| /* Support for sbrk() regions. |
| Copyright 1992, 2000 Free Software Foundation, Inc. |
| Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com |
| |
| 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. */ |
| |
| #ifdef HAVE_UNISTD_H |
| #include <unistd.h> /* Prototypes for sbrk (maybe) */ |
| #endif |
| #include <string.h> /* Prototypes for memcpy, memmove, memset, etc */ |
| |
| #include "mmprivate.h" |
| |
| 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 |
| descriptor. For these operations, sbrk() is used to obtain more core |
| from the system, or return core. This allows mmalloc() to provide |
| backwards compatibility with the non-mmap'd version. */ |
| |
| struct mdesc *__mmalloc_default_mdp; |
| |
| /* Use sbrk() to get more core. */ |
| |
| static PTR |
| sbrk_morecore (mdp, size) |
| struct mdesc *mdp; |
| int size; |
| { |
| PTR result; |
| |
| if ((result = sbrk (size)) == (PTR) -1) |
| { |
| result = NULL; |
| } |
| else |
| { |
| mdp -> breakval += size; |
| mdp -> top += size; |
| } |
| return (result); |
| } |
| |
| /* Initialize the default malloc descriptor if this is the first time |
| 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)); |
| 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); |
| __mmalloc_default_mdp -> fd = -1; |
| return (__mmalloc_default_mdp); |
| } |
| |
| |