/* Support for sbrk() regions.
- Copyright 1992 Free Software Foundation, Inc.
+ Copyright 1992, 2000 Free Software Foundation, Inc.
Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
+This file is part of the GNU C Library.
-This program 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 General Public License for more details.
+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.
-You should have received a copy of the GNU General Public License
-along with this program; if not, write to the Free Software
-Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+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. */
+#ifdef HAVE_UNISTD_H
+#include <unistd.h> /* Prototypes for sbrk (maybe) */
+#endif
#include <string.h> /* Prototypes for memcpy, memmove, memset, etc */
-#include "mmalloc.h"
+#include "mmprivate.h"
-extern PTR sbrk ();
+static PTR sbrk_morecore PARAMS ((struct mdesc *, int));
+#if NEED_DECLARATION_SBRK
+extern PTR sbrk PARAMS ((int));
+#endif
/* The mmalloc() package can use a single implicit malloc descriptor
for mmalloc/mrealloc/mfree operations which do not supply an explicit
{
PTR result;
- if ((result = sbrk (size)) != NULL)
+ if ((result = sbrk (size)) == (PTR) -1)
+ {
+ result = NULL;
+ }
+ else
{
mdp -> breakval += size;
mdp -> top += size;
}
/* Initialize the default malloc descriptor if this is the first time
- a request has been made to use the default sbrk'd region. */
+ a request has been made to use the default sbrk'd region.
+
+ Since no alignment guarantees are made about the initial value returned
+ by sbrk, test the initial value and (if necessary) sbrk enough additional
+ memory to start off with alignment to BLOCKSIZE. We actually only need
+ it aligned to an alignment suitable for any object, so this is overkill.
+ But at most it wastes just part of one BLOCKSIZE chunk of memory and
+ minimizes portability problems by avoiding us having to figure out
+ what the actual minimal alignment is. The rest of the malloc code
+ avoids this as well, by always aligning to the minimum of the requested
+ size rounded up to a power of two, or to BLOCKSIZE.
+
+ Note that we are going to use some memory starting at this initial sbrk
+ address for the sbrk region malloc descriptor, which is a struct, so the
+ base address must be suitably aligned. */
struct mdesc *
__mmalloc_sbrk_init ()
{
PTR base;
+ unsigned int adj;
base = sbrk (0);
+ adj = RESIDUAL (base, BLOCKSIZE);
+ if (adj != 0)
+ {
+ sbrk (BLOCKSIZE - adj);
+ base = sbrk (0);
+ }
__mmalloc_default_mdp = (struct mdesc *) sbrk (sizeof (struct mdesc));
- (void) memset ((char *) __mmalloc_default_mdp, 0, sizeof (struct mdesc));
+ memset ((char *) __mmalloc_default_mdp, 0, sizeof (struct mdesc));
__mmalloc_default_mdp -> morecore = sbrk_morecore;
__mmalloc_default_mdp -> base = base;
__mmalloc_default_mdp -> breakval = __mmalloc_default_mdp -> top = sbrk (0);