[PATCH] Fix set-environment-variable! for Windows

[felix . winkelmann]

Attached a patch to use the win32 API function for setting env vars. Previously
we were falling back on a hack to use putenv("...="), which doesn't clear the
variable and just sets it to empty (that fallback is still used for iOS, 
though...)

I have not tested this on Windows yet, if someone could do this, I'd be 
grateful.


felix

From 07f03cf852d2ffe499689cf082a895dcac1420de Mon Sep 17 00:00:00 2001
From: felix <fe...@call-with-current-continuation.org>
Date: Wed, 12 Jun 2024 16:29:41 +0200
Subject: [PATCH] Use proper win32 API to set environment variable instead of
 falling back on putenv

---
 library.scm | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/library.scm b/library.scm
index 4a8a2d33..ed0f53b7 100644
--- a/library.scm
+++ b/library.scm
@@ -6014,9 +6014,14 @@ extern char **environ;
 #else
 # if defined(_WIN32) && !defined(__CYGWIN__)
 #  define C_unsetenv(s)   C_setenv(s, C_SCHEME_FALSE)
+static C_word C_fcall C_setenv(C_word x, C_word y) {
+  char *sx = C_c_string(x);
+  if(y == C_SCHEME_FALSE) SetEnvironmentVariable(sx, NULL);
+  else SetEnvironmentVariable(sx, C_c_string(y));
+  return C_fix(0);
+}
 # else
 #  define C_unsetenv(s)   C_fix(putenv((char *)C_data_pointer(s)))
-# endif
 static C_word C_fcall C_setenv(C_word x, C_word y) {
   char *sx = C_c_string(x),
        *sy = (y == C_SCHEME_FALSE ? "" : C_c_string(y));
@@ -6031,6 +6036,7 @@ static C_word C_fcall C_setenv(C_word x, C_word y) {
     return(C_fix(putenv(buf)));
   }
 }
+# endif
 #endif
 
 <#
-- 
2.42.0