reintroduce support for GRAAL_PYTHON_ARGS

Author: timfel

graalpython/com.oracle.graal.python.shell/src/com/oracle/graal/python/shell/GraalPythonMain.java

@@ -88,7 +88,8 @@ public static void main(String[] args) {
     @Override
     protected List<String> preprocessArguments(List<String> givenArgs, Map<String, String> polyglotOptions) {
         ArrayList<String> unrecognized = new ArrayList<>();
-        ArrayList<String> inputArgs = new ArrayList<>();
+        List<String> defaultEnvironmentArgs = getDefaultEnvironmentArgs();
+        ArrayList<String> inputArgs = new ArrayList<>(defaultEnvironmentArgs);
         inputArgs.addAll(givenArgs);
         givenArguments = new ArrayList<>(inputArgs);
         List<String> arguments = new ArrayList<>(inputArgs);
@@ -576,6 +577,10 @@ protected void printHelp(OptionCategory maxCategory) {
                         "   as specifying the -R option: a random value is used to seed the hashes of\n" +
                         "   str, bytes and datetime objects.  It can also be set to an integer\n" +
                         "   in the range [0,4294967295] to get hash values with a predictable seed.\n" +
+                        "GRAAL_PYTHON_ARGS: the value is added as arguments as if passed on the\n" +
+                        "   commandline. There is one special case: any `$$' in the value is replaced\n" +
+                        "   with the current process id. To pass a literal `$$', you must escape the\n" +
+                        "   second `$' like so: `$\\$'\n" +
                         (wantsExperimental ? "\nArguments specific to the Graal Python launcher:\n" +
                                         "--show-version : print the Python version number and continue.\n" +
                                         "-CC            : run the C compiler used for generating GraalPython C extensions.\n" +
@@ -808,6 +813,72 @@ private static final class ExitException extends RuntimeException {
         }
     }
 
+    private static enum State {
+        NORMAL,
+        SINGLE_QUOTE,
+        DOUBLE_QUOTE,
+        ESCAPE_SINGLE_QUOTE,
+        ESCAPE_DOUBLE_QUOTE,
+    }
+
+    private static List<String> getDefaultEnvironmentArgs() {
+        String pid;
+        if (isAOT()) {
+            pid = String.valueOf(ProcessProperties.getProcessID());
+        } else {
+            pid = ManagementFactory.getRuntimeMXBean().getName().split("@")[0];
+        }
+        String envArgsOpt = System.getenv("GRAAL_PYTHON_ARGS");
+        ArrayList<String> envArgs = new ArrayList<>();
+        State s = State.NORMAL;
+        StringBuilder sb = new StringBuilder();
+        if (envArgsOpt != null) {
+            for (char x : envArgsOpt.toCharArray()) {
+                if (s == State.NORMAL && Character.isWhitespace(x)) {
+                    addArgument(pid, envArgs, sb);
+                } else {
+                    if (x == '"') {
+                        if (s == State.NORMAL) {
+                            s = State.DOUBLE_QUOTE;
+                        } else if (s == State.DOUBLE_QUOTE) {
+                            s = State.NORMAL;
+                        } else if (s == State.ESCAPE_DOUBLE_QUOTE) {
+                            s = State.DOUBLE_QUOTE;
+                            sb.append(x);
+                        }
+                    } else if (x == '\'') {
+                        if (s == State.NORMAL) {
+                            s = State.SINGLE_QUOTE;
+                        } else if (s == State.SINGLE_QUOTE) {
+                            s = State.NORMAL;
+                        } else if (s == State.ESCAPE_SINGLE_QUOTE) {
+                            s = State.SINGLE_QUOTE;
+                            sb.append(x);
+                        }
+                    } else if (x == '\\') {
+                        if (s == State.SINGLE_QUOTE) {
+                            s = State.ESCAPE_SINGLE_QUOTE;
+                        } else if (s == State.DOUBLE_QUOTE) {
+                            s = State.ESCAPE_DOUBLE_QUOTE;
+                        }
+                    } else {
+                        sb.append(x);
+                    }
+                }
+            }
+            addArgument(pid, envArgs, sb);
+        }
+        return envArgs;
+    }
+
+    private static void addArgument(String pid, ArrayList<String> envArgs, StringBuilder sb) {
+        if (sb.length() > 0) {
+            String arg = sb.toString().replace("$$", pid).replace("\\$", "$");
+            envArgs.add(arg);
+            sb.setLength(0);
+        }
+    }
+
     private static boolean doEcho(@SuppressWarnings("unused") Context context) {
         return true;
     }