glibc/misc/hsearch_r.c
Ulrich Drepper 6d52618b15 Update from main archive 961219
Thu Dec 19 23:28:33 1996  Ulrich Drepper  <drepper@cygnus.com>

	* resolv/resolv.h: Update from BIND 4.9.5-P1.
	* resolv/res_comp.c: Likewise.
	* resolv/res_debug.c: Likewise.
	* resolv/Banner: Update version number.

Thu Dec 19 20:58:53 1996  Ulrich Drepper  <drepper@cygnus.com>

	* elf/dlfcn.h: Add extern "C" wrapper.

	* io/utime.h: Don't define NULL since this isn't allowed in POSIX.
	* io/sys/stat.h: Declare `lstat' only if __USE_BSD ||
	__USE_XOPEN_EXTENDED.
	* locale/locale.h: Define NULL.
	* math/math.c: Don't include <errno.h> to define math errors.
	* stdlib/stdlib.h: Likewise.
	* posix/unistd.h: Don't declare environ.
	* posix/sys/utsname.h (struct utsname): Declare member domainname
	as __domainname is !__USE_GNU.
	* signal/signal.h: Declare size_t only if __USE_BSD ||
	__USE_XOPEN_EXTENDED.
	* stdio/stdio.h: Don't declare cuserid when __USE_POSIX, but
	instead when __USE_XOPEN.
	* string/string.h: Define strndup only if __USE_GNU.
	* sysdeps/unix/sysv/linux/clock.c: New file.
	* sysdeps/unix/sysv/linux/timebits.h: Define CLOCKS_PER_SEC as
	1000000 per X/Open standard.
	* features.h: Add code to recognize _POSIX_C_SOURCE value 199309.
	Define __USE_POSIX199309.
	* posix/unistd.h: Declare fdatasync only if __USE_POSIX199309.
	* time/time.c: Declare nanosleep only if __USE_POSIX199309.
	Patches by Rüdiger Helsch <rh@unifix.de>.

	* locale/locale.h: Add declaration of newlocale and freelocale.

	* new-malloc/Makefile (distibute): Add mtrace.awk.
	(dist-routines): Add mcheck and mtrace.
	(install-lib, non-lib.a): Define as libmcheck.a.
	* new-malloc/malloc.h: Add declaration of __malloc_initialized.
	* new-malloc/mcheck.c: New file.
	* new-malloc/mcheck.h: New file.
	* new-malloc/mtrace.c: New file.
	* new-malloc/mtrace.awk: New file.

	* posix/unistd.h: Correct prototype for usleep.
	* sysdeps/unix/bsd/usleep.c: De-ANSI-declfy.  Correct return type.
	* sysdeps/unix/sysv/linux/usleep.c: Real implementation based on
	nanosleep.

	* signal/signal.h: Change protoype of __sigpause to take two
	arguments.  Remove prototype for sigpause.  Add two different
	macros named sigpause selected when __USE_BSD or __USE_XOPEN
	are defined.  This is necessary since the old BSD definition
	of theis function collides with the X/Open definition.
	* sysdeps/posix/sigpause.c: Change function definition to also
	fit X/Open definition.

	* sysdeps/libm-i387/e_exp.S: Make sure stack is empty when the
	function is left.
	* sysdeps/libm-i387/e_expl.S: Likewise.
	Patch by HJ Lu.

1996-12-17  Paul Eggert  <eggert@twinsun.com>

	* many, many files: Spelling corrections.
	* catgets/catgetsinfo.h (mmapped):
	Renamed from mmaped (in struct catalog_info.status).
	* mach/err_kern.sub (err_codes_unix), string/stratcliff.c (main):
	Fix spelling in message.
	* po/libc.pot: Fix spelling in message for `zic'; this anticipates
	a fix in the tzcode distribution.

Wed Dec 18 15:48:02 1996  Ulrich Drepper  <drepper@cygnus.com>

	* time/strftime.c: Implement ^ flag to cause output be converted
	to use upper case characters.

	* time/zic.c: Update from ADO tzcode1996n.

Wed Dec 18 14:29:24 1996  Erik Naggum  <erik@naggum.no>

	* time/strftime.c (add): Don't change global `i' until all is over.
	Define NULL is not already defined.

Tue Dec 17 09:49:03 1996  Andreas Schwab  <schwab@issan.informatik.uni-dortmund.de>

	* libio/iovsprintf.c (_IO_vsprintf): Change `&sf' to `&sf._sbf._f'
	to avoid the need for a cast.
	* libio/iovsscanf.c (_IO_vsscanf): Likewise.

	* sunrpc/rpc/xdr.h: Add prototype for xdr_free.
1996-12-20 01:39:50 +00:00

229 lines
6.3 KiB
C

/* Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc.
Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <errno.h>
#include <malloc.h>
#include <string.h>
#include <search.h>
/* [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
[Knuth] The Art of Computer Programming, part 3 (6.4) */
/* The reentrant version has no static variables to maintain the state.
Instead the interface of all functions is extended to take an argument
which describes the current status. */
typedef struct _ENTRY
{
unsigned int used;
ENTRY entry;
}
_ENTRY;
/* For the used double hash method the table size has to be a prime. To
correct the user given table size we need a prime test. This trivial
algorithm is adequate because
a) the code is (most probably) called a few times per program run and
b) the number is small because the table must fit in the core */
static int
isprime (unsigned int number)
{
/* no even number will be passed */
unsigned int div = 3;
while (div * div < number && number % div != 0)
div += 2;
return number % div != 0;
}
/* Before using the hash table we must allocate memory for it.
Test for an existing table are done. We allocate one element
more as the found prime number says. This is done for more effective
indexing as explained in the comment for the hsearch function.
The contents of the table is zeroed, especially the field used
becomes zero. */
int
hcreate_r (nel, htab)
size_t nel;
struct hsearch_data *htab;
{
/* Test for correct arguments. */
if (htab == NULL)
{
__set_errno (EINVAL);
return 0;
}
/* There is still another table active. Return with error. */
if (htab->table != NULL)
return 0;
/* Change nel to the first prime number not smaller as nel. */
nel |= 1; /* make odd */
while (!isprime (nel))
nel += 2;
htab->size = nel;
htab->filled = 0;
/* allocate memory and zero out */
htab->table = (_ENTRY *) calloc (htab->size + 1, sizeof (_ENTRY));
if (htab->table == NULL)
return 0;
/* everything went alright */
return 1;
}
/* After using the hash table it has to be destroyed. The used memory can
be freed and the local static variable can be marked as not used. */
void
hdestroy_r (htab)
struct hsearch_data *htab;
{
/* Test for correct arguments. */
if (htab == NULL)
{
__set_errno (EINVAL);
return;
}
if (htab->table != NULL)
/* free used memory */
free (htab->table);
/* the sign for an existing table is an value != NULL in htable */
htab->table = NULL;
}
/* This is the search function. It uses double hashing with open addressing.
The argument item.key has to be a pointer to an zero terminated, most
probably strings of chars. The function for generating a number of the
strings is simple but fast. It can be replaced by a more complex function
like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
We use an trick to speed up the lookup. The table is created by hcreate
with one more element available. This enables us to use the index zero
special. This index will never be used because we store the first hash
index in the field used where zero means not used. Every other value
means used. The used field can be used as a first fast comparison for
equality of the stored and the parameter value. This helps to prevent
unnecessary expensive calls of strcmp. */
int
hsearch_r (item, action, retval, htab)
ENTRY item;
ACTION action;
ENTRY **retval;
struct hsearch_data *htab;
{
unsigned int hval;
unsigned int count;
unsigned int len = strlen (item.key);
unsigned int idx;
/* If table is full and another entry should be entered return with
error. */
if (action == ENTER && htab->filled == htab->size)
{
__set_errno (ENOMEM);
*retval = NULL;
return 0;
}
/* Compute an value for the given string. Perhaps use a better method. */
hval = len;
count = len;
while (count-- > 0)
{
hval <<= 4;
hval += item.key[count];
}
/* First hash function: simply take the modul but prevent zero. */
hval %= htab->size;
if (hval == 0)
++hval;
/* The first index tried. */
idx = hval;
if (htab->table[idx].used)
{
/* Further action might be required according to the action value. */
unsigned hval2;
if (htab->table[idx].used == hval
&& strcmp (item.key, htab->table[idx].entry.key) == 0)
{
if (action == ENTER)
htab->table[idx].entry.data = item.data;
*retval = &htab->table[idx].entry;
return 1;
}
/* Second hash function, as suggested in [Knuth] */
hval2 = 1 + hval % (htab->size - 2);
do
{
/* Because SIZE is prime this guarantees to step through all
available indeces. */
if (idx <= hval2)
idx = htab->size + idx - hval2;
else
idx -= hval2;
/* If entry is found use it. */
if (htab->table[idx].used == hval
&& strcmp (item.key, htab->table[idx].entry.key) == 0)
{
if (action == ENTER)
htab->table[idx].entry.data = item.data;
*retval = &htab->table[idx].entry;
return 1;
}
}
while (htab->table[idx].used);
}
/* An empty bucket has been found. */
if (action == ENTER)
{
htab->table[idx].used = hval;
htab->table[idx].entry = item;
++htab->filled;
*retval = &htab->table[idx].entry;
return 1;
}
__set_errno (ESRCH);
*retval = NULL;
return 0;
}