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我正在尝试增加一个数组以添加新的 malloc 指针。realloc 似乎并没有增加大小。另外，我从数组中一个指针的足够空间开始，所以即使 realloc 没有增加大小，我仍然希望能够复制一个指针，但我得到一个 SIGSEGV 分段错误。

typedef struct active_allocation {
    size_t sz;
    void *ptr;
} ACTIVE_ALLOCATION;

struct m61_state {
    ACTIVE_ALLOCATION **active_allocations_ptrs_arr; //Array of Points to Active Allocations
    size_t sz;
};
struct m61_state m61_state;
...
ACTIVE_ALLOCATION **active_allocations_ptrs_arr = malloc(sizeof(ACTIVE_ALLOCATION*) *1); 
m61_state.active_allocations_ptrs_arr = active_allocations_ptrs_arr;
...
//Create a New pointer, to add to the array
ACTIVE_ALLOCATION *active_allocation_record = malloc(sizeof(ACTIVE_ALLOCATION));

// ** Initially there's space for one pointer, but it hasn't been used yet.  
//m61_state->sz equals 0.
//Trying to increase the size of an array to 8 for one more ACTIVE_ALLOCATION* Last 4 can be set to NULl
//sizeof(new_active_alloc_array_ptr) equals 4 at this point
new_active_alloc_array_ptr = realloc(m61_state->active_allocations_ptrs_arr, m61_state->sz + sizeof(ACTIVE_ALLOCATION*));

//** sizeof(new_active_alloc_array_ptr) still equals 4.  I want it to be 8. I'm not sure why the size didn't change.

//Copy the new pointer that was just created active_allocation_record to the array
memset(m61_state->active_allocations_ptrs_arr[sizeof(ACTIVE_ALLOCATION*)* m61_state->sz], (int)active_allocation_record, sizeof(ACTIVE_ALLOCATION*));
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1 回答 1

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我不知道为什么您会期望 的大小发生new_active_alloc_array_ptr变化，它是一个指针，并且始终具有相同的大小-指针的大小。

有许多错误都可能导致您的崩溃：

m61_state->sz + sizeof(ACTIVE_ALLOCATION*)(1)当您似乎需要足够的空间来容纳m61_state->sz大小条目时，您正在重新调整大小，sizeof(ACTIVE_ALLOCATION*)因此它应该是m61_state->sz * sizeof(ACTIVE_ALLOCATION*).

(2) 您似乎将重新分配的指针存储到临时 ( new_active_alloc_array_ptr) 中，然后访问原始m61_state->active_allocations_ptrs_arr值。

(3) 当您访问数组时，您正在访问元素[sizeof(ACTIVE_ALLOCATION*)* m61_state->sz]- 这里没有调用sizeof(ACTIVE_ALLOCATION*)*，它应该是[m61_state->sz].

(4) 大小数组中的元素n是从0to访问的，n-1因此即使您已正确分配以创建大小数组，m61_state->sz那么[m61_state->sz]仍然会指向超出您分配的空间末尾的元素。

于 2013-09-08T17:24:52.793 回答