lbbs/src/section_list.c

/***************************************************************************
                                           section_list.c  -  description
                                                         -------------------
        Copyright            : (C) 2004-2025 by Leaflet
        Email                : leaflet@leafok.com
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 3 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "section_list.h"
#include "log.h"
#include "io.h"
#include "trie_dict.h"
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/shm.h>
#include <sys/ipc.h>

#define ARTICLE_BLOCK_PER_SHM 50 // sizeof(ARTICLE_BLOCK) * ARTICLE_BLOCK_PER_SHM is the size of each shm segment to allocate
#define ARTICLE_BLOCK_SHM_COUNT_LIMIT 256

struct article_block_shm_t
{
        int shmid;
        void *p_shm;
};
typedef struct article_block_shm_t ARTICLE_BLOCK_SHM;

static ARTICLE_BLOCK_SHM *p_article_block_shm_pool;
static int article_block_shm_count;
static ARTICLE_BLOCK *p_article_block_free_list;

static SECTION_DATA *p_section_data_pool;
static int section_data_count;
static TRIE_NODE *p_trie_dict_section_data;

int section_data_pool_init(const char *filename, int article_block_count)
{
        int shmid;
        int proj_id;
        key_t key;
        size_t size;
        void *p_shm;
        int i;
        int article_block_count_in_shm;
        ARTICLE_BLOCK *p_article_block_in_shm;
        ARTICLE_BLOCK **pp_article_block_next;

        if (p_article_block_shm_pool != NULL ||
                p_article_block_free_list != NULL ||
                p_section_data_pool != NULL ||
                p_trie_dict_section_data != NULL)
        {
                log_error("section_data_pool already initialized\n");
                return -1;
        }

        if (article_block_count > ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT)
        {
                log_error("article_block_count exceed limit %d\n", ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT);
                return -2;
        }

        p_article_block_shm_pool = calloc((size_t)article_block_count / ARTICLE_BLOCK_PER_SHM + 1, sizeof(ARTICLE_BLOCK_SHM));
        if (p_article_block_shm_pool == NULL)
        {
                log_error("calloc(%d ARTICLE_BLOCK_SHM) OOM\n", article_block_count / ARTICLE_BLOCK_PER_SHM + 1);
                return -2;
        }

        p_section_data_pool = calloc(BBS_max_section, sizeof(SECTION_DATA));
        if (p_section_data_pool == NULL)
        {
                log_error("calloc(%d SECTION_DATA) OOM\n", BBS_max_section);
                return -2;
        }
        section_data_count = 0;

        p_trie_dict_section_data = trie_dict_create();
        if (p_trie_dict_section_data == NULL)
        {
                log_error("trie_dict_create() OOM\n", BBS_max_section);
                return -2;
        }

        // Allocate shared memory
        article_block_shm_count = 0;
        pp_article_block_next = &p_article_block_free_list;

        while (article_block_count > 0)
        {
                article_block_count_in_shm =
                        (article_block_count < ARTICLE_BLOCK_PER_SHM ? article_block_count : ARTICLE_BLOCK_PER_SHM);
                article_block_count -= article_block_count_in_shm;

                proj_id = getpid() + article_block_shm_count;
                key = ftok(filename, proj_id);
                if (key == -1)
                {
                        log_error("ftok(%s, %d) error (%d)\n", filename, proj_id, errno);
                        section_data_pool_cleanup();
                        return -3;
                }

                size = sizeof(shmid) + sizeof(ARTICLE_BLOCK) * (size_t)article_block_count_in_shm;
                shmid = shmget(key, size, IPC_CREAT | IPC_EXCL | 0600);
                if (shmid == -1)
                {
                        log_error("shmget(shm_index = %d, size = %d) error (%d)\n", article_block_shm_count, size, errno);
                        section_data_pool_cleanup();
                        return -3;
                }
                p_shm = shmat(shmid, NULL, 0);
                if (p_shm == (void *)-1)
                {
                        log_error("shmat(shmid = %d) error (%d)\n", shmid, errno);
                        section_data_pool_cleanup();
                        return -3;
                }

                (p_article_block_shm_pool + article_block_shm_count)->shmid = shmid;
                (p_article_block_shm_pool + article_block_shm_count)->p_shm = p_shm;
                article_block_shm_count++;

                p_article_block_in_shm = p_shm;
                *pp_article_block_next = p_article_block_in_shm;

                for (i = 0; i < article_block_count_in_shm; i++)
                {
                        if (i < article_block_count_in_shm - 1)
                        {
                                (p_article_block_in_shm + i)->p_next_block = (p_article_block_in_shm + i + 1);
                        }
                        else
                        {
                                (p_article_block_in_shm + i)->p_next_block = NULL;
                                pp_article_block_next = &((p_article_block_in_shm + i)->p_next_block);
                        }
                }
        }

        return 0;
}

void section_data_pool_cleanup(void)
{
        int i;

        if (p_trie_dict_section_data != NULL)
        {
                trie_dict_destroy(p_trie_dict_section_data);
                p_trie_dict_section_data = NULL;
                section_data_count = 0;
        }

        if (p_section_data_pool != NULL)
        {
                free(p_section_data_pool);
                p_section_data_pool = NULL;
        }

        if (p_article_block_free_list != NULL)
        {
                p_article_block_free_list = NULL;
        }

        if (p_article_block_shm_pool != NULL)
        {
                for (i = 0; i < article_block_shm_count; i++)
                {
                        if (shmdt((p_article_block_shm_pool + i)->p_shm) == -1)
                        {
                                log_error("shmdt(shmid = %d) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
                        }

                        if (shmctl((p_article_block_shm_pool + i)->shmid, IPC_RMID, NULL) == -1)
                        {
                                log_error("shmctl(shmid = %d, IPC_RMID) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
                        }
                }

                p_article_block_shm_pool = NULL;
                article_block_shm_count = 0;
        }
}

inline static ARTICLE_BLOCK *pop_free_article_block(void)
{
        ARTICLE_BLOCK *p_article_block = NULL;

        if (p_article_block_free_list != NULL)
        {
                p_article_block = p_article_block_free_list;
                p_article_block_free_list = p_article_block_free_list->p_next_block;
        }

        return p_article_block;
}

inline static void push_free_article_block(ARTICLE_BLOCK *p_article_block)
{
        p_article_block->p_next_block = p_article_block_free_list;
        p_article_block_free_list = p_article_block;
}

SECTION_DATA *section_data_create(const char *sname, const char *stitle, const char *master_name)
{
        SECTION_DATA *p_section;
        int index;

        if (p_section_data_pool == NULL || p_trie_dict_section_data == NULL)
        {
                log_error("section_data not initialized\n");
                return NULL;
        }

        if (section_data_count >= BBS_max_section)
        {
                log_error("section_data_count exceed limit %d\n", BBS_max_section);
                return NULL;
        }

        index = section_data_count;
        p_section = p_section_data_pool + index;

        strncpy(p_section->sname, sname, sizeof(p_section->sname - 1));
        p_section->sname[sizeof(p_section->sname - 1)] = '\0';

        strncpy(p_section->stitle, stitle, sizeof(p_section->stitle - 1));
        p_section->stitle[sizeof(p_section->stitle - 1)] = '\0';

        strncpy(p_section->master_name, master_name, sizeof(p_section->master_name - 1));
        p_section->master_name[sizeof(p_section->master_name - 1)] = '\0';

        p_section->p_head_block = NULL;
        p_section->p_tail_block = NULL;
        p_section->block_count = 0;
        p_section->article_count = 0;
        p_section->delete_count = 0;

        if (trie_dict_set(p_trie_dict_section_data, sname, index) != 1)
        {
                log_error("trie_dict_set(section_data, %s, %d) error\n", sname, index);
                return NULL;
        }

        section_data_count++;

        return p_section;
}

int section_data_free_block(SECTION_DATA *p_section)
{
        ARTICLE_BLOCK *p_block;

        if (p_section == NULL)
        {
                log_error("section_data_free_block() NULL pointer error\n");
                return -1;
        }

        if (p_section_data_pool == NULL)
        {
                log_error("section_data not initialized\n");
                return -1;
        }

        while (p_section->p_head_block != NULL)
        {
                p_block = p_section->p_head_block;
                p_section->p_head_block = p_block->p_next_block;
                push_free_article_block(p_block);
        }

        p_section->p_tail_block = NULL;
        p_section->block_count = 0;
        p_section->article_count = 0;
        p_section->delete_count = 0;

        return 0;
}

SECTION_DATA *section_data_find_by_name(const char *sname)
{
        int64_t index;

        if (p_section_data_pool == NULL || p_trie_dict_section_data == NULL)
        {
                log_error("section_data not initialized\n");
                return NULL;
        }

        if (trie_dict_get(p_trie_dict_section_data, sname, &index) != 1)
        {
                log_error("trie_dict_get(section_data, %s) error\n", sname);
                return NULL;
        }

        return (p_section_data_pool + index);
}

int section_data_append_article(SECTION_DATA *p_section, const ARTICLE *p_article)
{
        ARTICLE_BLOCK *p_block;
        int32_t last_aid = 0;
        ARTICLE *p_topic_head;
        ARTICLE *p_topic_tail;

        if (p_section == NULL || p_article == NULL)
        {
                log_error("section_data_append_article() NULL pointer error\n");
                return -1;
        }

        if (p_section_data_pool == NULL)
        {
                log_error("section_data not initialized\n");
                return -1;
        }

        if (p_section->p_tail_block == NULL || p_section->p_tail_block->article_count >= BBS_article_limit_per_block)
        {
                if (p_section->block_count >= BBS_article_block_limit_per_section)
                {
                        log_error("section block count %d reach limit\n", p_section->block_count);
                        return -2;
                }

                if ((p_block = pop_free_article_block()) == NULL)
                {
                        log_error("pop_free_article_block() error\n");
                        return -2;
                }

                p_block->article_count = 0;
                p_block->p_next_block = NULL;

                if (p_section->p_tail_block == NULL)
                {
                        p_section->p_head_block = p_block;
                        last_aid = 0;
                }
                else
                {
                        p_section->p_tail_block->p_next_block = p_block;
                        last_aid = p_section->p_tail_block->articles[BBS_article_limit_per_block - 1].aid;
                }
                p_section->p_tail_block = p_block;
                p_section->p_block[p_section->block_count] = p_block;
                p_section->block_count++;
        }
        else
        {
                p_block = p_section->p_tail_block;
                last_aid = p_block->articles[p_block->article_count - 1].aid;
        }

        // AID of articles should be strictly ascending
        if (p_article->aid <= last_aid)
        {
                log_error("section_data_append_article(aid=%d) error: last_aid=%d\n", p_article->aid, last_aid);
                return -3;
        }

        if (p_block->article_count == 0)
        {
                p_section->block_head_aid[p_section->block_count - 1] = p_article->aid;
        }

        if (p_article->tid != 0)
        {
                p_topic_head = section_data_search_article(p_section, p_article->tid);
                if (p_topic_head == NULL)
                {
                        log_error("search head of topic (aid=%d) error\n", p_article->tid);
                        return -4;
                }

                p_topic_tail = section_data_search_article(p_section, p_topic_head->prior_aid);
                if (p_topic_tail == NULL)
                {
                        log_error("search tail of topic (aid=%d) error\n", p_topic_head->prior_aid);
                        return -4;
                }
        }
        else
        {
                p_topic_head = &(p_block->articles[p_block->article_count]);
                p_topic_tail = p_topic_head;
        }

        // Copy article data
        p_block->articles[p_block->article_count] = *p_article;

        // Link appended article as tail node of topic bi-directional list;
        p_block->articles[p_block->article_count].prior_aid = p_topic_tail->aid;
        p_block->articles[p_block->article_count].next_aid = p_topic_head->aid;
        p_topic_head->prior_aid = p_article->aid;
        p_topic_tail->next_aid = p_article->aid;

        p_block->article_count++;
        p_section->article_count++;

        return 0;
}

ARTICLE *section_data_search_article(SECTION_DATA *p_section, int32_t aid)
{
        ARTICLE *p_article;
        ARTICLE_BLOCK *p_block;
        int left;
        int right;
        int mid;

        if (p_section == NULL)
        {
                log_error("section_data_append_article() NULL pointer error\n");
                return NULL;
        }

        if (p_section->block_count == 0) // empty section
        {
                return NULL;
        }

        left = 0;
        right = p_section->block_count;

        // aid in the range [ head aid of blocks[left], tail aid of blocks[right - 1] ]
        while (left < right - 1)
        {
                // get block offset no less than mid value of left and right block offsets
                mid = (left + right) / 2 + (right - left) % 2;
                
                if (mid >= BBS_article_block_limit_per_section)
                {
                        log_error("block_m(%d) is out of boundary\n", mid);
                        return NULL;
                }

                if (aid < p_section->block_head_aid[mid])
                {
                        right = mid;
                }
                else
                {
                        left = mid;
                }
        }

        p_block = p_section->p_block[left];

        left = 0;
        right = p_block->article_count - 1;

        // aid in the range [ aid of articles[left], aid of articles[right] ]
        while (left < right)
        {
                mid = (left + right) / 2;

                if (aid <= p_block->articles[mid].aid)
                {
                        right = mid;
                }
                else
                {
                        left = mid + 1;
                }
        }

        p_article = &(p_block->articles[left]);

        return p_article;
}

int section_data_mark_del_article(SECTION_DATA *p_section, int32_t aid)
{
        ARTICLE *p_article;

        p_article = section_data_search_article(p_section, aid);
        if (p_article == NULL)
        {
                return -1; // Not found
        }

        if (p_article->visible == 0)
        {
                return 0; // Already deleted
        }

        p_article->visible = 0;
        p_section->delete_count++;

        return 1;
}
1	/***************************************************************************
2	section_list.c - description
3	-------------------
4	Copyright : (C) 2004-2025 by Leaflet
5	Email : leaflet@leafok.com
6	***************************************************************************/
7
8	/***************************************************************************
9	* *
10	* This program is free software; you can redistribute it and/or modify *
11	* it under the terms of the GNU General Public License as published by *
12	* the Free Software Foundation; either version 3 of the License, or *
13	* (at your option) any later version. *
14	* *
15	***************************************************************************/
16
17	#include "section_list.h"
18	#include "log.h"
19	#include "io.h"
20	#include "trie_dict.h"
21	#include <stdio.h>
22	#include <string.h>
23	#include <signal.h>
24	#include <unistd.h>
25	#include <stdlib.h>
26	#include <errno.h>
27	#include <sys/shm.h>
28	#include <sys/ipc.h>
29
30	#define ARTICLE_BLOCK_PER_SHM 50 // sizeof(ARTICLE_BLOCK) * ARTICLE_BLOCK_PER_SHM is the size of each shm segment to allocate
31	#define ARTICLE_BLOCK_SHM_COUNT_LIMIT 256
32
33	struct article_block_shm_t
34	{
35	int shmid;
36	void *p_shm;
37	};
38	typedef struct article_block_shm_t ARTICLE_BLOCK_SHM;
39
40	static ARTICLE_BLOCK_SHM *p_article_block_shm_pool;
41	static int article_block_shm_count;
42	static ARTICLE_BLOCK *p_article_block_free_list;
43
44	static SECTION_DATA *p_section_data_pool;
45	static int section_data_count;
46	static TRIE_NODE *p_trie_dict_section_data;
47
48	int section_data_pool_init(const char *filename, int article_block_count)
49	{
50	int shmid;
51	int proj_id;
52	key_t key;
53	size_t size;
54	void *p_shm;
55	int i;
56	int article_block_count_in_shm;
57	ARTICLE_BLOCK *p_article_block_in_shm;
58	ARTICLE_BLOCK **pp_article_block_next;
59
60	if (p_article_block_shm_pool != NULL \|\|
61	p_article_block_free_list != NULL \|\|
62	p_section_data_pool != NULL \|\|
63	p_trie_dict_section_data != NULL)
64	{
65	log_error("section_data_pool already initialized\n");
66	return -1;
67	}
68
69	if (article_block_count > ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT)
70	{
71	log_error("article_block_count exceed limit %d\n", ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT);
72	return -2;
73	}
74
75	p_article_block_shm_pool = calloc((size_t)article_block_count / ARTICLE_BLOCK_PER_SHM + 1, sizeof(ARTICLE_BLOCK_SHM));
76	if (p_article_block_shm_pool == NULL)
77	{
78	log_error("calloc(%d ARTICLE_BLOCK_SHM) OOM\n", article_block_count / ARTICLE_BLOCK_PER_SHM + 1);
79	return -2;
80	}
81
82	p_section_data_pool = calloc(BBS_max_section, sizeof(SECTION_DATA));
83	if (p_section_data_pool == NULL)
84	{
85	log_error("calloc(%d SECTION_DATA) OOM\n", BBS_max_section);
86	return -2;
87	}
88	section_data_count = 0;
89
90	p_trie_dict_section_data = trie_dict_create();
91	if (p_trie_dict_section_data == NULL)
92	{
93	log_error("trie_dict_create() OOM\n", BBS_max_section);
94	return -2;
95	}
96
97	// Allocate shared memory
98	article_block_shm_count = 0;
99	pp_article_block_next = &p_article_block_free_list;
100
101	while (article_block_count > 0)
102	{
103	article_block_count_in_shm =
104	(article_block_count < ARTICLE_BLOCK_PER_SHM ? article_block_count : ARTICLE_BLOCK_PER_SHM);
105	article_block_count -= article_block_count_in_shm;
106
107	proj_id = getpid() + article_block_shm_count;
108	key = ftok(filename, proj_id);
109	if (key == -1)
110	{
111	log_error("ftok(%s, %d) error (%d)\n", filename, proj_id, errno);
112	section_data_pool_cleanup();
113	return -3;
114	}
115
116	size = sizeof(shmid) + sizeof(ARTICLE_BLOCK) * (size_t)article_block_count_in_shm;
117	shmid = shmget(key, size, IPC_CREAT \| IPC_EXCL \| 0600);
118	if (shmid == -1)
119	{
120	log_error("shmget(shm_index = %d, size = %d) error (%d)\n", article_block_shm_count, size, errno);
121	section_data_pool_cleanup();
122	return -3;
123	}
124	p_shm = shmat(shmid, NULL, 0);
125	if (p_shm == (void *)-1)
126	{
127	log_error("shmat(shmid = %d) error (%d)\n", shmid, errno);
128	section_data_pool_cleanup();
129	return -3;
130	}
131
132	(p_article_block_shm_pool + article_block_shm_count)->shmid = shmid;
133	(p_article_block_shm_pool + article_block_shm_count)->p_shm = p_shm;
134	article_block_shm_count++;
135
136	p_article_block_in_shm = p_shm;
137	*pp_article_block_next = p_article_block_in_shm;
138
139	for (i = 0; i < article_block_count_in_shm; i++)
140	{
141	if (i < article_block_count_in_shm - 1)
142	{
143	(p_article_block_in_shm + i)->p_next_block = (p_article_block_in_shm + i + 1);
144	}
145	else
146	{
147	(p_article_block_in_shm + i)->p_next_block = NULL;
148	pp_article_block_next = &((p_article_block_in_shm + i)->p_next_block);
149	}
150	}
151	}
152
153	return 0;
154	}
155
156	void section_data_pool_cleanup(void)
157	{
158	int i;
159
160	if (p_trie_dict_section_data != NULL)
161	{
162	trie_dict_destroy(p_trie_dict_section_data);
163	p_trie_dict_section_data = NULL;
164	section_data_count = 0;
165	}
166
167	if (p_section_data_pool != NULL)
168	{
169	free(p_section_data_pool);
170	p_section_data_pool = NULL;
171	}
172
173	if (p_article_block_free_list != NULL)
174	{
175	p_article_block_free_list = NULL;
176	}
177
178	if (p_article_block_shm_pool != NULL)
179	{
180	for (i = 0; i < article_block_shm_count; i++)
181	{
182	if (shmdt((p_article_block_shm_pool + i)->p_shm) == -1)
183	{
184	log_error("shmdt(shmid = %d) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
185	}
186
187	if (shmctl((p_article_block_shm_pool + i)->shmid, IPC_RMID, NULL) == -1)
188	{
189	log_error("shmctl(shmid = %d, IPC_RMID) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
190	}
191	}
192
193	p_article_block_shm_pool = NULL;
194	article_block_shm_count = 0;
195	}
196	}
197
198	inline static ARTICLE_BLOCK *pop_free_article_block(void)
199	{
200	ARTICLE_BLOCK *p_article_block = NULL;
201
202	if (p_article_block_free_list != NULL)
203	{
204	p_article_block = p_article_block_free_list;
205	p_article_block_free_list = p_article_block_free_list->p_next_block;
206	}
207
208	return p_article_block;
209	}
210
211	inline static void push_free_article_block(ARTICLE_BLOCK *p_article_block)
212	{
213	p_article_block->p_next_block = p_article_block_free_list;
214	p_article_block_free_list = p_article_block;
215	}
216
217	SECTION_DATA section_data_create(const char sname, const char stitle, const char master_name)
218	{
219	SECTION_DATA *p_section;
220	int index;
221
222	if (p_section_data_pool == NULL \|\| p_trie_dict_section_data == NULL)
223	{
224	log_error("section_data not initialized\n");
225	return NULL;
226	}
227
228	if (section_data_count >= BBS_max_section)
229	{
230	log_error("section_data_count exceed limit %d\n", BBS_max_section);
231	return NULL;
232	}
233
234	index = section_data_count;
235	p_section = p_section_data_pool + index;
236
237	strncpy(p_section->sname, sname, sizeof(p_section->sname - 1));
238	p_section->sname[sizeof(p_section->sname - 1)] = '\0';
239
240	strncpy(p_section->stitle, stitle, sizeof(p_section->stitle - 1));
241	p_section->stitle[sizeof(p_section->stitle - 1)] = '\0';
242
243	strncpy(p_section->master_name, master_name, sizeof(p_section->master_name - 1));
244	p_section->master_name[sizeof(p_section->master_name - 1)] = '\0';
245
246	p_section->p_head_block = NULL;
247	p_section->p_tail_block = NULL;
248	p_section->block_count = 0;
249	p_section->article_count = 0;
250	p_section->delete_count = 0;
251
252	if (trie_dict_set(p_trie_dict_section_data, sname, index) != 1)
253	{
254	log_error("trie_dict_set(section_data, %s, %d) error\n", sname, index);
255	return NULL;
256	}
257
258	section_data_count++;
259
260	return p_section;
261	}
262
263	int section_data_free_block(SECTION_DATA *p_section)
264	{
265	ARTICLE_BLOCK *p_block;
266
267	if (p_section == NULL)
268	{
269	log_error("section_data_free_block() NULL pointer error\n");
270	return -1;
271	}
272
273	if (p_section_data_pool == NULL)
274	{
275	log_error("section_data not initialized\n");
276	return -1;
277	}
278
279	while (p_section->p_head_block != NULL)
280	{
281	p_block = p_section->p_head_block;
282	p_section->p_head_block = p_block->p_next_block;
283	push_free_article_block(p_block);
284	}
285
286	p_section->p_tail_block = NULL;
287	p_section->block_count = 0;
288	p_section->article_count = 0;
289	p_section->delete_count = 0;
290
291	return 0;
292	}
293
294	SECTION_DATA section_data_find_by_name(const char sname)
295	{
296	int64_t index;
297
298	if (p_section_data_pool == NULL \|\| p_trie_dict_section_data == NULL)
299	{
300	log_error("section_data not initialized\n");
301	return NULL;
302	}
303
304	if (trie_dict_get(p_trie_dict_section_data, sname, &index) != 1)
305	{
306	log_error("trie_dict_get(section_data, %s) error\n", sname);
307	return NULL;
308	}
309
310	return (p_section_data_pool + index);
311	}
312
313	int section_data_append_article(SECTION_DATA p_section, const ARTICLE p_article)
314	{
315	ARTICLE_BLOCK *p_block;
316	int32_t last_aid = 0;
317	ARTICLE *p_topic_head;
318	ARTICLE *p_topic_tail;
319
320	if (p_section == NULL \|\| p_article == NULL)
321	{
322	log_error("section_data_append_article() NULL pointer error\n");
323	return -1;
324	}
325
326	if (p_section_data_pool == NULL)
327	{
328	log_error("section_data not initialized\n");
329	return -1;
330	}
331
332	if (p_section->p_tail_block == NULL \|\| p_section->p_tail_block->article_count >= BBS_article_limit_per_block)
333	{
334	if (p_section->block_count >= BBS_article_block_limit_per_section)
335	{
336	log_error("section block count %d reach limit\n", p_section->block_count);
337	return -2;
338	}
339
340	if ((p_block = pop_free_article_block()) == NULL)
341	{
342	log_error("pop_free_article_block() error\n");
343	return -2;
344	}
345
346	p_block->article_count = 0;
347	p_block->p_next_block = NULL;
348
349	if (p_section->p_tail_block == NULL)
350	{
351	p_section->p_head_block = p_block;
352	last_aid = 0;
353	}
354	else
355	{
356	p_section->p_tail_block->p_next_block = p_block;
357	last_aid = p_section->p_tail_block->articles[BBS_article_limit_per_block - 1].aid;
358	}
359	p_section->p_tail_block = p_block;
360	p_section->p_block[p_section->block_count] = p_block;
361	p_section->block_count++;
362	}
363	else
364	{
365	p_block = p_section->p_tail_block;
366	last_aid = p_block->articles[p_block->article_count - 1].aid;
367	}
368
369	// AID of articles should be strictly ascending
370	if (p_article->aid <= last_aid)
371	{
372	log_error("section_data_append_article(aid=%d) error: last_aid=%d\n", p_article->aid, last_aid);
373	return -3;
374	}
375
376	if (p_block->article_count == 0)
377	{
378	p_section->block_head_aid[p_section->block_count - 1] = p_article->aid;
379	}
380
381	if (p_article->tid != 0)
382	{
383	p_topic_head = section_data_search_article(p_section, p_article->tid);
384	if (p_topic_head == NULL)
385	{
386	log_error("search head of topic (aid=%d) error\n", p_article->tid);
387	return -4;
388	}
389
390	p_topic_tail = section_data_search_article(p_section, p_topic_head->prior_aid);
391	if (p_topic_tail == NULL)
392	{
393	log_error("search tail of topic (aid=%d) error\n", p_topic_head->prior_aid);
394	return -4;
395	}
396	}
397	else
398	{
399	p_topic_head = &(p_block->articles[p_block->article_count]);
400	p_topic_tail = p_topic_head;
401	}
402
403	// Copy article data
404	p_block->articles[p_block->article_count] = *p_article;
405
406	// Link appended article as tail node of topic bi-directional list;
407	p_block->articles[p_block->article_count].prior_aid = p_topic_tail->aid;
408	p_block->articles[p_block->article_count].next_aid = p_topic_head->aid;
409	p_topic_head->prior_aid = p_article->aid;
410	p_topic_tail->next_aid = p_article->aid;
411
412	p_block->article_count++;
413	p_section->article_count++;
414
415	return 0;
416	}
417
418	ARTICLE section_data_search_article(SECTION_DATA p_section, int32_t aid)
419	{
420	ARTICLE *p_article;
421	ARTICLE_BLOCK *p_block;
422	int left;
423	int right;
424	int mid;
425
426	if (p_section == NULL)
427	{
428	log_error("section_data_append_article() NULL pointer error\n");
429	return NULL;
430	}
431
432	if (p_section->block_count == 0) // empty section
433	{
434	return NULL;
435	}
436
437	left = 0;
438	right = p_section->block_count;
439
440	// aid in the range [ head aid of blocks[left], tail aid of blocks[right - 1] ]
441	while (left < right - 1)
442	{
443	// get block offset no less than mid value of left and right block offsets
444	mid = (left + right) / 2 + (right - left) % 2;
445
446	if (mid >= BBS_article_block_limit_per_section)
447	{
448	log_error("block_m(%d) is out of boundary\n", mid);
449	return NULL;
450	}
451
452	if (aid < p_section->block_head_aid[mid])
453	{
454	right = mid;
455	}
456	else
457	{
458	left = mid;
459	}
460	}
461
462	p_block = p_section->p_block[left];
463
464	left = 0;
465	right = p_block->article_count - 1;
466
467	// aid in the range [ aid of articles[left], aid of articles[right] ]
468	while (left < right)
469	{
470	mid = (left + right) / 2;
471
472	if (aid <= p_block->articles[mid].aid)
473	{
474	right = mid;
475	}
476	else
477	{
478	left = mid + 1;
479	}
480	}
481
482	p_article = &(p_block->articles[left]);
483
484	return p_article;
485	}
486
487	int section_data_mark_del_article(SECTION_DATA *p_section, int32_t aid)
488	{
489	ARTICLE *p_article;
490
491	p_article = section_data_search_article(p_section, aid);
492	if (p_article == NULL)
493	{
494	return -1; // Not found
495	}
496
497	if (p_article->visible == 0)
498	{
499	return 0; // Already deleted
500	}
501
502	p_article->visible = 0;
503	p_section->delete_count++;
504
505	return 1;
506	}
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