70 lines
2.1 KiB
C
70 lines
2.1 KiB
C
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/* Support for sbrk() regions.
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Copyright 1992 Free Software Foundation, Inc.
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Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com
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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 of the License, or
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(at your option) 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
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include <string.h> /* Prototypes for memcpy, memmove, memset, etc */
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#include "mmalloc.h"
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extern PTR sbrk ();
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/* The mmalloc() package can use a single implicit malloc descriptor
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for mmalloc/mrealloc/mfree operations which do not supply an explicit
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descriptor. For these operations, sbrk() is used to obtain more core
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from the system, or return core. This allows mmalloc() to provide
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backwards compatibility with the non-mmap'd version. */
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struct mdesc *__mmalloc_default_mdp;
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/* Use sbrk() to get more core. */
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static PTR
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sbrk_morecore (mdp, size)
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struct mdesc *mdp;
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int size;
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{
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PTR result;
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if ((result = sbrk (size)) != NULL)
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{
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mdp -> breakval += size;
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mdp -> top += size;
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}
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return (result);
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}
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/* Initialize the default malloc descriptor if this is the first time
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a request has been made to use the default sbrk'd region. */
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struct mdesc *
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__mmalloc_sbrk_init ()
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{
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PTR base;
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base = sbrk (0);
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__mmalloc_default_mdp = (struct mdesc *) sbrk (sizeof (struct mdesc));
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(void) memset ((char *) __mmalloc_default_mdp, 0, sizeof (struct mdesc));
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__mmalloc_default_mdp -> morecore = sbrk_morecore;
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__mmalloc_default_mdp -> base = base;
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__mmalloc_default_mdp -> breakval = __mmalloc_default_mdp -> top = sbrk (0);
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__mmalloc_default_mdp -> fd = -1;
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return (__mmalloc_default_mdp);
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}
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