/* cdb_find routine * * This file is a part of tinycdb package by Michael Tokarev, mjt@corpit.ru. * Public domain. */#include "common/setup_before.h"#include "cdb_int.h"#include "common/setup_after.h"intcdb_find(struct cdb *cdbp, const void *key, unsigned klen){  const unsigned char *htp;	/* hash table pointer */  const unsigned char *htab;	/* hash table */  const unsigned char *htend;	/* end of hash table */  unsigned httodo;		/* ht bytes left to look */  unsigned pos, n;  unsigned hval;  if (klen >= cdbp->cdb_dend)	/* if key size is too large */    return 0;  hval = cdb_hash(key, klen);  /* find (pos,n) hash table to use */  /* first 2048 bytes (toc) are always available */  /* (hval % 256) * 8 */  htp = cdbp->cdb_mem + ((hval << 3) & 2047); /* index in toc (256x8) */  n = cdb_unpack(htp + 4);	/* table size */  if (!n)			/* empty table */    return 0;			/* not found */  httodo = n << 3;		/* bytes of htab to lookup */  pos = cdb_unpack(htp);	/* htab position */  if (n > (cdbp->cdb_fsize >> 3) /* overflow of httodo ? */      || pos < cdbp->cdb_dend /* is htab inside data section ? */      || pos > cdbp->cdb_fsize /* htab start within file ? */      || httodo > cdbp->cdb_fsize - pos) /* entrie htab within file ? */    return errno = EPROTO, -1;  htab = cdbp->cdb_mem + pos;	/* htab pointer */  htend = htab + httodo;	/* after end of htab */  /* htab starting position: rest of hval modulo htsize, 8bytes per elt */  htp = htab + (((hval >> 8) % n) << 3);  for(;;) {    pos = cdb_unpack(htp + 4);	/* record position */    if (!pos)      return 0;    if (cdb_unpack(htp) == hval) {      if (pos > cdbp->cdb_dend - 8) /* key+val lengths */	return errno = EPROTO, -1;      if (cdb_unpack(cdbp->cdb_mem + pos) == klen) {	if (cdbp->cdb_dend - klen < pos + 8)	  return errno = EPROTO, -1;	if (memcmp(key, cdbp->cdb_mem + pos + 8, klen) == 0) {	  n = cdb_unpack(cdbp->cdb_mem + pos + 4);	  pos += 8;	  if (cdbp->cdb_dend < n || cdbp->cdb_dend - n < pos + klen)	    return errno = EPROTO, -1;	  cdbp->cdb_kpos = pos;	  cdbp->cdb_klen = klen;	  cdbp->cdb_vpos = pos + klen;	  cdbp->cdb_vlen = n;	  return 1;	}      }    }    httodo -= 8;    if (!httodo)      return 0;    if ((htp += 8) >= htend)      htp = htab;  }}