Windows平台下使用C++和Windows API计算文件MD5的方法

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

#include <iostream>
#include <windows.h>
#include <tchar.h>
#include <string>
#include <cassert>
#include <functional>
 
typedef std::basic_string<TCHAR> StringT;
typedef std::string StringA;
 
#define _PP_CAT_IMPL_(a, b ) a ## b
#define PP_CAT(a, b) _PP_CAT_IMPL_( a, b )
 
namespace Details
{
    template <typename TCallable>
    class ScopedExit
    {
    public:
        ScopedExit(TCallable func) :
            Func(func)
        {
        }
 
        ~ScopedExit()
        {
            Func();
        }
 
        ScopedExit(const ScopedExit&) = delete;
        const ScopedExit& operator=(const ScopedExit&) = delete;
 
    private:
        TCallable Func;
    };
}
 
#define SCOPED_EXIT(expression) \
    ::Details::ScopedExit<std::function<void()> > PP_CAT(ScopedExitInstalce_, __COUNTER__)([&]()\
{ \
    expression;\
})
 
 
StringA CalculateFileMD5(const StringT& filepath)
{
#define BUFSIZE 1024
#define MD5LEN  16
 
    DWORD dwStatus = 0;
    BOOL bResult = FALSE;
    HCRYPTPROV hProv = 0;
    HCRYPTHASH hHash = 0;
    HANDLE hFile = NULL;
    BYTE rgbFile[BUFSIZE];
    DWORD cbRead = 0;
    BYTE rgbHash[MD5LEN];
    DWORD cbHash = 0;
    CHAR rgbDigits[] = "0123456789abcdef";
    // Logic to check usage goes here.
 
    hFile = CreateFile(filepath.c_str(),
        GENERIC_READ,
        FILE_SHARE_READ,
        NULL,
        OPEN_EXISTING,
        FILE_FLAG_SEQUENTIAL_SCAN,
        NULL);
 
    if (INVALID_HANDLE_VALUE == hFile)
    {
        return "";
    }
 
    SCOPED_EXIT(CloseHandle(hFile));
 
    // Get handle to the crypto provider
    if (!CryptAcquireContext(&hProv,
        NULL,
        NULL,
        PROV_RSA_FULL,
        CRYPT_VERIFYCONTEXT))
    {
        return "";
    }
 
    SCOPED_EXIT(CryptReleaseContext(hProv, 0));
 
    if (!CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash))
    {
        return "";
    }
 
    SCOPED_EXIT(CryptDestroyHash(hHash));
 
    while (bResult = ReadFile(hFile, rgbFile, BUFSIZE, &cbRead, NULL))
    {
        if (0 == cbRead)
        {
            break;
        }
 
        if (!CryptHashData(hHash, rgbFile, cbRead, 0))
        {
            return "";
        }
    }
 
    if (!bResult)
    {
        return "";
    }
 
    cbHash = MD5LEN;
    if (CryptGetHashParam(hHash, HP_HASHVAL, rgbHash, &cbHash, 0))
    {
        StringA result;
        result.reserve(40);
 
        for (DWORD i = 0; i < cbHash; i++)
        {
            result.push_back(rgbDigits[rgbHash[i] >> 4]);
            result.push_back(rgbDigits[rgbHash[i] & 0xf]);
        }
 
        return result;
    }
 
    return "";
}
 
int main()
{
    auto md5 = CalculateFileMD5(_T("E:\\aow-install-apk-100.xml"));
    std::cout << md5 << std::endl;
 
    return 0;
}