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#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>
#include "error.h"
#include "seek.h"
#include "byte.h"
#include "cdbread.h"
/**
* @file cdbread.c
* @author djb
* @ref ucspi-tcp, fastforward
* @brief read entries from a cdb
*/
uint32 cdb_unpack(unsigned char *buf)
{
uint32 num;
num = buf[3]; num <<= 8;
num += buf[2]; num <<= 8;
num += buf[1]; num <<= 8;
num += buf[0];
return num;
}
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 == EINTR));
if (r == -1) return -1;
if (r == 0) goto FORMAT;
buf += r;
len -= r;
}
}
return 0;
FORMAT:
errno = EPROTO;
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);
}
uint32 cdb_hashadd(uint32 h,unsigned char c)
{
h += (h << 5);
return h ^ c;
}
uint32 cdb_hash(char *buf,unsigned int len)
{
uint32 h;
h = CDB_HASHSTART;
while (len) {
h = cdb_hashadd(h,*buf++);
--len;
}
return h;
}
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