path: root/mbbsd/brc.c

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

/**
 * 關於本檔案的細節，請見 docs/brc.txt。
 * v3: add last modified time for comment system. double max size.
 *     original time_t as 'create'.
 */

// WARNING: Check ../pttbbs.conf, you may have overide these value there
// TODO MAXSIZE may be better smaller to fit into memory page.
#ifndef BRC_MAXNUM
#define BRC_MAXSIZE     49152   /* Effective size of brc rc file, 8192 * 3 * 2 */
#define BRC_MAXNUM      80      /* Upper bound of brc_num, size of brc_list  */
#endif

#define BRC_BLOCKSIZE   1024

// Note: BRC v3 should already support MAX_BOARD > 65535 and BRC_MAXSIZE > 65535,
// but not widely tested yet.
#if MAX_BOARD > 65535 || BRC_MAXSIZE > 65535
#error Max number of boards or BRC_MAXSIZE cannot fit in unsigned short, \
please rewrite brc.c (v2)
#endif

typedef uint32_t brcbid_t;
typedef uint16_t brcnbrd_t;

typedef struct {
    time4_t create;
    time4_t modified;
} brc_rec;

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

static char brc_initialized = 0;
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; /**< brc_list/brc_num changed */
/* 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;

// read records for currbid
static int             brc_currbid;
static int             brc_num;
static brc_rec         brc_list[BRC_MAXNUM];

static char * const fn_brc2= ".brc2";
static char * const fn_brc = ".brc3";

/**
 * find read records of bid in given buffer region
 *
 * @param[in]   begin
 * @param[in]   endp
 * @param   bid
 * @param[out]  num number of records, which could be written for \a bid
 *          = brc_num       if found
 *          = 0 or dangling size    if not found
 *                  
 * @return  address of record. \a begin <= addr < \a endp.
 *      0   if not found
 */
/* 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(brc_rec); /* 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;
}

static brc_rec *
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 (brc_rec*)(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 brc_rec *list)
{
    char * tmp;
    if (num > 0 && list[0].create > 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(brc_rec);
    if (tmp <= endp)
        memcpy(ptr, list, num * sizeof(brc_rec)); /* 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);
    assert(buffer);

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

#ifdef DEBUG
    vmsgf("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);
    assert(brc_buf);
}

static inline void
brc_insert_record(brcbid_t bid, brcnbrd_t num, const brc_rec* 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].create < 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(brc_rec);
        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(brc_rec);
    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(brc_rec));
        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;
}

/**
 * write \a brc_num and \a brc_list back to \a brc_buf.
 */
void
brc_update(){
    if (brc_currbid && brc_changed && cuser.userlevel && brc_num > 0) {
    brc_initialize();
    brc_insert_record(brc_currbid, brc_num, brc_list);
    }
}

void 
read_brc2(void)
{
    char            brcfile[STRLEN];
    int             fd;
    size_t sz2 = 0, sz3 = 0;
    char        *cvt = NULL, *cvthead = NULL;

    // brc v2 is using 16 bit for brcbid_t and brcnbrd_t.
    uint16_t bid2, num2;

    brcbid_t  bid;
    brcnbrd_t num;
    time4_t   create;
    brc_rec   rec;

    setuserfile(brcfile, fn_brc2);

    if ((fd = open(brcfile, O_RDONLY)) == -1)
    return;

    sz2 = dashs(brcfile);
    sz3 = sz2 * 2; // max double size

    cvthead = cvt = malloc (sz3);
    memset(cvthead, 0, sz3);
    // now calculate real sz3

    while (read(fd, &bid2, sizeof(bid2)) > 0)
    {
    if (read(fd, &num2, sizeof(num2)) < 1)
        break;

    bid = bid2;
    num = num2;

    // some brc v2 contains bad structure.
    // check pointer here.
    if (cvt + sizeof(brcbid_t) + sizeof(brcnbrd_t) - cvthead >= sz3)
        break;

    *(brcbid_t*) cvt = bid; cvt += sizeof(brcbid_t);
    *(brcnbrd_t*)cvt = num; cvt += sizeof(brcnbrd_t);

    // some brc v2 contains bad structure.
    // check pointer here.
    for (; num > 0 && (cvt + sizeof(brc_rec) - cvthead) <= sz3 ; num--)
    {
        if (read(fd, &create, sizeof(create)) < 1)
        break;

        rec.create = create;
        rec.modified = create;

        *(brc_rec*)cvt = rec; cvt += sizeof(brc_rec);
    }
    }
    close(fd);

    // now cvthead is ready for v3.
    sz3 = cvt - cvthead;
    brc_get_buf(sz3);
    // new size maybe smaller, check brc_alloc instead
    if (sz3 > brc_alloc)
    sz3 = brc_alloc;
    brc_size = sz3;
    memcpy(brc_buf, cvthead, sz3);

    free(cvthead);
}

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

    if (brc_buf != NULL)
    return;

    brc_size = 0;
    setuserfile(brcfile, fn_brc);

    if ((fd = open(brcfile, O_RDONLY)) == -1)
    {
    read_brc2();
    return;
    }

    fstat(fd, &brcstat);
    brc_get_buf(brcstat.st_size);
    brc_size = read(fd, brc_buf, brc_alloc);
    close(fd);
}

/* release allocated memory
 *
 * Do not destory brc_currbid, brc_num, brc_list.
 */
void
brc_release()
{
    if (brc_buf) {
    free(brc_buf);
    brc_buf = NULL;
    }
    brc_changed = 0;
    brc_size = brc_alloc = 0;
}

void
brc_finalize(){
    char brcfile[STRLEN];
    char tmpfile[STRLEN];

    if(!brc_initialized)
    return;

    brc_update();
    setuserfile(brcfile, fn_brc);
    snprintf(tmpfile, sizeof(tmpfile), "%s.tmp.%x", brcfile, getpid());
    if (brc_buf != NULL) {
    int fd = open(tmpfile, O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (fd != -1) {
        int ok=0;
        if(write(fd, brc_buf, brc_size)==brc_size)
        ok=1;
        close(fd);
        if(ok)
        Rename(tmpfile, brcfile);
        else
        unlink(tmpfile);
    }
    }

    brc_release();
    brc_initialized = 0;
}

int
brc_initialize(){
    if (brc_initialized)
    return 1;
    brc_initialized = 1;
    brc_expire_time = login_start_time - 365 * DAY_SECONDS;
    read_brc_buf();
    return 0;
}

/** 
 * get the read records for bid
 *
 * @param bid
 * @param[out] num  number of record for \a bid. 1 <= \a num <= \a BRC_MAXNUM
 *          \a num = 1 if no records.
 * @param[out] list the list of records, length \a num
 *
 * @return number of read record, 0 if no records
 */
static int
brc_read_record(int bid, int *num, brc_rec *list){
    char *ptr;
    brcnbrd_t tnum;
    ptr = brc_findrecord_in(brc_buf, brc_buf + brc_size, bid, &tnum);
    *num = tnum;
    if ( ptr ){
    assert(0 <= *num && *num <= BRC_MAXNUM);
    memcpy(list, ptr + sizeof(brcbid_t) + sizeof(brcnbrd_t),
           *num * sizeof(brc_rec));
    return *num;
    }
    list[0].create = *num = 1;
    return 0;
}

/**
 * @return number of records in \a boardname
 */
int
brc_initial_board(const char *boardname)
{
    brc_initialize();

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

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

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

static void
brc_trunc(int bid, time4_t ftime){
    brc_rec r;

    r.create = ftime;
    r.modified = ftime;
    brc_insert_record(bid, 1, &r);
    if ( bid == brc_currbid ){
    brc_num = 1;
    brc_list[0] = r;
    brc_changed = 0;
    }
}

void
brc_toggle_all_read(int bid, int is_all_read)
{
    brc_initialize();
    if (is_all_read)
        brc_trunc(bid, now);
    else
        brc_trunc(bid, 1);
}

void
brc_addlist(const char *fname, time4_t modified)
{
    int             n, i;
    brc_rec         frec;

    assert(currbid == brc_currbid);
    if (!cuser.userlevel)
    return;
    brc_initialize();

    frec.create = atoi(&fname[2]);
    frec.modified = modified;

    if (frec.create <= brc_expire_time /* too old, don't do any thing  */
     /* || fname[0] != 'M' || fname[1] != '.' */ ) {
    return;
    }
    if (brc_num <= 0) { /* uninitialized */
    brc_list[0] = frec;
    brc_num = 1;
    brc_changed = 1;
    return;
    }
    if ((brc_num == 1) && (frec.create < brc_list[0].create)) /* most when after 'v' */
    return;
    for (n = 0; n < brc_num; n++) { /* using linear search */
    if (frec.create == brc_list[n].create) {
        // check if we got bad value.
        if (modified == (time4_t)-1) 
        return;

        if (brc_list[n].modified == (time4_t)-1)
        brc_list[n].modified = 0;

        // special case here:
        // in order to support special system like 'always bottom',
        // they may share same create time and different time.
        if (brc_list[n].modified < modified)
        {
        brc_list[n].modified = modified;
        brc_changed = 1;
        }
        return;
    } else if (frec.create > brc_list[n].create) {
        if (brc_num < BRC_MAXNUM)
        brc_num++;
        /* insert frec into brc_list */
        for (i = brc_num - 1; --i >= n; brc_list[i + 1] = brc_list[i]);
        brc_list[n] = frec;
        brc_changed = 1;
        return;
    }
    }
}

// return:
//   0 - read
//   1 - unread (by create)
//   2 - unread (by modified)
int
brc_unread_time(int bid, time4_t ftime, time4_t modified)
{
    int             i;
    int bnum;
    const brc_rec *blist;

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

    if (brc_currbid && bid == brc_currbid) {
    blist = brc_list;
    bnum = brc_num;
    } else {
    blist = brc_find_record(bid, &bnum);
    }

    if (bnum <= 0)
    return 1;

    for (i = 0; i < bnum; i++) { /* using linear search */
    if (ftime > blist[i].create)
        return 1;
    else if (ftime == blist[i].create)
    {
        time4_t brcm = blist[i].modified;
        if (modified == 0 || brcm == 0)
        return 0;

        // bad  case... seems like that someone is making -1.
        if (modified == (time4_t)-1 || brcm == (time4_t)-1)
        return 0;

        // one case is, some special file headers (ex, 
        // always bottom) may cause issue. They share create
        // time (filename) and apply different modify time.
        // so let's back to 'greater'.
        return modified > brcm ? 2 : 0;
    }
    }
    return 0;
}

int
brc_unread(int bid, const char *fname, time4_t modified)
{
    int             ftime;

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

    return brc_unread_time(bid, ftime, modified);
}