C - sYSMALLOc：聲明失敗（realloc）

我正在嘗試編寫一個函數，用於搜索所有出現的模式，並返回與該模式匹配的文件中的偏移量數組。我想使用realloc動態增長我返回的數組，但我得到sYSMALLOC斷言錯誤。有時候，如果我使用不同的搜索模式，我可能會收到無效的下一個大小錯誤。我的機器上沒有valgrind（需要用調試標誌重建glibc）。這似乎是一個這樣簡單的問題，我只觸摸這個指針兩次 - 一次聲明它並將其設置爲NULL，並再次重新分配以增加它。我知道sizeof（char）是1，在我的realloc語句中沒有用處。C - sYSMALLOc：聲明失敗（realloc）

這裏是有問題的函數的代碼。使用「根」作爲搜索圖案

unsigned long long* searchBytes(FILE* fp, char* byteString, char* searchType, unsigned long long fileSize) 
{ 
if (fp == NULL) 
    return NULL; 

unsigned long long* foundBytes = NULL; 
long numBytes = 0; 

// make some memory for the array of found bytes 
if (strcmp(searchType, "ascii") == 0) 
{ 
    numBytes = strlen(byteString); 
    //foundBytes = realloc(NULL, numBytes * sizeof(char)); 
} 
else 
{ 
    // TODO strip the spaces from the string and handle hex searches 
    printf("hex-search not implemented yet.\n"); 
    return NULL; 
} 

// loop over all the bytes in the file looking for this ascii pattern 
unsigned long long currentOffset = 0; 
unsigned long long origOffset = 0; 
unsigned long long m = 0; 
foundWords = 0; 
char* possibleWord = malloc(numBytes * sizeof(char)); 

do 
{ 
    fseek(fp, currentOffset, SEEK_SET); 
    unsigned long long i; 
    int n = 0; 
    int failed = 0; 
    origOffset = currentOffset; 

    for(i=currentOffset; i<currentOffset+numBytes; i++) 
    { 
     possibleWord[n] = fgetc(fp); 
     n++; 
    } 
    //printf("possibleWord: %s\n", possibleWord); 

    // is this our word? use strstr just in case 
    char* found = strstr((const char*) byteString, (const char*) possibleWord); 
    if (found) 
    { 
     foundWords++; 
     // make a bigger spot for it 
     printf("allocating %ld bytes to add word %d to list...\n", (numBytes*foundWords) * sizeof(char), foundWords); 
     unsigned long long* p = realloc(foundBytes, (numBytes*foundWords) * sizeof(char)); 
     if (p) 
     { 
      foundBytes = p; 

      for (i = origOffset; i<origOffset+numBytes; i++) 
      { 
       foundBytes[m] = i; 
       //printf("added offset %llu to foundBytes[%llu]\n", i, m); 
       m++; 
      } 

     } 
     else 
     { 
      return NULL; 
     } 

    } 
    else 
    { 
     failed = 1; 
    } 

    if (failed == 0) 
    { 
     currentOffset += numBytes; 
     //printf("Yay! moving forward %ld bytes.\n", numBytes); 
    } 
    else 
    { 
     currentOffset++; 
    } 
} 
while (currentOffset < fileSize); 

if (foundWords > 0) 
{ 
    //printf("returning foundBytes!\n"); 

    //unsigned long long z; 
    //for (z=0; z<foundWords*numBytes; z++) 
    // printf("%llu\n", foundBytes[z]); 
    //printf("...\n"); 
    return foundBytes; 
} 
//printf("returning NULL\n"); 
return NULL; 
}

時上運行/ etc/passwd中：

allocating 4 bytes to add word 1 to list... 
allocating 8 bytes to add word 2 to list... 
*** glibc detected *** ./chex3: realloc(): invalid next size: 0x0000000001a59270 ***

或上/ etc/passwd中使用「守護程序」作爲搜索模式：

allocating 6 bytes to add word 1 to list... 
allocating 12 bytes to add word 2 to list... 
chex3: malloc.c:2451: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed.

有人可以看看這個，看看它看起來好嗎？謝謝！我是一個小白努力學習:)

來源

2012-12-18 raidzero

'strlen（）'不計算每個字符串末尾的尾部NUL（''\ 0''）字符。另外，不要用'sizeof（char）'乘以alloc計數，它總是爲'1'。 –

的解決方案是decalure p往上頂與foundBytes，然後更改realloc的行：

p = realloc(foundBytes, (numBytes*foundWords) * sizeof(*p));

我必須承認，我真的不明白這是爲什麼必要的，似乎我分配了足夠多的這種方式。（每次添加24個字節，而不是3個字符的搜索模式）

來源

2012-12-18 16:57:22 raidzero

C - sYSMALLOc：聲明失敗（realloc）

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