/* Public domain. */

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/mman.h>

#include "readwrite.h"

#include "error.h"

#include "seek.h"

#include "byte.h"

#include "cdb.h"

void cdb_free(struct cdb *c)

{

  if (c->map) {

    munmap(c->map,c->size);

    c->map = 0;

  }

}

void cdb_findstart(struct cdb *c)

{

  c->loop = 0;

}

void cdb_init(struct cdb *c,int fd)

{

  struct stat st;

  char *x;

  cdb_free(c);

  cdb_findstart(c);

  c->fd = fd;

  if (fstat(fd,&st) == 0)

    if (st.st_size <= 0xffffffff) {

      x = mmap(0,st.st_size,PROT_READ,MAP_SHARED,fd,0);

      if (x + 1) {

	c->size = st.st_size;

	c->map = x;

      }

    }

}

int cdb_read(struct cdb *c,char *buf,unsigned int len,uint32 pos)

{

  if (c->map) {

    if ((pos > c->size) || (c->size - pos < len)) goto FORMAT;

    byte_copy(buf,len,c->map + pos);

  }

  else {

    if (seek_set(c->fd,pos) == -1) return -1;

    while (len > 0) {

      int r;

      do

        r = read(c->fd,buf,len);

      while ((r == -1) && (errno == error_intr));

      if (r == -1) return -1;

      if (r == 0) goto FORMAT;

      buf += r;

      len -= r;

    }

  }

  return 0;

  FORMAT:

  errno = error_proto;

  return -1;

}

static int match(struct cdb *c,char *key,unsigned int len,uint32 pos)

{

  char buf[32];

  int n;

  while (len > 0) {

    n = sizeof buf;

    if (n > len) n = len;

    if (cdb_read(c,buf,n,pos) == -1) return -1;

    if (byte_diff(buf,n,key)) return 0;

    pos += n;

    key += n;

    len -= n;

  }

  return 1;

}

int cdb_findnext(struct cdb *c,char *key,unsigned int len)

{

  char buf[8];

  uint32 pos;

  uint32 u;

  if (!c->loop) {

    u = cdb_hash(key,len);

    if (cdb_read(c,buf,8,(u << 3) & 2047) == -1) return -1;

    uint32_unpack(buf + 4,&c->hslots);

    if (!c->hslots) return 0;

    uint32_unpack(buf,&c->hpos);

    c->khash = u;

    u >>= 8;

    u %= c->hslots;

    u <<= 3;

    c->kpos = c->hpos + u;

  }

  while (c->loop < c->hslots) {

    if (cdb_read(c,buf,8,c->kpos) == -1) return -1;

    uint32_unpack(buf + 4,&pos);

    if (!pos) return 0;

    c->loop += 1;

    c->kpos += 8;

    if (c->kpos == c->hpos + (c->hslots << 3)) c->kpos = c->hpos;

    uint32_unpack(buf,&u);

    if (u == c->khash) {

      if (cdb_read(c,buf,8,pos) == -1) return -1;

      uint32_unpack(buf,&u);

      if (u == len)

	switch(match(c,key,len,pos + 8)) {

	  case -1:

	    return -1;

	  case 1:

	    uint32_unpack(buf + 4,&c->dlen);

	    c->dpos = pos + 8 + len;

	    return 1;

	}

    }

  }

  return 0;

}

int cdb_find(struct cdb *c,char *key,unsigned int len)

{

  cdb_findstart(c);

  return cdb_findnext(c,key,len);

}