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       1                 :             : /* cdb_findnext.c: sequential cdb_find routines
       2                 :             :  *
       3                 :             :  * This file is a part of tinycdb package.
       4                 :             :  * Copyright (C) 2001-2023 Michael Tokarev <mjt+cdb@corpit.ru>
       5                 :             :  *
       6                 :             :  * Permission is hereby granted, free of charge, to any person obtaining a
       7                 :             :  * copy of this software and associated documentation files (the "Software"),
       8                 :             :  * to deal in the Software without restriction, including without limitation
       9                 :             :  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      10                 :             :  * and/or sell copies of the Software, and to permit persons to whom the
      11                 :             :  * Software is furnished to do so, subject to the following conditions:
      12                 :             :  *
      13                 :             :  * The above copyright notice and this permission notice shall be included
      14                 :             :  * in all copies or substantial portions of the Software.
      15                 :             :  *
      16                 :             :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
      17                 :             :  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
      18                 :             :  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
      19                 :             :  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
      20                 :             :  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
      21                 :             :  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
      22                 :             :  * DEALINGS IN THE SOFTWARE.
      23                 :             :  */
      24                 :             : 
      25                 :             : /* see cdb_find.c for comments */
      26                 :             : 
      27                 :             : #include "cdb_int.h"
      28                 :             : 
      29                 :             : int
      30                 :           0 : cdb_findinit(struct cdb_find *cdbfp, struct cdb *cdbp,
      31                 :             :              const void *key, unsigned klen)
      32                 :             : {
      33                 :             :   unsigned n, pos;
      34                 :             : 
      35                 :           0 :   cdbfp->cdb_cdbp = cdbp;
      36                 :           0 :   cdbfp->cdb_key = key;
      37                 :           0 :   cdbfp->cdb_klen = klen;
      38                 :           0 :   cdbfp->cdb_hval = cdb_hash(key, klen);
      39                 :             : 
      40                 :           0 :   cdbfp->cdb_htp = cdbp->cdb_mem + ((cdbfp->cdb_hval << 3) & 2047);
      41                 :           0 :   n = cdb_unpack(cdbfp->cdb_htp + 4);
      42                 :           0 :   cdbfp->cdb_httodo = n << 3;
      43         [ #  # ]:           0 :   if (!n)
      44                 :           0 :     return 0;
      45                 :           0 :   pos = cdb_unpack(cdbfp->cdb_htp);
      46         [ #  # ]:           0 :   if (n > (cdbp->cdb_fsize >> 3)
      47         [ #  # ]:           0 :       || pos < cdbp->cdb_dend
      48         [ #  # ]:           0 :       || pos > cdbp->cdb_fsize
      49         [ #  # ]:           0 :       || cdbfp->cdb_httodo > cdbp->cdb_fsize - pos)
      50                 :           0 :     return errno = EPROTO, -1;
      51                 :             : 
      52                 :           0 :   cdbfp->cdb_htab = cdbp->cdb_mem + pos;
      53                 :           0 :   cdbfp->cdb_htend = cdbfp->cdb_htab + cdbfp->cdb_httodo;
      54                 :           0 :   cdbfp->cdb_htp = cdbfp->cdb_htab + (((cdbfp->cdb_hval >> 8) % n) << 3);
      55                 :             : 
      56                 :           0 :   return 1;
      57                 :             : }
      58                 :             : 
      59                 :             : int
      60                 :           0 : cdb_findnext(struct cdb_find *cdbfp) {
      61                 :           0 :   struct cdb *cdbp = cdbfp->cdb_cdbp;
      62                 :             :   unsigned pos, n;
      63                 :           0 :   unsigned klen = cdbfp->cdb_klen;
      64                 :             : 
      65         [ #  # ]:           0 :   while(cdbfp->cdb_httodo) {
      66                 :           0 :     pos = cdb_unpack(cdbfp->cdb_htp + 4);
      67         [ #  # ]:           0 :     if (!pos)
      68                 :           0 :       return 0;
      69                 :           0 :     n = cdb_unpack(cdbfp->cdb_htp) == cdbfp->cdb_hval;
      70         [ #  # ]:           0 :     if ((cdbfp->cdb_htp += 8) >= cdbfp->cdb_htend)
      71                 :           0 :       cdbfp->cdb_htp = cdbfp->cdb_htab;
      72                 :           0 :     cdbfp->cdb_httodo -= 8;
      73         [ #  # ]:           0 :     if (n) {
      74         [ #  # ]:           0 :       if (pos > cdbp->cdb_fsize - 8)
      75                 :           0 :         return errno = EPROTO, -1;
      76         [ #  # ]:           0 :       if (cdb_unpack(cdbp->cdb_mem + pos) == klen) {
      77         [ #  # ]:           0 :         if (cdbp->cdb_fsize - klen < pos + 8)
      78                 :           0 :           return errno = EPROTO, -1;
      79                 :           0 :         if (memcmp(cdbfp->cdb_key,
      80         [ #  # ]:           0 :             cdbp->cdb_mem + pos + 8, klen) == 0) {
      81                 :           0 :           n = cdb_unpack(cdbp->cdb_mem + pos + 4);
      82                 :           0 :           pos += 8;
      83         [ #  # ]:           0 :           if (cdbp->cdb_fsize < n ||
      84         [ #  # ]:           0 :               cdbp->cdb_fsize - n < pos + klen)
      85                 :           0 :             return errno = EPROTO, -1;
      86                 :           0 :           cdbp->cdb_kpos = pos;
      87                 :           0 :           cdbp->cdb_klen = klen;
      88                 :           0 :           cdbp->cdb_vpos = pos + klen;
      89                 :           0 :           cdbp->cdb_vlen = n;
      90                 :           0 :           return 1;
      91                 :             :         }
      92                 :             :       }
      93                 :             :     }
      94                 :             :   }
      95                 :             : 
      96                 :           0 :   return 0;
      97                 :             : 
      98                 :             : }