path: root/mbbsd/brc.c

/* $Id$ */
#include "bbs.h"

/**
 * 關於本檔案的細節，請見 docs/brc.txt。
 */

#ifndef BRC_MAXNUM
#define BRC_STRLEN      15  /* Length of board name */
#define BRC_MAXSIZE     24576   /* Effective size of brc rc file, 8192 * 3 */
#define BRC_MAXNUM      80      /* Upper bound of brc_num, size of brc_list  */
#endif

#define BRC_BLOCKSIZE   1024

#if MAX_BOARD > 65535 || BRC_MAXSIZE > 65535
#error Max number of boards or BRC_MAXSIZE cannot fit in unsighed short, \
please rewrite brc.c
#endif

typedef unsigned short brcbid_t;
typedef unsigned short brcnbrd_t;

/* old brc rc file form:
 * board_name     15 bytes
 * brc_num         1 byte, binary integer
 * brc_list       brc_num * sizeof(int) bytes, brc_num binary integer(s) */

static time4_t brc_expire_time;
 /* Will be set to the time one year before login. All the files created
  * before then will be recognized read. */

static int     brc_changed = 0;
/* The below two will be filled by read_brc_buf() and brc_update() */
static char   *brc_buf = NULL;
static int     brc_size;
static int     brc_alloc;

static char * const fn_oldboardrc = ".boardrc";
static char * const fn_brc = ".brc2";

#if 0
/* unused after brc2 */
static char *
brc_getrecord(char *ptr, char *endp, brcbid_t *bid,
          brcnbrd_t *pnum, time4_t *list)
{
    brcnbrd_t num;
    char   *tmp;

    if (ptr + sizeof(brcbid_t) + sizeof(brcnbrd_t) > endp)
    return endp + 1; /* dangling, ignoring it */
    *bid = *(brcbid_t*)ptr;    /* bid */
    ptr += sizeof(brcbid_t);
    num = *(brcnbrd_t*)ptr;    /* brc_num */
    ptr += sizeof(brcnbrd_t);
    tmp = ptr + num * sizeof(time4_t);     /* end of this record */
    if (tmp <= endp){
    memcpy(list, ptr, num * sizeof(time4_t)); /* brc_list */
    if (num > BRC_MAXNUM)
        num = BRC_MAXNUM;
    *pnum = num;
    }
    return tmp;
}
#endif

/* Returns the address of the record strictly between begin and endp with
 * bid equal to the parameter. Returns 0 if not found.
 * brcnbrd_t *num is an output parameter which will filled with brc_num
 * if the record is found. If not found the record, *num will be the number
 * of dangling bytes. */
static char *
brc_findrecord_in(char *begin, char *endp, brcbid_t bid, brcnbrd_t *num)
{
    char     *tmpp, *ptr = begin;
    brcbid_t tbid;
    while (ptr + sizeof(brcbid_t) + sizeof(brcnbrd_t) < endp) {
    /* for each available records */
    tmpp = ptr;
    tbid = *(brcbid_t*)tmpp;
    tmpp += sizeof(brcbid_t);
    *num = *(brcnbrd_t*)tmpp;
    tmpp += sizeof(brcnbrd_t) + *num * sizeof(time4_t); /* end of record */

    if ( tmpp > endp ){
        /* dangling, ignore the trailing data */
        *num = (brcnbrd_t)(endp - ptr); /* for brc_insert_record() */
        return 0;
    }
    if ( tbid == bid )
        return ptr;
    ptr = tmpp;
    }

    *num = 0;
    return 0;
}

time4_t *
brc_find_record(int bid, int *num)
{
    char *p;
    brcnbrd_t tnum;
    p = brc_findrecord_in(brc_buf, brc_buf + brc_size, bid, &tnum);
    *num = tnum;
    if (p)
    return (time4_t*)(p + sizeof(brcbid_t) + sizeof(brcnbrd_t));
    *num = 0;
    return 0;
}

static char *
brc_putrecord(char *ptr, char *endp, brcbid_t bid,
          brcnbrd_t num, const time4_t *list)
{
    char * tmp;
    if (num > 0 && list[0] > brc_expire_time &&
        ptr + sizeof(brcbid_t) + sizeof(brcnbrd_t) < endp) {
    if (num > BRC_MAXNUM)
        num = BRC_MAXNUM;

    if (num == 0) return ptr;

    *(brcbid_t*)ptr  = bid;         /* write in bid */
    ptr += sizeof(brcbid_t);
    *(brcnbrd_t*)ptr = num;         /* write in brc_num */
    ptr += sizeof(brcnbrd_t);
    tmp = ptr + num * sizeof(time4_t);
    if (tmp <= endp)
        memcpy(ptr, list, num * sizeof(time4_t)); /* write in brc_list */
    ptr = tmp;
    }
    return ptr;
}

static inline int
brc_enlarge_buf(void)
{
    char *buffer;
    if (brc_alloc >= BRC_MAXSIZE)
    return 0;

#ifdef CRITICAL_MEMORY
#define THE_MALLOC(X) MALLOC(X)
#define THE_FREE(X) FREE(X)
#else
#define THE_MALLOC(X) alloca(X)
#define THE_FREE(X) (void)(X)
    /* alloca get memory from stack and automatically freed when
     * function returns. */
#endif

    buffer = (char*)THE_MALLOC(brc_alloc);

    memcpy(buffer, brc_buf, brc_alloc);
    free(brc_buf);
    brc_alloc += BRC_BLOCKSIZE;
    brc_buf = (char*)malloc(brc_alloc);
    memcpy(brc_buf, buffer, brc_alloc - BRC_BLOCKSIZE);

#ifdef DEBUG
    vmsg("brc enlarged to %d bytes", brc_alloc);
#endif

    THE_FREE(buffer);
    return 1;

#undef THE_MALLOC
#undef THE_FREE
}

static inline void
brc_get_buf(int size){
    if (!size)
    brc_alloc = BRC_BLOCKSIZE;
    else
    brc_alloc = (size + BRC_BLOCKSIZE - 1) / BRC_BLOCKSIZE * BRC_BLOCKSIZE;
    if (brc_alloc > BRC_MAXSIZE)
    brc_alloc = BRC_MAXSIZE;
    brc_buf = (char*)malloc(brc_alloc);
}

static inline void
brc_insert_record(brcbid_t bid, brcnbrd_t num, time4_t* list)
{
    char           *ptr;
    int             new_size, end_size;
    brcnbrd_t       tnum;

    ptr = brc_findrecord_in(brc_buf, brc_buf + brc_size, bid, &tnum);

    while (num > 0 && list[num - 1] < brc_expire_time)
    num--; /* don't write the times before brc_expire_time */

    if (!ptr) {
    brc_size -= (int)tnum;

    /* put on the beginning */
    if (num){
        new_size = sizeof(brcbid_t) + sizeof(brcnbrd_t)
        + num * sizeof(time4_t);
        brc_size += new_size;
        if (brc_size > brc_alloc && !brc_enlarge_buf())
        brc_size = BRC_MAXSIZE;
        if (brc_size > new_size)
        memmove(brc_buf + new_size, brc_buf, brc_size - new_size);
        brc_putrecord(brc_buf, brc_buf + new_size, bid, num, list);
    }
    } else {
    /* ptr points to the old current brc list.
     * tmpp is the end of it (exclusive).       */
    int len = sizeof(brcbid_t) + sizeof(brcnbrd_t) + tnum * sizeof(time4_t);
    char *tmpp = ptr + len;
    end_size = brc_buf + brc_size - tmpp;
    if (num) {
        int sindex = ptr - brc_buf;
        new_size = (sizeof(brcbid_t) + sizeof(brcnbrd_t)
            + num * sizeof(time4_t));
        brc_size += new_size - len;
        if (brc_size > brc_alloc) {
        if (brc_enlarge_buf()) {
            ptr = brc_buf + sindex;
            tmpp = ptr + len;
        } else {
            end_size -= brc_size - BRC_MAXSIZE;
            brc_size = BRC_MAXSIZE;
        }
        }
        if (end_size > 0 && ptr + new_size != tmpp)
        memmove(ptr + new_size, tmpp, end_size);
        brc_putrecord(ptr, brc_buf + brc_alloc, bid, num, list);
    } else { /* deleting record */
        memmove(ptr, tmpp, end_size);
        brc_size -= len;
    }
    }

    brc_changed = 0;
}

void
brc_update(){
    if (brc_changed && cuser.userlevel && brc_num > 0)
    brc_insert_record(currbid, brc_num, brc_list);
}

/* return 1 if successfully read from old .boardrc file.
 * otherwise, return 0. */
inline static void
read_old_brc(int fd)
{
    char        brdname[BRC_STRLEN + 1];
    char       *ptr;
    brcnbrd_t   num;
    brcbid_t    bid;
    brcbid_t    read_brd[512];
    int         nRead = 0, i;

    ptr = brc_buf;
    brc_size = 0;
    while (read(fd, brdname, BRC_STRLEN + 1) == BRC_STRLEN + 1) {
    num = brdname[BRC_STRLEN];
    brdname[BRC_STRLEN] = 0;
    bid = getbnum(brdname);

    for (i = 0; i < nRead; ++i)
        if (read_brd[i] == bid)
        break;
    if (i != nRead){
        lseek(fd, num * sizeof(int), SEEK_CUR);
        continue;
    }
    read_brd[nRead >= 512 ? nRead = 0 : nRead++] = bid;

    *(brcbid_t*)ptr = bid;
    ptr += sizeof(brcbid_t);
    *(brcnbrd_t*)ptr = num;
    ptr += sizeof(brcnbrd_t);
    if (read(fd, ptr, sizeof(int) * num) != sizeof(int) * num)
        break;

    brc_size += sizeof(brcbid_t) + sizeof(brcnbrd_t)
        + sizeof(time4_t) * num;
    ptr += sizeof(time4_t) * num;
    }
}

inline static void
read_brc_buf(void)
{
    if (brc_buf == NULL) {
    char            brcfile[STRLEN];
    int             fd;
    struct stat     brcstat;

    setuserfile(brcfile, fn_brc);
    if ((fd = open(brcfile, O_RDONLY)) != -1) {
        fstat(fd, &brcstat);
        brc_get_buf(brcstat.st_size);
        brc_size = read(fd, brc_buf, brc_alloc);
        close(fd);
    } else {
        setuserfile(brcfile, fn_oldboardrc);
        if ((fd = open(brcfile, O_RDONLY)) != -1) {
        fstat(fd, &brcstat);
        brc_get_buf(brcstat.st_size);
        read_old_brc(fd);
        close(fd);
        } else
        brc_size = 0;
    }
    }
}

void
brc_finalize(){
    char brcfile[STRLEN];
    int fd;
    brc_update();
    setuserfile(brcfile, fn_brc);
    if (brc_buf != NULL &&
    (fd = open(brcfile, O_WRONLY | O_CREAT | O_TRUNC, 0644)) != -1) {
    write(fd, brc_buf, brc_size);
    close(fd);
    }
}

int
brc_initialize(){
    static char done = 0;
    if (done)
    return 1;
    done = 1;
    brc_expire_time = login_start_time - 365 * 86400;
    read_brc_buf();
    return 0;
}

int
brc_read_record(int bid, int *num, time4_t *list){
    char *ptr;
    brcnbrd_t tnum;
    ptr = brc_findrecord_in(brc_buf, brc_buf + brc_size, bid, &tnum);
    *num = tnum;
    if ( ptr ){
    memcpy(list, ptr + sizeof(brcbid_t) + sizeof(brcnbrd_t),
           *num * sizeof(time4_t));
    return *num;
    }
    list[0] = *num = 1;
    return 0;
}

int
brc_initial_board(const char *boardname)
{
    brc_initialize();

    if (strcmp(currboard, boardname) == 0) {
    return brc_num;
    }

    brc_update(); /* write back first */
    currbid = getbnum(boardname);
    if( currbid == 0 )
    currbid = getbnum(DEFAULT_BOARD);
    currboard = bcache[currbid - 1].brdname;
    currbrdattr = bcache[currbid - 1].brdattr;

    return brc_read_record(currbid, &brc_num, brc_list);
}

void
brc_trunc(int bid, time4_t ftime){
    brc_insert_record(bid, 1, &ftime);
    if ( bid == currbid ){
    brc_num = 1;
    brc_list[0] = ftime;
    brc_changed = 0;
    }
}

void
brc_addlist(const char *fname)
{
    int             n, i;
    time4_t         ftime;

    if (!cuser.userlevel)
    return;

    ftime = atoi(&fname[2]);
    if (ftime <= brc_expire_time /* too old, don't do any thing  */
     /* || fname[0] != 'M' || fname[1] != '.' */ ) {
    return;
    }
    if (brc_num <= 0) { /* uninitialized */
    brc_list[0] = ftime;
    brc_num = 1;
    brc_changed = 1;
    return;
    }
    if ((brc_num == 1) && (ftime < brc_list[0])) /* most when after 'v' */
    return;
    for (n = 0; n < brc_num; n++) { /* using linear search */
    if (ftime == brc_list[n]) {
        return;
    } else if (ftime > brc_list[n]) {
        if (brc_num < BRC_MAXNUM)
        brc_num++;
        /* insert ftime into brc_list */
        for (i = brc_num - 1; --i >= n; brc_list[i + 1] = brc_list[i]);
        brc_list[n] = ftime;
        brc_changed = 1;
        return;
    }
    }
}

int
brc_unread_time(time4_t ftime, int bnum, const time4_t *blist)
{
    int             n;

    if (ftime <= brc_expire_time) /* too old */
    return 0;

    if (bnum <= 0)
    return 1;
    for (n = 0; n < bnum; n++) { /* using linear search */
    if (ftime > blist[n])
        return 1;
    else if (ftime == blist[n])
        return 0;
    }
    return 0;
}

int
brc_unread(const char *fname, int bnum, const time4_t *blist)
{
    int             ftime, n;

    ftime = atoi(&fname[2]); /* this will get the time of the file created */

    if (ftime <= brc_expire_time) /* too old */
    return 0;

    if (bnum <= 0)
    return 1;
    for (n = 0; n < bnum; n++) { /* using linear search */
    if (ftime > blist[n])
        return 1;
    else if (ftime == blist[n])
        return 0;
    }
    return 0;
}