/* old interface for reading cdb file * * This file is a part of tinycdb package by Michael Tokarev, mjt@corpit.ru. * Public domain. */#include "common/setup_before.h"#include <stdio.h>#include "cdb_int.h"#include "common/setup_after.h"#ifndef SEEK_SET# define SEEK_SET 0#endif/* read a chunk from file, ignoring interrupts (EINTR) */intcdb_bread(FILE *fd, void *buf, int len){  int l;  while(len > 0) {    do l = fread(buf, 1, len, fd);    while(l < 0 && errno == EINTR);    if (l <= 0) {      if (!l)        errno = EIO;      return -1;    }    buf = (char*)buf + l;    len -= l;  }  return 0;}/* find a given key in cdb file, seek a file pointer to it's value and   place data length to *dlenp. */intcdb_seek(FILE *fd, const void *key, unsigned klen, unsigned *dlenp){  unsigned htstart;		/* hash table start position */  unsigned htsize;		/* number of elements in a hash table */  unsigned httodo;		/* hash table elements left to look */  unsigned hti;			/* hash table index */  unsigned pos;			/* position in a file */  unsigned hval;			/* key's hash value */  unsigned char rbuf[64];	/* read buffer */  int needseek = 1;		/* if we should seek to a hash slot */  hval = cdb_hash(key, klen);  pos = (hval & 0xff) << 3; /* position in TOC */  /* read the hash table parameters */  if (fseek(fd, pos, SEEK_SET) || cdb_bread(fd, rbuf, 8) < 0)    return -1;  if ((htsize = cdb_unpack(rbuf + 4)) == 0)    return 0;  hti = (hval >> 8) % htsize;	/* start position in hash table */  httodo = htsize;  htstart = cdb_unpack(rbuf);  for(;;) {    if (needseek && fseek(fd, htstart + (hti << 3), SEEK_SET))      return -1;    if (cdb_bread(fd, rbuf, 8) < 0)      return -1;    if ((pos = cdb_unpack(rbuf + 4)) == 0) /* not found */      return 0;    if (cdb_unpack(rbuf) != hval) /* hash value not matched */      needseek = 0;    else { /* hash value matched */      if (fseek(fd, pos, SEEK_SET) || cdb_bread(fd, rbuf, 8) < 0)	return -1;      if (cdb_unpack(rbuf) == klen) { /* key length matches */	/* read the key from file and compare with wanted */	unsigned l = klen, c;	const char *k = (const char*)key;	if (*dlenp)	  *dlenp = cdb_unpack(rbuf + 4); /* save value length */	for(;;) {	  if (!l) /* the whole key read and matches, return */	    return 1;	  c = l > sizeof(rbuf) ? sizeof(rbuf) : l;	  if (cdb_bread(fd, rbuf, c) < 0)	    return -1;	  if (memcmp(rbuf, k, c) != 0) /* no, it differs, stop here */	    break;	  k += c; l -= c;	}      }      needseek = 1; /* we're looked to other place, should seek back */    }    if (!--httodo)      return 0;    if (++hti == htsize) {      hti = 0;      needseek = 1;    }  }}