Update.

src/stdlib/eval/eval_stdlib.c

@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <pthread.h>
 #include "../../types.h"
 #include "../../tokenizer.h"
 #include "../../interpreter.h"
@@ -19,6 +20,7 @@ extern long ax;
 extern int return_flag;
 extern char str_pool[];
 extern int str_pool_idx;
+extern pthread_mutex_t token_mutex;
 
 long native_eval(long *args, int argc) {
     if (argc < 1 || !args) {
@@ -86,6 +88,9 @@ long native_eval(long *args, int argc) {
 
         Token *t = &temp_tokens[temp_tk_idx++];
         t->text = s;
+        t->line = 1;
+        t->column = 1;
+        t->filename = "<eval>";
 
         if (*s >= '0' && *s <= '9') {
             t->type = 128;
@@ -115,27 +120,47 @@ long native_eval(long *args, int argc) {
         temp_tokens[temp_tk_idx].type = 0;
     }
 
+    pthread_mutex_lock(&token_mutex);
+
+    Token *saved_tokens = (Token*)malloc(sizeof(Token) * MAX_TOK);
+    if (!saved_tokens) {
+        pthread_mutex_unlock(&token_mutex);
+        free(eval_copy);
+        return 0;
+    }
+
+    int saved_tk_idx = tk_idx;
+    for (int i = 0; i < tk_idx && i < MAX_TOK; i++) {
+        saved_tokens[i] = tokens[i];
+    }
+
     pc = 0;
     long result = 0;
 
     if (temp_tk_idx > 0) {
         for (int i = 0; i < temp_tk_idx && i < 100; i++) {
-            tokens[inserted_pos + i] = temp_tokens[i];
+            tokens[i] = temp_tokens[i];
         }
-        tk_idx = inserted_pos + temp_tk_idx;
+        tk_idx = temp_tk_idx;
         if (tk_idx < MAX_TOK) {
             tokens[tk_idx].type = 0;
         }
 
-        pc = inserted_pos;
+        pc = 0;
         result = expression();
     }
 
-    free(eval_copy);
-
-    tk_idx = original_tk_idx;
+    for (int i = 0; i < saved_tk_idx && i < MAX_TOK; i++) {
+        tokens[i] = saved_tokens[i];
+    }
+    tk_idx = saved_tk_idx;
     pc = saved_pc;
 
+    free(saved_tokens);
+    pthread_mutex_unlock(&token_mutex);
+
+    free(eval_copy);
+
     return result;
 }