c++ - 抛出异常返回内存异常错误

Question

我正在尝试在 sdl-2 中呈现文本.文本应出现在剪辑区域 SDL_Rect rcTextOutput 的 SDL_Rect destination 中，但它返回 sigabrt错误。我尝试用 valgrind 调试它和 gdb但我仍然没有看到问题。

我将把整个代码留在最后，但这是呈现文本的部分:

SDL_SetRenderDrawColor(gRenderer, 0x40, 0x40, 0x40, 0x40);

gTextSurface = TTF_RenderText_Solid(gFont, "text", gTextColor);
if (gTextSurface == NULL)
{
  throw "Unable to render texture! ERROR: ";
}
gTextTexture = SDL_CreateTextureFromSurface(gRenderer, gTextSurface);
if (gTextTexture == NULL)
{
  throw "Unable to render texture! ERROR: ";
}

SDL_Rect destination;
destination.x = rcTextOutput.x + rcTextOutput.w - 800;
destination.y = rcTextOutput.y;
destination.w = 800;
destination.h = 20;

SDL_RenderSetClipRect(gRenderer, &rcTextOutput);
SDL_RenderCopy(gRenderer, gTextTexture, NULL, &destination);
SDL_RenderSetClipRect(gRenderer, NULL);

// ...

SDL_RenderPresent(gRenderer);

我注意到了来自 this answer 的 SDL_SetClipRect()及其示例，但它不起作用。

我已经看过这个 Lazy Foo' tutorial并且代码似乎是有序的。我也跑过 gdb在它上面并返回:

Starting program: /home/pradana/Projects/sierra/caventure/build/caventure 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[New Thread 0x7fffeb5f1700 (LWP 25319)]
[New Thread 0x7fffeadf0700 (LWP 25320)]
terminate called after throwing an instance of 'char const*'

Thread 1 "caventure" received signal SIGABRT, Aborted.
0x00007ffff6c92a10 in raise () from /usr/lib/libc.so.6

我什至试过valgrind :

==25239== Memcheck, a memory error detector
==25239== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==25239== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info
==25239== Command: build/./caventure
==25239== 
==25239== Syscall param writev(vector[...]) points to uninitialised byte(s)
==25239==    at 0x5CF218D: ??? (in /usr/lib/libc-2.25.so)
==25239==    by 0x8088BAC: ??? (in /usr/lib/libxcb.so.1.1.0)
==25239==    by 0x8088FAC: ??? (in /usr/lib/libxcb.so.1.1.0)
==25239==    by 0x808902C: xcb_writev (in /usr/lib/libxcb.so.1.1.0)
==25239==    by 0x7D7EF3D: _XSend (in /usr/lib/libX11.so.6.3.0)
==25239==    by 0x7D7F431: _XReply (in /usr/lib/libX11.so.6.3.0)
==25239==    by 0x7D6A2EE: XInternAtom (in /usr/lib/libX11.so.6.3.0)
==25239==    by 0x4EFB79A: ??? (in /usr/lib/libSDL2-2.0.so.0.4.1)
==25239==    by 0x4EFC694: ??? (in /usr/lib/libSDL2-2.0.so.0.4.1)
==25239==    by 0x4EEB87F: ??? (in /usr/lib/libSDL2-2.0.so.0.4.1)
==25239==    by 0x4EEB60E: ??? (in /usr/lib/libSDL2-2.0.so.0.4.1)
==25239==    by 0x4E4F1C6: ??? (in /usr/lib/libSDL2-2.0.so.0.4.1)
==25239==  Address 0x79c5573 is 35 bytes inside a block of size 16,384 alloc'd
==25239==    at 0x4C2CF35: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==25239==    by 0x7D6F385: XOpenDisplay (in /usr/lib/libX11.so.6.3.0)
==25239==    by 0x4EFA84F: ??? (in /usr/lib/libSDL2-2.0.so.0.4.1)
==25239==    by 0x4EEB5BB: ??? (in /usr/lib/libSDL2-2.0.so.0.4.1)
==25239==    by 0x4E4F1C6: ??? (in /usr/lib/libSDL2-2.0.so.0.4.1)
==25239==    by 0x4011F3: init() (in /home/pradana/Projects/sierra/caventure/build/caventure)
==25239==    by 0x40148A: main (in /home/pradana/Projects/sierra/caventure/build/caventure)
==25239== 
terminate called after throwing an instance of 'char const*'
==25239== 
==25239== Process terminating with default action of signal 6 (SIGABRT): dumping core
==25239==    at 0x5C41A10: raise (in /usr/lib/libc-2.25.so)
==25239==    by 0x5C43139: abort (in /usr/lib/libc-2.25.so)
==25239==    by 0x53ED4EC: __gnu_cxx::__verbose_terminate_handler() (vterminate.cc:95)
==25239==    by 0x53EB2A5: __cxxabiv1::__terminate(void (*)()) (eh_terminate.cc:47)
==25239==    by 0x53EB2F0: std::terminate() (eh_terminate.cc:57)
==25239==    by 0x53EB507: __cxa_throw (eh_throw.cc:87)
==25239==    by 0x4013FC: loadMedia() (in /home/pradana/Projects/sierra/caventure/build/caventure)
==25239==    by 0x40148F: main (in /home/pradana/Projects/sierra/caventure/build/caventure)
==25239== 
==25239== HEAP SUMMARY:
==25239==     in use at exit: 13,232,031 bytes in 33,989 blocks
==25239==   total heap usage: 76,191 allocs, 42,202 frees, 50,434,525 bytes allocated
==25239== 
==25239== LEAK SUMMARY:
==25239==    definitely lost: 16 bytes in 1 blocks
==25239==    indirectly lost: 176 bytes in 4 blocks
==25239==      possibly lost: 4,143,500 bytes in 29,652 blocks
==25239==    still reachable: 9,088,339 bytes in 4,332 blocks
==25239==         suppressed: 0 bytes in 0 blocks
==25239== Rerun with --leak-check=full to see details of leaked memory
==25239== 
==25239== For counts of detected and suppressed errors, rerun with: -v
==25239== Use --track-origins=yes to see where uninitialised values come from
==25239== ERROR SUMMARY: 5 errors from 1 contexts (suppressed: 0 from 0)

这是脚本的其余部分(删除了不相关的代码):

#include <stdio.h>
#include <string>
#include <SDL2/SDL.h>
#include <SDL2/SDL_ttf.h>

// Screen dimensions, constants
const int SCREEN_WIDTH = 800;
const int SCREEN_HEIGHT = 900; // 600 for ground, 280 for output, 20 for input

SDL_Surface* gScreenSurface = NULL; // The surface contained by the window
SDL_Surface* gCurrentSurface = NULL; // Current displayed image
SDL_Surface* gTextSurface = NULL; // SDL_Surface for the text.
SDL_Texture* gTextTexture = NULL; // SDL_Texture for the text.
TTF_Font* gFont = NULL; // Font pointer.
SDL_Color gTextColor = { 0, 0, 0, 0xFF }; // Text color, white.


SDL_Renderer* gRenderer = NULL; // The renderer we'll be using
SDL_Rect rcGround, rcSprite, rcTextInput, rcTextOutput;

void init();
void loadMedia();
void quit();

void init()
{
  if (SDL_Init(SDL_INIT_VIDEO) > 0)
  {
    throw "SDL failed to initialise! ERROR: ";
  }
  else
  {
    // CODE REDACTED: gWindow and gRenderer is initialised
    if (TTF_Init() > 0)
    {
      throw "TTF could not be initialised! ERROR: ";
    }
  }
}

void loadMedia()
{
  // Ground rendering
  rcGround.x = 0;
  rcGround.y = 0;
  rcGround.w = 800;
  rcGround.h = 600;

  // Sprite rendering
  rcSprite.x = 400;
  rcSprite.y = 300;
  rcSprite.w = 4;
  rcSprite.h = 4;

  // TextOutput box rendering
  rcTextOutput.x = 0;
  rcTextOutput.y = 600;
  rcTextOutput.w = 800;
  rcTextOutput.h = 280;

  // TextInput box rendering
  rcTextInput.x = 0;
  rcTextInput.y = 880;
  rcTextInput.w = 800;
  rcTextInput.h = 20;

  gFont = TTF_OpenFont("resources/consolas.ttf", 14);
  if (gFont == NULL)
  {
    throw "Font load error";
  }
}

void quit()
{
  // Destroy window
    SDL_DestroyWindow(gWindow);
    SDL_DestroyRenderer(gRenderer);
  SDL_DestroyTexture(gTextTexture);
  SDL_FreeSurface(gTextSurface);
  TTF_CloseFont(gFont);
    gWindow = NULL;
  gRenderer = NULL;
  gFont = NULL;

    // Quit SDL subsystems
  TTF_Quit();
    SDL_Quit();
}

int main()
{
  try
  {
    init();
    loadMedia();

    bool quit = false;
    SDL_Event event;

    while(!quit)
    {
      // CODE REDACTED: event & sprite movement
      }
      if (rcSprite.x < 0 || rcSprite.y < 0 || rcSprite.y > rcGround.h || rcSprite.x > rcGround.w)
      {
        rcSprite.x = 400;
        rcSprite.y = 300;
      }

      SDL_SetRenderDrawColor(gRenderer, 0x00, 0x00, 0x00, 0x00);
      SDL_RenderClear(gRenderer);

      SDL_RenderFillRect(gRenderer, &rcGround);
      SDL_BlitSurface(gCurrentSurface, NULL, gScreenSurface, &rcGround);

      SDL_RenderFillRect(gRenderer, &rcTextInput);
      SDL_BlitSurface(gCurrentSurface, NULL, gScreenSurface, &rcTextInput);

      SDL_SetRenderDrawColor(gRenderer, 0x40, 0x40, 0x40, 0x40);

      gTextSurface = TTF_RenderText_Solid(gFont, "text", gTextColor);
      if (gTextSurface == NULL)
      {
        throw "Unable to render texture! ERROR: ";
      }
      gTextTexture = SDL_CreateTextureFromSurface(gRenderer, gTextSurface);
      if (gTextTexture == NULL)
      {
        throw "Unable to render texture! ERROR: ";
      }

      SDL_Rect destination;
      destination.x = rcTextOutput.x + rcTextOutput.w - 800;
      destination.y = rcTextOutput.y;
      destination.w = 800;
      destination.h = 20;

      SDL_RenderSetClipRect(gRenderer, &rcTextOutput);
      SDL_RenderCopy(gRenderer, gTextTexture, NULL, &destination);
      SDL_RenderSetClipRect(gRenderer, NULL);

      SDL_SetRenderDrawColor(gRenderer, 0xFF, 0xFF, 0xFF, 0xFF);

      SDL_RenderDrawLine(gRenderer, 0, 600, 800, 600);
      SDL_RenderDrawLine(gRenderer, 0, 880, 800, 880);

      SDL_RenderFillRect(gRenderer, &rcSprite);
      SDL_BlitSurface(gCurrentSurface, NULL, gScreenSurface, &rcSprite);

      SDL_RenderPresent(gRenderer);
    }
  }
  catch (const std::string& msg)
    {
        printf("%s", msg.c_str());
        if (SDL_GetError() != NULL)
        {
            printf("%s", SDL_GetError());
        }
    else if (TTF_GetError() != NULL)
        {
            printf("%s", TTF_GetError());
        }
    else
    {
      printf("%s", "NULL");
    }
    quit();
        exit(EXIT_FAILURE);
    }
  quit();
  return 0;
}

Answer 1

您抛出一个指向字符数组的指针，但 try catch 对 ::std::string 的引用。这显然是行不通的，并且您的程序由于未捕获的异常而终止。您应该在抛出时显式构造一个字符串，或者实际上您应该抛出并捕获一个可以包含描述的 std::runtime_error 实例。

throw(::std::runtime_error("Unable to render texture!"));
...
catch(::std::runtime_error const & exception)
{
    printf("%s", exception.what());