Linux 中的链表list 使用示例

转：http://www.cnblogs.com/westfly/archive/2011/04/07/2007549.html

学习链表的实现，还是觉得linux下的显得不错。

今天爬取了份可以用在linux下的代码。不必要重复造轮子了。对于这份代码的详细说明，请参考 《Linux Kernel Linked List Explained》

如下代码的获取路径

http://isis.poly.edu/kulesh/stuff/src/klist/list.h

list.h

  1 #ifndef __LIST_H  2 #define __LIST_H  3   4 /* This file is from Linux Kernel (include/linux/list.h)  5 * and modified by simply removing hardware prefetching of list items.  6 * Here by copyright, credits attributed to wherever they belong.  7 * Kulesh Shanmugasundaram (kulesh [squiggly] isis.poly.edu)  8 */  9  10 /* 11 * Simple doubly linked list implementation. 12 * 13 * Some of the internal functions (“__xxx”) are useful when 14 * manipulating whole lists rather than single entries, as 15 * sometimes we already know the next/prev entries and we can 16 * generate better code by using them directly rather than 17 * using the generic single-entry routines. 18 */ 19  20 struct list_head { 21     struct list_head *next, *prev; 22 }; 23  24 #define LIST_HEAD_INIT(name) { &(name), &(name) } 25  26 #define LIST_HEAD(name) \ 27 struct list_head name = LIST_HEAD_INIT(name) 28  29 static inline void INIT_LIST_HEAD(struct list_head *list) 30 { 31     list->next = list; 32     list->prev = list; 33 } 34 /* 35 * Insert a new entry between two known consecutive entries. 36 * 37 * This is only for internal list manipulation where we know 38 * the prev/next entries already! 39 */ 40 static inline void __list_add(struct list_head *new, 41                               struct list_head *prev, 42                               struct list_head *next) 43 { 44     next->prev = new; 45     new->next = next; 46     new->prev = prev; 47     prev->next = new; 48 } 49  50 /** 51 * list_add – add a new entry 52 * @new: new entry to be added 53 * @head: list head to add it after 54 * 55 * Insert a new entry after the specified head. 56 * This is good for implementing stacks. 57 */ 58 static inline void list_add(struct list_head *new, struct list_head *head) 59 { 60     __list_add(new, head, head->next); 61 } 62  63 /** 64 * list_add_tail – add a new entry 65 * @new: new entry to be added 66 * @head: list head to add it before 67 * 68 * Insert a new entry before the specified head. 69 * This is useful for implementing queues. 70 */ 71 static inline void list_add_tail(struct list_head *new, struct list_head *head) 72 { 73     __list_add(new, head->prev, head); 74 } 75  76 /* 77 * Delete a list entry by making the prev/next entries 78 * point to each other. 79 * 80 * This is only for internal list manipulation where we know 81 * the prev/next entries already! 82 */ 83 static inline void __list_del(struct list_head *prev, struct list_head *next) 84 { 85     next->prev = prev; 86     prev->next = next; 87 } 88  89 /** 90 * list_del – deletes entry from list. 91 * @entry: the element to delete from the list. 92 * Note: list_empty on entry does not return true after this, the entry is in an undefined state. 93 */ 94 static inline void list_del(struct list_head *entry) 95 { 96     __list_del(entry->prev, entry->next); 97     entry->next = (void *) 0; 98     entry->prev = (void *) 0; 99 }100 101 /**102 * list_del_init – deletes entry from list and reinitialize it.103 * @entry: the element to delete from the list.104 */105 static inline void list_del_init(struct list_head *entry)106 {107     __list_del(entry->prev, entry->next);108     INIT_LIST_HEAD(entry);109 }110 111 /**112 * list_move – delete from one list and add as another’s head113 * @list: the entry to move114 * @head: the head that will precede our entry115 */116 static inline void list_move(struct list_head *list, struct list_head *head)117 {118     __list_del(list->prev, list->next);119     list_add(list, head);120 }121 122 /**123 * list_move_tail – delete from one list and add as another’s tail124 * @list: the entry to move125 * @head: the head that will follow our entry126 */127 static inline void list_move_tail(struct list_head *list,128 struct list_head *head)129 {130     __list_del(list->prev, list->next);131     list_add_tail(list, head);132 }133 134 /**135 * list_empty – tests whether a list is empty136 * @head: the list to test.137 */138 static inline int list_empty(struct list_head *head)139 {140     return head->next == head;141 }142 143 static inline void __list_splice(struct list_head *list,144 struct list_head *head)145 {146     struct list_head *first = list->next;147     struct list_head *last = list->prev;148     struct list_head *at = head->next;149 150     first->prev = head;151     head->next = first;152 153     last->next = at;154     at->prev = last;155 }156 157 /**158 * list_splice – join two lists159 * @list: the new list to add.160 * @head: the place to add it in the first list.161 */162 static inline void list_splice(struct list_head *list, struct list_head *head)163 {164     if (!list_empty(list))165         __list_splice(list, head);166 }167 168 /**169 * list_splice_init – join two lists and reinitialise the emptied list.170 * @list: the new list to add.171 * @head: the place to add it in the first list.172 *173 * The list at @list is reinitialised174 */175 static inline void list_splice_init(struct list_head *list,176                                     struct list_head *head)177 {178     if (!list_empty(list)) {179         __list_splice(list, head);180         INIT_LIST_HEAD(list);181     }182 }183 184 /**185 * list_entry – get the struct for this entry186 * @ptr:    the &struct list_head pointer.187 * @type:    the type of the struct this is embedded in.188 * @member:    the name of the list_struct within the struct.189 */190 #define list_entry(ptr, type, member) \191     ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))192 193 /**194 * list_for_each    -    iterate over a list195 * @pos:    the &struct list_head to use as a loop counter.196 * @head:    the head for your list.197 */198 #define list_for_each(pos, head) \199     for (pos = (head)->next; pos != (head); \200         pos = pos->next)201 /**202 * list_for_each_prev    -    iterate over a list backwards203 * @pos:    the &struct list_head to use as a loop counter.204 * @head:    the head for your list.205 */206 #define list_for_each_prev(pos, head) \207     for (pos = (head)->prev; pos != (head); \208         pos = pos->prev)209 210 /**211 * list_for_each_safe    -    iterate over a list safe against removal of list entry212 * @pos:    the &struct list_head to use as a loop counter.213 * @n:        another &struct list_head to use as temporary storage214 * @head:    the head for your list.215 */216 #define list_for_each_safe(pos, n, head) \217     for (pos = (head)->next, n = pos->next; pos != (head);\218         pos = n, n = pos->next)219 220 221 /**222 * list_for_each_entry    -    iterate over list of given type223 * @pos:    the type * to use as a loop counter.224 * @head:    the head for your list.225 * @member:    the name of the list_struct within the struct.226 */227 #define list_for_each_entry(pos, head, member)                \228     for (pos = list_entry((head)->next,typeof(*pos), member); \229         &pos->member != (head);                                  \230             pos = list_entry(pos->member.next, typeof(*pos), member))231 232 /**233 * list_for_each_entry_safe – iterate over list of given type safe against removal of list entry234 * @pos:    the type * to use as a loop counter.235 * @n:        another type * to use as temporary storage236 * @head:    the head for your list.237 * @member:    the name of the list_struct within the struct.238 */239 #define list_for_each_entry_safe(pos, n, head, member)            \240 for (pos = list_entry((head)->next, typeof(*pos), member),    \241     n = list_entry(pos->member.next, typeof(*pos), member);    \242         &pos->member != (head);                     \243             pos = n, n = list_entry(n->member.next, typeof(*n), member))244 245 #endif

下面代码是给出的测试用例（也可以作为其函数的用法示例哦）

其可以从http://isis.poly.edu/kulesh/stuff/src/klist/test_list.c 下载

mylist.c

  1 #include <stdio.h>  2 #include <stdlib.h>  3   4 #include "list.h"  5   6   7 struct kool_list{  8     int to;  9     struct list_head list; 10     int from; 11     }; 12  13 int main(int argc, char **argv){ 14  15     struct kool_list *tmp; 16     struct list_head *pos, *q; 17     unsigned int i; 18  19     struct kool_list mylist; 20     INIT_LIST_HEAD(&mylist.list); 21     /* or you could have declared this with the following macro 22      * LIST_HEAD(mylist); which declares and initializes the list 23      */ 24  25     /* adding elements to mylist */ 26     for(i=5; i!=0; --i){ 27         tmp= (struct kool_list *)malloc(sizeof(struct kool_list)); 28          29         /* INIT_LIST_HEAD(&tmp->list);  30          * 31          * this initializes a dynamically allocated list_head. we 32          * you can omit this if subsequent call is add_list() or  33          * anything along that line because the next, prev 34          * fields get initialized in those functions. 35          */ 36         printf("enter to and from:"); 37         scanf("%d %d", &tmp->to, &tmp->from); 38  39         /* add the new item 'tmp' to the list of items in mylist */ 40         list_add(&(tmp->list), &(mylist.list)); 41         /* you can also use list_add_tail() which adds new items to 42          * the tail end of the list 43          */ 44     } 45     printf("\n"); 46  47  48     /* now you have a circularly linked list of items of type struct kool_list. 49      * now let us go through the items and print them out 50      */ 51  52  53     /* list_for_each() is a macro for a for loop.  54      * first parameter is used as the counter in for loop. in other words, inside the 55      * loop it points to the current item's list_head. 56      * second parameter is the pointer to the list. it is not manipulated by the macro. 57      */ 58     printf("traversing the list using list_for_each()\n"); 59     list_for_each(pos, &mylist.list){ 60  61         /* at this point: pos->next points to the next item's 'list' variable and  62          * pos->prev points to the previous item's 'list' variable. Here item is  63          * of type struct kool_list. But we need to access the item itself not the  64          * variable 'list' in the item! macro list_entry() does just that. See "How 65          * does this work?" below for an explanation of how this is done. 66          */ 67          tmp= list_entry(pos, struct kool_list, list); 68  69          /* given a pointer to struct list_head, type of data structure it is part of, 70           * and it's name (struct list_head's name in the data structure) it returns a 71           * pointer to the data structure in which the pointer is part of. 72           * For example, in the above line list_entry() will return a pointer to the 73           * struct kool_list item it is embedded in! 74           */ 75  76          printf("to= %d from= %d\n", tmp->to, tmp->from); 77  78     } 79     printf("\n"); 80     /* since this is a circularly linked list. you can traverse the list in reverse order 81      * as well. all you need to do is replace 'list_for_each' with 'list_for_each_prev' 82      * everything else remain the same! 83      * 84      * Also you can traverse the list using list_for_each_entry() to iterate over a given 85      * type of entries. For example: 86      */ 87     printf("traversing the list using list_for_each_entry()\n"); 88     list_for_each_entry(tmp, &mylist.list, list){ 89          printf("to= %d from= %d\n", tmp->to, tmp->from); 90     } 91     list_for_each_entry(tmp,&mylist.list,list){ 92         if(tmp->to == 2) 93             break; 94     } 95     printf("to = %d from %d\n",tmp->to,tmp->from); 96     printf("\n"); 97      98  99     /* now let's be good and free the kool_list items. since we will be removing items100      * off the list using list_del() we need to use a safer version of the list_for_each() 101      * macro aptly named list_for_each_safe(). Note that you MUST use this macro if the loop 102      * involves deletions of items (or moving items from one list to another).103      */104     printf("deleting the list using list_for_each_safe()\n");105     list_for_each_safe(pos, q, &mylist.list){106          tmp= list_entry(pos, struct kool_list, list);107          printf("freeing item to= %d from= %d\n", tmp->to, tmp->from);108          list_del(pos);109          free(tmp);110     }111 112     return 0;113 }