Guard getenv with spinlock

Author: mat-hek

src/libAtomVM/nifs.c

@@ -1811,6 +1811,7 @@ static term nif_os_getenv_1(Context *ctx, int argc, term argv[])
 {
     UNUSED(argc);
 
+    term result;
     term env_var_list = argv[0];
     VALIDATE_VALUE(env_var_list, term_is_list);
 
@@ -1820,17 +1821,45 @@ static term nif_os_getenv_1(Context *ctx, int argc, term argv[])
         RAISE_ERROR(OUT_OF_MEMORY_ATOM);
     }
 
-    const char *env_var_value = getenv(env_var);
-    if (IS_NULL_PTR(env_var_value)) {
-        return FALSE_ATOM;
+#ifndef AVM_NO_SMP
+    smp_spinlock_lock(&ctx->global->env_spinlock);
+#endif
+
+    const char *env_var_value_tmp = getenv(env_var);
+
+    if (IS_NULL_PTR(env_var_value_tmp)) {
+        result = FALSE_ATOM;
+        goto nif_os_getenv_1_unlock_return;
     }
 
-    size_t len = strlen(env_var_value);
-    if (UNLIKELY(memory_ensure_free_opt(ctx, LIST_SIZE(len, 1), MEMORY_CAN_SHRINK) != MEMORY_GC_OK)) {
+    size_t env_value_len = strlen(env_var_value_tmp);
+    char *env_var_value = malloc(env_value_len + 1);
+
+    if (UNLIKELY(IS_NULL_PTR(env_var_value))) {
+        result = OUT_OF_MEMORY_ATOM;
+        goto nif_os_getenv_1_unlock_return;
+    }
+
+    strcpy(env_var_value, env_var_value_tmp);
+
+#ifndef AVM_NO_SMP
+    smp_spinlock_unlock(&ctx->global->env_spinlock);
+#endif
+
+    if (UNLIKELY(memory_ensure_free_opt(ctx, LIST_SIZE(env_value_len, 1), MEMORY_CAN_SHRINK) != MEMORY_GC_OK)) {
         RAISE_ERROR(OUT_OF_MEMORY_ATOM);
     }
 
-    return interop_bytes_to_list(env_var_value, len, &ctx->heap);
+    result = interop_bytes_to_list(env_var_value, env_value_len, &ctx->heap);
+    free(env_var_value);
+    return result;
+
+nif_os_getenv_1_unlock_return:
+#ifndef AVM_NO_SMP
+    smp_spinlock_unlock(&ctx->global->env_spinlock);
+#endif
+
+    return result;
 }
 
 static term nif_erlang_make_tuple_2(Context *ctx, int argc, term argv[])