Allow different ways to manipulate environment for XP vs 64-bit

Commit fa147bd 'Use putenv to implement unsetenv/clearenv' allowed
BusyBox to run on ReactOS but broke it on Windows XP so it was
reverted.

It turns out that the same change is required on 64-bit Windows.
Reinstate the 'safe' environment manipulation code but make it a
configuration option.  Add a config file for 64-bit Windows that
does the right thing.

1 files changed, 59 insertions, 0 deletions

diff --git a/win32/env.c b/win32/env.c
index f8d231a8f..48b86c555 100644
--- a/win32/env.c
+++ b/win32/env.c
@@ -104,12 +104,70 @@ char **env_setenv(char **env, const char *name)
                 else {
                         for (; env[i]; i++)
                                 env[i] = env[i+1];
+#if !ENABLE_SAFE_ENV
                         SetEnvironmentVariable(name, NULL);
+#endif
                 }
         }
         return env;
 }
 
+#if ENABLE_SAFE_ENV
+/*
+ * Removing an environment variable with WIN32 putenv requires an argument
+ * like "NAME="; glibc omits the '='.  The implementations of unsetenv and
+ * clearenv allow for this.
+ *
+ * It isn't possible to create an environment variable with an empty value
+ * using WIN32 putenv.
+ */
+#undef putenv
+int unsetenv(const char *env)
+{
+        char *name;
+        int ret;
+
+        name = xmalloc(strlen(env)+2);
+        strcat(strcpy(name, env), "=");
+        ret = putenv(name);
+        free(name);
+
+        return ret;
+}
+
+int clearenv(void)
+{
+        char *name, *s;
+
+        while ( environ && *environ ) {
+                if ( (s=strchr(*environ, '=')) != NULL ) {
+                        name = xstrndup(*environ, s-*environ+1);
+                        putenv(name);
+                        free(name);
+                }
+                else {
+                        return -1;
+                }
+        }
+        return 0;
+}
+
+int mingw_putenv(const char *env)
+{
+        char *s;
+
+        if ( (s=strchr(env, '=')) == NULL ) {
+                return unsetenv(env);
+        }
+
+        if ( s[1] != '\0' ) {
+                return putenv(env);
+        }
+
+        /* can't set empty value */
+        return 0;
+}
+#else
 void unsetenv(const char *env)
 {
         env_setenv(environ, env);
@@ -128,3 +186,4 @@ int clearenv(void)
         environ = NULL;
         return 0;
 }
+#endif