lbbs/src/user_list.c

/***************************************************************************
                         user_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 "common.h"
#include "database.h"
#include "log.h"
#include "user_list.h"
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <sys/ipc.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/sem.h>
#include <sys/shm.h>

#ifdef _SEM_SEMUN_UNDEFINED
union semun
{
    int val;               /* Value for SETVAL */
    struct semid_ds *buf;  /* Buffer for IPC_STAT, IPC_SET */
    unsigned short *array; /* Array for GETALL, SETALL */
    struct seminfo *__buf; /* Buffer for IPC_INFO
                              (Linux-specific) */
};
#endif // #ifdef _SEM_SEMUN_UNDEFINED

#define USER_LIST_TRY_LOCK_WAIT_TIME 1 // second
#define USER_LIST_TRY_LOCK_TIMES 10

struct user_list_pool_t
{
    int shmid;
    int semid;
    USER_LIST user_list[2];
    USER_LIST *p_current;
    USER_LIST *p_new;
};
typedef struct user_list_pool_t USER_LIST_POOL;

static USER_LIST_POOL *p_user_list_pool = NULL;

int user_list_load(MYSQL *db, USER_LIST *p_list)
{
    MYSQL_RES *rs = NULL;
    MYSQL_ROW row;
    char sql[SQL_BUFFER_LEN];
    int ret = 0;
    int i;

    if (db == NULL || p_list == NULL)
    {
        log_error("NULL pointer error\n");
        return -1;
    }

    snprintf(sql, sizeof(sql),
             "SELECT user_list.UID AS UID, username, nickname, gender, gender_pub, life, exp, "
             "UNIX_TIMESTAMP(signup_dt), UNIX_TIMESTAMP(last_login_dt), UNIX_TIMESTAMP(birthday) "
             "FROM user_list INNER JOIN user_pubinfo ON user_list.UID = user_pubinfo.UID "
             "INNER JOIN user_reginfo ON user_list.UID = user_reginfo.UID "
             "WHERE enable ORDER BY UID");

    if (mysql_query(db, sql) != 0)
    {
        log_error("Query user info error: %s\n", mysql_error(db));
        ret = -1;
        goto cleanup;
    }

    if ((rs = mysql_use_result(db)) == NULL)
    {
        log_error("Get user info data failed\n");
        ret = -1;
        goto cleanup;
    }

    i = 0;
    while ((row = mysql_fetch_row(rs)))
    {
        p_list->users[i].uid = atoi(row[0]);
        strncpy(p_list->users[i].username, row[1], sizeof(p_list->users[i].username) - 1);
        p_list->users[i].username[sizeof(p_list->users[i].username) - 1] = '\0';
        strncpy(p_list->users[i].nickname, row[2], sizeof(p_list->users[i].nickname) - 1);
        p_list->users[i].nickname[sizeof(p_list->users[i].nickname) - 1] = '\0';
        p_list->users[i].gender = row[3][0];
        p_list->users[i].gender_pub = (int8_t)(row[4] == NULL ? 0 : atoi(row[4]));
        p_list->users[i].life = (row[5] == NULL ? 0 : atoi(row[5]));
        p_list->users[i].exp = (row[6] == NULL ? 0 : atoi(row[6]));
        p_list->users[i].signup_dt = (row[7] == NULL ? 0 : atol(row[7]));
        p_list->users[i].last_login_dt = (row[8] == NULL ? 0 : atol(row[8]));
        p_list->users[i].birthday = (row[9] == NULL ? 0 : atol(row[9]));

        i++;
        if (i >= BBS_max_user_count)
        {
            log_error("Too many users, exceed limit %d\n", BBS_max_user_count);
            break;
        }
    }
    mysql_free_result(rs);
    rs = NULL;

    p_list->user_count = i;

#ifdef _DEBUG
    log_error("Loaded %d users\n", p_list->user_count);
#endif

cleanup:
    mysql_free_result(rs);

    return ret;
}

int user_list_pool_init(void)
{
    int shmid;
    int semid;
    int proj_id;
    key_t key;
    size_t size;
    void *p_shm;
    union semun arg;
    int i;

    if (p_user_list_pool != NULL)
    {
        log_error("p_user_list_pool already initialized\n");
        return -1;
    }

    // Allocate shared memory
    proj_id = (int)(time(NULL) % getpid());
    key = ftok(VAR_USER_LIST_SHM, proj_id);
    if (key == -1)
    {
        log_error("ftok(%s %d) error (%d)\n", VAR_USER_LIST_SHM, proj_id, errno);
        return -2;
    }

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

    p_user_list_pool = p_shm;
    p_user_list_pool->shmid = shmid;

    // Allocate semaphore as user list pool lock
    size = 2; // r_sem and w_sem
    semid = semget(key, (int)size, IPC_CREAT | IPC_EXCL | 0600);
    if (semid == -1)
    {
        log_error("semget(user_list_pool_sem, size = %d) error (%d)\n", size, errno);
        return -3;
    }

    // Initialize sem value to 0
    arg.val = 0;
    for (i = 0; i < size; i++)
    {
        if (semctl(semid, i, SETVAL, arg) == -1)
        {
            log_error("semctl(user_list_pool_sem, SETVAL) error (%d)\n", errno);
            return -3;
        }
    }

    p_user_list_pool->semid = semid;

    // Set user counts to 0
    p_user_list_pool->user_list[0].user_count = 0;
    p_user_list_pool->user_list[1].user_count = 0;

    p_user_list_pool->p_current = &(p_user_list_pool->user_list[0]);
    p_user_list_pool->p_new = &(p_user_list_pool->user_list[1]);

    return 0;
}

void user_list_pool_cleanup(void)
{
    int shmid;

    if (p_user_list_pool == NULL)
    {
        return;
    }

    shmid = p_user_list_pool->shmid;

    if (semctl(p_user_list_pool->semid, 0, IPC_RMID) == -1)
    {
        log_error("semctl(semid = %d, IPC_RMID) error (%d)\n", p_user_list_pool->semid, errno);
    }

    if (shmdt(p_user_list_pool) == -1)
    {
        log_error("shmdt(shmid = %d) error (%d)\n", shmid, errno);
    }

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

    p_user_list_pool = NULL;
}

int set_user_list_pool_shm_readonly(void)
{
    int shmid;
    void *p_shm;

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

    shmid = p_user_list_pool->shmid;

    // Remap shared memory in read-only mode
    p_shm = shmat(shmid, p_user_list_pool, SHM_RDONLY | SHM_REMAP);
    if (p_shm == (void *)-1)
    {
        log_error("shmat(user_list_pool shmid = %d) error (%d)\n", shmid, errno);
        return -3;
    }

    p_user_list_pool = p_shm;

    return 0;
}

int detach_user_list_pool_shm(void)
{
    if (p_user_list_pool != NULL && shmdt(p_user_list_pool) == -1)
    {
        log_error("shmdt(user_list_pool) error (%d)\n", errno);
        return -1;
    }

    p_user_list_pool = NULL;

    return 0;
}

int user_list_pool_reload(void)
{
    MYSQL *db = NULL;
    USER_LIST *p_tmp;

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

    db = db_open();
    if (db == NULL)
    {
        log_error("db_open() error: %s\n", mysql_error(db));
        return -1;
    }

    if (user_list_load(db, p_user_list_pool->p_new) < 0)
    {
        log_error("user_list_rw_lock() error\n");
        return -2;
    }

    mysql_close(db);

    if (user_list_rw_lock() < 0)
    {
        log_error("user_list_rw_lock() error\n");
        return -3;
    }

    // Swap p_current and p_new
    p_tmp = p_user_list_pool->p_current;
    p_user_list_pool->p_current = p_user_list_pool->p_new;
    p_user_list_pool->p_new = p_tmp;

    if (user_list_rw_unlock() < 0)
    {
        log_error("user_list_rw_unlock() error\n");
        return -3;
    }

    return 0;
}

int user_list_try_rd_lock(int wait_sec)
{
    struct sembuf sops[2];
    struct timespec timeout;
    int ret;

    sops[0].sem_num = 1; // w_sem
    sops[0].sem_op = 0;  // wait until unlocked
    sops[0].sem_flg = 0;

    sops[1].sem_num = 0;        // r_sem
    sops[1].sem_op = 1;         // lock
    sops[1].sem_flg = SEM_UNDO; // undo on terminate

    timeout.tv_sec = wait_sec;
    timeout.tv_nsec = 0;

    ret = semtimedop(p_user_list_pool->semid, sops, 2, &timeout);
    if (ret == -1 && errno != EAGAIN && errno != EINTR)
    {
        log_error("semtimedop(lock read) error %d\n", errno);
    }

    return ret;
}

int user_list_try_rw_lock(int wait_sec)
{
    struct sembuf sops[3];
    struct timespec timeout;
    int ret;

    sops[0].sem_num = 1; // w_sem
    sops[0].sem_op = 0;  // wait until unlocked
    sops[0].sem_flg = 0;

    sops[1].sem_num = 1;        // w_sem
    sops[1].sem_op = 1;         // lock
    sops[1].sem_flg = SEM_UNDO; // undo on terminate

    sops[2].sem_num = 0; // r_sem
    sops[2].sem_op = 0;  // wait until unlocked
    sops[2].sem_flg = 0;

    timeout.tv_sec = wait_sec;
    timeout.tv_nsec = 0;

    ret = semtimedop(p_user_list_pool->semid, sops, 3, &timeout);
    if (ret == -1 && errno != EAGAIN && errno != EINTR)
    {
        log_error("semtimedop(lock write) error %d\n", errno);
    }

    return ret;
}

int user_list_rd_unlock(void)
{
    struct sembuf sops[2];
    int ret;

    sops[0].sem_num = 0;                     // r_sem
    sops[0].sem_op = -1;                     // unlock
    sops[0].sem_flg = IPC_NOWAIT | SEM_UNDO; // no wait

    ret = semop(p_user_list_pool->semid, sops, 1);
    if (ret == -1 && errno != EAGAIN && errno != EINTR)
    {
        log_error("semop(unlock read) error %d\n", errno);
    }

    return ret;
}

int user_list_rw_unlock(void)
{
    struct sembuf sops[1];
    int ret;

    sops[0].sem_num = 1;                     // w_sem
    sops[0].sem_op = -1;                     // unlock
    sops[0].sem_flg = IPC_NOWAIT | SEM_UNDO; // no wait

    ret = semop(p_user_list_pool->semid, sops, 1);
    if (ret == -1 && errno != EAGAIN && errno != EINTR)
    {
        log_error("semop(unlock write) error %d\n", errno);
    }

    return ret;
}

int user_list_rd_lock(void)
{
    int timer = 0;
    int ret = -1;

    while (!SYS_server_exit)
    {
        ret = user_list_try_rd_lock(USER_LIST_TRY_LOCK_WAIT_TIME);
        if (ret == 0) // success
        {
            break;
        }
        else if (errno == EAGAIN || errno == EINTR) // retry
        {
            timer++;
            if (timer % USER_LIST_TRY_LOCK_TIMES == 0)
            {
                log_error("user_list_try_rd_lock() tried %d times\n", timer);
            }
        }
        else // failed
        {
            log_error("user_list_try_rd_lock() failed\n");
            break;
        }
    }

    return ret;
}

int user_list_rw_lock(void)
{
    int timer = 0;
    int ret = -1;

    while (!SYS_server_exit)
    {
        ret = user_list_try_rw_lock(USER_LIST_TRY_LOCK_WAIT_TIME);
        if (ret == 0) // success
        {
            break;
        }
        else if (errno == EAGAIN || errno == EINTR) // retry
        {
            timer++;
            if (timer % USER_LIST_TRY_LOCK_TIMES == 0)
            {
                log_error("user_list_try_rw_lock() tried %d times\n", timer);
            }
        }
        else // failed
        {
            log_error("user_list_try_rw_lock() failed\n");
            break;
        }
    }

    return ret;
}

int query_user_list(int page_id, USER_INFO *p_users, int *p_user_count, int *p_page_count)
{
    int ret = 0;

    if (p_users == NULL || p_user_count == NULL || p_page_count == NULL)
    {
        log_error("NULL pointer error\n");
        return -1;
    }

    // acquire lock of user list
    if (user_list_rd_lock() < 0)
    {
        log_error("user_list_rd_lock() error\n");
        return -2;
    }

    if (p_user_list_pool->p_current->user_count == 0)
    {
        // empty list
        ret = 0;
        goto cleanup;
    }

    *p_page_count = p_user_list_pool->p_current->user_count / BBS_user_limit_per_page +
                    (p_user_list_pool->p_current->user_count % BBS_user_limit_per_page == 0 ? 0 : 1);

    if (page_id < 0 || page_id >= *p_page_count)
    {
        log_error("Invalid page_id = %d, not in range [0, %d)\n", page_id, *p_page_count);
        ret = -3;
        goto cleanup;
    }

    *p_user_count = MIN(BBS_user_limit_per_page,
                        p_user_list_pool->p_current->user_count -
                            page_id * BBS_user_limit_per_page);

    memcpy(p_users,
           p_user_list_pool->p_current->users + page_id * BBS_user_limit_per_page,
           sizeof(USER_INFO) * (size_t)(*p_user_count));

cleanup:
    // release lock of user list
    if (user_list_rd_unlock() < 0)
    {
        log_error("user_list_rd_unlock() error\n");
        ret = -1;
    }

    return ret;
}
1	/***************************************************************************
2	user_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 "common.h"
18	#include "database.h"
19	#include "log.h"
20	#include "user_list.h"
21	#include <errno.h>
22	#include <stdlib.h>
23	#include <string.h>
24	#include <time.h>
25	#include <sys/ipc.h>
26	#include <sys/mman.h>
27	#include <sys/param.h>
28	#include <sys/sem.h>
29	#include <sys/shm.h>
30
31	#ifdef _SEM_SEMUN_UNDEFINED
32	union semun
33	{
34	int val; /* Value for SETVAL */
35	struct semid_ds buf; / Buffer for IPC_STAT, IPC_SET */
36	unsigned short array; / Array for GETALL, SETALL */
37	struct seminfo __buf; / Buffer for IPC_INFO
38	(Linux-specific) */
39	};
40	#endif // #ifdef _SEM_SEMUN_UNDEFINED
41
42	#define USER_LIST_TRY_LOCK_WAIT_TIME 1 // second
43	#define USER_LIST_TRY_LOCK_TIMES 10
44
45	struct user_list_pool_t
46	{
47	int shmid;
48	int semid;
49	USER_LIST user_list[2];
50	USER_LIST *p_current;
51	USER_LIST *p_new;
52	};
53	typedef struct user_list_pool_t USER_LIST_POOL;
54
55	static USER_LIST_POOL *p_user_list_pool = NULL;
56
57	int user_list_load(MYSQL db, USER_LIST p_list)
58	{
59	MYSQL_RES *rs = NULL;
60	MYSQL_ROW row;
61	char sql[SQL_BUFFER_LEN];
62	int ret = 0;
63	int i;
64
65	if (db == NULL \|\| p_list == NULL)
66	{
67	log_error("NULL pointer error\n");
68	return -1;
69	}
70
71	snprintf(sql, sizeof(sql),
72	"SELECT user_list.UID AS UID, username, nickname, gender, gender_pub, life, exp, "
73	"UNIX_TIMESTAMP(signup_dt), UNIX_TIMESTAMP(last_login_dt), UNIX_TIMESTAMP(birthday) "
74	"FROM user_list INNER JOIN user_pubinfo ON user_list.UID = user_pubinfo.UID "
75	"INNER JOIN user_reginfo ON user_list.UID = user_reginfo.UID "
76	"WHERE enable ORDER BY UID");
77
78	if (mysql_query(db, sql) != 0)
79	{
80	log_error("Query user info error: %s\n", mysql_error(db));
81	ret = -1;
82	goto cleanup;
83	}
84
85	if ((rs = mysql_use_result(db)) == NULL)
86	{
87	log_error("Get user info data failed\n");
88	ret = -1;
89	goto cleanup;
90	}
91
92	i = 0;
93	while ((row = mysql_fetch_row(rs)))
94	{
95	p_list->users[i].uid = atoi(row[0]);
96	strncpy(p_list->users[i].username, row[1], sizeof(p_list->users[i].username) - 1);
97	p_list->users[i].username[sizeof(p_list->users[i].username) - 1] = '\0';
98	strncpy(p_list->users[i].nickname, row[2], sizeof(p_list->users[i].nickname) - 1);
99	p_list->users[i].nickname[sizeof(p_list->users[i].nickname) - 1] = '\0';
100	p_list->users[i].gender = row[3][0];
101	p_list->users[i].gender_pub = (int8_t)(row[4] == NULL ? 0 : atoi(row[4]));
102	p_list->users[i].life = (row[5] == NULL ? 0 : atoi(row[5]));
103	p_list->users[i].exp = (row[6] == NULL ? 0 : atoi(row[6]));
104	p_list->users[i].signup_dt = (row[7] == NULL ? 0 : atol(row[7]));
105	p_list->users[i].last_login_dt = (row[8] == NULL ? 0 : atol(row[8]));
106	p_list->users[i].birthday = (row[9] == NULL ? 0 : atol(row[9]));
107
108	i++;
109	if (i >= BBS_max_user_count)
110	{
111	log_error("Too many users, exceed limit %d\n", BBS_max_user_count);
112	break;
113	}
114	}
115	mysql_free_result(rs);
116	rs = NULL;
117
118	p_list->user_count = i;
119
120	#ifdef _DEBUG
121	log_error("Loaded %d users\n", p_list->user_count);
122	#endif
123
124	cleanup:
125	mysql_free_result(rs);
126
127	return ret;
128	}
129
130	int user_list_pool_init(void)
131	{
132	int shmid;
133	int semid;
134	int proj_id;
135	key_t key;
136	size_t size;
137	void *p_shm;
138	union semun arg;
139	int i;
140
141	if (p_user_list_pool != NULL)
142	{
143	log_error("p_user_list_pool already initialized\n");
144	return -1;
145	}
146
147	// Allocate shared memory
148	proj_id = (int)(time(NULL) % getpid());
149	key = ftok(VAR_USER_LIST_SHM, proj_id);
150	if (key == -1)
151	{
152	log_error("ftok(%s %d) error (%d)\n", VAR_USER_LIST_SHM, proj_id, errno);
153	return -2;
154	}
155
156	size = sizeof(USER_LIST_POOL);
157	shmid = shmget(key, size, IPC_CREAT \| IPC_EXCL \| 0600);
158	if (shmid == -1)
159	{
160	log_error("shmget(size = %d) error (%d)\n", size, errno);
161	return -3;
162	}
163	p_shm = shmat(shmid, NULL, 0);
164	if (p_shm == (void *)-1)
165	{
166	log_error("shmat(shmid=%d) error (%d)\n", shmid, errno);
167	return -3;
168	}
169
170	p_user_list_pool = p_shm;
171	p_user_list_pool->shmid = shmid;
172
173	// Allocate semaphore as user list pool lock
174	size = 2; // r_sem and w_sem
175	semid = semget(key, (int)size, IPC_CREAT \| IPC_EXCL \| 0600);
176	if (semid == -1)
177	{
178	log_error("semget(user_list_pool_sem, size = %d) error (%d)\n", size, errno);
179	return -3;
180	}
181
182	// Initialize sem value to 0
183	arg.val = 0;
184	for (i = 0; i < size; i++)
185	{
186	if (semctl(semid, i, SETVAL, arg) == -1)
187	{
188	log_error("semctl(user_list_pool_sem, SETVAL) error (%d)\n", errno);
189	return -3;
190	}
191	}
192
193	p_user_list_pool->semid = semid;
194
195	// Set user counts to 0
196	p_user_list_pool->user_list[0].user_count = 0;
197	p_user_list_pool->user_list[1].user_count = 0;
198
199	p_user_list_pool->p_current = &(p_user_list_pool->user_list[0]);
200	p_user_list_pool->p_new = &(p_user_list_pool->user_list[1]);
201
202	return 0;
203	}
204
205	void user_list_pool_cleanup(void)
206	{
207	int shmid;
208
209	if (p_user_list_pool == NULL)
210	{
211	return;
212	}
213
214	shmid = p_user_list_pool->shmid;
215
216	if (semctl(p_user_list_pool->semid, 0, IPC_RMID) == -1)
217	{
218	log_error("semctl(semid = %d, IPC_RMID) error (%d)\n", p_user_list_pool->semid, errno);
219	}
220
221	if (shmdt(p_user_list_pool) == -1)
222	{
223	log_error("shmdt(shmid = %d) error (%d)\n", shmid, errno);
224	}
225
226	if (shmctl(shmid, IPC_RMID, NULL) == -1)
227	{
228	log_error("shmctl(shmid = %d, IPC_RMID) error (%d)\n", shmid, errno);
229	}
230
231	p_user_list_pool = NULL;
232	}
233
234	int set_user_list_pool_shm_readonly(void)
235	{
236	int shmid;
237	void *p_shm;
238
239	if (p_user_list_pool == NULL)
240	{
241	log_error("p_user_list_pool not initialized\n");
242	return -1;
243	}
244
245	shmid = p_user_list_pool->shmid;
246
247	// Remap shared memory in read-only mode
248	p_shm = shmat(shmid, p_user_list_pool, SHM_RDONLY \| SHM_REMAP);
249	if (p_shm == (void *)-1)
250	{
251	log_error("shmat(user_list_pool shmid = %d) error (%d)\n", shmid, errno);
252	return -3;
253	}
254
255	p_user_list_pool = p_shm;
256
257	return 0;
258	}
259
260	int detach_user_list_pool_shm(void)
261	{
262	if (p_user_list_pool != NULL && shmdt(p_user_list_pool) == -1)
263	{
264	log_error("shmdt(user_list_pool) error (%d)\n", errno);
265	return -1;
266	}
267
268	p_user_list_pool = NULL;
269
270	return 0;
271	}
272
273	int user_list_pool_reload(void)
274	{
275	MYSQL *db = NULL;
276	USER_LIST *p_tmp;
277
278	if (p_user_list_pool == NULL)
279	{
280	log_error("p_user_list_pool not initialized\n");
281	return -1;
282	}
283
284	db = db_open();
285	if (db == NULL)
286	{
287	log_error("db_open() error: %s\n", mysql_error(db));
288	return -1;
289	}
290
291	if (user_list_load(db, p_user_list_pool->p_new) < 0)
292	{
293	log_error("user_list_rw_lock() error\n");
294	return -2;
295	}
296
297	mysql_close(db);
298
299	if (user_list_rw_lock() < 0)
300	{
301	log_error("user_list_rw_lock() error\n");
302	return -3;
303	}
304
305	// Swap p_current and p_new
306	p_tmp = p_user_list_pool->p_current;
307	p_user_list_pool->p_current = p_user_list_pool->p_new;
308	p_user_list_pool->p_new = p_tmp;
309
310	if (user_list_rw_unlock() < 0)
311	{
312	log_error("user_list_rw_unlock() error\n");
313	return -3;
314	}
315
316	return 0;
317	}
318
319	int user_list_try_rd_lock(int wait_sec)
320	{
321	struct sembuf sops[2];
322	struct timespec timeout;
323	int ret;
324
325	sops[0].sem_num = 1; // w_sem
326	sops[0].sem_op = 0; // wait until unlocked
327	sops[0].sem_flg = 0;
328
329	sops[1].sem_num = 0; // r_sem
330	sops[1].sem_op = 1; // lock
331	sops[1].sem_flg = SEM_UNDO; // undo on terminate
332
333	timeout.tv_sec = wait_sec;
334	timeout.tv_nsec = 0;
335
336	ret = semtimedop(p_user_list_pool->semid, sops, 2, &timeout);
337	if (ret == -1 && errno != EAGAIN && errno != EINTR)
338	{
339	log_error("semtimedop(lock read) error %d\n", errno);
340	}
341
342	return ret;
343	}
344
345	int user_list_try_rw_lock(int wait_sec)
346	{
347	struct sembuf sops[3];
348	struct timespec timeout;
349	int ret;
350
351	sops[0].sem_num = 1; // w_sem
352	sops[0].sem_op = 0; // wait until unlocked
353	sops[0].sem_flg = 0;
354
355	sops[1].sem_num = 1; // w_sem
356	sops[1].sem_op = 1; // lock
357	sops[1].sem_flg = SEM_UNDO; // undo on terminate
358
359	sops[2].sem_num = 0; // r_sem
360	sops[2].sem_op = 0; // wait until unlocked
361	sops[2].sem_flg = 0;
362
363	timeout.tv_sec = wait_sec;
364	timeout.tv_nsec = 0;
365
366	ret = semtimedop(p_user_list_pool->semid, sops, 3, &timeout);
367	if (ret == -1 && errno != EAGAIN && errno != EINTR)
368	{
369	log_error("semtimedop(lock write) error %d\n", errno);
370	}
371
372	return ret;
373	}
374
375	int user_list_rd_unlock(void)
376	{
377	struct sembuf sops[2];
378	int ret;
379
380	sops[0].sem_num = 0; // r_sem
381	sops[0].sem_op = -1; // unlock
382	sops[0].sem_flg = IPC_NOWAIT \| SEM_UNDO; // no wait
383
384	ret = semop(p_user_list_pool->semid, sops, 1);
385	if (ret == -1 && errno != EAGAIN && errno != EINTR)
386	{
387	log_error("semop(unlock read) error %d\n", errno);
388	}
389
390	return ret;
391	}
392
393	int user_list_rw_unlock(void)
394	{
395	struct sembuf sops[1];
396	int ret;
397
398	sops[0].sem_num = 1; // w_sem
399	sops[0].sem_op = -1; // unlock
400	sops[0].sem_flg = IPC_NOWAIT \| SEM_UNDO; // no wait
401
402	ret = semop(p_user_list_pool->semid, sops, 1);
403	if (ret == -1 && errno != EAGAIN && errno != EINTR)
404	{
405	log_error("semop(unlock write) error %d\n", errno);
406	}
407
408	return ret;
409	}
410
411	int user_list_rd_lock(void)
412	{
413	int timer = 0;
414	int ret = -1;
415
416	while (!SYS_server_exit)
417	{
418	ret = user_list_try_rd_lock(USER_LIST_TRY_LOCK_WAIT_TIME);
419	if (ret == 0) // success
420	{
421	break;
422	}
423	else if (errno == EAGAIN \|\| errno == EINTR) // retry
424	{
425	timer++;
426	if (timer % USER_LIST_TRY_LOCK_TIMES == 0)
427	{
428	log_error("user_list_try_rd_lock() tried %d times\n", timer);
429	}
430	}
431	else // failed
432	{
433	log_error("user_list_try_rd_lock() failed\n");
434	break;
435	}
436	}
437
438	return ret;
439	}
440
441	int user_list_rw_lock(void)
442	{
443	int timer = 0;
444	int ret = -1;
445
446	while (!SYS_server_exit)
447	{
448	ret = user_list_try_rw_lock(USER_LIST_TRY_LOCK_WAIT_TIME);
449	if (ret == 0) // success
450	{
451	break;
452	}
453	else if (errno == EAGAIN \|\| errno == EINTR) // retry
454	{
455	timer++;
456	if (timer % USER_LIST_TRY_LOCK_TIMES == 0)
457	{
458	log_error("user_list_try_rw_lock() tried %d times\n", timer);
459	}
460	}
461	else // failed
462	{
463	log_error("user_list_try_rw_lock() failed\n");
464	break;
465	}
466	}
467
468	return ret;
469	}
470
471	int query_user_list(int page_id, USER_INFO p_users, int p_user_count, int *p_page_count)
472	{
473	int ret = 0;
474
475	if (p_users == NULL \|\| p_user_count == NULL \|\| p_page_count == NULL)
476	{
477	log_error("NULL pointer error\n");
478	return -1;
479	}
480
481	// acquire lock of user list
482	if (user_list_rd_lock() < 0)
483	{
484	log_error("user_list_rd_lock() error\n");
485	return -2;
486	}
487
488	if (p_user_list_pool->p_current->user_count == 0)
489	{
490	// empty list
491	ret = 0;
492	goto cleanup;
493	}
494
495	*p_page_count = p_user_list_pool->p_current->user_count / BBS_user_limit_per_page +
496	(p_user_list_pool->p_current->user_count % BBS_user_limit_per_page == 0 ? 0 : 1);
497
498	if (page_id < 0 \|\| page_id >= *p_page_count)
499	{
500	log_error("Invalid page_id = %d, not in range [0, %d)\n", page_id, *p_page_count);
501	ret = -3;
502	goto cleanup;
503	}
504
505	*p_user_count = MIN(BBS_user_limit_per_page,
506	p_user_list_pool->p_current->user_count -
507	page_id * BBS_user_limit_per_page);
508
509	memcpy(p_users,
510	p_user_list_pool->p_current->users + page_id * BBS_user_limit_per_page,
511	sizeof(USER_INFO) * (size_t)(*p_user_count));
512
513	cleanup:
514	// release lock of user list
515	if (user_list_rd_unlock() < 0)
516	{
517	log_error("user_list_rd_unlock() error\n");
518	ret = -1;
519	}
520
521	return ret;
522	}
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