From b56f26ec59aed035a8c9c06a5d3ca466b68f9f2c Mon Sep 17 00:00:00 2001
From: Alistair John Strachan <alistair@devzero.co.uk>
Date: Wed, 29 Dec 2010 20:23:40 +0000
Subject: [PATCH] Fixed label list corruption bug.

---
 arch/nds/extmem.c  |  4 ++--
 docs/changelog.txt |  3 +++
 src/counter.c      |  4 ++--
 src/robot.c        | 30 +++++-------------------------
 4 files changed, 12 insertions(+), 29 deletions(-)

diff --git a/arch/nds/extmem.c b/arch/nds/extmem.c
index 7e88a3c2..9dfca10c 100644
--- a/arch/nds/extmem.c
+++ b/arch/nds/extmem.c
@@ -43,7 +43,7 @@ static void store_robot_to_extram(struct robot *robot)
   if(robot->used)
   {
     clear_label_cache(robot->label_list, robot->num_labels);
-    robot->label_list = cache_robot_labels(robot, &(robot->num_labels));
+    robot->label_list = cache_robot_labels(robot, &robot->num_labels);
   }
 }
 
@@ -62,7 +62,7 @@ static void retrieve_robot_from_extram(struct robot *robot)
   if(robot->used)
   {
     clear_label_cache(robot->label_list, robot->num_labels);
-    robot->label_list = cache_robot_labels(robot, &(robot->num_labels));
+    robot->label_list = cache_robot_labels(robot, &robot->num_labels);
   }
 }
 
diff --git a/docs/changelog.txt b/docs/changelog.txt
index 4006b62c..d9720056 100644
--- a/docs/changelog.txt
+++ b/docs/changelog.txt
@@ -69,6 +69,9 @@ USERS
   properly on all platforms.
 + Fixed a bug where a file would be re-opened for read/write, even if
   the file was missing or an I/O error occurred before saving.
++ Fixed a bug where MZX could occasionally crash due to label list
+  corruption when copying robots from heap locations greater than
+  2^32 bytes apart (only affected 64bit builds).
 
 DEVELOPERS
 
diff --git a/src/counter.c b/src/counter.c
index 7b2a1dd4..3f2bee6d 100644
--- a/src/counter.c
+++ b/src/counter.c
@@ -2500,7 +2500,7 @@ int set_counter_special(struct world *mzx_world, char *char_value,
           cur_robot->stack_pointer = 0;
           cur_robot->cur_prog_line = 1;
           cur_robot->label_list =
-           cache_robot_labels(cur_robot, &(cur_robot->num_labels));
+           cache_robot_labels(cur_robot, &cur_robot->num_labels);
 
           // Restart this robot if either it was just a LOAD_ROBOT
           // OR LOAD_ROBOTn was used where n is &robot_id&.
@@ -2537,7 +2537,7 @@ int set_counter_special(struct world *mzx_world, char *char_value,
           cur_robot->cur_prog_line = 1;
           cur_robot->stack_pointer = 0;
           cur_robot->label_list =
-            cache_robot_labels(cur_robot, &(cur_robot->num_labels));
+           cache_robot_labels(cur_robot, &cur_robot->num_labels);
 
           // Restart this robot if either it was just a LOAD_BC
           // OR LOAD_BCn was used where n is &robot_id&.
diff --git a/src/robot.c b/src/robot.c
index b6ef2243..91465349 100644
--- a/src/robot.c
+++ b/src/robot.c
@@ -274,7 +274,7 @@ void load_robot(struct robot *cur_robot, FILE *fp, int savegame, int version)
 
     // TODO: This has to be made part of what's saved one day.
     cur_robot->label_list =
-     cache_robot_labels(cur_robot, &(cur_robot->num_labels));
+     cache_robot_labels(cur_robot, &cur_robot->num_labels);
 #endif /* CONFIG_DEBYTECODE */
   }
   else
@@ -346,7 +346,7 @@ void load_robot(struct robot *cur_robot, FILE *fp, int savegame, int version)
   if(cur_robot->used)
   {
     cur_robot->label_list =
-     cache_robot_labels(cur_robot, &(cur_robot->num_labels));
+     cache_robot_labels(cur_robot, &cur_robot->num_labels);
   }
 #endif /* !CONFIG_DEBYTECODE */
 }
@@ -2806,12 +2806,9 @@ __editor_maybe_static
 void duplicate_robot_direct(struct robot *cur_robot,
  struct robot *copy_robot, int x, int y)
 {
-  struct label *src_label, *dest_label;
   char *dest_program_location, *src_program_location;
-  int program_offset;
   int program_length;
   int num_labels;
-  int i;
 
 #ifdef CONFIG_DEBYTECODE
   prepare_robot_bytecode(cur_robot);
@@ -2829,25 +2826,8 @@ void duplicate_robot_direct(struct robot *cur_robot,
 
   memcpy(dest_program_location, src_program_location, program_length);
 
-  if(num_labels)
-    copy_robot->label_list = ccalloc(num_labels, sizeof(struct label *));
-  else
-    copy_robot->label_list = NULL;
-
-  program_offset = (int)(dest_program_location - src_program_location);
-
-  // Copy each individual label pointer over
-  for(i = 0; i < num_labels; i++)
-  {
-    copy_robot->label_list[i] = cmalloc(sizeof(struct label));
-
-    src_label = cur_robot->label_list[i];
-    dest_label = copy_robot->label_list[i];
-
-    memcpy(dest_label, src_label, sizeof(struct label));
-    // The name pointer actually has to be readjusted to match the new program
-    dest_label->name += program_offset;
-  }
+  copy_robot->label_list =
+   cache_robot_labels(cur_robot, &cur_robot->num_labels);
 
 #ifdef CONFIG_DEBYTECODE
   copy_robot->program_source = NULL;
@@ -3138,7 +3118,7 @@ void prepare_robot_bytecode(struct robot *cur_robot)
     // robot's actually used. But eventually this should be combined with
     // assemble_program.
     cur_robot->label_list =
-     cache_robot_labels(cur_robot, &(cur_robot->num_labels));
+     cache_robot_labels(cur_robot, &cur_robot->num_labels);
 
     // Can free source code now.
     free(cur_robot->program_source);