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	sysadm	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	sysadm	1.3	// 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	sysadm	1.1	#define ARTICLE_BLOCK_PER_SHM 50 // sizeof(ARTICLE_BLOCK) * ARTICLE_BLOCK_PER_SHM is the size of each shm segment to allocate
34	sysadm	1.3	#define ARTICLE_BLOCK_SHM_COUNT_LIMIT 256 // limited by length (8-bit) of proj_id in ftok(path, proj_id)
35	sysadm	1.1
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	sysadm	1.2	p_topic_head = section_data_find_article_by_aid(p_section, p_article->tid);
387	sysadm	1.1	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	sysadm	1.2	p_topic_tail = section_data_find_article_by_aid(p_section, p_topic_head->prior_aid);
394	sysadm	1.1	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	sysadm	1.2	ARTICLE section_data_find_article_by_aid(SECTION_DATA p_section, int32_t aid)
422	sysadm	1.1	{
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	sysadm	1.2	log_error("section_data_find_article_by_aid() NULL pointer error\n");
432	sysadm	1.1	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	sysadm	1.2	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	sysadm	1.1	int section_data_mark_del_article(SECTION_DATA *p_section, int32_t aid)
514			{
515			ARTICLE *p_article;
516
517	sysadm	1.2	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	sysadm	1.1	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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