在调试器中运行时 VC++ 6.0 访问冲突 [英] VC++ 6.0 access violation when run in debugger
问题描述
我正在尝试为一个已有 4 年历史的 VC++ 6.0 程序添加增强功能.调试构建从命令行运行，但不在调试器中运行:它因 printf() 内部的访问冲突而崩溃.如果我跳过 printf，那么它会在 malloc()(从 fopen() 中调用)中崩溃，我无法跳过它.
I am trying to add enhancements to a 4 year old VC++ 6.0 program. The debug build runs from the command line but not in the debugger: it crashes with an access violation inside printf(). If I skip the printf, then it crashes in malloc() (called from within fopen()) and I can't skip over that.
这意味着我无法在调试器中运行，必须依靠旧的 printf 语句来查看发生了什么.这显然使它变得更加困难.
This means I cannot run in the debugger and have to rely on the old printf statements to see what's going on. This obviously makes it a lot harder.
知道为什么 printf() 和 malloc() 在 VC++ 调试器下运行时会失败吗?我不擅长这种低级的东西！
Any idea why printf() and malloc() would fail when running under the VC++ debugger? I am no good at this low level stuff!
这里是访问冲突后的调用栈:
Here is the call stack after the access violation:
_heap_alloc_dbg(unsigned int 24, int 2, const char * 0x0046b3d8 `string', int 225) line 394 + 8 bytes
_nh_malloc_dbg(unsigned int 24, int 0, int 2, const char * 0x0046b3d8 `string', int 225) line 242 + 21 bytes
_malloc_dbg(unsigned int 24, int 2, const char * 0x0046b3d8 `string', int 225) line 163 + 27 bytes
_lock(int 2) line 225 + 19 bytes
_getstream() line 55 + 7 bytes
_fsopen(const char * 0x00468000 `string', const char * 0x00466280 `string', int 64) line 61 + 5 bytes
fopen(const char * 0x00468000 `string', const char * 0x00466280 `string') line 104 + 15 bytes
open_new_log(const char * 0x00468000 `string') line 66 + 14 bytes
log_open(const char * 0x00468000 `string', int 0) line 106 + 9 bytes
Xlog_open(const char * 0x00468000 `string', int 0) line 51 + 13 bytes
service_start(unsigned long 1, char * * 0x009a0e50) line 3152 + 12 bytes
service_init2(char * 0x00471fcc char * NTPROGRAM, char * 0x004723c4 char * NTSERVICE, char * 0x00466540 `string', unsigned long 1, char * * 0x009a0e50) line 508 + 13 bytes
service_init(char * 0x00471fcc char * NTPROGRAM, char * 0x004723c4 char * NTSERVICE, unsigned long 2, char * * 0x009a0e50) line 548
main(unsigned long 2, char * * 0x009a0e50) line 3131
mainCRTStartup() line 206 + 25 bytes
KERNEL32! 7c817067()
这是直到失败的操作的调试反汇编:
Here is the debug dissassembly up to the operation that fails:
0041EA7E jmp _heap_alloc_dbg+2B3h (0041eb23)
0041EA83 mov edx,dword ptr [_lTotalAlloc (004b4294)]
0041EA89 add edx,dword ptr [nSize]
0041EA8C mov dword ptr [_lTotalAlloc (004b4294)],edx
0041EA92 mov eax,[_lCurAlloc (004b429c)]
0041EA97 add eax,dword ptr [nSize]
0041EA9A mov [_lCurAlloc (004b429c)],eax
0041EA9F mov ecx,dword ptr [_lCurAlloc (004b429c)]
0041EAA5 cmp ecx,dword ptr [_lMaxAlloc (004b42a0)]
0041EAAB jbe _heap_alloc_dbg+249h (0041eab9)
0041EAAD mov edx,dword ptr [_lCurAlloc (004b429c)]
0041EAB3 mov dword ptr [_lMaxAlloc (004b42a0)],edx
0041EAB9 cmp dword ptr [_pFirstBlock (004b4298)],0
0041EAC0 je _heap_alloc_dbg+25Fh (0041eacf)
0041EAC2 mov eax,[_pFirstBlock (004b4298)]
0041EAC7 mov ecx,dword ptr [pHead]
0041EACA mov dword ptr [eax+4],ecx
这是我们调用 fopen() 并在 malloc() 中失败的来源
Here is our source for that calls fopen() and fails in malloc()
FILE *open_new_log( const char *logfile )
{
FILE *fp;
int retry = 0;
while( ( fp = fopen( logfile, "w" ) ) == NULL && ++retry < 300 )
Sleep( 1000 );
return( fp );
}
我得到的错误是
Unhandled exception inPISCOOP.exe: 0xC00000005: Access Violation
问候，
---阿利斯泰尔.
推荐答案
您可以使用 _CrtSetDbgFlag() 启用一堆有用的堆调试技术.还有许多其他 CRT 调试功能可用这应该可以帮助您找到问题所在.
You can use _CrtSetDbgFlag() to enable a bunch of useful heap debugging techniques. There's a host of other CRT debugging functions available that should help you track down where your problem is.
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