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Unix System Administration Handbook 1997 October
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usah_oct97.iso
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news
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nn.tar
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nn-6.5.1
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hash.c
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C/C++ Source or Header
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1995-04-29
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5KB
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186 lines
/*******************WARNING*********************
This is a *MODIFIED* version of Geoff Coller's proof-of-concept NOV
implementation.
It has been modified to support threading directly from a file handle
to a NNTP server without a temporary file.
This is not a complete distribution. We have only distributed enough
to support NN's needs.
The original version came from world.std.com:/src/news/nov.dist.tar.Z
and was dated 11 Aug 1993.
In any case, bugs you find here are probably my fault, as I've trimmed
a fair bit of unused code.
-Peter Wemm <peter@DIALix.oz.au>
*/
/*
* Copyright (c) Geoffrey Collyer 1992, 1993.
* All rights reserved.
* Written by Geoffrey Collyer.
* Thanks to UUNET Communications Services Inc for financial support.
*
* This software is not subject to any license of the American Telephone
* and Telegraph Company, the Regents of the University of California, or
* the Free Software Foundation.
*
* Permission is granted to anyone to use this software for any purpose on
* any computer system, and to alter it and redistribute it freely, subject
* to the following restrictions:
*
* 1. The authors are not responsible for the consequences of use of this
* software, no matter how awful, even if they arise from flaws in it.
*
* 2. The origin of this software must not be misrepresented, either by
* explicit claim or by omission. Since few users ever read sources,
* credits must appear in the documentation.
*
* 3. Altered versions must be plainly marked as such, and must not be
* misrepresented as being the original software. Since few users
* ever read sources, credits must appear in the documentation.
*
* 4. This notice may not be removed or altered.
*/
/*
* general-purpose in-core hashing, normal interface (wrapper)
*/
#include "config.h"
#include "hdbm.h"
#include "hash.h"
#ifdef notdef
static unsigned /* not yet taken modulus table size */
hashdef(key)
register HASHDATUM key;
{
register unsigned hash = 0;
register char c;
while ((c = *key++) != '\0')
hash += c;
return hash;
}
#endif
HASHTABLE *
hashcreate(size, hashfunc)
unsigned size; /* a crude guide to size */
unsigned (*hashfunc)();
{
return hdbmcreate(size, hashfunc);
}
hashdestroy(tbl)
register HASHTABLE *tbl;
{
hdbmdestroy(tbl);
}
int
hashstore(tbl, key, data)
HASHTABLE *tbl;
register HASHDATUM key, data;
{
register HDBMDATUM hdbmkey, hdbmdata;
hdbmkey.dat_ptr = key; /* actually a string */
hdbmkey.dat_len = strlen(key);
hdbmdata.dat_ptr = data; /* just an address */
hdbmdata.dat_len = 0; /* no promises */
return hdbmstore(tbl, hdbmkey, hdbmdata);
}
static HASHDATUM (*hashalloc)();
static HDBMDATUM
hdbmalloc(key) /* hdbm->hash->hdbm allocator translator */
HDBMDATUM key;
{
register HDBMDATUM hdbmdata;
hdbmdata.dat_ptr = (*hashalloc)(key.dat_ptr);
hdbmdata.dat_len = 0; /* just a string */
return hdbmdata;
}
/* return any existing entry for key; otherwise call allocator to make one */
HASHDATUM
hashentry(tbl, key, allocator)
register HASHTABLE *tbl;
HASHDATUM key;
HASHDATUM (*allocator)();
{
register HDBMDATUM hdbmkey, hdbmdata;
hdbmkey.dat_ptr = key; /* just a string */
hdbmkey.dat_len = strlen(key);
hashalloc = allocator;
hdbmdata = hdbmentry(tbl, hdbmkey, hdbmalloc);
return hdbmdata.dat_ptr;
}
HASHDATUM /* data corresponding to key */
hashfetch(tbl, key)
HASHTABLE *tbl;
register HASHDATUM key;
{
register HDBMDATUM hdbmkey, hdbmdata;
hdbmkey.dat_ptr = key; /* actually a string */
hdbmkey.dat_len = strlen(key);
hdbmdata = hdbmfetch(tbl, hdbmkey);
return hdbmdata.dat_ptr; /* just an address */
}
int
hashdelete(tbl, key)
HASHTABLE *tbl;
register HASHDATUM key;
{
register HDBMDATUM hdbmkey;
hdbmkey.dat_ptr = key; /* actually a string */
hdbmkey.dat_len = strlen(key);
return hdbmdelete(tbl, hdbmkey);
}
struct translate {
char *realhook;
int (*func)();
};
static
hdbmtohash(key, data, hook)
HDBMDATUM key, data;
char *hook;
{
register struct translate *thp = (struct translate *)hook;
(*thp->func)(key.dat_ptr, data.dat_ptr, thp->realhook);
}
/*
* arrange that at each node, hdbmtohash gets called to map the
* HDBMDATUM arguments to HASHDATUM arguments. this also demonstrates
* how to use the hook argument.
*/
hashwalk(tbl, nodefunc, hook)
HASHTABLE *tbl;
int (*nodefunc)();
char *hook; /* (void *) really */
{
struct translate transhook;
register struct translate *tp = &transhook;
tp->realhook = hook;
tp->func = nodefunc;
hdbmwalk(tbl, hdbmtohash, (char *)tp);
}