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今天研究了一下vc6函數(shù)調(diào)用，看看vc6調(diào)用函數(shù)時候都做了什么。有些意思。 我寫下了如下代碼：
int fun(int a,int b)
{
int i = 3;
return a+b+i;
}
int main()
{
int a = 1,b=2;
int result ;
result = fun(1,2);
return result;
} 非常簡單。反匯編后(Debug版)變成這樣
1: int fun(int a,int b)
2: {
00401020 push ebp
00401021 mov ebp,esp
00401023 sub esp,44h
00401026 push ebx
00401027 push esi
00401028 push edi
00401029 lea edi,[ebp-44h]
0040102C mov ecx,11h
00401031 mov eax,0CCCCCCCCh
00401036 rep stos dword ptr [edi]
3: int i = 3;
00401038 mov dword ptr [ebp-4],3
4: return a+b+i;
0040103F mov eax,dword ptr [ebp+8]
00401042 add eax,dword ptr [ebp+0Ch]
00401045 add eax,dword ptr [ebp-4]
5: }
00401048 pop edi
00401049 pop esi
0040104A pop ebx
0040104B mov esp,ebp
0040104D pop ebp
0040104E ret
7: int main()
8: {
00401060 push ebp
00401061 mov ebp,esp
00401063 sub esp,4Ch
00401066 push ebx
00401067 push esi
00401068 push edi
00401069 lea edi,[ebp-4Ch]
0040106C mov ecx,13h
00401071 mov eax,0CCCCCCCCh
00401076 rep stos dword ptr [edi]
9: int a = 1,b=2;
00401078 mov dword ptr [ebp-4],1
0040107F mov dword ptr [ebp-8],2
10: int result ;
11: result = fun(1,2);
00401086 push 2
00401088 push 1
0040108A call @ILT+5(fun) (0040100a)
0040108F add esp,8
00401092 mov dword ptr [ebp-0Ch],eax
12: return result;
00401095 mov eax,dword ptr [ebp-0Ch]
13: }
00401098 pop edi
00401099 pop esi
0040109A pop ebx
0040109B add esp,4Ch
0040109E cmp ebp,esp
004010A0 call __chkesp (004010c0)
004010A5 mov esp,ebp
004010A7 pop ebp
004010A8 ret 我們主要來看看函數(shù)調(diào)用部分 1.參數(shù)壓棧push 2 push 1 參數(shù)從右向左壓棧(__cdcel),esp遞減 2.調(diào)用函數(shù) call @ILT+5(fun) (0040100a) 這條指令會把下一行代碼的地址壓棧，也就是函數(shù)返回地址。同時跳轉(zhuǎn)到函數(shù)入口處 3.進(jìn)入函數(shù)體push ebp mov ebp,esp 首先保存ebp的地址，然后把esp保存到ebp中去 00401023 sub esp,44h 00401026 push ebx 00401027 push esi 00401028 push edi 減小stack的指針(注意，stack是從內(nèi)存的高端向低端生長的)，為局部變量保留一些空間，這里的44h不是固定的，由編譯器計算得來 00401029 lea edi,[ebp-44h] 0040102C mov ecx,11h 00401031 mov eax,0CCCCCCCCh 00401036 rep stos dword ptr [edi] 用0xCC填充局部變量空間。這是Debug模式特有的，如果是字符串，你就看到被初始化成"燙燙燙燙燙燙" 至此，整個堆棧變成 |-----------------| | 局部變量2 | |-----------------| | 局部變量1 |<----ebp-4 |-----------------| | old ebp |<----ebp |-----------------| | 函數(shù)返回地址| <----ebp+4 |-----------------| | 參數(shù)1 | <----ebp+8 |-----------------| | 參數(shù)2 | |-----------------| Next: int i = 3; 00401038 mov dword ptr [ebp-4],3 這里你看到[ebp-4]就是第一個局部變量i了 0040103F mov eax,dword ptr [ebp+8] 00401042 add eax,dword ptr [ebp+0Ch] 00401045 add eax,dword ptr [ebp-4] [ebp+8],[ebp+0Ch]分別是a和b了 4.函數(shù)返回函數(shù)的結(jié)果都是放在eax中(ps:你可以在vc的watch窗口輸入@EAX，就可以直接看到函數(shù)返回值了） 00401048 pop edi 00401049 pop esi 0040104A pop ebx 0040104B mov esp,ebp 0040104D pop ebp 0040104E ret 把edi,esi,ebx恢復(fù)，然后恢復(fù)esp,ebp,這時函數(shù)的返回地址就在棧頂，調(diào)用ret就可以返回了。 那如果改變函數(shù)的返回地址會怎樣？ ok,我們修改一下代碼：
#include <stdio.h>
void fun2()
{
printf("fun2() called");
}
int fun(int a,int b)
{
int i = 3;
printf("return address:0x%x\n",&i+2);
printf("fun2 address:0x%x\n",&fun2);
/*int *p = (int*)&fun2;
__asm
{
mov ebx,p
mov dword ptr[ebp+4],ebx
}*/
*(&i+2)=(int)&fun2; //modify return address
return a+b+i;
}
int main()
{
int a = 1,b=2;
int result ;
result = fun(1,2);
return result;
} Wow,這時，我們就會發(fā)現(xiàn)fun2被調(diào)用了。這就是Buffer overrun(緩沖溢出)所做的事情吧。 5.最后一步，調(diào)用者調(diào)整堆棧指針call @ILT+5(fun) (0040100a) add esp,8 為什么要調(diào)整呢，因為調(diào)用之前push兩個參數(shù)進(jìn)入棧，現(xiàn)在要恢復(fù)它 mov dword ptr [ebp-0Ch],eax 這句話就是享用函數(shù)調(diào)用的果實了(EAX保存了函數(shù)的返回值) ------end--------
記得以前在程序員雜志上面，看見有人提到這個問題，試了很多種方法，結(jié)果是沒辦法將程序刪除。 真的沒辦法刪除自身么？ 請運行下面的代碼：
#include <windows.h>
#include <shlobj.h>
BOOL SelfDelete()
{
SHELLEXECUTEINFO sei;
TCHAR szModule [MAX_PATH], szComspec[MAX_PATH], szParams [MAX_PATH];
// get file path names:
if((GetModuleFileName(0,szModule,MAX_PATH)!=0) &&
(GetShortPathName(szModule,szModule,MAX_PATH)!=0) &&
(GetEnvironmentVariable("COMSPEC",szComspec,MAX_PATH)!=0))
{
// set command shell parameters
lstrcpy(szParams,"/c del ");
lstrcat(szParams, szModule);
lstrcat(szParams, " > nul");
// set struct members
sei.cbSize = sizeof(sei);
sei.hwnd = 0;
sei.lpVerb = "Open";
sei.lpFile = szComspec;
sei.lpParameters = szParams;
sei.lpDirectory = 0;
sei.nShow = SW_HIDE;
sei.fMask = SEE_MASK_NOCLOSEPROCESS;
// increase resource allocation to program
SetPriorityClass(GetCurrentProcess(),
REALTIME_PRIORITY_CLASS);
SetThreadPriority(GetCurrentThread(),
THREAD_PRIORITY_TIME_CRITICAL);
// invoke command shell
if(ShellExecuteEx(&sei))
{
// suppress command shell process until program exits
SetPriorityClass(sei.hProcess,IDLE_PRIORITY_CLASS);
SetProcessPriorityBoost(sei.hProcess,TRUE);
// notify explorer shell of deletion
SHChangeNotify(SHCNE_DELETE,SHCNF_PATH,szModule,0);
return TRUE;
}
else // if error, normalize allocation
{
SetPriorityClass(GetCurrentProcess(),
NORMAL_PRIORITY_CLASS);
SetThreadPriority(GetCurrentThread(),
THREAD_PRIORITY_NORMAL);
}
}
return FALSE;
}
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
// on program exit
// close all handles etc.
if(!SelfDelete())
{
// add error messaging
}
return 0; // WinMain exit
}
程序的思想是通過創(chuàng)建一個另外的進(jìn)程(ShellExecuteEx)，再賦予本進(jìn)程比較高的權(quán)限(SetPriorityClass),
等這個程序退出以后，那個殺進(jìn)程的進(jìn)程就可以刪除程序了，另外程序通過SHChangeNotify通知Explorer:程序被刪除。
具體API的使用方法請看MSDN.
ps:這個程序是我在老外的網(wǎng)站上找到的，不是我寫的。我在VC6,Win2000 Professional上面調(diào)試通過
這是小明我自編的題目。 1.請在不運行程序的情況下，說出下面的程序運行后會崩潰么？如果是，在哪一行。
1 #include <stdio.h>
2 #include <memory.h>
3 class Test
4 {
5 public:
6 Test()
7 {
8 memset(this,0,sizeof(*this));
9 }
10 int s;
11 void test()
12 {
13 printf("test()\n");
14 }
15 void test1()
16 {
17 printf("test1():%d\n",this->s);
18 }
19 virtual void test2()
20 {
21 printf("test2()\n");
22 }
23 };
24
25 int main()
26 {
27 Test *s;
28 s->test();
29 s->test2();
30 s->test1();
31 return 0;
32 } 2 .修改一下，又是在哪一行呢？
1 #include <stdio.h>
2 #include <memory.h>
3 class Test
4 {
5 public:
6 Test()
7 {
8 memset(this,0,sizeof(*this));
9 }
10 int s;
11 void test()
12 {
13 printf("test()\n");
14 }
15 void test1()
16 {
17 printf("test1():%d\n",this->s);
18 }
19 virtual void test2()
20 {
21 printf("test2()\n");
22 }
23 };
24
25 int main()
26 {
27 Test *s = new Test();
28 s->test();
29 s->test1();
30 s->test2();
31 return 0;
32 } 3.再修改一下，情況會如何呢？
1 #include <stdio.h>
2 #include <memory.h>
3 class Test
4 {
5 public:
6 Test()
7 {
8 memset(this,0,sizeof(*this));
9 }
10 int s;
11 void test()
12 {
13 printf("test()\n");
14 }
15 void test1()
16 {
17 printf("test1():%d\n",this->s);
18 }
19 virtual void test2()
20 {
21 printf("test2()\n");
22 }
23 };
24
25 int main()
26 {
27 Test s ;
28 s.test();
29 s.test1();
30 s.test2();
31 return 0;
32 }
最后說一下答案吧
第一題是在29行，第二題在30行，最后一題不報錯。
如果你不知道為什么，建議看看<<Inside the c++ Object Model>>
當(dāng)我回想起來我剛剛學(xué)習(xí)C語言，Turbo C2.0提供的豐富的函數(shù)，可以讓枯燥的文本界面，顯示出花花綠綠的文字界面。在windows時代，這些函數(shù)都不在標(biāo)準(zhǔn)庫中。不過WINAPI可以幫你實現(xiàn)。
#include <windows.h>
#include <string>
#include <ctime>
enum Colors
{
BLACK = 0,
BLUE = 1,
DARK_GREEN = 2,
LIGHT_BLUE = 3,
RED = 4,
PURPLE = 5,
ORANGE = 6,
GREY = 7,
DARKER_GREY = 8,
MEDIUM_BLUE = 9,
LIGHT_GREEN = 10,
TEAL = 11,
RED_ORANGE = 12,
LIGHT_PURPLE = 13,
YELLOW = 14,
WHITE = 15
};
void set_cursor(short x, short y)
{
COORD point = {x, y};
::SetConsoleCursorPosition(::GetStdHandle(STD_OUTPUT_HANDLE), point);
}
void set_color(unsigned short color)
{
::SetConsoleTextAttribute(::GetStdHandle(STD_OUTPUT_HANDLE), color);
}
void delay(unsigned int delay)
{
::Sleep(delay);
}
void set_title(std::string title)
{
::SetConsoleTitle(title.c_str());
}
void show_cursor(bool show, int size = 25)
{
CONSOLE_CURSOR_INFO cci;
if (size <= 0) size = 1;
if (size > 100) size = 100;
cci.dwSize = size;
cci.bVisible = show;
::SetConsoleCursorInfo(::GetStdHandle(STD_OUTPUT_HANDLE), &cci);
}
void clear_screen()
{
system("cls");
} 代碼很簡單，不用多作解釋了
條件：不借助任何文件操作，輸出程序的source code. 程序：
#include <stdio.h>
char c[] = {0x7d,0x3b,0xa,0x69,0x6e,0x74,0x20,0x6d,0x61,0x69,0x6e,0x28,0x29,0xa,0x7b,0xa,0x20,0x20,0x20,0x20,0x70,0x72,0x69,0x6e,0x74,0x66,0x28,0x22,0x23,0x69,0x6e,0x63,0x6c,0x75,0x64,0x65,0x20,0x3c,0x73,0x74,0x64,0x69,0x6f,0x2e,0x68,0x3e,0x5c,0x6e,0x63,0x68,0x61,0x72,0x20,0x63,0x5b,0x5d,0x20,0x3d,0x20,0x7b,0x22,0x29,0x3b,0xa,0x20,0x20,0x20,0x20,0x66,0x6f,0x72,0x28,0x69,0x6e,0x74,0x20,0x69,0x3d,0x30,0x3b,0x69,0x3c,0x73,0x69,0x7a,0x65,0x6f,0x66,0x28,0x63,0x29,0x3b,0x2b,0x2b,0x69,0x29,0xa,0x20,0x20,0x20,0x20,0x7b,0xa,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x70,0x72,0x69,0x6e,0x74,0x66,0x28,0x22,0x30,0x78,0x25,0x78,0x2c,0x22,0x2c,0x63,0x5b,0x69,0x5d,0x29,0x3b,0xa,0x20,0x20,0x20,0x20,0x7d,0xa,0x20,0x20,0x20,0x20,0x70,0x72,0x69,0x6e,0x74,0x66,0x28,0x22,0x25,0x73,0x22,0x2c,0x63,0x29,0x3b,0xa,0x20,0x20,0x20,0x20,0x72,0x65,0x74,0x75,0x72,0x6e,0x20,0x30,0x3b,0xa,0x7d,};
int main()
{
printf("#include <stdio.h>\nchar c[] = {");
for(int i=0;i<sizeof(c);++i)
{
printf("0x%x,",c[i]);
}
printf("%s",c);
return 0;
} 至于怎么做到的，大家可以自己琢磨 不過不要以為只有C能做到，java也可以哦
我接收到一個任務(wù)，是把公司的一個產(chǎn)品從vc6遷移到vs2005，結(jié)果發(fā)現(xiàn)了很多的warning和error
warning 主要是使用了strcpy,strcat這樣的函數(shù)
這些在2005中都是unsafe_api.
在vs2005都推薦使用strcpy_s,strcat_s.
我想微軟這么做固然跟C++ standard有偏差
但是這些函數(shù)的使用確實造成了微軟產(chǎn)品經(jīng)常有的漏洞
微軟深受這些函數(shù)的危害阿
所以在vs2005這些都是warning
error的類型主要是以下幾種,多半和STL有關(guān)
1.include 帶.h的舊式頭文件，比如 #include <iostream.h>改為include <iostream>
2.vc6的string iterator的 char *,而vs2005中卻不是
strcpy(s.begin(), str);是不能compile的，應(yīng)改為strcpy((char *) s.c_str(),str);
3.函數(shù)返回類型不支持缺省是int
missing type specifier - int assumed. Note: c++ does not support default-int
<Code>
extern IsWindowsNT();
<Fix>
extern int IsWindowsNT();
www.ogre3d.org
OGRE: A 3D library for OpenGL and/or Direct3D
template <typename T> class Singleton
{
protected:
static T* ms_Singleton;
public:
Singleton( void )
{
assert( !ms_Singleton );
ms_Singleton = static_cast< T* >( this );
}
~Singleton( void )
{ assert( ms_Singleton ); ms_Singleton = 0; }
static T& getSingleton( void )
{ assert( ms_Singleton ); return ( *ms_Singleton ); }
static T* getSingletonPtr( void )
{ return ( ms_Singleton ); }
};
//client端的代碼
//Singleton的類
//Root.h
class Root:public Singleton<Root>
{
public:
void Use();
};
//初始化
//Root.cpp
Root * Singleton<Root>::ms_Singleton =0;
Root g_root;//must declare once only
//使用
//Test.Cpp
Root::getSingleton().Use();
很簡單，使用的技巧是template base class
這種實現(xiàn)方法的好處是復(fù)用性好。
不過使用者要聲明Root * Singleton<Root>::ms_Singleton =0;挺討厭的
改進(jìn)方法：template static member function
也就是改變聲明一個static T*在template class，換成使用靜態(tài)成員函數(shù)取出instance
template <typename T> class Singleton
{
private:
static T* & ms_Singleton()
{
static T* ms_Singleton_ =0 ;
return ms_Singleton_;
}
public:
Singleton( void )
{
assert( !ms_Singleton() );
ms_Singleton() = static_cast< T* >( this );
}
~Singleton( void )
{ assert( ms_Singleton() ); ms_Singleton() = 0; }
static T& getSingleton( void )
{ assert( ms_Singleton() ); return ( *ms_Singleton() ); }
static T* getSingletonPtr( void )
{ return ( ms_Singleton() ); }
};
1.download ACE from: www.cs.wustl.edu/~schmidt/ACE.html
2.build ACE in Visual Studio,generate ACE.lib(dll)[for release] & ACEd.lib(dll)[for debug]
3.create a empty project named: ACETest
4.add ACE path into Project Include Path and add ACE/lib into project lib path
5.create a file(hello.cpp)
#ifdef _DEBUG
#pragma comment(lib,"ACED.lib")
#else
#pragma comment(lib,"ACE.lib")
#endif
#include <ace/OS_main.h>
#include <ace/ACE.h>
#include <ace/Log_Msg.h>
#include <ace/SOCK_Connector.h>
int main(int argc, char *argv[])
{
ACE_INET_Addr addr(1500,"127.0.0.1"); //remote address
ACE_SOCK_Connector con; // connetor for socket client
ACE_SOCK_Stream stream; // stream is for socket read/write
if(con.connect(stream,addr)==-1) //connect to remote address
{
ACE_DEBUG ((LM_DEBUG,
ACE_TEXT ("(%P|%t) %p\n"),
ACE_TEXT ("connection failed")));
return 1;
}
const char msg[] = "Hello,ACE!";
stream.send_n(msg,sizeof(msg)); // send_n function send exactly n bytes
char buffer[1024] = {0};
if(stream.recv(buffer,sizeof(buffer)-1)==-1) // just call socket recv
{
ACE_DEBUG ((LM_DEBUG,
ACE_TEXT ("(%P|%t) %p\n"),
ACE_TEXT ("recv failed")));
return 1;
}
ACE_DEBUG ((LM_DEBUG,
ACE_TEXT ("(%P|%t) recv:%s\n"),
buffer));
if (stream.close () == -1) //close the connection
{
ACE_ERROR ((LM_ERROR,
ACE_TEXT ("(%P|%t) %p\n"),
ACE_TEXT ("close")));
return 1;
}
return 0;
}
6.build & execute
摘要: 1.boost::any
boost::any是一種通用的數(shù)據(jù)類型，可以將各種類型包裝后統(tǒng)一放入容器內(nèi)最重要的它是類型安全的。有點象COM里面的variant.
使用方法：any::type() 返回包裝的類型any_cast可用于any到其他類型的轉(zhuǎn)化
#include <boost/any.hpp>void test_any(){ ... 閱讀全文
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