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 "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 400 // 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_section_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 "trie_dict.h"
20			#include <stdio.h>
21			#include <string.h>
22			#include <signal.h>
23			#include <unistd.h>
24			#include <stdlib.h>
25			#include <errno.h>
26			#include <sys/shm.h>
27			#include <sys/ipc.h>
28
29	sysadm	1.3	// ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT should be
30			// no less than BBS_article_block_limit_per_section * BBS_max_section,
31			// in order to allocate enough memory for blocks
32	sysadm	1.4	#define ARTICLE_BLOCK_PER_SHM 400 // sizeof(ARTICLE_BLOCK) * ARTICLE_BLOCK_PER_SHM is the size of each shm segment to allocate
33	sysadm	1.3	#define ARTICLE_BLOCK_SHM_COUNT_LIMIT 256 // limited by length (8-bit) of proj_id in ftok(path, proj_id)
34	sysadm	1.1
35			struct article_block_shm_t
36			{
37			int shmid;
38			void *p_shm;
39			};
40			typedef struct article_block_shm_t ARTICLE_BLOCK_SHM;
41
42			static ARTICLE_BLOCK_SHM *p_article_block_shm_pool;
43			static int article_block_shm_count;
44			static ARTICLE_BLOCK *p_article_block_free_list;
45
46			static SECTION_DATA *p_section_data_pool;
47			static int section_data_count;
48			static TRIE_NODE *p_trie_dict_section_data;
49
50			int section_data_pool_init(const char *filename, int article_block_count)
51			{
52			int shmid;
53			int proj_id;
54			key_t key;
55			size_t size;
56			void *p_shm;
57			int i;
58			int article_block_count_in_shm;
59			ARTICLE_BLOCK *p_article_block_in_shm;
60			ARTICLE_BLOCK **pp_article_block_next;
61
62			if (p_article_block_shm_pool != NULL \|\|
63			p_article_block_free_list != NULL \|\|
64			p_section_data_pool != NULL \|\|
65			p_trie_dict_section_data != NULL)
66			{
67			log_error("section_data_pool already initialized\n");
68			return -1;
69			}
70
71			if (article_block_count > ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT)
72			{
73			log_error("article_block_count exceed limit %d\n", ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT);
74			return -2;
75			}
76
77			p_article_block_shm_pool = calloc((size_t)article_block_count / ARTICLE_BLOCK_PER_SHM + 1, sizeof(ARTICLE_BLOCK_SHM));
78			if (p_article_block_shm_pool == NULL)
79			{
80			log_error("calloc(%d ARTICLE_BLOCK_SHM) OOM\n", article_block_count / ARTICLE_BLOCK_PER_SHM + 1);
81			return -2;
82			}
83
84			p_section_data_pool = calloc(BBS_max_section, sizeof(SECTION_DATA));
85			if (p_section_data_pool == NULL)
86			{
87			log_error("calloc(%d SECTION_DATA) OOM\n", BBS_max_section);
88			return -2;
89			}
90			section_data_count = 0;
91
92			p_trie_dict_section_data = trie_dict_create();
93			if (p_trie_dict_section_data == NULL)
94			{
95			log_error("trie_dict_create() OOM\n", BBS_max_section);
96			return -2;
97			}
98
99			// Allocate shared memory
100			article_block_shm_count = 0;
101			pp_article_block_next = &p_article_block_free_list;
102
103			while (article_block_count > 0)
104			{
105			article_block_count_in_shm =
106			(article_block_count < ARTICLE_BLOCK_PER_SHM ? article_block_count : ARTICLE_BLOCK_PER_SHM);
107			article_block_count -= article_block_count_in_shm;
108
109			proj_id = getpid() + article_block_shm_count;
110			key = ftok(filename, proj_id);
111			if (key == -1)
112			{
113			log_error("ftok(%s, %d) error (%d)\n", filename, proj_id, errno);
114			section_data_pool_cleanup();
115			return -3;
116			}
117
118			size = sizeof(shmid) + sizeof(ARTICLE_BLOCK) * (size_t)article_block_count_in_shm;
119			shmid = shmget(key, size, IPC_CREAT \| IPC_EXCL \| 0600);
120			if (shmid == -1)
121			{
122			log_error("shmget(shm_index = %d, size = %d) error (%d)\n", article_block_shm_count, size, errno);
123			section_data_pool_cleanup();
124			return -3;
125			}
126			p_shm = shmat(shmid, NULL, 0);
127			if (p_shm == (void *)-1)
128			{
129			log_error("shmat(shmid = %d) error (%d)\n", shmid, errno);
130			section_data_pool_cleanup();
131			return -3;
132			}
133
134			(p_article_block_shm_pool + article_block_shm_count)->shmid = shmid;
135			(p_article_block_shm_pool + article_block_shm_count)->p_shm = p_shm;
136			article_block_shm_count++;
137
138			p_article_block_in_shm = p_shm;
139			*pp_article_block_next = p_article_block_in_shm;
140
141			for (i = 0; i < article_block_count_in_shm; i++)
142			{
143			if (i < article_block_count_in_shm - 1)
144			{
145			(p_article_block_in_shm + i)->p_next_block = (p_article_block_in_shm + i + 1);
146			}
147			else
148			{
149			(p_article_block_in_shm + i)->p_next_block = NULL;
150			pp_article_block_next = &((p_article_block_in_shm + i)->p_next_block);
151			}
152			}
153			}
154
155			return 0;
156			}
157
158			void section_data_pool_cleanup(void)
159			{
160			int i;
161
162			if (p_trie_dict_section_data != NULL)
163			{
164			trie_dict_destroy(p_trie_dict_section_data);
165			p_trie_dict_section_data = NULL;
166			section_data_count = 0;
167			}
168
169			if (p_section_data_pool != NULL)
170			{
171			free(p_section_data_pool);
172			p_section_data_pool = NULL;
173			}
174
175			if (p_article_block_free_list != NULL)
176			{
177			p_article_block_free_list = NULL;
178			}
179
180			if (p_article_block_shm_pool != NULL)
181			{
182			for (i = 0; i < article_block_shm_count; i++)
183			{
184			if (shmdt((p_article_block_shm_pool + i)->p_shm) == -1)
185			{
186			log_error("shmdt(shmid = %d) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
187			}
188
189			if (shmctl((p_article_block_shm_pool + i)->shmid, IPC_RMID, NULL) == -1)
190			{
191			log_error("shmctl(shmid = %d, IPC_RMID) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
192			}
193			}
194
195			p_article_block_shm_pool = NULL;
196			article_block_shm_count = 0;
197			}
198			}
199
200			inline static ARTICLE_BLOCK *pop_free_article_block(void)
201			{
202			ARTICLE_BLOCK *p_article_block = NULL;
203
204			if (p_article_block_free_list != NULL)
205			{
206			p_article_block = p_article_block_free_list;
207			p_article_block_free_list = p_article_block_free_list->p_next_block;
208			}
209
210			return p_article_block;
211			}
212
213			inline static void push_free_article_block(ARTICLE_BLOCK *p_article_block)
214			{
215			p_article_block->p_next_block = p_article_block_free_list;
216			p_article_block_free_list = p_article_block;
217			}
218
219			SECTION_DATA section_data_create(const char sname, const char stitle, const char master_name)
220			{
221			SECTION_DATA *p_section;
222			int index;
223
224			if (p_section_data_pool == NULL \|\| p_trie_dict_section_data == NULL)
225			{
226			log_error("section_data not initialized\n");
227			return NULL;
228			}
229
230			if (section_data_count >= BBS_max_section)
231			{
232			log_error("section_data_count exceed limit %d\n", BBS_max_section);
233			return NULL;
234			}
235
236			index = section_data_count;
237			p_section = p_section_data_pool + index;
238
239			strncpy(p_section->sname, sname, sizeof(p_section->sname - 1));
240			p_section->sname[sizeof(p_section->sname - 1)] = '\0';
241
242			strncpy(p_section->stitle, stitle, sizeof(p_section->stitle - 1));
243			p_section->stitle[sizeof(p_section->stitle - 1)] = '\0';
244
245			strncpy(p_section->master_name, master_name, sizeof(p_section->master_name - 1));
246			p_section->master_name[sizeof(p_section->master_name - 1)] = '\0';
247
248			p_section->p_head_block = NULL;
249			p_section->p_tail_block = NULL;
250			p_section->block_count = 0;
251			p_section->article_count = 0;
252			p_section->delete_count = 0;
253
254			if (trie_dict_set(p_trie_dict_section_data, sname, index) != 1)
255			{
256			log_error("trie_dict_set(section_data, %s, %d) error\n", sname, index);
257			return NULL;
258			}
259
260			section_data_count++;
261
262			return p_section;
263			}
264
265			int section_data_free_block(SECTION_DATA *p_section)
266			{
267			ARTICLE_BLOCK *p_block;
268
269			if (p_section == NULL)
270			{
271			log_error("section_data_free_block() NULL pointer error\n");
272			return -1;
273			}
274
275			if (p_section_data_pool == NULL)
276			{
277			log_error("section_data not initialized\n");
278			return -1;
279			}
280
281			while (p_section->p_head_block != NULL)
282			{
283			p_block = p_section->p_head_block;
284			p_section->p_head_block = p_block->p_next_block;
285			push_free_article_block(p_block);
286			}
287
288			p_section->p_tail_block = NULL;
289			p_section->block_count = 0;
290			p_section->article_count = 0;
291			p_section->delete_count = 0;
292
293			return 0;
294			}
295
296	sysadm	1.5	SECTION_DATA section_data_find_section_by_name(const char sname)
297	sysadm	1.1	{
298			int64_t index;
299
300			if (p_section_data_pool == NULL \|\| p_trie_dict_section_data == NULL)
301			{
302			log_error("section_data not initialized\n");
303			return NULL;
304			}
305
306			if (trie_dict_get(p_trie_dict_section_data, sname, &index) != 1)
307			{
308			log_error("trie_dict_get(section_data, %s) error\n", sname);
309			return NULL;
310			}
311
312			return (p_section_data_pool + index);
313			}
314
315			int section_data_append_article(SECTION_DATA p_section, const ARTICLE p_article)
316			{
317			ARTICLE_BLOCK *p_block;
318			int32_t last_aid = 0;
319			ARTICLE *p_topic_head;
320			ARTICLE *p_topic_tail;
321
322			if (p_section == NULL \|\| p_article == NULL)
323			{
324			log_error("section_data_append_article() NULL pointer error\n");
325			return -1;
326			}
327
328			if (p_section_data_pool == NULL)
329			{
330			log_error("section_data not initialized\n");
331			return -1;
332			}
333
334			if (p_section->p_tail_block == NULL \|\| p_section->p_tail_block->article_count >= BBS_article_limit_per_block)
335			{
336			if (p_section->block_count >= BBS_article_block_limit_per_section)
337			{
338			log_error("section block count %d reach limit\n", p_section->block_count);
339			return -2;
340			}
341
342			if ((p_block = pop_free_article_block()) == NULL)
343			{
344			log_error("pop_free_article_block() error\n");
345			return -2;
346			}
347
348			p_block->article_count = 0;
349			p_block->p_next_block = NULL;
350
351			if (p_section->p_tail_block == NULL)
352			{
353			p_section->p_head_block = p_block;
354			last_aid = 0;
355			}
356			else
357			{
358			p_section->p_tail_block->p_next_block = p_block;
359			last_aid = p_section->p_tail_block->articles[BBS_article_limit_per_block - 1].aid;
360			}
361			p_section->p_tail_block = p_block;
362			p_section->p_block[p_section->block_count] = p_block;
363			p_section->block_count++;
364			}
365			else
366			{
367			p_block = p_section->p_tail_block;
368			last_aid = p_block->articles[p_block->article_count - 1].aid;
369			}
370
371			// AID of articles should be strictly ascending
372			if (p_article->aid <= last_aid)
373			{
374			log_error("section_data_append_article(aid=%d) error: last_aid=%d\n", p_article->aid, last_aid);
375			return -3;
376			}
377
378			if (p_block->article_count == 0)
379			{
380			p_section->block_head_aid[p_section->block_count - 1] = p_article->aid;
381			}
382
383			if (p_article->tid != 0)
384			{
385	sysadm	1.2	p_topic_head = section_data_find_article_by_aid(p_section, p_article->tid);
386	sysadm	1.1	if (p_topic_head == NULL)
387			{
388			log_error("search head of topic (aid=%d) error\n", p_article->tid);
389			return -4;
390			}
391
392	sysadm	1.2	p_topic_tail = section_data_find_article_by_aid(p_section, p_topic_head->prior_aid);
393	sysadm	1.1	if (p_topic_tail == NULL)
394			{
395			log_error("search tail of topic (aid=%d) error\n", p_topic_head->prior_aid);
396			return -4;
397			}
398			}
399			else
400			{
401			p_topic_head = &(p_block->articles[p_block->article_count]);
402			p_topic_tail = p_topic_head;
403			}
404
405			// Copy article data
406			p_block->articles[p_block->article_count] = *p_article;
407
408			// Link appended article as tail node of topic bi-directional list;
409			p_block->articles[p_block->article_count].prior_aid = p_topic_tail->aid;
410			p_block->articles[p_block->article_count].next_aid = p_topic_head->aid;
411			p_topic_head->prior_aid = p_article->aid;
412			p_topic_tail->next_aid = p_article->aid;
413
414			p_block->article_count++;
415			p_section->article_count++;
416
417			return 0;
418			}
419
420	sysadm	1.2	ARTICLE section_data_find_article_by_aid(SECTION_DATA p_section, int32_t aid)
421	sysadm	1.1	{
422			ARTICLE *p_article;
423			ARTICLE_BLOCK *p_block;
424			int left;
425			int right;
426			int mid;
427
428			if (p_section == NULL)
429			{
430	sysadm	1.2	log_error("section_data_find_article_by_aid() NULL pointer error\n");
431	sysadm	1.1	return NULL;
432			}
433
434			if (p_section->block_count == 0) // empty section
435			{
436			return NULL;
437			}
438
439			left = 0;
440			right = p_section->block_count;
441
442			// aid in the range [ head aid of blocks[left], tail aid of blocks[right - 1] ]
443			while (left < right - 1)
444			{
445			// get block offset no less than mid value of left and right block offsets
446			mid = (left + right) / 2 + (right - left) % 2;
447
448			if (mid >= BBS_article_block_limit_per_section)
449			{
450			log_error("block_m(%d) is out of boundary\n", mid);
451			return NULL;
452			}
453
454			if (aid < p_section->block_head_aid[mid])
455			{
456			right = mid;
457			}
458			else
459			{
460			left = mid;
461			}
462			}
463
464			p_block = p_section->p_block[left];
465
466			left = 0;
467			right = p_block->article_count - 1;
468
469			// aid in the range [ aid of articles[left], aid of articles[right] ]
470			while (left < right)
471			{
472			mid = (left + right) / 2;
473
474			if (aid <= p_block->articles[mid].aid)
475			{
476			right = mid;
477			}
478			else
479			{
480			left = mid + 1;
481			}
482			}
483
484			p_article = &(p_block->articles[left]);
485
486			return p_article;
487			}
488
489	sysadm	1.2	ARTICLE section_data_find_article_by_index(SECTION_DATA p_section, int index)
490			{
491			ARTICLE *p_article;
492			ARTICLE_BLOCK *p_block;
493
494			if (p_section == NULL)
495			{
496			log_error("section_data_find_article_by_index() NULL pointer error\n");
497			return NULL;
498			}
499
500			if (index < 0 \|\| index >= p_section->article_count)
501			{
502			log_error("section_data_find_article_by_index(%d) is out of boundary [0, %d)\n", index, p_section->article_count);
503			return NULL;
504			}
505
506			p_block = p_section->p_block[index / BBS_article_limit_per_block];
507			p_article = &(p_block->articles[index % BBS_article_limit_per_block]);
508
509			return p_article;
510			}
511
512	sysadm	1.1	int section_data_mark_del_article(SECTION_DATA *p_section, int32_t aid)
513			{
514			ARTICLE *p_article;
515
516	sysadm	1.2	if (p_section == NULL)
517			{
518			log_error("section_data_mark_del_article() NULL pointer error\n");
519			return -2;
520			}
521
522			p_article = section_data_find_article_by_aid(p_section, aid);
523	sysadm	1.1	if (p_article == NULL)
524			{
525			return -1; // Not found
526			}
527
528			if (p_article->visible == 0)
529			{
530			return 0; // Already deleted
531			}
532
533			p_article->visible = 0;
534			p_section->delete_count++;
535
536			return 1;
537			}
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