ENV leaks on win32 (was Re: Comments on ENV patch sought)

Subject: [PATCH] for NETaa13787: %ENV=(); doesn't clear the environment

Perl maintains two representations of the environment:

(A) a hash named %ENV, used by the perl script
(B) a char** named environ, which is passed to child processes

Obviously, the intent is to keep tho two in sync.
This fails in two situations:

(1) A list assignment to %ENV clears (A) but not (B);
(2) Assigning to $0 has the side effect of deleting the key
	NoNeSuCh form (B) but not from (A).

$ perl -e '%ENV=(); print "home\n" if exists $ENV{HOME}; exec "echo \$HOME";'
/Users/hansm
$ perl -e '$ENV{NoNeSuCh} = "foo"; $0 = "bar"; exec "echo \$NoNeSuCh";'

$ perl -e '$ENV{NoNeSuCh} = "foo"; exec "echo \$NoNeSuCh";'
foo
$ 

I've complained about rpoblem (1) before; and Larry assigned
it bug ID NETaa13787 when he entered it into DDTS.

The patch below attempts to remedy both problems, at least on
Unix platforms.  I don't know how to handle the environment
on VMS and WIN32; my code simply calls DIE('unimplemented"),
which is honest but won't make users on those plaforms happy.

p5p-msgid: 199705292240.AAA01135@mail.euronet.nl
Signed-off-by: Peter Prymmer <pvhp@forte.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/mg.c b/mg.c
index cab0e5973e..3d1e1ee16b 100644
--- a/mg.c
+++ b/mg.c
@@ -654,6 +654,25 @@ MAGIC* mg;
 }
 
 int
+magic_clear_all_env()
+{
+#if defined(VMS) || defined(WIN32)
+    DIE("'%ENV = @list;' is not implemented on this machine");
+#else
+    I32 i;
+
+    if (environ == origenviron)
+	New(901, environ, 1, char*);
+    else
+	for (i = 0; environ[i]; i++)
+	    Safefree(environ[i]);
+    environ[0] = Nullch;
+
+    return 0;
+#endif
+}
+
+int
 magic_getsig(sv,mg)
 SV* sv;
 MAGIC* mg;
@@ -1574,7 +1593,7 @@ MAGIC* mg;
 	    }
 	    /* can grab env area too? */
 	    if (origenviron && origenviron[0] == s + 1) {
-		my_setenv("NoNeSuCh", Nullch);
+		my_setenv("NoNe  SuCh", Nullch);
 					    /* force copy of environment */
 		for (i = 0; origenviron[i]; i++)
 		    if (origenviron[i] == s + 1)