Question

我尝试复制我在项目中遇到的这个错误，但所有的努力都失败了，我的复制完全编译和测试。

基本上，我不断收到一个seg错误，该错误追溯到我的一个文件中对strcpy的调用。我已经成功地将其隔离了一些，并且我倾向于认为问题是由于之前调用了memcpy，因为没有该行，代码工作正常。

void play(char * p1, char * p2, 
    struct result * final_res)
{
    enum icons my_board[WIDTH][HEIGHT];
    initialize(my_board);  /* potentially causing the seg fault */

    strcpy(final_res -> won, "Hello"); /* the seg fault */
    strcpy(final_res -> lost, "Goodbye"); 

    /* rest of my code, commented out */
}

result中的一个结构：

struct result
{
    char won[21];
    char lost[21];
};

有问题的函数，它复制全局枚举的状态master：

void intialize(enum icons board[][WIDTH])
{
    int i, j;

    for(i=0; i < WIDTH; i++) {
        for(j=0; j < WIDTH; j++) {
            memcpy(&board[i][j], &master[i][j], WIDTH-1);
        }
    }

}

master全局变量：

static const enum icons master[WIDTH][HEIGHT] = 
{
    {CIRCLE, CIRCLE, CIRCLE, CIRCLE, CIRCLE}, 
    {CIRCLE, CIRCLE, CIRCLE, CIRCLE, CIRCLE}, 
    {SQUARE, SQUARE, SQUARE, SQUARE, SQUARE}, 
    {TRIANGLE, TRIANGLE, TRIANGLE, TRIANGLE, TRIANGLE}, 
    {TRIANGLE, TRIANGLE, TRIANGLE, TRIANGLE, TRIANGLE}, 
};

我的valgrind输出：

==11706== Invalid write of size 1
==11706==    at 0x343040: _platform_memmove$VARIANT$Nehalem (in /usr/lib/system/libsystem_platform.dylib)
==11706==    by 0x1547E2: stpcpy (in /usr/lib/system/libsystem_c.dylib)
==11706==    by 0x1C2A43: __strcpy_chk (in /usr/lib/system/libsystem_c.dylib)
==11706==    by 0x1000013CD: play (game.c:21)
==11706==    by 0x1000012EF: main (starter.c:63)
==11706==  Address 0x104000001 is not stack'd, malloc'd or (recently) free'd
==11706==
==11706==
==11706== Process terminating with default action of signal 11 (SIGSEGV)
==11706==  Access not within mapped region at address 0x104000001
==11706==    at 0x343040: _platform_memmove$VARIANT$Nehalem (in /usr/lib/system/libsystem_platform.dylib)
==11706==    by 0x1547E2: stpcpy (in /usr/lib/system/libsystem_c.dylib)
==11706==    by 0x1C2A43: __strcpy_chk (in /usr/lib/system/libsystem_c.dylib)
==11706==    by 0x1000013CD: play (game.c:21)
==11706==    by 0x1000012EF: main (starter.c:63)
==11706==  If you believe this happened as a result of a stack
==11706==  overflow in your program's main thread (unlikely but
==11706==  possible), you can try to increase the size of the
==11706==  main thread stack using the --main-stacksize= flag.
==11706==  The main thread stack size used in this run was 8388608.
==11706==
==11706== HEAP SUMMARY:
==11706==     in use at exit: 33,497 bytes in 377 blocks
==11706==   total heap usage: 455 allocs, 78 frees, 39,513 bytes allocated
==11706==
==11706== LEAK SUMMARY:
==11706==    definitely lost: 0 bytes in 0 blocks
==11706==    indirectly lost: 0 bytes in 0 blocks
==11706==      possibly lost: 0 bytes in 0 blocks
==11706==    still reachable: 8,192 bytes in 2 blocks
==11706==         suppressed: 25,305 bytes in 375 blocks
==11706== Rerun with --leak-check=full to see details of leaked memory
==11706==
==11706== For counts of detected and suppressed errors, rerun with: -v
==11706== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 133 from 34)
Segmentation fault: 11

如果没有提供可编辑的示例或遗漏任何相关信息，请发表评论，如果还有其他任何我需要提供的信息，请发表评论！

知道这里发生了什么吗？

谢谢！

Answer 1

我认为问题在于你的初始化程序：您遍历所有字段（行和列）并复制完整的行而不是单个元素。当你达到indice的上限时，你会复制超出数组的限制。

Answer 2

初始化中的memcpy是错误。第三个参数应该是sizeof（master）而不是width-1。这假设数组1中元素的大小与master（数组2）中的元素大小相同

Answer 3

这段代码不对：

void intialize(enum icons board[][WIDTH])
{
    int i, j;

    for(i=0; i < WIDTH; i++) {
        for(j=0; j < WIDTH; j++) {
            memcpy(&board[i][j], &master[i][j], WIDTH-1);
        }
    }
}

board[i][j]的类型为enum icons。使用memcpy时，您需要使用sizeof(enum icons)而不是WIDTH-1。

你可以通过两种方式解决这个问题。

一次将master的值分配给board一个元素。

void intialize(enum icons board[][WIDTH])
{
   int i, j;

   for(i=0; i < WIDTH; i++) {
      for(j=0; j < WIDTH; j++) {
         board[i][j] = master[i][j];
      }
   }
}

或

使用memcpy将数据行从master复制到board。

void intialize(enum icons board[][WIDTH])
{
   int i;

   for(i=0; i < WIDTH; i++) {
      // Copy WIDTH enum icons from master to board.
      memcpy(board[i], master[i], sizeof(enum icons)*WIDTH);
   }
}

Memcpy在strcpy中导致seg错误？包括Valgrind输出

3 个答案: