FTPc 1.49

The penny drops! I was sure I must have been missing something in our email communications. Thanks for the explanation.
Chris. A satisfied and grateful user!

Clicking on a link in the User menu generates the following ZeroPain error. Occurs up to the latest 1.51 build.

Time: Sun Oct 11 09:40:20 2015
Location: Offset 00001c2c in module Menu
Current Wimp task: FTPc
Last app to start: <FTPc$dir>.!runimage 

R0  = fa207ef8 R1  = 414649a8 R2  = ec02ed8c R3  = 00000000
R4  = 23fac694 R5  = 23d2ffc8 R6  = 4147fd8c R7  = ec02ed8c
R8  = 20000113 R9  = fa207f8c R10 = fa20021c R11 = 00000000
R12 = 414649a8 R13 = fa207ef8 R14 = fc42e374 R15 = fc42fd64
DFAR = 0000000c  Mode SVC32  Flags nZCv if   PSR = 60000113

fc42fd1c : e51a2218 : LDR     R2,[R10,#-536]
fc42fd20 : e0822001 : ADD     R2,R2,R1
fc42fd24 : e5923014 : LDR     R3,[R2,#20]
fc42fd28 : e1530000 : CMP     R3,R0
fc42fd2c : 05923008 : LDREQ   R3,[R2,#8]
fc42fd30 : 03830002 : ORREQ   R0,R3,#2
fc42fd34 : 05a20008 : STREQ   R0,[R2,#8]!
fc42fd38 : e3a00000 : MOV     R0,#0
fc42fd3c : e1a0f00e : MOV     PC,R14
fc42fd40 : e59f3030 : LDR     R3,&FC42FD78
fc42fd44 : e51ac218 : LDR     R12,[R10,#-536]
fc42fd48 : e5902004 : LDR     R2,[R0,#4]
fc42fd4c : e08c3003 : ADD     R3,R12,R3
fc42fd50 : e593c014 : LDR     R12,[R3,#20]
fc42fd54 : e15c0001 : CMP     R12,R1
fc42fd58 : 0593300c : LDREQ   R3,[R3,#12]
fc42fd5c * 05b3100c * LDREQ   R1,[R3,#12]!
fc42fd60 : 01510002 : CMPEQ   R1,R2
fc42fd64 : 13a03000 : MOVNE   R3,#0
fc42fd68 : 03a03001 : MOVEQ   R3,#1
fc42fd6c : e5803000 : STR     R3,[R0,#0]
fc42fd70 : e3a00000 : MOV     R0,#0
fc42fd74 : e1a0f00e : MOV     PC,R14
fc42fd78 : fc431ed4 : MCRR2   CP14,13,R1,R3,C4   ; ARMv6 or later
fc42fd7c : e1a0c00d : MOV     R12,R13
fc42fd80 : e92dd800 : STMDB   R13!,{R11,R12,R14,PC}
fc42fd84 : e24dd028 : SUB     R13,R13,#&28       ; ="("
fc42fd88 : e5b02004 : LDR     R2,[R0,#4]!
fc42fd8c : e59f0048 : LDR     R0,&FC42FDDC
fc42fd90 : e51a3218 : LDR     R3,[R10,#-536]
fc42fd94 : e24cb004 : SUB     R11,R12,#4
fc42fd98 : e0833000 : ADD     R3,R3,R0

That’s caused when calling Toolbox_GetObjectState for a menu object. I tested the object id of the menu by calling Toolbox_GetClientHandle and that wasn’t a problem.

In castle.riscos.sources.toolbox.menu.c.getstate getstate_menu() needs to begin with:

if (global_menu.top == NULL)
{
  r->r[0] = 0;
  return NULL;
}

Does it need raising in the Bugs forum?

Bug forum never works – someone will be reading recent posts.

Yep, it’s not the bug forum, but the forum of bugs :)

In castle.riscos.sources.toolbox.menu.c.getstate getstate_menu() needs to begin with

I have done a home build with that included, and indeed No Pain. Many thanks.

Menu 0.39 should contain Colin’s fix, along with a fix for the handling of Toolbox_HideObject, which I spotted was broken in the same way.

Thanks for the help!

If you want to be more proactive, running find ‘global_menu.top-’ on toolbox.menu directory finds a number of instances of global_menu.top being dereferenced in menu.c.auxiliary and menu.c.event

The 2 in c.event are like this

_kernel_oserror *event_menu_warning (wimp_Message message_block, TaskDescriptor *t) {

   MenuInternal      *menu_int     = global_menu.top;
   MenuInternalEntry *int_entry;
   wimp_MenuEntry    *entry;
   int               *pposition    = (int *) message_block.data.menu_warning.data,
                      submenu_event;
   Menu_SubMenu_Event
                     *menu_sm;
   ToolboxEvent       toolbox_event;
   ObjectID           object_id    = global_menu.top->hdr.object_id;
   ObjectID           submenu;
   ComponentID        component_id;
   DisplayInfo       *coords;
   _kernel_swi_regs   regs;
   _kernel_oserror   *e;

   DEBUG debug_output ("e","Menu: event menu warning entered\n");

   if (!menu_int || (*pposition == -1)) {
      /* We're not handling a menu OR menu tree V.short */
      return NULL;
   }

where menu_int, which has the value global_menu.top, is checked for null but global_menu.top is dereferenced earlier. I’d just move the object_id declaration after the menu_int null check.

I did a search for ’ = global_menu.top’ but that didn’t show up any instances where the alias wasn’t checked for null.

There are 11 hits in menu.c.auxiliary not all need changes.

Menu 0.39 should contain Colin’s fix

It does, !FTPc 1.51 is fine, many thanks.