            String backslashes = platform_path.replace('/', '\\');
+
+            Pattern root_pattern =
+                Pattern.compile("(?i)" + Pattern.quote(cygwin_root) + "(?:\\\\+|\\z)(.*)");
+            Matcher root_matcher = root_pattern.matcher(backslashes);
+
+            Pattern drive_pattern = Pattern.compile("([a-zA-Z]):\\\\*(.*)");
+            Matcher drive_matcher = drive_pattern.matcher(backslashes);
+
+            if (root_matcher.matches()) {
+                String rest = root_matcher.group(1);
+                return "/" + slashes(rest);
+            }
+            else if (drive_matcher.matches()) {
+                String letter = drive_matcher.group(1).toLowerCase(Locale.ROOT);
+                String rest = drive_matcher.group(2);
+                return "/cygdrive/" + letter + (rest.isEmpty() ? "" : "/" + slashes(rest));
+            }
+            else { return slashes(backslashes); }
+        }
+        else { return platform_path; }
+    }
+
+    public static String platform_path(String cygwin_root, String standard_path)
+    {
+        if (is_windows()) {
+            StringBuilder result_path = new StringBuilder();
+
+            Pattern cygdrive_pattern = Pattern.compile("/cygdrive/([a-zA-Z])($|/.*)");
+            Matcher cygdrive_matcher = cygdrive_pattern.matcher(standard_path);
+
+            Pattern named_root_pattern = Pattern.compile("//+([^/]*)(.*)");
+            Matcher named_root_matcher = named_root_pattern.matcher(standard_path);
+
+            String rest;
+            if (cygdrive_matcher.matches()) {
+                String drive = cygdrive_matcher.group(1).toUpperCase(Locale.ROOT);
+                rest = cygdrive_matcher.group(2);
+                result_path.append(drive);
+                result_path.append(':');
+                result_path.append(File.separatorChar);
+            }
+            else if (named_root_matcher.matches()) {
+                String root = named_root_matcher.group(1);
+                rest = named_root_matcher.group(2);
+                result_path.append(File.separatorChar);
+                result_path.append(File.separatorChar);
+                result_path.append(root);
+            }
+            else {
+                if (standard_path.startsWith("/")) { result_path.append(cygwin_root); }
+                rest = standard_path;
+            }
+
+            for (String p : rest.split("/", -1)) {
+                if (!p.isEmpty()) {
+                    int len = result_path.length();
+                    if (len > 0 && result_path.charAt(len - 1) != File.separatorChar) {
+                        result_path.append(File.separatorChar);
+                    }
+                    result_path.append(p);
+                }
+            }
+
+            return result_path.toString();
+        }
+        else { return standard_path; }
+    }
+
+
+    /* raw process */
+
+    public static ProcessBuilder process_builder(
+        List<String> cmd, File cwd, Map<String,String> env, boolean redirect)
+    {
+        ProcessBuilder builder = new ProcessBuilder();
+
+        // fragile on Windows:
+        // see https://docs.microsoft.com/en-us/cpp/cpp/main-function-command-line-args?view=msvc-160
+        builder.command(cmd);
+
+        if (cwd != null) builder.directory(cwd);
+        if (env != null) {
+            builder.environment().clear();
+            builder.environment().putAll(env);
+        }
+        builder.redirectErrorStream(redirect);
+
+        return builder;
+    }
+
+    public static class Exec_Result
+    {
+        private final int _rc;
+        private final String _out;
+        private final String _err;
+
+        Exec_Result(int rc, String out, String err)
+        {
+            _rc = rc;
+            _out = out;
+            _err = err;
+        }
+
+        public int rc() { return _rc; }
+        public boolean ok() { return _rc == 0; }
+        public String out() { return _out; }
+        public String err() { return _err; }
+    }
+
+    public static Exec_Result exec_process(
+        List<String> command_line,
+        File cwd,
+        Map<String,String> env,
+        boolean redirect) throws IOException, InterruptedException
+    {
+        Path out_file = Files.createTempFile(null, null);
+        Path err_file = Files.createTempFile(null, null);
+        Exec_Result res;
+        try {
+            ProcessBuilder builder = process_builder(command_line, cwd, env, redirect);
+            builder.redirectOutput(out_file.toFile());
+            builder.redirectError(err_file.toFile());
+
+            Process proc = builder.start();
+            proc.getOutputStream().close();
+            try { proc.waitFor(); }
+            finally {
+                proc.getInputStream().close();
+                proc.getErrorStream().close();
+                proc.destroy();
+                Thread.interrupted();
+            }
+
+            int rc = proc.exitValue();
+            String out = Files.readString(out_file);
+            String err = Files.readString(err_file);
+            res = new Exec_Result(rc, out, err);
+        }
+        finally {
+            Files.deleteIfExists(out_file);
+            Files.deleteIfExists(err_file);
+        }
+        return res;
+    }
+
+
+    /* init (e.g. after extraction via 7zip) */
+
+    private static String bootstrap_directory(
+        String preference, String variable, String property, String description)
+    {
+        String a = preference;  // explicit argument
+        String b = System.getenv(variable);  // e.g. inherited from running isabelle tool
+        String c = System.getProperty(property);  // e.g. via JVM application boot process
+        String dir;
+
+        if (a != null && !a.isEmpty()) { dir = a; }
+        else if (b != null && !b.isEmpty()) { dir = b; }
+        else if (c != null && !c.isEmpty()) { dir = c; }
+        else { throw new RuntimeException("Unknown " + description + " directory"); }
+
+        if ((new File(dir)).isDirectory()) { return dir; }
+        else { throw new RuntimeException("Bad " + description + " directory " + quote(dir)); }
+    }
+
+    private static void cygwin_exec(String isabelle_root, List<String> cmd)
+        throws IOException, InterruptedException
+    {
+        File cwd = new File(isabelle_root);
+        Map<String,String> env = new HashMap<String,String>(System.getenv());
+        env.put("CYGWIN", "nodosfilewarning");
+        Exec_Result res = exec_process(cmd, cwd, env, true);
+        if (!res.ok()) throw new RuntimeException(res.out());
+    }
+
+    public static void cygwin_link(String content, File target) throws IOException
+    {
+        Path target_path = target.toPath();
+        Files.writeString(target_path, "!<symlink>" + content + "\u0000");
+        Files.setAttribute(target_path, "dos:system", true);
+    }
+
+    public static void cygwin_init(String isabelle_root, String cygwin_root)
+        throws IOException, InterruptedException
+    {
+        if (is_windows()) {
+            File uninitialized_file = new File(cygwin_root, "isabelle\\uninitialized");
+            boolean uninitialized = uninitialized_file.isFile() && uninitialized_file.delete();
+
+            if (uninitialized) {
+                Path symlinks_path = (new File(cygwin_root + "\\isabelle\\symlinks")).toPath();
+                String[] symlinks = Files.readAllLines(symlinks_path).toArray(new String[0]);
+
+                // recover symlinks
+                int i = 0;
+                int m = symlinks.length;
+                int n = (m > 0 && symlinks[m - 1].isEmpty()) ? m - 1 : m;
+                while (i < n) {
+                    if (i + 1 < n) {
+                        String target = symlinks[i];
+                        String content = symlinks[i + 1];
+                        cygwin_link(content, new File(isabelle_root, target));
+                        i += 2;
+                    } else { throw new RuntimeException("Unbalanced symlinks list"); }
+                }
+
+                cygwin_exec(isabelle_root,
+                    List.of(cygwin_root + "\\bin\\dash.exe", "/isabelle/rebaseall"));
+                cygwin_exec(isabelle_root,
+                    List.of(cygwin_root + "\\bin\\bash.exe", "/isabelle/postinstall"));
+            }
+        }
+    }
+
+
+    /* implicit settings environment */
+
+    private static volatile Map<String,String> _settings = null;
+
+    public static Map<String,String> settings()
+        throws IOException, InterruptedException
+    {
+        if (_settings == null) { init("", ""); }  // unsynchronized check
+        return _settings;
+    }
+
+    public static synchronized void init(String _isabelle_root, String _cygwin_root)
+        throws IOException, InterruptedException
+    {
+        if (_settings == null) {
+            String isabelle_root =
+                bootstrap_directory(_isabelle_root, "ISABELLE_ROOT", "isabelle.root", "Isabelle root");
+
+            String cygwin_root = "";
+            if (is_windows()) {
+                cygwin_root = bootstrap_directory(_cygwin_root, "CYGWIN_ROOT", "cygwin.root", "Cygwin root");
+                cygwin_init(isabelle_root, cygwin_root);
+            }
+
+            Map<String,String> env = new HashMap<String,String>(System.getenv());
+
+            BiFunction<String,String,Void> env_default =
+                (String a, String b) -> { if (!b.isEmpty()) env.putIfAbsent(a, b); return null; };
+
+            String temp_windows = is_windows() ? System.getenv("TEMP") : null;
+
+            env_default.apply("CYGWIN_ROOT", cygwin_root);
+            env_default.apply("TEMP_WINDOWS",
+                (temp_windows != null && temp_windows.contains("\\")) ? temp_windows : "");
+            env_default.apply("ISABELLE_JDK_HOME",
+                standard_path(cygwin_root, System.getProperty("java.home", "")));
+            env_default.apply("HOME", System.getProperty("user.home", ""));
+            env_default.apply("ISABELLE_APP", System.getProperty("isabelle.app", ""));
+
+            Map<String,String> settings = new HashMap<String,String>();
+            Path settings_file = Files.createTempFile(null, null);
+            try {
+                List<String> cmd = new LinkedList<String>();
+                if (is_windows()) {
+                    cmd.add(cygwin_root + "\\bin\\bash");
+                    cmd.add("-l");
+                    cmd.add(standard_path(cygwin_root, isabelle_root + "\\bin\\isabelle"));
+                } else {
+                    cmd.add(isabelle_root + "/bin/isabelle");
+                }
+                cmd.add("getenv");
+                cmd.add("-d");
+                cmd.add(settings_file.toString());
+
+                Exec_Result res = exec_process(cmd, null, env, true);
+                if (!res.ok()) throw new RuntimeException(res.out());
+
+                for (String s : Files.readString(settings_file).split("\u0000", -1)) {
+                    int i = s.indexOf('=');
+                    if (i > 0) { settings.put(s.substring(0, i), s.substring(i + 1)); }
+                    else if (i < 0 && !s.isEmpty()) { settings.put(s, ""); }
+                }
+            }
+            finally { Files.delete(settings_file); }
+
+            if (is_windows()) { settings.put("CYGWIN_ROOT", cygwin_root); }
+
+            settings.put("PATH", settings.get("PATH_JVM"));
+            settings.remove("PATH_JVM");
+
+            _settings = Map.copyOf(settings);
+        }
+    }
+}