2 files changed, 49 insertions, 12 deletions

diff --git a/include/mingw.h b/include/mingw.h
index 7caedd063..654ca3ee6 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -180,13 +180,15 @@ int mingw_system(const char *cmd);
 
 int clearenv(void);
 char *mingw_getenv(const char *name);
+int mingw_putenv(const char *env);
 char *mingw_mktemp(char *template);
 int mkstemp(char *template);
 char *realpath(const char *path, char *resolved_path);
 int setenv(const char *name, const char *value, int replace);
-void unsetenv(const char *env);
+int unsetenv(const char *env);
 
 #define getenv mingw_getenv
+#define putenv mingw_putenv
 #define mktemp mingw_mktemp
 
 /*
diff --git a/win32/env.c b/win32/env.c
index f8d231a8f..eb2e1f004 100644
--- a/win32/env.c
+++ b/win32/env.c
@@ -104,27 +104,62 @@ char **env_setenv(char **env, const char *name)
                 else {
                         for (; env[i]; i++)
                                 env[i] = env[i+1];
-                        SetEnvironmentVariable(name, NULL);
                 }
         }
         return env;
 }
 
-void unsetenv(const char *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)
 {
-        env_setenv(environ, 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 **env = environ;
-        if (!env)
-                return 0;
-        while (*env) {
-                free(*env);
-                env++;
+        char *name, *s;
+
+        while ( environ && *environ ) {
+                if ( (s=strchr(*environ, '=')) != NULL ) {
+                        name = xstrndup(*environ, s-*environ+1);
+                        putenv(name);
+                        free(name);
+                }
+                else {
+                        return -1;
+                }
         }
-        free(env);
-        environ = NULL;
+        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;
 }