2011-06-04 81 views
1

前阵子我试图使用Visual Studio 2010来编译使用我写在Visual Studio 2003中不出意外库MFC程序的Visual Studio版本使用#define ,我收到了一堆关于弃用和使用各种字符串函数的安全版本的警告。极品,其中包括安全字符串函数(避免_CRT_SECURE_NO_DEPRECATE)

然后我更新了相关的功能在图书馆使用的安全功能,它编译罚款。

我后来又尝试过使用Visual Studio 2003中重新编译其他系统上,并得到了大约喋喋不休的安全功能不存在。


我决定创建一个混合的方法,让我来编译在任何环境中使用的库程序,利用的安全功能,如果有的话,如果没有,他们混叠旧的。

起初我考虑检查每一个功能,看是否安全版本存在,但将无法工作,需要为每一个功能独立的工作:

#ifndef strcpy_s 
    #define strcpy_s(a,b,c) strcpy(a,c) 
#endif 

#ifndef strcat_s 
    #define strcat_s(a,b,c) strcat(a,c) 
#endif 

… 

那么,我想图out是确定安全功能是否存在的一种方法。我知道它们是在Visual Studio 2005中引入的,但是有一个#define或者其他可以用于如下的东西?

#ifndef SECURE_FUNCTIONS // or #ifdef VS_VER_2005, #if (VS_VER >= 0x2005) etc. 
    #define strcpy_s(a,b,c) strcpy(a,c) 
    #define strcat_s(a,b,c) strcat(a,c) 
    … 
#endif 

我检查了crtdefs.h,但没有发现任何用处。

回答

0

我发现的溶液; macro/define的_MSC_VER使这个很简单。由于secure string functionsadded in的Visual Studio 2005(VC++版本1400,那么它足以做这样的事情:

#if _MSC_VER < 1400 
    #define _itoa_s(a,b,c)    _itoa(a,b,c) 
    #define wcscpy_s(a,b,c)   wcscpy(a,c) 
    #define _tprintf_s     _tprintf 
    #define _sntprintf_s(a,b,c,d,...) _sntprintf(a,c,d,...) 
    … 
#endif 

现在,当代码是在VS2005 +编译,它会增加安全性,并在编制上VS2003-,尽管没有额外的安全性,它仍然可以在没有修改的情况下编译。

这使得移植和更新更容易,因为您可以更新库函数并在代码中使用安全字符串函数,即使您无法编译它们VS2005 +还没有完成,这样当你升级编译器时,你不需要做任何改变图书馆或代码来获取收益。它还使得在同一代码基础上同时处理较旧版本和较新版本的Visual Studio更容易(至少在某种程度上)。

+0

权,_MSC_VER的适当临界值是1400,即MSVC 2005年我用MSVC 2010(_MSC_VER = 1600)时,我开始编写宏来处理不兼容的安全功能。我怀疑我会再次使用2005年,但有人会。精确是件好事。 – riderBill 2016-02-04 03:40:49

+0

谢谢。我在函数宏包含文件中没有任何四个函数。是否已将_sntprintf_s_s测试为_sntprintf映射?我没有想到椭圆在RHS上工作。 – riderBill 2016-02-04 03:53:04

+0

此外,_sntprintf_s到_sntprintf宏应该读'的#define _sntprintf_s(A,B,C,...)_sntprintf((a)中,(c)中,__VA_ARGS __)'。否则,当格式后面没有参数时,您将会挂起一个逗号(语法错误)。我想这对于sprintf函数调用来说是个不寻常的例子。 strncpy将是可能的选择。围绕rhs上的参数的额外括号是函数宏的良好习惯;没有他们,你会在某天得到意想不到的结果。根据墨菲的说法,这将是最糟糕的一天。 – riderBill 2016-02-04 04:13:12

0

微软的一些安全功能的C++ 11的一部分,所以他们现在应该可以移植。 安全功能和传统安全功能之间的一个重要区别是异常行为,有时是返回值。许多程序员都没有注意到;这些差异往往被忽视。 例如snprintf的除外行为是从_snprintf_s不同:

snprintf返回缓冲器的大小无关,打印字符串,而不是 计数终止空字符所需的字符数。 我不认为snprintf的自筹例外,但无效的内存访问 会。

_snprintf_s返回相同的值的snprintf如果抛光轮是足够大的,但 如果浅黄色过少,或浅黄色或FMT是NULL指针,_snprintf_s调用 无效参数处理程序,设置分别的errno = ERANGE或EINVAL, 并返回-1。 如果在遗留代码中异常行为很重要,请注意将旧传统功能转换为安全版本。

我用微软的安全“_s”功能挣扎了几年,尤其是写作已编译在Visual Studio中的Windows平台和使用gcc /克+ +“nix平台代码时。这也是重新使用旧的源代码时,因为这是一个苦差事通过代码改变的fprintf中疼痛()来fprintf_s()等。_CRT_SECURE_NO_DEPRICAT宏观抑制废弃警告,但我从来没有关闭了编译器的粉丝警告没有解决根本问题;警告是由于某种原因而发布的。

我的临时补丁(我承认我仍然不时使用的)是一个包含文件全宏和一些内联函数映射的传统和安全功能。当然映射不会模仿异常行为和返回值。如果你愿意,你可以编写函数来模仿它,但是在某些时候,使用安全函数和改变你的旧代码来做同样的事情会更容易。而且,一些安全功能不容易被映射,例如, sprinf sprintf_s。

这是我的包含文件(比代码更多的评论,但值得一读,他们恕我直言):

#pragma once 
#if !defined(FCN_S_MACROS_H) 
    #define FCN_S_MACROS_H 

/////////////////////////////////////////////////////////////////////////////// 
// 
// These macros provide (partial) compatibility of source code developed 
// for older MSVC versions and non-MSVC c++ compilers for some of Microsoft's 
// security enhanced funcions, e.g. fscanf_s, sscanf_s, printf_s, strcpy_s, 
// fopen_s.... Of course the standard functions still work in MSVS, but 
// the choice is either to live with the annoying warning messages (bad idea) 
// or set a compiler directive to stop the warnings (bad idea--there might 
// important warnings as well as the annoying ones). 
// 
// It looks like a lot of the secure functions are now part of C++11. Those 
// functions should be used in new code. The macros below can be used for 
// for as a bridge for older code, but at some point it would be best to 
// upgrade the code with the more secure functions. Eventually, the depricated 
// functions may be removed, but probably not for a long time. 
// 
// Bill Brinson 
// 21 February 2011 (updated once or twice since then). 
// 
/////////////////////////////////////////////////////////////////////////////// 
// Does It Work: 
// 
// *** No warranty expresed nor implied. Use at your own risk. *** 
// 
// I've tested most of the standard function to MS specific macros. They 
// work in my codes so far, but Murphy says ... 
// 
// I usually write code in MSVS, using the standard functions, then port to 
// linux if needed. I haven't though as much about the inverse macros, 
// nor have I tested all of them. They seem unnecessary anyway. Too bad: they 
// tend to be simpler. 
// Test the macros yourself, and investigate exception behaviors before using 
// them. 
// 
/////////////////////////////////////////////////////////////////////////////// 
// 
// String Functions With No Count Parameter: 
// 
// The string functions that don't specify the maximum number of bytes to copy 
// into the buffer (sprintf, strcpy, ...) are a problem. Using the sizeof() 
// operator is a terrible idea (I should know--I though of it myself. 
// Fortunately sanity prevailed before I used it in real code. 
// In case you are tempted: the sizeof(buff) method WILL FAIL at runtime 
// if buffer is not defined as an array (char cstring[32] or similar). For 
// dynamically allocated memory, sizeof(ptr) returns the size of the pointer 
// itself, not the allocated memory, so if your are copying no more than four 
// bytes and you allocated at least that many, it would work due to blind luck. 
// _memsize() (MS specific, but that's were it's needed) can be used for 
// memory allocated with malloc, calloc, or realloc, but it doesn't work 
// for char buff[size] or memory allocated with the new opperator. Does anyone 
// still use malloc()? 
// Overloaded functions taking char[] and *char to differentiate them might 
// work for arrays and pointers to memory allocated by malloc et. al., but not 
// for pointers to memory allocated by new (which have the same type, so not 
// differentiated by the overloaded functions). 
// If someone an idea, please let me know. 
// 
// This should only be an issue for legacy code; use snprintf, strncpy, etc. 
// in new code (which you already do, right?), and make sure count has an 
// appropriate value. For legacy code containing sprintf, strcpy, etc., 
// I've decided to just bite the bullet: let the MS compiler point out the 
// unsafe functions, then change them to the safer (but standard) versions 
// that specify the allowable number of bytes to copy. 
// 
/////////////////////////////////////////////////////////////////////////////// 
// Exception Behavior: 
// 
// This is an important difference between the MS decreed safe functions and 
// the traditional C/C++ functions. 
// I suspect all of the MS specific functions have different exception behaviors. 
// For example the exception behavior of snprintf is different from _snprintf_s: 
// snprintf returns the number of characters required to print the string, not 
// counting the terminating null character, regardless of the size of the buffer. 
// I don't think snprintf raises exceptions. 
//  
// _snprintf_s returns same value as snprintf if buff is sufficiently large, but 
// if buff is too small, or buff or fmt is a NULL pointer, _snprintf_s invokes the 
// invalid parameter handler, sets errno = ERANGE or EINVAL, respectively, 
// and returns -1. 
// If return values and exception behaviors are important in your code, create 
// your own functions to handle the conversions. 
// 
/////////////////////////////////////////////////////////////////////////////// 
// Overloads: 
// 
// The macros below handle only the most common (for me, at least) overloads. 
// 
/////////////////////////////////////////////////////////////////////////////// 
// Suggetions: 
// 
// Yes please. There are a ton of these MS specific "safe" functions. I've 
// only done a few. 
// 
/////////////////////////////////////////////////////////////////////////////// 
// License: 
// 
// I suppose someone might care about this. 
// Sure, use what you like, delete what you don't. Modify it to your hearts 
// content. 
// I wouldn't mind getting an attaboy or something if it works (not required). 
// If it doesn't work, blame MS. 
// 
/////////////////////////////////////////////////////////////////////////////// 

// #include <cstdlib> // Do I need cstdlib? Hmm...maybe for sizeof()? 
    #include <cstdio> 
    #include <string> // Need this for _stricmp 
    using namespace std; 

    // _MSC_VER = 1400 is MSVC 2005. _MSC_VER = 1600 (MSVC 2010) was the current 
    // value when I wrote (some of) these macros. 
    #if (defined(_MSC_VER) && (_MSC_VER >= 1400)) 

     // The function plus macro strategy could be used for most of the offending 
     // MS functions, particularly for maintaining consistent exception behaviors 
     // and return values. T 
     // inline is for run time efficiency, but the compiler is not 
     // constrained to comply. 
     inline extern 
     FILE* fcnSMacro_fopen_s(char *fname, char *mode) 
     { FILE *fptr; 
     fopen_s(&fptr, fname, mode); 
     return fptr; 
     } 
     #define fopen(fname, mode)   fcnSMacro_fopen_s((fname), (mode)) 

     inline extern 
     char* fcnSMacro_strtok_s(char *strng, char *delimiters) 
     { static char *cntx; // This static variable causes the same problem 
          // as the original strtok: can't alternate search 
          // strings in the same process (MS says "thread"). 
     if(strng != NULL) *cntx = NULL; 
     char *cptr = strtok_s(strng, delimiters, &cntx); 
     return cptr; 
     } 
     #define strtok(strng, delim)   fcnSMacro_strtok_s((strng), (delim)) 

     #define fcloseall()     _fcloseall() 

     // I substituded count+1 for snprintf's buffer size argument. For well 
     // written code, the buffer size should be at least one more than count 
     // to leave room for the terminating '\0'. 
     #define snprintf(buff, count, ...) _snprintf_s((buff), (count+1), (count), __VA_ARGS__) 

     #define printf(...)     printf_s(__VA_ARGS__) 
     #define fprintf(fptr, ...)   fprintf_s((fptr), __VA_ARGS__) 

     // I don't have a solution for mapping sprinf to sprintf_s. There are other 
     // functions like this. 
// #define sprintf      ??? 
// #define strcpy(s1, s2)    ??? 

     // These mappings look trivial, but the secure functions likely have different 
     // exception behaviors and maybe different return values. 
     #define fscanf      fscanf_s 
     #define sscanf      sscanf_s 
     #define scanf       scanf_s       

     // strcmpi is deprecated in VS 2015. Don't know about 2013 or 2014 
     #define strcmpi      _stricmp 

     // No conversion needed for strncmp (yet). I guess MS hasn't gotten around 
     // to it yet. 
// #define strncmp      ??? 

     #define strncpy(dest, source, count) strcpy_s((dest), (count), (source)) 
     #define strncat(dest, source, count) strcat_s((dest), (count), (source)) 

    #else 
     // I usually write code in MSVS, using the standard functions, then port to linux if needed. 
     // I haven't though as much about the inverse macros, nor have I tested all of them. 
     // Test them yourself and investigate exception behaviors before using them. 

     #define fscanf_s       fscanf 
     #define sscanf_s       sscanf 
     #define scanf_s       scanf 
     #define printf_s       printf 
     #define sprintf_s      snprintf 
     #define fprintf_s      fprintf 
     #define strcpy_s(dest, count, source) strncpy((dest), (source), (count)) 
     #define fopen_s(fp, fmt, mode)   *(fp)=fopen((fmt), (mode)) 
     #define _fcloseall      fcloseall 
     #define strtok_s       strtok 
     #define _strcmpi       strcmpi 
    #endif //_MSC_VER 
#endif // FCN_S_MACROS_H 
+0

我看到@Synetech用于'_MSC_VER <1400'为截止(这将是'_MSC_VER> = 1400'在我的代码)。用他的号码(1400)而不是1600;我将编辑我的解决方案以反映这一点。另外,我在上面的代码中没有他的四个函数映射。如果你想添加它们。我不会等到我有机会去测试它们。只有其中两个可以重写为传统来保护函数映射。 – riderBill 2016-02-04 03:16:21