我在運行C++應用程序時遇到seg故障。在gdb中,它顯示了我的一個指針位置被破壞了。但是我在應用程序中創建了成千上萬個這樣的對象指針。我如何看一個導致崩潰的問題 我可以在bt命令中執行任何操作來查看該指針的生命週期嗎?在C++代碼中追蹤指針gdb
感謝 魯奇
我在運行C++應用程序時遇到seg故障。在gdb中,它顯示了我的一個指針位置被破壞了。但是我在應用程序中創建了成千上萬個這樣的對象指針。我如何看一個導致崩潰的問題 我可以在bt命令中執行任何操作來查看該指針的生命週期嗎?在C++代碼中追蹤指針gdb
感謝 魯奇
我在過去的一些mem-leaks問題(由編譯器錯誤引起)在約256K指針的應用程序中,所以我不得不以某種方式檢查它。經過一番努力,我創建了一個所有分配的指針和它們的大小以及一些函數來保持它的更新。結果是這樣的:
文件:mmap.h
//---------------------------------------------------------------------------
//--- Memory map system ver: 2.03 -------------------------------------------
//---------------------------------------------------------------------------
#ifndef _mmap_h
#define _mmap_h
//---------------------------------------------------------------------------
#define _mmap_aprox
//---------------------------------------------------------------------------
/*
new
#ifdef _mmap_h
if() mmap_new('Main',,sizeof());
#endif
#ifdef _mmap_h
if() mmap_del('Main',);
#endif
delete
*/
//---------------------------------------------------------------------------
struct _mmap_entry
{
char ids[4]; // id string
DWORD beg,end; // mem adr <beg,end)
_mmap_entry(){ beg=0; end=0; ((DWORD*)(ids))[0]='LLUN'; };
_mmap_entry(_mmap_entry& a) { *this=a; }
~_mmap_entry() {}
_mmap_entry* operator = (const _mmap_entry *a) { *this=*a; return this; }
//_mmap_entry* operator = (const _mmap_entry &a) { ...copy... return this; }
};
//---------------------------------------------------------------------------
const int _mmap_entries=4*1024; // max num of allocated memory chunks (pointers)
const int _mmapn_entries=32; // num of last news to remember
const int _mmapd_entries=32; // num of last dels to remember
static _mmap_entry mmap [_mmap_entries]; // memory map table active ptrs
static _mmap_entry mmapn[_mmapn_entries]; // memory map table last news
static _mmap_entry mmapd[_mmapd_entries]; // memory map table last dels
static int mmaps=0; // num of used entries in memory map table
static int mmapn_ix=0; // num of last deletes to remember
static int mmapd_ix=0; // num of last deletes to remember
static int mmap_errs=0; // error count
static int mmap_news=0; // allocations count
static int mmap_dels=0; // deallocations count
//---------------------------------------------------------------------------
void mmap_err(const char* msg,DWORD ptr) // breakpointeable error
{
mmap_errs++;
}
//---------------------------------------------------------------------------
int mmap_new(DWORD ids,void* ptr,DWORD siz) // tracks all allocations return false if error
{
mmap_news++;
int i,j; _mmap_entry e,*p;
e.beg=DWORD(ptr);
e.end=e.beg+siz;
e.ids[0]=((char*)&ids)[3];
e.ids[1]=((char*)&ids)[2];
e.ids[2]=((char*)&ids)[1];
e.ids[3]=((char*)&ids)[0];
if (e.beg==0)
{
mmap_err("Not enough memory.",e.beg);
return 0;
}
// find first i where mmap[i].end >= e.beg
#ifdef _mmap_aprox
if (!mmaps) i=0;
else{
for (j=1;j<mmaps;j<<=1); j>>=1; if (!j) j=1;
for (i=0;j;j>>=1)
{
i|=j;
p=mmap+i;
if ((i>=mmaps)||(e.beg<p->end)) i^=j;
if ((e.beg<p->end)&&(e.end>p->beg))
{
mmap_err("Bad allocation.",e.beg); // memory already allocated
return 0;
}
}
if (e.beg>=mmap[i].end) i++;
}
#endif
#ifndef _mmap_aprox
for (i=mmaps-1,p=mmap+i;i>=0;i--,p--)
if (e.beg<p->end)
{
if (e.end>p->beg)
{
mmap_err("Bad allocation.",e.beg); // memory already allocated
return 0;
}
} else break; i++;
#endif
// insert new pointer at i
if (mmaps>=_mmap_entries)
{
mmap_err("Too many pointers.",e.beg); // _mmap_entries is too low
return 0;
}
for (j=mmaps;j>i;j--) mmap[j]=mmap[j-1];
mmap[i]=e; mmaps++;
// remember last new in mmapn table
mmapn[mmapn_ix]=e; mmapn_ix++;
if (mmapn_ix>=_mmapn_entries) mmapn_ix=0;
return 1;
};
//---------------------------------------------------------------------------
int mmap_del(DWORD ids,void* ptr) // tracks all deallocations return false if error
{
mmap_dels++;
int i,j; _mmap_entry *p;
DWORD adr=DWORD(ptr);
if (adr==0)
{
mmap_err("Can not delete NULL.",adr);
return 0;
}
if (mmap<=0)
{
mmap_err("Nothing to delete.",adr);
return 0;
}
// find mmap[i] where beg==ptr and delete it if found
#ifdef _mmap_aprox
if (!mmaps) i=0;
else{
for (j=1;j<mmaps;j<<=1); j>>=1; if (!j) j=1;
for (i=0;j;j>>=1)
{
i|=j;
p=mmap+i;
if ((i>=mmaps)||(adr<p->beg)) i^=j;
}
if (adr==mmap[i].beg)
{
if (mmaps>1) for (j=i;j<mmaps-1;j++) mmap[j]=mmap[j+1];
mmaps--;
// remember last delete in mmapd table
mmapd[mmapd_ix]=mmap[mmaps]; mmapd_ix++;
if (mmapd_ix>=_mmapd_entries) mmapd_ix=0;
// delete ptr from mmap table
mmap[mmaps].beg=0;
mmap[mmaps].end=0;
return 1;
}
for (p=mmap,j=0;j<=i;j++,p++) // test all mmap[j].beg < adr
if (adr<p->end) // if overlap then ...
{
mmap_err("Wrong delete pointer.",adr); // pointer inside already allocated space
return 0;
}
}
#endif
#ifndef _mmap_aprox
for (p=mmap,i=0;i<mmaps;i++,p++)
if (p->beg==adr)
{
if (mmaps>1) for (j=i;j<mmaps-1;j++) mmap[j]=mmap[j+1];
mmaps--;
mmap[mmaps].beg=0;
mmap[mmaps].end=0;
return 1;
} else if (p->beg>adr) break;
for (p=mmap,i=0;i<mmaps;i++,p++)
if ((adr>p->beg)&&(adr<p->end))
{
mmap_err("Wrong delete pointer.",adr); // pointer inside already allocated space
return 0;
}
#endif
mmap_err("Delete pointer not found.",adr);
return 0;
};
//---------------------------------------------------------------------------
#endif
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
現在在你的代碼只是這樣做:
// edit the safe big enough number of pointers to use for your application in begin of the mmap.h
_mmap_entries=512*1024;
// before any delete/delete[] of pointer ptr add this:
#ifdef _mmap_h
if (ptr!=NULL) mmap_del('info',ptr);
#endif
if (ptr!=NULL) delete[] ptr;
// after any new of pointer ptr of size siz [byte] add this:
ptr=new BYTE[siz];
#ifdef _mmap_h
if (ptr!=NULL) mmap_new('info',ptr,siz);
#endif
所以,如果你有mmap.h 作爲第一包括: !內部函數void mmap_err
可以一步代碼我BDS2006的Turbo C++的用戶,所以如果我忘了一些VCL東西只是將它轉換爲MSVC++或評論我,我會做,但我沒有看到任何可能導致麻煩的事情。
PS。我發現我的編譯器是一個致命的錯誤:
在這兩種情況下不會引發任何異常,但內存管理器之後被破壞,所以它分配錯誤,因此例外
適當的構造函數/析構函數爲我的編譯器
所有結構和類將被動態分配或它們的組成
的紐約是這樣的:
class/struct T
{
public:
T() {}
T(T& a) { *this=a; }
~T() {}
T* operator = (const T *a) { *this=*a; return this; }
// if any dynamic allocation occur then this must be done also else not
//T* operator = (const T &a) { ... copy a to this ... return this; }
};
看看Valgrind的,它應該給你你需要 – Jupotter