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tag: djb/1.01
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154 lines (129 sloc) 3.707 kb
/* Public domain. */
#include "readwrite.h"
#include "seek.h"
#include "error.h"
#include "alloc.h"
#include "cdb.h"
#include "cdb_make.h"
int cdb_make_start(struct cdb_make *c,int fd)
{
c->head = 0;
c->split = 0;
c->hash = 0;
c->numentries = 0;
c->fd = fd;
c->pos = sizeof c->final;
buffer_init(&c->b,write,fd,c->bspace,sizeof c->bspace);
return seek_set(fd,c->pos);
}
static int posplus(struct cdb_make *c,uint32 len)
{
uint32 newpos = c->pos + len;
if (newpos < len) { errno = error_nomem; return -1; }
c->pos = newpos;
return 0;
}
int cdb_make_addend(struct cdb_make *c,unsigned int keylen,unsigned int datalen,uint32 h)
{
struct cdb_hplist *head;
head = c->head;
if (!head || (head->num >= CDB_HPLIST)) {
head = (struct cdb_hplist *) alloc(sizeof(struct cdb_hplist));
if (!head) return -1;
head->num = 0;
head->next = c->head;
c->head = head;
}
head->hp[head->num].h = h;
head->hp[head->num].p = c->pos;
++head->num;
++c->numentries;
if (posplus(c,8) == -1) return -1;
if (posplus(c,keylen) == -1) return -1;
if (posplus(c,datalen) == -1) return -1;
return 0;
}
int cdb_make_addbegin(struct cdb_make *c,unsigned int keylen,unsigned int datalen)
{
char buf[8];
if (keylen > 0xffffffff) { errno = error_nomem; return -1; }
if (datalen > 0xffffffff) { errno = error_nomem; return -1; }
uint32_pack(buf,keylen);
uint32_pack(buf + 4,datalen);
if (buffer_putalign(&c->b,buf,8) == -1) return -1;
return 0;
}
int cdb_make_add(struct cdb_make *c,char *key,unsigned int keylen,char *data,unsigned int datalen)
{
if (cdb_make_addbegin(c,keylen,datalen) == -1) return -1;
if (buffer_putalign(&c->b,key,keylen) == -1) return -1;
if (buffer_putalign(&c->b,data,datalen) == -1) return -1;
return cdb_make_addend(c,keylen,datalen,cdb_hash(key,keylen));
}
int cdb_make_finish(struct cdb_make *c)
{
char buf[8];
int i;
uint32 len;
uint32 u;
uint32 memsize;
uint32 count;
uint32 where;
struct cdb_hplist *x;
struct cdb_hp *hp;
for (i = 0;i < 256;++i)
c->count[i] = 0;
for (x = c->head;x;x = x->next) {
i = x->num;
while (i--)
++c->count[255 & x->hp[i].h];
}
memsize = 1;
for (i = 0;i < 256;++i) {
u = c->count[i] * 2;
if (u > memsize)
memsize = u;
}
memsize += c->numentries; /* no overflow possible up to now */
u = (uint32) 0 - (uint32) 1;
u /= sizeof(struct cdb_hp);
if (memsize > u) { errno = error_nomem; return -1; }
c->split = (struct cdb_hp *) alloc(memsize * sizeof(struct cdb_hp));
if (!c->split) return -1;
c->hash = c->split + c->numentries;
u = 0;
for (i = 0;i < 256;++i) {
u += c->count[i]; /* bounded by numentries, so no overflow */
c->start[i] = u;
}
for (x = c->head;x;x = x->next) {
i = x->num;
while (i--)
c->split[--c->start[255 & x->hp[i].h]] = x->hp[i];
}
for (i = 0;i < 256;++i) {
count = c->count[i];
len = count + count; /* no overflow possible */
uint32_pack(c->final + 8 * i,c->pos);
uint32_pack(c->final + 8 * i + 4,len);
for (u = 0;u < len;++u)
c->hash[u].h = c->hash[u].p = 0;
hp = c->split + c->start[i];
for (u = 0;u < count;++u) {
where = (hp->h >> 8) % len;
while (c->hash[where].p)
if (++where == len)
where = 0;
c->hash[where] = *hp++;
}
for (u = 0;u < len;++u) {
uint32_pack(buf,c->hash[u].h);
uint32_pack(buf + 4,c->hash[u].p);
if (buffer_putalign(&c->b,buf,8) == -1) return -1;
if (posplus(c,8) == -1) return -1;
}
}
if (buffer_flush(&c->b) == -1) return -1;
if (seek_begin(c->fd) == -1) return -1;
return buffer_putflush(&c->b,c->final,sizeof c->final);
}
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