date and time created 83/12/02 17:14:58 by ralph

[unix-history] / usr / src / old / libndbm / ndbm.c

#ifndef lint
static char sccsid[] = "@(#)ndbm.c      4.1 (Berkeley) %G%";
#endif

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <errno.h>
#include <ndbm.h>

#define NULL    (char *)0
#define BYTESIZ 8

static  datum firsthash();
static  dbm_access();
static  getbit();
static  setbit();
static  datum makdatum();
static  cmpdatum();
static  long hashinc();
static  long dcalchash();
static  delitem();
static  additem();
static  chkblk();
extern  int errno;

DBM *
ndbmopen(file, flags, mode)
       char *file;
       int flags, mode;
{
       struct stat statb;
       register DBM *db;

       if ((db = (DBM *)malloc(sizeof *db)) == 0) {
               errno = ENOMEM;
               return ((DBM *)0);
       }
       if ((flags & 03) == O_WRONLY)
               flags = (flags & ~03) | O_RDWR;
       db->db_flags = 0;
       strcpy(db->db_pagbuf, file);
       strcat(db->db_pagbuf, ".pag");
       db->db_pagf = open(db->db_pagbuf, flags, mode);
       if (db->db_pagf < 0)
               goto bad;
       strcpy(db->db_pagbuf, file);
       strcat(db->db_pagbuf, ".dir");
       db->db_dirf = open(db->db_pagbuf, flags, mode);
       if (db->db_dirf < 0)
               goto bad1;
       fstat(db->db_dirf, &statb);
       db->db_maxbno = statb.st_size*BYTESIZ-1;
       db->db_pagbno = db->db_dirbno = -1;
       return (db);
bad1:
       (void) close(db->db_pagf);
bad:
       free((char *)db);
       return ((DBM *)0);
}

void
ndbmclose(db)
       DBM *db;
{

       (void) close(db->db_dirf);
       (void) close(db->db_pagf);
       free((char *)db);
}

long
dbmforder(db, key)
       register DBM *db;
       datum key;
{
       long hash;

       hash = dcalchash(key);
       for (db->db_hmask=0;; db->db_hmask=(db->db_hmask<<1)+1) {
               db->db_blkno = hash & db->db_hmask;
               db->db_bitno = db->db_blkno + db->db_hmask;
               if (getbit(db) == 0)
                       break;
       }
       return (db->db_blkno);
}

datum
dbmfetch(db, key)
       register DBM *db;
       datum key;
{
       register i;
       datum item;

       dbm_access(db, dcalchash(key));
       for (i=0;; i+=2) {
               item = makdatum(db->db_pagbuf, i);
               if (item.dptr == NULL)
                       return (item);
               if (cmpdatum(key, item) == 0) {
                       item = makdatum(db->db_pagbuf, i+1);
                       if (item.dptr == NULL)
                               printf("items not in pairs\n");
                       return (item);
               }
       }
}

dbmdelete(db, key)
       register DBM *db;
       datum key;
{
       register i;
       datum item;

       if (dbrdonly(db)) {
               errno = EPERM;
               return (-1);
       }
       dbm_access(db, dcalchash(key));
       for (i=0;; i+=2) {
               item = makdatum(db->db_pagbuf, i);
               if (item.dptr == NULL)
                       return (-1);
               if (cmpdatum(key, item) == 0) {
                       delitem(db->db_pagbuf, i);
                       delitem(db->db_pagbuf, i);
                       break;
               }
       }
       (void) lseek(db->db_pagf, db->db_blkno*PBLKSIZ, L_SET);
       (void) write(db->db_pagf, db->db_pagbuf, PBLKSIZ);
       db->db_pagbno = db->db_blkno;
       return (0);
}

dbmstore(db, key, dat)
       register DBM *db;
       datum key, dat;
{
       register i;
       datum item;
       char ovfbuf[PBLKSIZ];

       if (dbrdonly(db)) {
               errno = EPERM;
               return (-1);
       }
loop:
       dbm_access(db, dcalchash(key));
       for (i=0;; i+=2) {
               item = makdatum(db->db_pagbuf, i);
               if (item.dptr == NULL)
                       break;
               if (cmpdatum(key, item) == 0) {
                       return(0);
/*
                       delitem(db->db_pagbuf, i);
                       delitem(db->db_pagbuf, i);
                       break;
*/
               }
       }
       i = additem(db->db_pagbuf, key);
       if (i < 0)
               goto split;
       if (additem(db->db_pagbuf, dat) < 0) {
               delitem(db->db_pagbuf, i);
               goto split;
       }
       (void) lseek(db->db_pagf, db->db_blkno*PBLKSIZ, L_SET);
       (void) write(db->db_pagf, db->db_pagbuf, PBLKSIZ);
       db->db_pagbno = db->db_blkno;
       return (0);

split:
       if (key.dsize+dat.dsize+2*sizeof(short) >= PBLKSIZ) {
               errno = ENOSPC;
               return (-1);
       }
       bzero(ovfbuf, PBLKSIZ);
       for (i=0;;) {
               item = makdatum(db->db_pagbuf, i);
               if (item.dptr == NULL)
                       break;
               if (dcalchash(item) & (db->db_hmask+1)) {
                       additem(ovfbuf, item);
                       delitem(db->db_pagbuf, i);
                       item = makdatum(db->db_pagbuf, i);
                       if (item.dptr == NULL) {
                               printf("ndbm: split not paired\n");
                               break;
                       }
                       additem(ovfbuf, item);
                       delitem(db->db_pagbuf, i);
                       continue;
               }
               i += 2;
       }
       (void) lseek(db->db_pagf, db->db_blkno*PBLKSIZ, L_SET);
       (void) write(db->db_pagf, db->db_pagbuf, PBLKSIZ);
       db->db_pagbno = db->db_blkno;
       (void) lseek(db->db_pagf, (db->db_blkno+db->db_hmask+1)*PBLKSIZ, L_SET);
       (void) write(db->db_pagf, ovfbuf, PBLKSIZ);
       setbit(db);
       goto loop;
}

datum
dbmfirstkey(db)
       DBM *db;
{

       return (firsthash(db, 0L));
}

datum
dbmnextkey(db, key)
       register DBM *db;
       datum key;
{
       register i;
       datum item, bitem;
       long hash;
       int f;

       hash = dcalchash(key);
       dbm_access(db, hash);
       f = 1;
       for (i=0;; i+=2) {
               item = makdatum(db->db_pagbuf, i);
               if (item.dptr == NULL)
                       break;
               if (cmpdatum(key, item) <= 0)
                       continue;
               if (f || cmpdatum(bitem, item) < 0) {
                       bitem = item;
                       f = 0;
               }
       }
       if (f == 0)
               return (bitem);
       hash = hashinc(db, hash);
       if (hash == 0)
               return (item);
       return (firsthash(db, hash));
}

static datum
firsthash(db, hash)
       register DBM *db;
       long hash;
{
       register i;
       datum item, bitem;

loop:
       dbm_access(db, hash);
       bitem = makdatum(db->db_pagbuf, 0);
       for (i=2;; i+=2) {
               item = makdatum(db->db_pagbuf, i);
               if (item.dptr == NULL)
                       break;
               if (cmpdatum(bitem, item) < 0)
                       bitem = item;
       }
       if (bitem.dptr != NULL)
               return (bitem);
       hash = hashinc(db, hash);
       if (hash == 0)
               return (item);
       goto loop;
}

static
dbm_access(db, hash)
       register DBM *db;
       long hash;
{
       
       for (db->db_hmask=0;; db->db_hmask=(db->db_hmask<<1)+1) {
               db->db_blkno = hash & db->db_hmask;
               db->db_bitno = db->db_blkno + db->db_hmask;
               if (getbit(db) == 0)
                       break;
       }
       if (db->db_blkno != db->db_pagbno) {
               bzero(db->db_pagbuf, PBLKSIZ);
               (void) lseek(db->db_pagf, db->db_blkno*PBLKSIZ, L_SET);
               (void) read(db->db_pagf, db->db_pagbuf, PBLKSIZ);
               chkblk(db->db_pagbuf);
               db->db_pagbno = db->db_blkno;
       }
}

static
getbit(db)
       register DBM *db;
{
       long bn;
       register b, i, n;
       

       if (db->db_bitno > db->db_maxbno)
               return (0);
       n = db->db_bitno % BYTESIZ;
       bn = db->db_bitno / BYTESIZ;
       i = bn % DBLKSIZ;
       b = bn / DBLKSIZ;
       if (b != db->db_dirbno) {
               bzero(db->db_dirbuf, DBLKSIZ);
               (void) lseek(db->db_dirf, (long)b*DBLKSIZ, L_SET);
               (void) read(db->db_dirf, db->db_dirbuf, DBLKSIZ);
               db->db_dirbno = b;
       }
       if (db->db_dirbuf[i] & (1<<n))
               return (1);
       return (0);
}

static
setbit(db)
       register DBM *db;
{
       long bn;
       register i, n, b;

       if (dbrdonly(db)) {
               errno = EPERM;
               return (-1);
       }
       if (db->db_bitno > db->db_maxbno) {
               db->db_maxbno = db->db_bitno;
               getbit(db);
       }
       n = db->db_bitno % BYTESIZ;
       bn = db->db_bitno / BYTESIZ;
       i = bn % DBLKSIZ;
       b = bn / DBLKSIZ;
       db->db_dirbuf[i] |= 1<<n;
       (void) lseek(db->db_dirf, (long)b*DBLKSIZ, L_SET);
       (void) write(db->db_dirf, db->db_dirbuf, DBLKSIZ);
       db->db_dirbno = b;
}

static datum
makdatum(buf, n)
       char buf[PBLKSIZ];
{
       register short *sp;
       register t;
       datum item;

       sp = (short *)buf;
       if (n < 0 || n >= sp[0])
               goto null;
       t = PBLKSIZ;
       if (n > 0)
               t = sp[n+1-1];
       item.dptr = buf+sp[n+1];
       item.dsize = t - sp[n+1];
       return (item);

null:
       item.dptr = NULL;
       item.dsize = 0;
       return (item);
}

static
cmpdatum(d1, d2)
       datum d1, d2;
{
       register n;
       register char *p1, *p2;

       n = d1.dsize;
       if (n != d2.dsize)
               return (n - d2.dsize);
       if (n == 0)
               return (0);
       p1 = d1.dptr;
       p2 = d2.dptr;
       do
               if (*p1++ != *p2++)
                       return (*--p1 - *--p2);
       while (--n);
       return (0);
}

static  int hitab[16]
/* ken's
{
       055,043,036,054,063,014,004,005,
       010,064,077,000,035,027,025,071,
};
*/
= {    61, 57, 53, 49, 45, 41, 37, 33,
       29, 25, 21, 17, 13,  9,  5,  1,
};
static  long hltab[64]
= {
       06100151277L,06106161736L,06452611562L,05001724107L,
       02614772546L,04120731531L,04665262210L,07347467531L,
       06735253126L,06042345173L,03072226605L,01464164730L,
       03247435524L,07652510057L,01546775256L,05714532133L,
       06173260402L,07517101630L,02431460343L,01743245566L,
       00261675137L,02433103631L,03421772437L,04447707466L,
       04435620103L,03757017115L,03641531772L,06767633246L,
       02673230344L,00260612216L,04133454451L,00615531516L,
       06137717526L,02574116560L,02304023373L,07061702261L,
       05153031405L,05322056705L,07401116734L,06552375715L,
       06165233473L,05311063631L,01212221723L,01052267235L,
       06000615237L,01075222665L,06330216006L,04402355630L,
       01451177262L,02000133436L,06025467062L,07121076461L,
       03123433522L,01010635225L,01716177066L,05161746527L,
       01736635071L,06243505026L,03637211610L,01756474365L,
       04723077174L,03642763134L,05750130273L,03655541561L,
};

static long
hashinc(db, hash)
       register DBM *db;
       long hash;
{
       long bit;

       hash &= db->db_hmask;
       bit = db->db_hmask+1;
       for (;;) {
               bit >>= 1;
               if (bit == 0)
                       return (0L);
               if ((hash&bit) == 0)
                       return (hash|bit);
               hash &= ~bit;
       }
}

static long
dcalchash(item)
       datum item;
{
       register i, j, f;
       long hashl;
       int hashi;

       hashl = 0;
       hashi = 0;
       for (i=0; i<item.dsize; i++) {
               f = item.dptr[i];
               for (j=0; j<BYTESIZ; j+=4) {
                       hashi += hitab[f&017];
                       hashl += hltab[hashi&63];
                       f >>= 4;
               }
       }
       return (hashl);
}

static
delitem(buf, n)
       char buf[PBLKSIZ];
{
       register short *sp;
       register i1, i2, i3;

       sp = (short *)buf;
       if (n < 0 || n >= sp[0])
               goto bad;
       i1 = sp[n+1];
       i2 = PBLKSIZ;
       if (n > 0)
               i2 = sp[n+1-1];
       i3 = sp[sp[0]+1-1];
       if (i2 > i1)
       while (i1 > i3) {
               i1--;
               i2--;
               buf[i2] = buf[i1];
               buf[i1] = 0;
       }
       i2 -= i1;
       for (i1=n+1; i1<sp[0]; i1++)
               sp[i1+1-1] = sp[i1+1] + i2;
       sp[0]--;
       sp[sp[0]+1] = 0;
       return;

bad:
       printf("ndbm: bad delitem\n");
       abort();
}

static
additem(buf, item)
       char buf[PBLKSIZ];
       datum item;
{
       register short *sp;
       register i1, i2;

       sp = (short *)buf;
       i1 = PBLKSIZ;
       if (sp[0] > 0)
               i1 = sp[sp[0]+1-1];
       i1 -= item.dsize;
       i2 = (sp[0]+2) * sizeof(short);
       if (i1 <= i2)
               return (-1);
       sp[sp[0]+1] = i1;
       for (i2=0; i2<item.dsize; i2++) {
               buf[i1] = item.dptr[i2];
               i1++;
       }
       sp[0]++;
       return (sp[0]-1);
}

static
chkblk(buf)
       char buf[PBLKSIZ];
{
       register short *sp;
       register t, i;

       sp = (short *)buf;
       t = PBLKSIZ;
       for (i=0; i<sp[0]; i++) {
               if (sp[i+1] > t)
                       goto bad;
               t = sp[i+1];
       }
       if (t < (sp[0]+1)*sizeof(short))
               goto bad;
       return;

bad:
       printf("ndbm: bad block\n");
       abort();
       bzero(buf, PBLKSIZ);
}