这个valgrind错误是什么意思？

Question

我有一个基本库，我用它来绘制OpenGL文本，并且当我使用valgrind来确保它是气密的。我不断收到一个不寻常的错误，看起来好像linux C++库存在错误。我想看看你们是否能够发现我的错误或认证我害怕的东西，那就是我的C++库有问题，需要更换。代码非常简单，但它同时使用了OpenGL和FreeImage，因此某些行将无意义。

这里是fontsystem.h：

#ifndef FONTSYSTEM_H 
#define FONTSYSTEM_H 

/* 
    The Font System works by loading all the font images (max image size 32px^2) into memory and storing 
    the OpenGL texture ID's into an array that can be access at all times. The DrawString() functions will 
    search through the string for the specified character requested to draw and then it will draw a quad 
    and paint the texture on it. Since all the images are pre-loaded, no loading of the images at load time 
    is necessary, this is memory consuming but efficiant for the CPU. ALL functions WILL return a character 
    string specifing errors or success. A function will work as long as it can and when an error happens, 
    unless the error is fatal, the functions will NOT rollback changes! This ensures that during testing, a 
    very certain bug can be spotted. 
*/ 

#include <cstdio> 
#include <cstdlib> 
#include <iostream> 
#include <string.h> 
#include <assert.h> 
#include <GL/gl.h> 
#include <GL/glu.h> 
#include <GL/glext.h> 
#include <FreeImage.h> 

#define REPORT(x) (std::cout<<x) 
#define TIME clock() 

class CFont 
{ 
public: 
    CFont(); 
    ~CFont(); 

    void DrawString(char *apString, int aiLetterSize, int aiX, int aiY); 
    void DrawString(long anNumber, int aiLetterSize, int aiX, int aiY); 
    void SetPath(char avPath[]); 
    void SetupFont(); // This function will load as many images as possible into memory. 

private: 
    GLuint *mpTextIDs; 
    int *mpDrawIDs; 
    char *mpPath; 

public: 
    CFont(const CFont& a): 
     mpTextIDs(a.mpTextIDs), 
     mpDrawIDs(a.mpDrawIDs), 
     mpPath(a.mpPath) 
    { 
     std::copy(a.mpTextIDs, a.mpTextIDs+128, mpTextIDs); 
     std::copy(a.mpDrawIDs, a.mpDrawIDs+128, mpDrawIDs); 
     std::copy(a.mpPath, a.mpPath + strlen(a.mpPath), mpPath); 
    } 

    CFont& operator=(const CFont& a) 
    { 
     GLuint *iTmpTex = new GLuint[128]; 
     int *iTmpDraw = new int[1024]; 
     char *vTmpPath = new char[4096]; 

     delete[] mpTextIDs; 
     delete[] mpDrawIDs; 
     delete[] mpPath; 

     std::copy(a.mpTextIDs, a.mpTextIDs+128, iTmpTex); 
     std::copy(a.mpDrawIDs, a.mpDrawIDs+128, iTmpDraw); 
     std::copy(a.mpPath, a.mpPath + strlen(a.mpPath), vTmpPath); 

     mpTextIDs = iTmpTex; 
     mpDrawIDs = iTmpDraw; 
     mpPath = vTmpPath; 

     return *this; 
    } 
}; 

#endif // FONTSYSTEM_H 

这里是fontsystem.cpp：

#include "fontsystem.h" 

CFont::CFont() 
{ 
    mpTextIDs = new GLuint[128]; 
    mpDrawIDs = new int[1024]; 
    mpPath = new char[4096]; 
} 

CFont::~CFont() 
{ 
    delete[] mpTextIDs; 
    delete[] mpDrawIDs; 
    delete[] mpPath; 
} 

void CFont::DrawString(char *apString, int aiLetterSize, int aiX, int aiY) 
{ 
    // Sanity check! 
    if(apString == NULL) 
    { 
     REPORT("{Gfx}["<< TIME<< "]Error: Drawing string is NULL! <Font System>\n"); 
     return; 
    } 

    if(aiLetterSize <= 0) 
    { 
     REPORT("{Gfx}["<< TIME<< "]Error: Letter size is less than zero! <Font System>\n"); 
     return; 
    } 

    // Search the string from most significant character to least significant. 
    int iSelectIndex = 0; 
    int iNumOfSymb = 0; 
    for(size_t i = 0; apString[i] != '\0'; ++i) 
    { 
     iSelectIndex = apString[i] >= '0' && apString[i] <= '9' ? (apString[i] - '0') : 
         apString[i] >= 'A' && apString[i] <= 'Z' ? (apString[i] - 'A' + 10) : 
         apString[i] >= 'a' && apString[i] <= 'z' ? (apString[i] - 'a' + 10) : 
         apString[i] == ' ' ? 36 : // This is a special case, This see's if the current character is a space or not. 
         -1; 

     if(iSelectIndex == -1) 
     { 
      return; 
     } 

     // Add the current selected character to the drawing array. 
     mpDrawIDs[i] = iSelectIndex; 
     ++iNumOfSymb; 
    } 

    // Go through and draw each and every character. 
    for(size_t i = 0; apString[i] != '\0'/*static_cast<size_t>(iNumOfSymb)*/; ++i) 
    { 
     // Paint each qaud with the X,Y coordinates. After each quad has been successfully drawn, 
     // Add the size to the X coordinate. NOTE: Each character is square!!! 

     glBindTexture(GL_TEXTURE_2D, mpTextIDs[(uint)apString[i]]); 

     int yPos = apString[i] != 'q' || apString[i] != 'j' || apString[i] != 'y' ? aiY : aiY + (aiLetterSize/2); 

     glBegin(GL_QUADS); 
      glTexCoord2d(0, 0); 
      glVertex2d(aiX, yPos); 

      glTexCoord2d(1, 0); 
      glVertex2d(aiX + aiLetterSize, yPos); 

      glTexCoord2d(1, 1); 
      glVertex2d(aiX + aiLetterSize, yPos + aiLetterSize); 

      glTexCoord2d(0, 1); 
      glVertex2d(aiX, yPos + aiLetterSize); 
     glEnd(); 

     // Now, increase the X position by the size. 
     aiX += aiLetterSize; 
    } 
} 

void CFont::DrawString(long anNumber, int aiLetterSize, int aiX, int aiY) 
{ 
    // Sanity Check! 
    if(aiLetterSize <= 0) 
    { 
     REPORT("{Gfx}["<< TIME<< "]Error: Letter size is less than zero! <Font System>\n"); 
     return; 
    } 

    // Convert the supplied number to a character string via snprintf(). 
    char *vTempString = new char[1024]; 
    snprintf(vTempString, 1024, "%ld", anNumber); 

    // Next, run DrawString(). 
    DrawString(vTempString, aiLetterSize, aiX, aiY); 
} 

void CFont::SetupFont() 
{ 
    // First Load The PNG file holding the font. 
    FreeImage_Initialise(false); 

    FIBITMAP *spBitmap = FreeImage_Load(FIF_PNG, mpPath, BMP_DEFAULT); 

    if(!spBitmap) 
    { 
     REPORT("{Gfx}["<< TIME<< "]Error: Was Unable to opne/decode font bitmap! <FreeImage>\n"); 
     return; 
    } 

    // Do an image sanity check. 
    if(!FreeImage_HasPixels(spBitmap)) 
    { 
     REPORT("{Gfx}["<< TIME<< "]Error: The font bitmap contains nothing! <FreeImage>\n"); 
     return; 
    } 

    // Retrieve all the image data from FreeImage. 
    unsigned char *pData = FreeImage_GetBits(spBitmap); 
    int iWidth = FreeImage_GetWidth(spBitmap); 
    int iHeight = FreeImage_GetHeight(spBitmap); 
    size_t const ciCharWidth = iHeight; 
    size_t const ciCharHeight = iHeight; 

    // Cutup the PNG. 
    int iFontElementSize = (ciCharWidth*ciCharHeight)*4; // The first two numbers, are the dimensions fo the element, the last number (4) is the number of color channels (Red Green Blue and Alpha) 
    unsigned char *pElemBuff = new unsigned char[iFontElementSize]; // The temporary element buffer. 

    // Create all 37 OpenGL textures. 0-9 and A-Z and finally space (' ') 
    glGenTextures(128, mpTextIDs); 

    for (size_t iCharIdx = 0; 128 > iCharIdx; ++iCharIdx) 
    { 
     // Create character texture. 
     size_t const ciScanOfst = ciCharWidth * iCharIdx * 4; 
     for (size_t iScanLineIdx = 0; ciCharHeight > iScanLineIdx; ++iScanLineIdx) 
     { 
      memcpy(pElemBuff + ciCharWidth * iScanLineIdx * 4, 
        pData + ciScanOfst + iWidth * (ciCharHeight - iScanLineIdx - 1) * 4, 
        ciCharWidth * 4); 
     } 

     // Create The OpenGL Texture with the current Element. 
     glBindTexture(GL_TEXTURE_2D, mpTextIDs[iCharIdx]); 
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 32, 32, 0, GL_RGBA, GL_UNSIGNED_BYTE, pElemBuff); 

     // Create the correct texture environment to the current texture. 
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); 
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); 
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); 
     glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE); 
    } 

    // Do a little house cleaning! 
    delete[] pElemBuff; 
    FreeImage_Unload(spBitmap); 
    FreeImage_DeInitialise(); 

    REPORT("{Gfx}["<< TIME<< "]Information: Font was created succesfully! <Font System>\n"); 
} 

void CFont::SetPath(char avPath[]) 
{ 
    mpPath = avPath; 
} 

Valgrind的报告如下：

Starting the FontSystem... 
FontSystem Started! 
==5058== Invalid free()/delete/delete[]/realloc() 
==5058== at 0x402A8DC: operator delete[](void*) (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) 
==5058== by 0x8048F03: CFont::~CFont() (fontsystem.cpp:14) 
==5058== by 0x8048DE0: main (main.cpp:13) 
==5058== Address 0x804972f is not stack'd, malloc'd or (recently) free'd 
==5058== 
==5058== 
==5058== HEAP SUMMARY: 
==5058==  in use at exit: 4,172 bytes in 3 blocks 
==5058== total heap usage: 153 allocs, 151 frees, 135,457 bytes allocated 
==5058== 
==5058== 20 bytes in 1 blocks are still reachable in loss record 1 of 3 
==5058== at 0x402A5E6: calloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) 
==5058== by 0x64DB3AD: _dlerror_run (dlerror.c:142) 
==5058== by 0x444EC64: ??? (in /usr/lib/libGL.so.295.59) 
==5058== 
==5058== 56 bytes in 1 blocks are still reachable in loss record 2 of 3 
==5058== at 0x402BE68: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) 
==5058== by 0x442860E: ??? (in /usr/lib/libGL.so.295.59) 
==5058== by 0xBE872481: ??? 
==5058== by 0x4E45504E: ??? 
==5058== 
==5058== 4,096 bytes in 1 blocks are definitely lost in loss record 3 of 3 
==5058== at 0x402B454: operator new[](unsigned int) (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) 
==5058== by 0x8048EAC: CFont::CFont() (fontsystem.cpp:7) 
==5058== by 0x8048D68: main (main.cpp:7) 
==5058== 
==5058== LEAK SUMMARY: 
==5058== definitely lost: 4,096 bytes in 1 blocks 
==5058== indirectly lost: 0 bytes in 0 blocks 
==5058==  possibly lost: 0 bytes in 0 blocks 
==5058== still reachable: 76 bytes in 2 blocks 
==5058==   suppressed: 0 bytes in 0 blocks 
==5058== 
==5058== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0) 

我希望你们能帮助我这是因为这些似乎是我所有程序中的常见错误。作为一名编码员，我不太喜欢微妙但令人讨厌的错误。

Answer 1

最突出的问题是这个：

==5058== Invalid free()/delete/delete[]/realloc() 
==5058== at 0x402A8DC: operator delete[](void*) (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) 
==5058== by 0x8048F03: CFont::~CFont() (fontsystem.cpp:14) 
==5058== by 0x8048DE0: main (main.cpp:13) 
==5058== Address 0x804972f is not stack'd, malloc'd or (recently) free'd 
==5058== 

正如你所看到的，它指的是线fontsystem.cpp 14，在CFont析构函数，在这里：

delete[] mpPath; 

显然你尝试delete []那里从来没有动态分配，或没有以正确的方式。怎么可能？在构造相应的声明看起来不错：

mpPath = new char[4096]; 

所以mpPath值必须被改变的地方的构造被称为后。事实上，有此功能：

void CFont::SetPath(char avPath[]) 
{ 
    mpPath = avPath; 
} 

你可能把这种地方，试图将堆栈分配的阵列转移到它。你不应该那样做。如果CFont负责分配和解除分配，则不应该有一个函数试图获取外部数组并为其设置成员指针。考虑替代方法，例如将avPath数组的副本复制到堆上新分配的数组中。并取消分配先前分配的一个。甚至更好，使用std::vector或智能指针。

另一个问题是相关的：

==5058== 4,096 bytes in 1 blocks are definitely lost in loss record 3 of 3 
==5058== at 0x402B454: operator new[](unsigned int) (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) 
==5058== by 0x8048EAC: CFont::CFont() (fontsystem.cpp:7) 
==5058== by 0x8048D68: main (main.cpp:7) 

这是关系到同一成员，mpPath内存泄漏。当然，这种泄漏发生的原因是setPath重置指针而不取消分配现有数组。与上面相同的问题。

其余消息与各种外部库调用有关。微小的内存泄漏你可能不会做太多的事情。

Answer 2

你失去4096个字节可能是从这里开始：

void CFont::SetPath(char avPath[]) 
{ 
    mpPath = avPath; 
} 

你只是复制指针（并覆盖旧的一个）;你需要strcpy或像在代码的其他部分一样使用std :: copy。