我根本找不到的C内存泄漏

Question

所以程序一切都很好，但我得到了一个非常烦人的内存泄漏。我在电脑前坐了几个小时，可以弄清楚。

我们有 2 个非常简单，一个结构是双链表，一个是存储双链表的哈希表。

现在我正在将一个键和一个数据插入双链表中，这就是函数。

void htable_insert(htable* ht, int key, int data) {
    // TODO: Insert a new entry with the given key and data
    // Overwrite the old data if the key already exists, duplicate keys are not allowed
    ht_entry *new_node;
    ht_entry *head;
    ht_entry *it;
    int sameKey;
    int bucketPosition;
    new_node = (ht_entry*)malloc(1*sizeof(ht_entry));
    bucketPosition = key % ht->size;
    sameKey = 0;
    for(it = ht->entries[bucketPosition]; it != NULL; it = it->next)
    {
      if(it->key == key) {
        it->data = data;
        sameKey = 1;
        free(new_node);
        new_node = NULL;
        break;
      }
    }
    if(!sameKey && new_node) {
      head = ht->entries[bucketPosition];
      if (head == NULL) {
        new_node->key = key;
        new_node->data = data;
        new_node->next = head;
        new_node->prev = NULL;
        ht->entries[bucketPosition] = new_node;
        new_node = NULL;
      } else {
        new_node->key = key;
        new_node->data = data;
        new_node->next = head;
        // new_node->prev = head;
        head->prev = new_node;
        head = new_node;
        ht->entries[bucketPosition] = head;
      }
    }
    // free(new_node);
    new_node = NULL;
    printf("%sn %d", "INSERT:", key);
    for(it = ht->entries[bucketPosition]; it != NULL; it = it->next){
      printf("it->key: %dnit->data: %dn", it->key, it->data);
    }

    printf("%sn", "-------------------------------");

}

这是我的瓦尔格林德信息：

==10692== Memcheck, a memory error detector
==10692== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==10692== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==10692== Command: ./chain_hash_table.out
==10692== 
==10692== 
==10692== HEAP SUMMARY:
==10692==     in use at exit: 72 bytes in 3 blocks
==10692==   total heap usage: 10 allocs, 7 frees, 376 bytes allocated
==10692== 
==10692== 24 bytes in 1 blocks are definitely lost in loss record 2 of 3
==10692==    at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==10692==    by 0x4007EE: htable_insert (htable.c:53)
==10692==    by 0x400BD2: main (main.c:14)
==10692== 
==10692== 48 (24 direct, 24 indirect) bytes in 1 blocks are definitely lost in loss record 3 of 3
==10692==    at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==10692==    by 0x4007EE: htable_insert (htable.c:53)
==10692==    by 0x400C25: main (main.c:18)
==10692== 
==10692== LEAK SUMMARY:
==10692==    definitely lost: 48 bytes in 2 blocks
==10692==    indirectly lost: 24 bytes in 1 blocks
==10692==      possibly lost: 0 bytes in 0 blocks
==10692==    still reachable: 0 bytes in 0 blocks
==10692==         suppressed: 0 bytes in 0 blocks
==10692== 
==10692== For counts of detected and suppressed errors, rerun with: -v
==10692== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)

我知道它总是用于第一个表插入，这就是为什么它在第一次插入后其余的 main (18( 行说没有泄漏。

谢谢你们的时间和帮助:)

Answer 1

检查循环中的 break 语句，它在第一次迭代时中断 并且它不会释放节点。

中断应放置在 for 循环内。

Answer 2

如果你在 C 程序中错误地分配空间，除非你在最后释放所有内容，否则你最终会得到内存泄漏。

对于您当前的程序，我假设您最终没有正确释放。因此，问题不在于htable_insert函数，而在于释放/清理函数。

如果你在htable_insert中释放链表节点，你将无法在程序的其余部分访问它们，并且会遇到段错误。