libc: Add clearenv

libc/include/stdlib.h

@@ -112,6 +112,9 @@ extern "C"
     /* Remove a variable from the environment. */
     int unsetenv(const char* key);
 
+    /* Clear all environment variables. */
+    int clearenv(void);
+
     void qsort(void*, size_t, size_t, int (*)(const void*, const void*));
     void* bsearch(const void*, const void*, size_t, size_t, int (*)(const void*, const void*));
 

libc/src/env.cpp

@@ -15,6 +15,8 @@ static isize _findenv(const char* key, char** value)
     char** env = environ;
     size_t len = strlen(key);
 
+    if (!env) return -1;
+
     while (*env)
     {
         // Retrieve an environment variable from environ.
@@ -51,6 +53,15 @@ static Result<void> _try_move_env()
         }
     });
 
+    if (!env)
+    {
+        guard.deactivate();
+        env_is_dynamic = true;
+        environ = g_dynamic_env.data();
+        check(!environ);
+        return {};
+    }
+
     while (*env)
     {
         char* ptr = strdup(*(env++));
@@ -91,6 +102,22 @@ extern "C"
 {
     char** environ = nullptr;
 
+    int clearenv()
+    {
+        if (env_is_dynamic)
+        {
+            for (auto element : g_dynamic_env)
+            {
+                if (element) free(element);
+            }
+        }
+
+        env_is_dynamic = false;
+        environ = nullptr;
+
+        return 0;
+    }
+
     int unsetenv(const char* key)
     {
         if (!key || *key == 0 || strchr(key, '='))