-/* Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc.
- Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>
+/* Copyright (C) 1993-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1993.
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.
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 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.
+ Lesser 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. */
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <malloc.h>
#include <string.h>
-
+#include <stdint.h>
#include <search.h>
+#include <limits.h>
/* [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
[Knuth] The Art of Computer Programming, part 3 (6.4) */
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;
+ for (unsigned int div = 3; div <= number / div; div += 2)
+ if (number % div == 0)
+ return 0;
+ return 1;
}
-
/* 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
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;
+__hcreate_r (size_t nel, struct hsearch_data *htab)
{
/* Test for correct arguments. */
if (htab == NULL)
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;
+ /* We need a size of at least 3. Otherwise the hash functions we
+ use will not work. */
+ if (nel < 3)
+ nel = 3;
+
+ /* Change nel to the first prime number in the range [nel, UINT_MAX - 2],
+ The '- 2' means 'nel += 2' cannot overflow. */
+ for (nel |= 1; ; nel += 2)
+ {
+ if (UINT_MAX - 2 < nel)
+ {
+ __set_errno (ENOMEM);
+ return 0;
+ }
+ if (isprime (nel))
+ break;
+ }
htab->size = nel;
htab->filled = 0;
/* everything went alright */
return 1;
}
+libc_hidden_def (__hcreate_r)
+weak_alias (__hcreate_r, hcreate_r)
/* 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;
+__hdestroy_r (struct hsearch_data *htab)
{
/* Test for correct arguments. */
if (htab == NULL)
return;
}
- if (htab->table != NULL)
- /* free used memory */
- free (htab->table);
+ /* Free used memory. */
+ free (htab->table);
/* the sign for an existing table is an value != NULL in htable */
htab->table = NULL;
}
+libc_hidden_def (__hdestroy_r)
+weak_alias (__hdestroy_r, hdestroy_r)
-/* This is the search function. It uses double hashing with open adressing.
+/* 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
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;
+__hsearch_r (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;
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;
+ /* First hash function: simply take the modul but prevent zero. */
+ idx = hval % htab->size + 1;
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);
+ unsigned int hval2 = 1 + hval % (htab->size - 2);
+ unsigned int first_idx = idx;
do
{
else
idx -= hval2;
+ /* If we visited all entries leave the loop unsuccessfully. */
+ if (idx == first_idx)
+ break;
+
/* 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;
}
/* An empty bucket has been found. */
if (action == ENTER)
{
+ /* If table is full and another entry should be entered return
+ with error. */
+ if (htab->filled == htab->size)
+ {
+ __set_errno (ENOMEM);
+ *retval = NULL;
+ return 0;
+ }
+
htab->table[idx].used = hval;
htab->table[idx].entry = item;
*retval = NULL;
return 0;
}
+libc_hidden_def (__hsearch_r)
+weak_alias (__hsearch_r, hsearch_r)
projects / thirdparty / glibc.git / blobdiff