Odd program interaction issue - Avalanche & Zap

Zap was crashing when opening a collection of files at a directory depth of 5, and I found out it happened when Avalanche was run. I also observed that the order in which I opened those directories was important.

I thought it would be helpful to highlight that running Zap and Avalanche causes Zap to crash- I’m happy to say that Zap gracefully recovers itself.

I hope knowing this is helpful to anyone who experiences a similar problem with Zap. A previous issue I’d experienced with Zap was partially resolved by updating LineEditor.

I’m happy that I raised the problem at the last meetup because without those folks coming up with ideas around the issue, I don’t believe I would have tracked it down alone- Thank you. :)

Reporter 2.74 (01 Aug 2021)     List              Fri 3rd Nov 2023  13:28  
13:27:54.04 Exec
Address &FC014A28 is not in any module.
Register dump (at &200032B0) is:
pc  = &FC014A28  Flags=&20000113=nzCv if  Mode=SVC 32 bit
r0  = &00000004 : .... :          4
r1  = &00009ABC : ¼š.. :      39612
r2  = &000464C0 : Àd.. :     287936
r3  = &00000100 : .... :        256
r4  = &FFFFFFFF : .... : 4294967295
r5  = &00000033 : 3... :         51
r6  = &00000005 : .... :          5
r7  = &ABC00DEF : ï.À« : 2881490415
r8  = &00048A08 : .Š.. :     297480
r9  = &00000000 : .... :          0
r10 = &0004E8D0 : Ðè.. :     321744
r11 = &00045FD4 : Ô_.. :     286676
r12 = &0004CC67 : gÌ.. :     314471
r13 = &FA207FD4 : Ô. ú : 4196433876
r14 = &FC01429C : œB.ü : 4227941020 => &2A000002 : ...* : 704643074
Code around address is:
FC0149F0 : 9AFFFFF7 : ÷..š : BLS     &FC0149D4
FC0149F4 : 0591A008 : . ‘. : LDREQ   R10,[R1,#8]
FC0149F8 : E35B0004 : ..[ã : CMP     R11,#4
FC0149FC : 03A0C010 : .À . : MOVEQ   R12,#&10           ; =16
FC014A00 : 0A000002 : .... : BEQ     &FC014A10
FC014A04 : E28BC004 : .À‹â : ADD     R12,R11,#4
FC014A08 : E791C00C : .À‘ç : LDR     R12,[R1,R12]
FC014A0C : E08BC00C : .À‹à : ADD     R12,R11,R12
FC014A10 : E52D4004 : .@-å : STR     R4,[R13,#-4]!
FC014A14 : EA000003 : ...ê : B       &FC014A28
FC014A18 : E15C0002 : ..\á : CMP     R12,R2
FC014A1C : 0A000007 : .... : BEQ     &FC014A40
FC014A20 > E79C4001 > .@ύ : LDR     R4,[R12,R1]
FC014A24 : E08CC004 : .ÀŒà : ADD     R12,R12,R4
FC014A28 : E15C000A : ..\á : CMP     R12,R10
FC014A2C : BAFFFFF9 : ù..º : BLT     &FC014A18

Reporter 2.74 (01 Aug 2021)     Listed 36 lines

Avalanche 0.28, Zap 1.49 Rick 07, RPi4, RISC OS 5.28-9

What was the Zap error? “Not a heap block”?

Zap may have gone wrong – &FC014A20 is at offset &00014A28 in the kernel. The other message has been “not a heap block”.

Error block: 80000002 Internal error: abort on data transfer at &FC014A20
R0 = 00000004
R1 = 00009abc
R2 = 000464c0
R3 = 00000100
R4 = ffffffff
R5 = 00000033
R6 = 00000005
R7 = abc00def
R8 = 00048a08
R9 = 00000000
R10 = 0004e8d0
R11 = 00045fd4
R12 = 0004cc67
R13 = fa207fd4
R14 = fc01429c
R15 = fc014a28
CPSR = 20000113
R13_usr = 00008778
R14_usr = 202c0980
R13_svc = fa207fd4
R14_svc = fc01429c
SPSR_svc = 40000193
R13_irq = fa102000
R14_irq = 20000113
SPSR_irq = 20000113
R13_abt = fa301fa8
R14_abt = fc014a28
SPSR_abt = 20000113
R13_und = fa402000
R14_und = fc173fa0
SPSR_und = 60000113
OSMem16: 2 = fa100000, 00002000, 00002000
OSMem16: 3 = fa200000, 00008000, 00008000
OSMem16: 4 = fa300000, 00002000, 00002000
OSMem16: 5 = fa400000, 00002000, 00002000
Memory: fa100000 - fa102000
Memory: fa200000 - fa208000
Memory: fa300000 - fa302000
Memory: fa400000 - fa402000
Memory: ffff0108 - ffff010c
OSRSI6: 69 = ffff0108

R15 = fc014a28 = +14a28 in the Kernel
R14_svc = fc01429c = +1429c in the Kernel

SVC stack:
fa207fd4 : 000434d4 :
fa207fd8 : fc0146d0 : - R14: fc0146d0 (ASM call to fc0149bc)
         :          : | fc0146d0 = +146d0 in the Kernel
         :          : | fc0149bc = +149bc in the Kernel
fa207fdc : 0004ff80 :
fa207fe0 : 00000100 :
fa207fe4 : 0004ff80 :
fa207fe8 : 20000110 : - PSR?
fa207fec : 0002001d : | SWI XOS_Heap
fa207ff0 : 202c06d0 : | R14: 202c06d0
         :          : | = Zap +3383c
         :          : | = heap_extend +70
fa207ff4 : 00000100 : | R10
fa207ff8 : 0000883c : | R11
fa207ffc : 202c5ab4 : | R12

R14_usr = 202c0980 = Zap +33aec = claim_list_block +94
          Function call to 202c0660 = Zap +337cc = heap_extend +0

USR stack:
00008778 : 00000100 : | R9
0000877c : 00052b80 : | R10
00008780 : 0000002c : | R11
00008784 : 0000002c : | R12
00008788 : 202c0980 : | R14: 202c0980 (ASM call to 202c0660)
         :          : | 202c0980 = Zap +33aec
         :          : | = claim_list_block +94
         :          : | 202c0660 = Zap +337cc
         :          : | = heap_extend +0
0000878c : 000002b7 : - R4
00008790 : 000002b7 : | R10
00008794 : 202b38a0 : | R14: 202b38a0 (ASM call to 202c08ec)
         :          : | 202b38a0 = Zap +26a0c
         :          : | = create_file_block +74
         :          : | 202c08ec = Zap +33a58
         :          : | = claim_list_block +0
00008798 : 0000893c : - R1
0000879c : ffffff5a : | R2
000087a0 : 2429f0fd : | R3
000087a4 : 000002b7 : | R4
000087a8 : 00000033 : | R5
000087ac : 00100041 : | R10
000087b0 : 202b34b0 : | R14: 202b34b0 (ASM call to 202b382c)
         :          : | 202b34b0 = Zap +2661c
         :          : | = install_new_file +a0
         :          : | 202b382c = Zap +26998
         :          : | = create_file_block +0
000087b4 : 0000883c : - R1
000087b8 : 00000001 : | R2
000087bc : fdb8b310 : | R3
000087c0 : 00030688 : | R4
000087c4 : ffffffff : | R5
000087c8 : 00000005 : | R6
000087cc : abc00def : | R7
000087d0 : 00048a08 : | R8
000087d4 : 00000000 : | R9
000087d8 : 00008868 : | R10
000087dc : 202b33dc : | R14: 202b33dc (ASM call to 202b3410)
         :          : | 202b33dc = Zap +26548
         :          : | = install_file +b0
         :          : | 202b3410 = Zap +2657c
         :          : | = install_new_file +0
000087e0 : 0000883c : - R1
000087e4 : abc00def : | R7
000087e8 : 00048a08 : | R8
000087ec : 0004b110 : | R9
000087f0 : 00026848 : | R10
000087f4 : 202bd58c : | R14: 202bd58c (ASM call to 202b332c)
         :          : | 202bd58c = Zap +306f8
         :          : | = data_open +70
         :          : | 202b332c = Zap +26498
         :          : | = install_file +0
000087f8 : 202bbbbc : - 202bbe60 return to 202bbbbc?
         :          : | 202bbe60 = Zap +2efcc
         :          : | = user_message +0
         :          : | 202bbbbc = Zap +2ed28
         :          : | = dispatch_wimp_poll +b8
000087fc : 202bb8e4 : - R14: 202bb8e4 (ASM call to 202bbb04)
         :          : | 202bb8e4 = Zap +2ea50
         :          : | = start_code +178
         :          : | 202bbb04 = Zap +2ec70
         :          : | = dispatch_wimp_poll +0
00008800 : 2070615a :
00008804 : 49534353 :
00008808 : 53533a3a :
0000880c : 242e3444 :
00008810 : 7070412e :
00008814 : 65442e73 :
00008818 : 6f6c6576 :
0000881c : 6e656d70 :
00008820 : 79502e74 :
00008824 : 6e6f6874 :
00008828 : 654c2e33 :
0000882c : 2e6e7261 :
00008830 : 682e4f4f :
00008834 : 702f7461 :
00008838 : 52002079 :
0000883c : 00000074 :
00008840 : 2a0039ec :
00008844 : 0000078b :
00008848 : 00000762 :
0000884c : 00000004 :
00008850 : fffffffe :
00008854 : ffffffff :
00008858 : 00000428 :
0000885c : 00000058 :
00008860 : 00000000 :
00008864 : 00000fff :
00008868 : 49534353 :
0000886c : 53533a3a :
00008870 : 242e3444 :
00008874 : 7070412e :
00008878 : 65442e73 :
0000887c : 6f6c6576 :
00008880 : 6e656d70 :
00008884 : 79502e74 :
00008888 : 6e6f6874 :
0000888c : 654c2e33 :
00008890 : 2e6e7261 :
00008894 : 656c6946 :
00008898 : 6e2e4f49 :
0000889c : 73656d61 :
000088a0 : 702f3530 :
000088a4 : 00000079 :
000088a8 : 00000418 :
000088ac : fffffff0 :
000088b0 : fffffff0 :
000088b4 : 00000000 :
-snipped-
00008938 : 00000000 :
0000893c : 49534353 :
00008940 : 53533a3a :
00008944 : 242e3444 :
00008948 : 7070412e :
0000894c : 65442e73 :
00008950 : 6f6c6576 :
00008954 : 6e656d70 :
00008958 : 79502e74 :
0000895c : 6e6f6874 :
00008960 : 654c2e33 :
00008964 : 2e6e7261 :
00008968 : 656c6946 :
0000896c : 6e2e4f49 :
00008970 : 73656d61 :
00008974 : 702f3530 :
00008978 : 00000079 :
0000897c : 2026ec39 :
00008980 : 0000045c :
00008984 : 000002b2 :
00008988 : 00000934 :
0000898c : 00000852 :
00008990 : fffffffc :
00008994 : 00000000 :
00008998 : ffffffff :
0000899c : ff130102 :
000089a0 : 00000000 :
-snipped-
00008b74 : 00000000 :

End of dump

On the back of David’s question, something started to bother me. I’ve now discovered what that was. I apologise to James P. for suggesting an odd interaction between Avalanche and Zap and anyone else I may have misled.

I appear to have been focused on the new lines of inquiry to the detriment of the order of my actions. The error can be reproduced or avoided by choosing which directory of files you open first.

In my example, I opened two directories of files and then opened both sets.

Since the original post, I have discovered that if I open the directory with the higher alphabetical name (O) before the lower one (F), Zap crashes with the above error details. Surprisingly, when opening the directories (F→O) and then the files (^A), there’s no error.

Both Edit and StrongED are unaffected.