checkfree.c

UNIX编程高级环境（第二版）的网络套接字部分的程序源码

#include    "db.h"

/* Check the consistency of the free list, and return a count of
   the number of records on the free list.
   This is an undocumented function and should be called when the
   db is not being updated. */

int
_db_checkfree(DB *db)
{
    off_t    offset, nextoffset, saveoffset;
    char    c, *ptr;
    int        count;

        /* Read the free list pointer */
    saveoffset = FREE_OFF;
    offset = _db_readptr(db, saveoffset);

        /* Loop through the free list */
    count = 0;
    while (offset != 0) {
        count++;
        nextoffset = _db_readidx(db, offset);

            /* make certain key is all blank */
        ptr = db->idxbuf;
        while ( (c = *ptr++) != 0)
            if (c != ' ')
                return(-1);    /* error */

            /* make certain data is all blank */
        ptr = _db_readdat(db);
        while ( (c = *ptr++) != 0)
            if (c != ' ')
                return(-1);    /* error */

        saveoffset = offset;
        offset = nextoffset;
    }
    return(count);        /* can be zero */
}