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91 lines
2.0 KiB
C
91 lines
2.0 KiB
C
/* extendbuf.c -- manage a dynamically-allocated buffer
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Copyright 2004 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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/* Written by James Yougnman <jay@gnu.org>. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <stddef.h>
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#include <stdlib.h>
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#include <assert.h>
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#include "xalloc.h"
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#include "extendbuf.h"
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/* We initially use a small default size to ensure that this code
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* gets exercised.
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*/
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#ifndef SIZE_DEFAULT
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# define SIZE_DEFAULT 16
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#endif
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static size_t
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decide_size(size_t current, size_t wanted)
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{
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size_t newsize;
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if (0 == current)
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newsize = SIZE_DEFAULT;
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else
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newsize = current;
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while (newsize < wanted)
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{
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if (2 * newsize < newsize)
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xalloc_die ();
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newsize *= 2;
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}
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return newsize;
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}
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void *
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extendbuf(void* existing, size_t wanted, size_t *allocated)
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{
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size_t newsize;
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assert(wanted > 0u);
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newsize = decide_size(*allocated, wanted);
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if ( (*allocated) == 0 )
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{
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/* Sanity check: If there is no existing allocation size, three
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* must be no existing allocated buffer.
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*/
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assert(NULL == existing);
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(*allocated) = newsize;
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return xmalloc(newsize);
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}
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else
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{
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if (newsize != (*allocated) )
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{
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(*allocated) = newsize;
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return xrealloc (existing, newsize);
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}
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else
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{
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return existing;
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}
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}
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}
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