HackMD
2025q1 Homework1 (lab0)
contributed by < vestata >
開發環境
$ gcc --version
gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Address sizes: 46 bits physical, 48 bits virtual
Byte Order: Little Endian
CPU(s): 24
On-line CPU(s) list: 0-23
Vendor ID: GenuineIntel
Model name: 13th Gen Intel(R) Core(TM) i7-13700
CPU family: 6
Model: 183
針對佇列操作的程式碼實作
- q_new
- q_free
- q_insert_head
- q_insert_tail
- q_remove_head
- q_remove_tail
- q_size
- q_delete_mid
- q_delete_dup
- q_swap
- q_reverse
- q_reverseK
- q_sort
- q_ascend
- q_descend
- q_merge
/* Free all storage used by queue */
void q_free(struct list_head *head) {
if(!head) return;
element_t *tmp, *safe;
list_for_each_entry_safe(tmp, safe, head, list) {
q_release_element(tmp);
}
free(head);
return;
}
要記得釋放 head，根據 queue.h 的敘述：
/**
* q_free() - Free all storage used by queue, no effect if header is NULL
* @head: header of queue
*/
若是 head 記憶體沒有被釋放會出現以下錯誤：
ERROR: There is no queue, but 1 blocks are still allocated
q_insert_head() and q_insert_tail()
原本的實做方法無法通過 trace-11-malloc、trace-12-malloc。 查看 traces/trace-11-malloc.cmd malloc 的失敗率設為 25%。
In strdup:
The strdup() function returns a pointer to a new string which is a duplicate of the strings. Memory for the new string is obtained with malloc(3), and can be freed with free(3).
Linux man page
在 harness.h 中，malloc、calloc、free 和 strdup 都透過對應的巨集 test_ 來執行自定義操作。而在 qtest 中，可以使用 malloc [probability] 命令來設定 fail_probability，導致 test_strdup 中的 test_malloc 可能因為 fail_probability 的影響而失敗。因此，需要加入相應的檢查機制。
return false;
new->value = strdup(s);
+ if (!new->value) {
+ free(new);
+ return false;
+ }
list_add(&new->list, head);
return true;
