[armedbear-devel] run-program :environment nil

[Ville Voutilainen]

On 27 March 2012 19:41, Ville Voutilainen <ville.voutilainen at gmail.com> wrote:
> On 27 March 2012 16:42, Pascal J. Bourguignon <pjb at informatimago.com> wrote:
>> I like the following API, which is implemented in clisp.
>> (getenv)        --> the current environment as an a-list.
>>                    (("LC_CTYPE" . "C") ("TERM" . "/bin/bash") …)
>> (getenv "TERM") --> the string value, or NIL if the variable is not
>>                    present in the environment.
>>                    "/bin/bash"
>> (setf (getenv "LC_CTYPE") "en_US.UTF-8")
>>                    changes the environment for the current process and
>>                    its future children.
>> (setf (getenv "LC_CTYPE") nil)
>
> I dcn't think we can get that far. Java doesn't seem to support
> environment modifications
> that way, see http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/System.html#getenv%28%29
> and in particular "Returns an unmodifiable string map view of the
> current system environment."
> Note the "unmodifiable".
>
> We could allow setting the environment for run-program. Here's what I'd do:
>
> 1) fix the documentation of run-program to mention the environment merging
> 2) add a new function that can completely replace the default
> environment for the program
> to run, use an alist or a hash. Also add a function that can return
> the full environment, for cases where you
> don't want to rebuild everything.
>
> Comments? Opinions?

Here's a tentative patch. I opted for a new keyword argument, since
the new function
approach would've led to duplication or to a macro that has the new
argument anyway.
Untested so far, so this is for general review. Also lacking the
docstring changes.

Index: src/org/armedbear/lisp/run-program.lisp
===================================================================
--- src/org/armedbear/lisp/run-program.lisp	(revision 13893)
+++ src/org/armedbear/lisp/run-program.lisp	(working copy)
@@ -40,11 +40,13 @@
 ;;; This implementation uses the JVM facilities for running external
 ;;; processes.
 ;;; <http://download.oracle.com/javase/6/docs/api/java/lang/ProcessBuilder.html>.
-(defun run-program (program args &key environment (wait t))
+(defun run-program (program args &key environment (wait t) clear-env)
   ;;For documentation, see below.
   (let ((pb (%make-process-builder program args)))
     (when environment
       (let ((env-map (%process-builder-environment pb)))
+        (when clear-env
+          (%process-builder-env-clear env-map))
         (dolist (entry environment)
           (%process-builder-env-put env-map
                                     (princ-to-string (car entry))
@@ -131,6 +133,9 @@
 (defun %process-builder-env-put (env-map key value)
   (java:jcall "put" env-map key value))

+(defun %process-builder-env-clear (env-map)
+  (java:jcall "clear" env-map))
+
 (defun %process-builder-start (pb)
   (java:jcall "start" pb))

Index: src/org/armedbear/lisp/Extensions.java
===================================================================
--- src/org/armedbear/lisp/Extensions.java	(revision 13893)
+++ src/org/armedbear/lisp/Extensions.java	(working copy)
@@ -37,6 +37,7 @@

 import java.io.File;
 import java.io.IOException;
+import java.util.*;

 public final class Extensions
 {
@@ -317,4 +318,28 @@
         return NIL;
     }
   }
+
+  // ### getenv variable => string
+  private static final Primitive GETENV_ALL = new getenv_all();
+  private static class getenv_all extends Primitive
+  {
+    getenv_all()
+    {
+      super("getenv-all", PACKAGE_EXT, true, "variable",
+             "Returns all environment variables as an alist
containing (name . value)");
+    }
+    @Override
+    public LispObject execute()
+    {
+      Cons result = new Cons(NIL);
+      Map<String, String> env = System.getenv();
+      for (Map.Entry<String, String> entry : env.entrySet()) {
+          Cons entryPair = new Cons(new SimpleString(entry.getKey()),
+                                    new SimpleString(entry.getValue()));
+          result = new Cons(entryPair, result);
+      }
+      return result;
+    }
+  }
+
 }