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>

// ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT should be
// no less than BBS_article_block_limit_per_section * BBS_max_section,
// in order to allocate enough memory for blocks
#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 // limited by length (8-bit) of proj_id in ftok(path, proj_id)

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_find_article_by_aid(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_find_article_by_aid(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_find_article_by_aid(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_find_article_by_aid() 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;
}

ARTICLE *section_data_find_article_by_index(SECTION_DATA *p_section, int index)
{
        ARTICLE *p_article;
        ARTICLE_BLOCK *p_block;

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

        if (index < 0 || index >= p_section->article_count)
        {
                log_error("section_data_find_article_by_index(%d) is out of boundary [0, %d)\n", index, p_section->article_count);
                return NULL;
        }

        p_block = p_section->p_block[index / BBS_article_limit_per_block];
        p_article = &(p_block->articles[index % BBS_article_limit_per_block]);

        return p_article;
}

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

        if (p_section == NULL)
        {
                log_error("section_data_mark_del_article() NULL pointer error\n");
                return -2;
        }

        p_article = section_data_find_article_by_aid(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	// ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT should be
31	// no less than BBS_article_block_limit_per_section * BBS_max_section,
32	// in order to allocate enough memory for blocks
33	#define ARTICLE_BLOCK_PER_SHM 50 // sizeof(ARTICLE_BLOCK) * ARTICLE_BLOCK_PER_SHM is the size of each shm segment to allocate
34	#define ARTICLE_BLOCK_SHM_COUNT_LIMIT 256 // limited by length (8-bit) of proj_id in ftok(path, proj_id)
35
36	struct article_block_shm_t
37	{
38	int shmid;
39	void *p_shm;
40	};
41	typedef struct article_block_shm_t ARTICLE_BLOCK_SHM;
42
43	static ARTICLE_BLOCK_SHM *p_article_block_shm_pool;
44	static int article_block_shm_count;
45	static ARTICLE_BLOCK *p_article_block_free_list;
46
47	static SECTION_DATA *p_section_data_pool;
48	static int section_data_count;
49	static TRIE_NODE *p_trie_dict_section_data;
50
51	int section_data_pool_init(const char *filename, int article_block_count)
52	{
53	int shmid;
54	int proj_id;
55	key_t key;
56	size_t size;
57	void *p_shm;
58	int i;
59	int article_block_count_in_shm;
60	ARTICLE_BLOCK *p_article_block_in_shm;
61	ARTICLE_BLOCK **pp_article_block_next;
62
63	if (p_article_block_shm_pool != NULL \|\|
64	p_article_block_free_list != NULL \|\|
65	p_section_data_pool != NULL \|\|
66	p_trie_dict_section_data != NULL)
67	{
68	log_error("section_data_pool already initialized\n");
69	return -1;
70	}
71
72	if (article_block_count > ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT)
73	{
74	log_error("article_block_count exceed limit %d\n", ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT);
75	return -2;
76	}
77
78	p_article_block_shm_pool = calloc((size_t)article_block_count / ARTICLE_BLOCK_PER_SHM + 1, sizeof(ARTICLE_BLOCK_SHM));
79	if (p_article_block_shm_pool == NULL)
80	{
81	log_error("calloc(%d ARTICLE_BLOCK_SHM) OOM\n", article_block_count / ARTICLE_BLOCK_PER_SHM + 1);
82	return -2;
83	}
84
85	p_section_data_pool = calloc(BBS_max_section, sizeof(SECTION_DATA));
86	if (p_section_data_pool == NULL)
87	{
88	log_error("calloc(%d SECTION_DATA) OOM\n", BBS_max_section);
89	return -2;
90	}
91	section_data_count = 0;
92
93	p_trie_dict_section_data = trie_dict_create();
94	if (p_trie_dict_section_data == NULL)
95	{
96	log_error("trie_dict_create() OOM\n", BBS_max_section);
97	return -2;
98	}
99
100	// Allocate shared memory
101	article_block_shm_count = 0;
102	pp_article_block_next = &p_article_block_free_list;
103
104	while (article_block_count > 0)
105	{
106	article_block_count_in_shm =
107	(article_block_count < ARTICLE_BLOCK_PER_SHM ? article_block_count : ARTICLE_BLOCK_PER_SHM);
108	article_block_count -= article_block_count_in_shm;
109
110	proj_id = getpid() + article_block_shm_count;
111	key = ftok(filename, proj_id);
112	if (key == -1)
113	{
114	log_error("ftok(%s, %d) error (%d)\n", filename, proj_id, errno);
115	section_data_pool_cleanup();
116	return -3;
117	}
118
119	size = sizeof(shmid) + sizeof(ARTICLE_BLOCK) * (size_t)article_block_count_in_shm;
120	shmid = shmget(key, size, IPC_CREAT \| IPC_EXCL \| 0600);
121	if (shmid == -1)
122	{
123	log_error("shmget(shm_index = %d, size = %d) error (%d)\n", article_block_shm_count, size, errno);
124	section_data_pool_cleanup();
125	return -3;
126	}
127	p_shm = shmat(shmid, NULL, 0);
128	if (p_shm == (void *)-1)
129	{
130	log_error("shmat(shmid = %d) error (%d)\n", shmid, errno);
131	section_data_pool_cleanup();
132	return -3;
133	}
134
135	(p_article_block_shm_pool + article_block_shm_count)->shmid = shmid;
136	(p_article_block_shm_pool + article_block_shm_count)->p_shm = p_shm;
137	article_block_shm_count++;
138
139	p_article_block_in_shm = p_shm;
140	*pp_article_block_next = p_article_block_in_shm;
141
142	for (i = 0; i < article_block_count_in_shm; i++)
143	{
144	if (i < article_block_count_in_shm - 1)
145	{
146	(p_article_block_in_shm + i)->p_next_block = (p_article_block_in_shm + i + 1);
147	}
148	else
149	{
150	(p_article_block_in_shm + i)->p_next_block = NULL;
151	pp_article_block_next = &((p_article_block_in_shm + i)->p_next_block);
152	}
153	}
154	}
155
156	return 0;
157	}
158
159	void section_data_pool_cleanup(void)
160	{
161	int i;
162
163	if (p_trie_dict_section_data != NULL)
164	{
165	trie_dict_destroy(p_trie_dict_section_data);
166	p_trie_dict_section_data = NULL;
167	section_data_count = 0;
168	}
169
170	if (p_section_data_pool != NULL)
171	{
172	free(p_section_data_pool);
173	p_section_data_pool = NULL;
174	}
175
176	if (p_article_block_free_list != NULL)
177	{
178	p_article_block_free_list = NULL;
179	}
180
181	if (p_article_block_shm_pool != NULL)
182	{
183	for (i = 0; i < article_block_shm_count; i++)
184	{
185	if (shmdt((p_article_block_shm_pool + i)->p_shm) == -1)
186	{
187	log_error("shmdt(shmid = %d) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
188	}
189
190	if (shmctl((p_article_block_shm_pool + i)->shmid, IPC_RMID, NULL) == -1)
191	{
192	log_error("shmctl(shmid = %d, IPC_RMID) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
193	}
194	}
195
196	p_article_block_shm_pool = NULL;
197	article_block_shm_count = 0;
198	}
199	}
200
201	inline static ARTICLE_BLOCK *pop_free_article_block(void)
202	{
203	ARTICLE_BLOCK *p_article_block = NULL;
204
205	if (p_article_block_free_list != NULL)
206	{
207	p_article_block = p_article_block_free_list;
208	p_article_block_free_list = p_article_block_free_list->p_next_block;
209	}
210
211	return p_article_block;
212	}
213
214	inline static void push_free_article_block(ARTICLE_BLOCK *p_article_block)
215	{
216	p_article_block->p_next_block = p_article_block_free_list;
217	p_article_block_free_list = p_article_block;
218	}
219
220	SECTION_DATA section_data_create(const char sname, const char stitle, const char master_name)
221	{
222	SECTION_DATA *p_section;
223	int index;
224
225	if (p_section_data_pool == NULL \|\| p_trie_dict_section_data == NULL)
226	{
227	log_error("section_data not initialized\n");
228	return NULL;
229	}
230
231	if (section_data_count >= BBS_max_section)
232	{
233	log_error("section_data_count exceed limit %d\n", BBS_max_section);
234	return NULL;
235	}
236
237	index = section_data_count;
238	p_section = p_section_data_pool + index;
239
240	strncpy(p_section->sname, sname, sizeof(p_section->sname - 1));
241	p_section->sname[sizeof(p_section->sname - 1)] = '\0';
242
243	strncpy(p_section->stitle, stitle, sizeof(p_section->stitle - 1));
244	p_section->stitle[sizeof(p_section->stitle - 1)] = '\0';
245
246	strncpy(p_section->master_name, master_name, sizeof(p_section->master_name - 1));
247	p_section->master_name[sizeof(p_section->master_name - 1)] = '\0';
248
249	p_section->p_head_block = NULL;
250	p_section->p_tail_block = NULL;
251	p_section->block_count = 0;
252	p_section->article_count = 0;
253	p_section->delete_count = 0;
254
255	if (trie_dict_set(p_trie_dict_section_data, sname, index) != 1)
256	{
257	log_error("trie_dict_set(section_data, %s, %d) error\n", sname, index);
258	return NULL;
259	}
260
261	section_data_count++;
262
263	return p_section;
264	}
265
266	int section_data_free_block(SECTION_DATA *p_section)
267	{
268	ARTICLE_BLOCK *p_block;
269
270	if (p_section == NULL)
271	{
272	log_error("section_data_free_block() NULL pointer error\n");
273	return -1;
274	}
275
276	if (p_section_data_pool == NULL)
277	{
278	log_error("section_data not initialized\n");
279	return -1;
280	}
281
282	while (p_section->p_head_block != NULL)
283	{
284	p_block = p_section->p_head_block;
285	p_section->p_head_block = p_block->p_next_block;
286	push_free_article_block(p_block);
287	}
288
289	p_section->p_tail_block = NULL;
290	p_section->block_count = 0;
291	p_section->article_count = 0;
292	p_section->delete_count = 0;
293
294	return 0;
295	}
296
297	SECTION_DATA section_data_find_by_name(const char sname)
298	{
299	int64_t index;
300
301	if (p_section_data_pool == NULL \|\| p_trie_dict_section_data == NULL)
302	{
303	log_error("section_data not initialized\n");
304	return NULL;
305	}
306
307	if (trie_dict_get(p_trie_dict_section_data, sname, &index) != 1)
308	{
309	log_error("trie_dict_get(section_data, %s) error\n", sname);
310	return NULL;
311	}
312
313	return (p_section_data_pool + index);
314	}
315
316	int section_data_append_article(SECTION_DATA p_section, const ARTICLE p_article)
317	{
318	ARTICLE_BLOCK *p_block;
319	int32_t last_aid = 0;
320	ARTICLE *p_topic_head;
321	ARTICLE *p_topic_tail;
322
323	if (p_section == NULL \|\| p_article == NULL)
324	{
325	log_error("section_data_append_article() NULL pointer error\n");
326	return -1;
327	}
328
329	if (p_section_data_pool == NULL)
330	{
331	log_error("section_data not initialized\n");
332	return -1;
333	}
334
335	if (p_section->p_tail_block == NULL \|\| p_section->p_tail_block->article_count >= BBS_article_limit_per_block)
336	{
337	if (p_section->block_count >= BBS_article_block_limit_per_section)
338	{
339	log_error("section block count %d reach limit\n", p_section->block_count);
340	return -2;
341	}
342
343	if ((p_block = pop_free_article_block()) == NULL)
344	{
345	log_error("pop_free_article_block() error\n");
346	return -2;
347	}
348
349	p_block->article_count = 0;
350	p_block->p_next_block = NULL;
351
352	if (p_section->p_tail_block == NULL)
353	{
354	p_section->p_head_block = p_block;
355	last_aid = 0;
356	}
357	else
358	{
359	p_section->p_tail_block->p_next_block = p_block;
360	last_aid = p_section->p_tail_block->articles[BBS_article_limit_per_block - 1].aid;
361	}
362	p_section->p_tail_block = p_block;
363	p_section->p_block[p_section->block_count] = p_block;
364	p_section->block_count++;
365	}
366	else
367	{
368	p_block = p_section->p_tail_block;
369	last_aid = p_block->articles[p_block->article_count - 1].aid;
370	}
371
372	// AID of articles should be strictly ascending
373	if (p_article->aid <= last_aid)
374	{
375	log_error("section_data_append_article(aid=%d) error: last_aid=%d\n", p_article->aid, last_aid);
376	return -3;
377	}
378
379	if (p_block->article_count == 0)
380	{
381	p_section->block_head_aid[p_section->block_count - 1] = p_article->aid;
382	}
383
384	if (p_article->tid != 0)
385	{
386	p_topic_head = section_data_find_article_by_aid(p_section, p_article->tid);
387	if (p_topic_head == NULL)
388	{
389	log_error("search head of topic (aid=%d) error\n", p_article->tid);
390	return -4;
391	}
392
393	p_topic_tail = section_data_find_article_by_aid(p_section, p_topic_head->prior_aid);
394	if (p_topic_tail == NULL)
395	{
396	log_error("search tail of topic (aid=%d) error\n", p_topic_head->prior_aid);
397	return -4;
398	}
399	}
400	else
401	{
402	p_topic_head = &(p_block->articles[p_block->article_count]);
403	p_topic_tail = p_topic_head;
404	}
405
406	// Copy article data
407	p_block->articles[p_block->article_count] = *p_article;
408
409	// Link appended article as tail node of topic bi-directional list;
410	p_block->articles[p_block->article_count].prior_aid = p_topic_tail->aid;
411	p_block->articles[p_block->article_count].next_aid = p_topic_head->aid;
412	p_topic_head->prior_aid = p_article->aid;
413	p_topic_tail->next_aid = p_article->aid;
414
415	p_block->article_count++;
416	p_section->article_count++;
417
418	return 0;
419	}
420
421	ARTICLE section_data_find_article_by_aid(SECTION_DATA p_section, int32_t aid)
422	{
423	ARTICLE *p_article;
424	ARTICLE_BLOCK *p_block;
425	int left;
426	int right;
427	int mid;
428
429	if (p_section == NULL)
430	{
431	log_error("section_data_find_article_by_aid() NULL pointer error\n");
432	return NULL;
433	}
434
435	if (p_section->block_count == 0) // empty section
436	{
437	return NULL;
438	}
439
440	left = 0;
441	right = p_section->block_count;
442
443	// aid in the range [ head aid of blocks[left], tail aid of blocks[right - 1] ]
444	while (left < right - 1)
445	{
446	// get block offset no less than mid value of left and right block offsets
447	mid = (left + right) / 2 + (right - left) % 2;
448
449	if (mid >= BBS_article_block_limit_per_section)
450	{
451	log_error("block_m(%d) is out of boundary\n", mid);
452	return NULL;
453	}
454
455	if (aid < p_section->block_head_aid[mid])
456	{
457	right = mid;
458	}
459	else
460	{
461	left = mid;
462	}
463	}
464
465	p_block = p_section->p_block[left];
466
467	left = 0;
468	right = p_block->article_count - 1;
469
470	// aid in the range [ aid of articles[left], aid of articles[right] ]
471	while (left < right)
472	{
473	mid = (left + right) / 2;
474
475	if (aid <= p_block->articles[mid].aid)
476	{
477	right = mid;
478	}
479	else
480	{
481	left = mid + 1;
482	}
483	}
484
485	p_article = &(p_block->articles[left]);
486
487	return p_article;
488	}
489
490	ARTICLE section_data_find_article_by_index(SECTION_DATA p_section, int index)
491	{
492	ARTICLE *p_article;
493	ARTICLE_BLOCK *p_block;
494
495	if (p_section == NULL)
496	{
497	log_error("section_data_find_article_by_index() NULL pointer error\n");
498	return NULL;
499	}
500
501	if (index < 0 \|\| index >= p_section->article_count)
502	{
503	log_error("section_data_find_article_by_index(%d) is out of boundary [0, %d)\n", index, p_section->article_count);
504	return NULL;
505	}
506
507	p_block = p_section->p_block[index / BBS_article_limit_per_block];
508	p_article = &(p_block->articles[index % BBS_article_limit_per_block]);
509
510	return p_article;
511	}
512
513	int section_data_mark_del_article(SECTION_DATA *p_section, int32_t aid)
514	{
515	ARTICLE *p_article;
516
517	if (p_section == NULL)
518	{
519	log_error("section_data_mark_del_article() NULL pointer error\n");
520	return -2;
521	}
522
523	p_article = section_data_find_article_by_aid(p_section, aid);
524	if (p_article == NULL)
525	{
526	return -1; // Not found
527	}
528
529	if (p_article->visible == 0)
530	{
531	return 0; // Already deleted
532	}
533
534	p_article->visible = 0;
535	p_section->delete_count++;
536
537	return 1;
538	}
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