[solved]tinyxml bus error

[foxss]

Hi,

I tried to parse a utf-8 xml file with tinyxml while get a bus error.
main.cpp

Code: Select all

#include "tinyxml.h"
#include <pspkernel.h>

PSP_MODULE_INFO&#40;"sample", 0, 1, 1&#41;;
PSP_MAIN_THREAD_ATTR&#40;THREAD_ATTR_USER | THREAD_ATTR_VFPU&#41;;
PSP_HEAP_SIZE_KB&#40;20*1024&#41;;

TiXmlDocument* doc;

/* Exit callback */
int exit_callback&#40;int arg1, int arg2, void *common&#41; &#123;
    return 0;
&#125;

/* Callback thread */
int CallbackThread&#40;SceSize args, void *argp&#41; &#123;
    int cbid;
    cbid = sceKernelCreateCallback&#40;"Exit Callback", exit_callback, NULL&#41;;
    sceKernelRegisterExitCallback&#40;cbid&#41;;
    sceKernelSleepThreadCB&#40;&#41;;
    return 0;
&#125;

/* Sets up the callback thread and returns its thread id */
int SetupCallbacks&#40;void&#41; &#123;
    int thid = 0;
    thid = sceKernelCreateThread&#40;"update_thread", CallbackThread, 0x11, 0xFA0, PSP_THREAD_ATTR_USER, 0&#41;;
    if&#40;thid >= 0&#41;
        sceKernelStartThread&#40;thid, 0, 0&#41;;
    return thid;
&#125;

bool LoadMenu&#40;&#41;&#123;
  doc = new TiXmlDocument&#40;"test.xml"&#41;;
  return doc->LoadFile&#40;&#41;;
&#125;


void GenUI&#40;TiXmlElement *elem&#41;&#123;
    return;
&#125;

void ParseMenu&#40;TiXmlDocument* doc1&#41;&#123;
  
  TiXmlElement* ele = doc1->FirstChildElement&#40;"Item"&#41;;
  do&#123;
    GenUI&#40;ele&#41;;
    ele = ele->NextSiblingElement&#40;&#41;;
  &#125;while&#40;ele&#41;;
  
  return;
&#125;

int main&#40;&#41; &#123;
    SetupCallbacks&#40;&#41;;
    
    if&#40;!LoadMenu&#40;&#41;&#41;&#123;
        //when config file missing, exit program
        sceKernelExitGame&#40;&#41;;
        return 0;
    &#125;
    ParseMenu&#40;doc&#41;;
    sceKernelExitGame&#40;&#41;;
    return 0;
&#125;

Code: Select all

host0:/> ./VersiPSP.prx
Load/Start host0:/VersiPSP.prx UID: 0x045EFC39 Name: "s
host0:/> Exception - Bus error (data)
Thread ID - 0x045E7745
Th Name   - user_main
Module ID - 0x045EFC39
Mod Name  - "sample"
EPC       - 0x088047D4
Cause     - 0x1000001C
BadVAddr  - 0x10500440
Status    - 0x40088613
zr:0x00000000 at:0xDEADBEEF v0:0x00000001 v1:0x00000A59
a0:0x00000000 a1:0x00000021 a2:0x00000A58 a3:0x08828984
t0:0x00000020 t1:0x088355A8 t2:0x0882DDF8 t3:0x088355BC
t4:0x00000000 t5:0xDEADBEEF t6:0xDEADBEEF t7:0xDEADBEEF
s0:0x00000000 s1:0x08835330 s2:0x00000001 s3:0x0BBBFEE0
s4:0x00000014 s5:0x00000013 s6:0xDEADBEEF s7:0xDEADBEEF
t8:0xDEADBEEF t9:0xDEADBEEF k0:0x0BBBFF00 k1:0x00000000
gp:0x088364A0 sp:0x0BBBFE08 fp:0x0BBBFEA0 ra:0x08804454
0x088047D4: 0x8C83001C '....' - lw         $v1, 28($a0)

Is someone know what this about?
I can't get clue over this.

Thanks,

[psPea]

You're trying to derefeence a null pointer at 0x3d4

lw $v1, 28($a0)
a0:0x00000000
EPC:0x088047D4

lw destinationRegister, offset(sourceRegester) # load contents of RAM at offset from sourceRegister into register destinationRegister: destinationRegister = *(destinationRegister+offset)

To calculate where the error occurs type in psplink
calc $epc-$mod
then use that address in psp-address
psp-address2line -fCe your_module.elf address
This will give you the file and the line the error occurs(for this to work need to have -g in CFLAGS in your makefile)


Okay I see 2 places where your crash could have happened
return doc->LoadFile();
ele = ele->NextSiblingElement();

Edit:
I'll go with "return doc->LoadFile();" since LoadFile() is the 8th member of TiXmlDocument. You should make sure you classes are created before you use them.

[foxss]

Thanks, psPea!

I finally find crash caused as ele is a null pointer. I should be more defensive, check it before using...

Code: Select all

ele = ele->NextSiblingElement();

You're trying to derefeence a null pointer at 0x3d4

lw $v1, 28($a0)
a0:0x00000000
EPC:0x088047D4

lw destinationRegister, offset(sourceRegester) # load contents of RAM at offset from sourceRegister into register destinationRegister: destinationRegister = *(destinationRegister+offset)

To calculate where the error occurs type in psplink
calc $epc-$mod
then use that address in psp-address
psp-address2line -fCe your_module.elf address
This will give you the file and the line the error occurs(for this to work need to have -g in CFLAGS in your makefile)


Okay I see 2 places where your crash could have happened
return doc->LoadFile();
ele = ele->NextSiblingElement();

Edit:
I'll go with "return doc->LoadFile();" since LoadFile() is the 8th member of TiXmlDocument. You should make sure you classes are created before you use them.