/*
* sdbm - ndbm work-alike hashed database library
* based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
* author: oz@nexus.yorku.ca
* status: public domain.
*
* core routines
*/
#include "INTERN.h"
#include "config.h"
#ifdef WIN32
#include "io.h"
#endif
#include "sdbm.h"
#include "tune.h"
#include "pair.h"
#ifdef I_FCNTL
# include <fcntl.h>
#endif
#ifdef I_SYS_FILE
# include <sys/file.h>
#endif
#ifdef I_STRING
# ifndef __ultrix__
# include <string.h>
# endif
#else
# include <strings.h>
#endif
/*
* externals
*/
#include <errno.h> /* See notes in perl.h about avoiding
extern int errno; */
#ifdef __cplusplus
extern "C" {
#endif
extern Malloc_t malloc proto((MEM_SIZE));
extern Free_t free proto((Malloc_t));
#ifdef __cplusplus
}
#endif
/*
* forward
*/
static int getdbit proto((DBM *, long));
static int setdbit proto((DBM *, long));
static int getpage proto((DBM *, long));
static datum getnext proto((DBM *));
static int makroom proto((DBM *, long, int));
/*
* useful macros
*/
#define bad(x) ((x).dptr == NULL || (x).dsize < 0)
#define exhash(item) sdbm_hash((item).dptr, (item).dsize)
#define ioerr(db) ((db)->flags |= DBM_IOERR)
#define OFF_PAG(off) (long) (off) * PBLKSIZ
#define OFF_DIR(off) (long) (off) * DBLKSIZ
static const long masks[] = {
000000000000, 000000000001, 000000000003, 000000000007,
000000000017, 000000000037, 000000000077, 000000000177,
000000000377, 000000000777, 000000001777, 000000003777,
000000007777, 000000017777, 000000037777, 000000077777,
000000177777, 000000377777, 000000777777, 000001777777,
000003777777, 000007777777, 000017777777, 000037777777,
000077777777, 000177777777, 000377777777, 000777777777,
001777777777, 003777777777, 007777777777, 017777777777
};
DBM *
sdbm_open(char *file, int flags, int mode)
{
DBM *db;
char *dirname;
char *pagname;
size_t filelen;
const size_t dirfext_size = sizeof(DIRFEXT "");
const size_t pagfext_size = sizeof(PAGFEXT "");
if (file == NULL || !*file)
return errno = EINVAL, (DBM *) NULL;
/*
* need space for two separate filenames
*/
filelen = strlen(file);
if ((dirname = (char *) malloc(filelen + dirfext_size
+ filelen + pagfext_size)) == NULL)
return errno = ENOMEM, (DBM *) NULL;
/*
* build the file names
*/
memcpy(dirname, file, filelen);
memcpy(dirname + filelen, DIRFEXT, dirfext_size);
pagname = dirname + filelen + dirfext_size;
memcpy(pagname, file, filelen);
memcpy(pagname + filelen, PAGFEXT, pagfext_size);
db = sdbm_prep(dirname, pagname, flags, mode);
free((char *) dirname);
return db;
}
DBM *
sdbm_prep(char *dirname, char *pagname, int flags, int mode)
{
DBM *db;
struct stat dstat;
if ((db = (DBM *) malloc(sizeof(DBM))) == NULL)
return errno = ENOMEM, (DBM *) NULL;
db->flags = 0;
db->hmask = 0;
db->blkptr = 0;
db->keyptr = 0;
/*
* adjust user flags so that WRONLY becomes RDWR,
* as required by this package. Also set our internal
* flag for RDONLY if needed.
*/
if (flags & O_WRONLY)
flags = (flags & ~O_WRONLY) | O_RDWR;
else if ((flags & 03) == O_RDONLY)
db->flags = DBM_RDONLY;
/*
* open the files in sequence, and stat the dirfile.
* If we fail anywhere, undo everything, return NULL.
*/
#if defined(OS2) || defined(MSDOS) || defined(WIN32) || defined(__CYGWIN__)
flags |= O_BINARY;
# endif
if ((db->pagf = open(pagname, flags, mode)) > -1) {
if ((db->dirf = open(dirname, flags, mode)) > -1) {
/*
* need the dirfile size to establish max bit number.
*/
if (fstat(db->dirf, &dstat) == 0) {
/*
* zero size: either a fresh database, or one with a single,
* unsplit data page: dirpage is all zeros.
*/
db->dirbno = (!dstat.st_size) ? 0 : -1;
db->pagbno = -1;
db->maxbno = dstat.st_size * BYTESIZ;
(void) memset(db->pagbuf, 0, PBLKSIZ);
(void) memset(db->dirbuf, 0, DBLKSIZ);
/*
* success
*/
return db;
}
(void) close(db->dirf);
}
(void) close(db->pagf);
}
free((char *) db);
return (DBM *) NULL;
}
void
sdbm_close(DBM *db)
{
if (db == NULL)
errno = EINVAL;
else {
(void) close(db->dirf);
(void) close(db->pagf);
free((char *) db);
}
}
datum
sdbm_fetch(DBM *db, datum key)
{
if (db == NULL || bad(key))
return errno = EINVAL, nullitem;
if (getpage(db, exhash(key)))
return getpair(db->pagbuf, key);
return ioerr(db), nullitem;
}
int
sdbm_exists(DBM *db, datum key)
{
if (db == NULL || bad(key))
return errno = EINVAL, -1;
if (getpage(db, exhash(key)))
return exipair(db->pagbuf, key);
return ioerr(db), -1;
}
int
sdbm_delete(DBM *db, datum key)
{
if (db == NULL || bad(key))
return errno = EINVAL, -1;
if (sdbm_rdonly(db))
return errno = EPERM, -1;
if (getpage(db, exhash(key))) {
if (!delpair(db->pagbuf, key))
return -1;
/*
* update the page file
*/
if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
|| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
return ioerr(db), -1;
return 0;
}
return ioerr(db), -1;
}
int
sdbm_store(DBM *db, datum key, datum val, int flags)
{
int need;
long hash;
if (db == NULL || bad(key))
return errno = EINVAL, -1;
if (sdbm_rdonly(db))
return errno = EPERM, -1;
need = key.dsize + val.dsize;
/*
* is the pair too big (or too small) for this database ??
*/
if (need < 0 || need > PAIRMAX)
return errno = EINVAL, -1;
if (getpage(db, (hash = exhash(key)))) {
/*
* if we need to replace, delete the key/data pair
* first. If it is not there, ignore.
*/
if (flags == DBM_REPLACE)
(void) delpair(db->pagbuf, key);
#ifdef SEEDUPS
else if (duppair(db->pagbuf, key))
return 1;
#endif
/*
* if we do not have enough room, we have to split.
*/
if (!fitpair(db->pagbuf, need))
if (!makroom(db, hash, need))
return ioerr(db), -1;
/*
* we have enough room or split is successful. insert the key,
* and update the page file.
*/
(void) putpair(db->pagbuf, key, val);
if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
|| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
return ioerr(db), -1;
/*
* success
*/
return 0;
}
return ioerr(db), -1;
}
/*
* makroom - make room by splitting the overfull page
* this routine will attempt to make room for SPLTMAX times before
* giving up.
*/
static int
makroom(DBM *db, long int hash, int need)
{
long newp;
char twin[PBLKSIZ];
#if defined(DOSISH) || defined(WIN32)
char zer[PBLKSIZ];
long oldtail;
#endif
char *pag = db->pagbuf;
char *New = twin;
int smax = SPLTMAX;
do {
/*
* split the current page
*/
(void) splpage(pag, New, db->hmask + 1);
/*
* address of the new page
*/
newp = (hash & db->hmask) | (db->hmask + 1);
/*
* write delay, read avoidance/cache shuffle:
* select the page for incoming pair: if key is to go to the new page,
* write out the previous one, and copy the new one over, thus making
* it the current page. If not, simply write the new page, and we are
* still looking at the page of interest. current page is not updated
* here, as sdbm_store will do so, after it inserts the incoming pair.
*/
#if defined(DOSISH) || defined(WIN32)
/*
* Fill hole with 0 if made it.
* (hole is NOT read as 0)
*/
oldtail = lseek(db->pagf, 0L, SEEK_END);
memset(zer, 0, PBLKSIZ);
while (OFF_PAG(newp) > oldtail) {
if (lseek(db->pagf, 0L, SEEK_END) < 0 ||
write(db->pagf, zer, PBLKSIZ) < 0) {
return 0;
}
oldtail += PBLKSIZ;
}
#endif
if (hash & (db->hmask + 1)) {
if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
|| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
return 0;
db->pagbno = newp;
(void) memcpy(pag, New, PBLKSIZ);
}
else if (lseek(db->pagf, OFF_PAG(newp), SEEK_SET) < 0
|| write(db->pagf, New, PBLKSIZ) < 0)
return 0;
if (!setdbit(db, db->curbit))
return 0;
/*
* see if we have enough room now
*/
if (fitpair(pag, need))
return 1;
/*
* try again... update curbit and hmask as getpage would have
* done. because of our update of the current page, we do not
* need to read in anything. BUT we have to write the current
* [deferred] page out, as the window of failure is too great.
*/
db->curbit = 2 * db->curbit +
((hash & (db->hmask + 1)) ? 2 : 1);
db->hmask |= db->hmask + 1;
if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
|| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
return 0;
} while (--smax);
/*
* if we are here, this is real bad news. After SPLTMAX splits,
* we still cannot fit the key. say goodnight.
*/
#ifdef BADMESS
(void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44);
#endif
return 0;
}
/*
* the following two routines will break if
* deletions aren't taken into account. (ndbm bug)
*/
datum
sdbm_firstkey(DBM *db)
{
if (db == NULL)
return errno = EINVAL, nullitem;
/*
* start at page 0
*/
if (lseek(db->pagf, OFF_PAG(0), SEEK_SET) < 0
|| read(db->pagf, db->pagbuf, PBLKSIZ) < 0)
return ioerr(db), nullitem;
db->pagbno = 0;
db->blkptr = 0;
db->keyptr = 0;
return getnext(db);
}
datum
sdbm_nextkey(DBM *db)
{
if (db == NULL)
return errno = EINVAL, nullitem;
return getnext(db);
}
/*
* all important binary trie traversal
*/
static int
getpage(DBM *db, long int hash)
{
int hbit;
long dbit;
long pagb;
dbit = 0;
hbit = 0;
while (dbit < db->maxbno && getdbit(db, dbit))
dbit = 2 * dbit + ((hash & (1 << hbit++)) ? 2 : 1);
debug(("dbit: %d...", dbit));
db->curbit = dbit;
db->hmask = masks[hbit];
pagb = hash & db->hmask;
/*
* see if the block we need is already in memory.
* note: this lookaside cache has about 10% hit rate.
*/
if (pagb != db->pagbno) {
/*
* note: here, we assume a "hole" is read as 0s.
* if not, must zero pagbuf first.
*/
if (lseek(db->pagf, OFF_PAG(pagb), SEEK_SET) < 0
|| read(db->pagf, db->pagbuf, PBLKSIZ) < 0)
return 0;
if (!chkpage(db->pagbuf))
return 0;
db->pagbno = pagb;
debug(("pag read: %d\n", pagb));
}
return 1;
}
static int
getdbit(DBM *db, long int dbit)
{
long c;
long dirb;
c = dbit / BYTESIZ;
dirb = c / DBLKSIZ;
if (dirb != db->dirbno) {
int got;
if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
|| (got=read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
return 0;
if (got==0)
memset(db->dirbuf,0,DBLKSIZ);
db->dirbno = dirb;
debug(("dir read: %d\n", dirb));
}
return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ);
}
static int
setdbit(DBM *db, long int dbit)
{
long c;
long dirb;
c = dbit / BYTESIZ;
dirb = c / DBLKSIZ;
if (dirb != db->dirbno) {
int got;
if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
|| (got=read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
return 0;
if (got==0)
memset(db->dirbuf,0,DBLKSIZ);
db->dirbno = dirb;
debug(("dir read: %d\n", dirb));
}
db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ);
#if 0
if (dbit >= db->maxbno)
db->maxbno += DBLKSIZ * BYTESIZ;
#else
if (OFF_DIR((dirb+1))*BYTESIZ > db->maxbno)
db->maxbno=OFF_DIR((dirb+1))*BYTESIZ;
#endif
if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
|| write(db->dirf, db->dirbuf, DBLKSIZ) < 0)
return 0;
return 1;
}
/*
* getnext - get the next key in the page, and if done with
* the page, try the next page in sequence
*/
static datum
getnext(DBM *db)
{
datum key;
for (;;) {
db->keyptr++;
key = getnkey(db->pagbuf, db->keyptr);
if (key.dptr != NULL)
return key;
/*
* we either run out, or there is nothing on this page..
* try the next one... If we lost our position on the
* file, we will have to seek.
*/
db->keyptr = 0;
if (db->pagbno != db->blkptr++)
if (lseek(db->pagf, OFF_PAG(db->blkptr), SEEK_SET) < 0)
break;
db->pagbno = db->blkptr;
if (read(db->pagf, db->pagbuf, PBLKSIZ) <= 0)
break;
if (!chkpage(db->pagbuf))
break;
}
return ioerr(db), nullitem;
}