/* Support for an sbrk-like function that uses mmap.
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/* Support for an sbrk-like function that uses mmap.
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Copyright 1992, 2000 Free Software Foundation, Inc.
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Copyright 1992, 2000 Free Software Foundation, Inc.
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Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com
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Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com
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This file is part of the GNU C Library.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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The GNU C Library 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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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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Boston, MA 02111-1307, USA. */
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#if defined(HAVE_MMAP)
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#if defined(HAVE_MMAP)
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#ifdef HAVE_UNISTD_H
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#ifdef HAVE_UNISTD_H
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#include <unistd.h> /* Prototypes for lseek */
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#include <unistd.h> /* Prototypes for lseek */
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#endif
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#endif
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#include <stdio.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/mman.h>
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#ifndef SEEK_SET
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#ifndef SEEK_SET
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#define SEEK_SET 0
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#define SEEK_SET 0
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#endif
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#endif
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#include "mmprivate.h"
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#include "mmprivate.h"
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/* Cache the pagesize for the current host machine. Note that if the host
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/* Cache the pagesize for the current host machine. Note that if the host
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does not readily provide a getpagesize() function, we need to emulate it
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does not readily provide a getpagesize() function, we need to emulate it
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elsewhere, not clutter up this file with lots of kluges to try to figure
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elsewhere, not clutter up this file with lots of kluges to try to figure
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it out. */
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it out. */
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static size_t pagesize;
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static size_t pagesize;
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#if NEED_DECLARATION_GETPAGESIZE
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#if NEED_DECLARATION_GETPAGESIZE
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extern int getpagesize PARAMS ((void));
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extern int getpagesize PARAMS ((void));
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#endif
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#endif
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#define PAGE_ALIGN(addr) (caddr_t) (((long)(addr) + pagesize - 1) & \
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#define PAGE_ALIGN(addr) (caddr_t) (((long)(addr) + pagesize - 1) & \
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~(pagesize - 1))
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~(pagesize - 1))
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/* Return MAP_PRIVATE if MDP represents /dev/zero. Otherwise, return
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/* Return MAP_PRIVATE if MDP represents /dev/zero. Otherwise, return
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MAP_SHARED. */
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MAP_SHARED. */
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#define MAP_PRIVATE_OR_SHARED(MDP) ((MDP -> flags & MMALLOC_DEVZERO) \
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#define MAP_PRIVATE_OR_SHARED(MDP) ((MDP -> flags & MMALLOC_DEVZERO) \
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? MAP_PRIVATE \
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? MAP_PRIVATE \
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: MAP_SHARED)
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: MAP_SHARED)
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/* Get core for the memory region specified by MDP, using SIZE as the
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/* Get core for the memory region specified by MDP, using SIZE as the
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amount to either add to or subtract from the existing region. Works
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amount to either add to or subtract from the existing region. Works
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like sbrk(), but using mmap(). */
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like sbrk(), but using mmap(). */
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PTR
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PTR
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__mmalloc_mmap_morecore (mdp, size)
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__mmalloc_mmap_morecore (mdp, size)
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struct mdesc *mdp;
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struct mdesc *mdp;
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int size;
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int size;
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{
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{
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PTR result = NULL;
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PTR result = NULL;
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off_t foffset; /* File offset at which new mapping will start */
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off_t foffset; /* File offset at which new mapping will start */
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size_t mapbytes; /* Number of bytes to map */
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size_t mapbytes; /* Number of bytes to map */
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caddr_t moveto; /* Address where we wish to move "break value" to */
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caddr_t moveto; /* Address where we wish to move "break value" to */
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caddr_t mapto; /* Address we actually mapped to */
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caddr_t mapto; /* Address we actually mapped to */
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char buf = 0; /* Single byte to write to extend mapped file */
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char buf = 0; /* Single byte to write to extend mapped file */
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if (pagesize == 0)
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if (pagesize == 0)
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{
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{
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pagesize = getpagesize ();
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pagesize = getpagesize ();
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}
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}
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if (size == 0)
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if (size == 0)
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{
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{
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/* Just return the current "break" value. */
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/* Just return the current "break" value. */
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result = mdp -> breakval;
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result = mdp -> breakval;
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}
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}
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else if (size < 0)
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else if (size < 0)
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{
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{
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/* We are deallocating memory. If the amount requested would cause
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/* We are deallocating memory. If the amount requested would cause
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us to try to deallocate back past the base of the mmap'd region
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us to try to deallocate back past the base of the mmap'd region
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then do nothing, and return NULL. Otherwise, deallocate the
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then do nothing, and return NULL. Otherwise, deallocate the
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memory and return the old break value. */
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memory and return the old break value. */
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if (mdp -> breakval + size >= mdp -> base)
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if (mdp -> breakval + size >= mdp -> base)
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{
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{
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result = (PTR) mdp -> breakval;
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result = (PTR) mdp -> breakval;
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mdp -> breakval += size;
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mdp -> breakval += size;
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moveto = PAGE_ALIGN (mdp -> breakval);
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moveto = PAGE_ALIGN (mdp -> breakval);
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munmap (moveto, (size_t) (mdp -> top - moveto));
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munmap (moveto, (size_t) (mdp -> top - moveto));
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mdp -> top = moveto;
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mdp -> top = moveto;
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}
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}
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}
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}
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else
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else
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{
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{
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/* We are allocating memory. Make sure we have an open file
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/* We are allocating memory. Make sure we have an open file
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descriptor and then go on to get the memory. */
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descriptor and then go on to get the memory. */
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if (mdp -> fd < 0)
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if (mdp -> fd < 0)
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{
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{
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result = NULL;
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result = NULL;
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}
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}
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else if (mdp -> breakval + size > mdp -> top)
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else if (mdp -> breakval + size > mdp -> top)
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{
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{
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/* The request would move us past the end of the currently
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/* The request would move us past the end of the currently
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mapped memory, so map in enough more memory to satisfy
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mapped memory, so map in enough more memory to satisfy
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the request. This means we also have to grow the mapped-to
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the request. This means we also have to grow the mapped-to
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file by an appropriate amount, since mmap cannot be used
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file by an appropriate amount, since mmap cannot be used
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to extend a file. */
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to extend a file. */
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moveto = PAGE_ALIGN (mdp -> breakval + size);
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moveto = PAGE_ALIGN (mdp -> breakval + size);
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mapbytes = moveto - mdp -> top;
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mapbytes = moveto - mdp -> top;
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foffset = mdp -> top - mdp -> base;
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foffset = mdp -> top - mdp -> base;
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/* FIXME: Test results of lseek() and write() */
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/* FIXME: Test results of lseek() and write() */
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lseek (mdp -> fd, foffset + mapbytes - 1, SEEK_SET);
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lseek (mdp -> fd, foffset + mapbytes - 1, SEEK_SET);
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write (mdp -> fd, &buf, 1);
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write (mdp -> fd, &buf, 1);
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if (mdp -> base == 0)
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if (mdp -> base == 0)
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{
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{
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/* Let mmap pick the map start address */
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/* Let mmap pick the map start address */
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mapto = mmap (0, mapbytes, PROT_READ | PROT_WRITE,
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mapto = mmap (0, mapbytes, PROT_READ | PROT_WRITE,
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MAP_PRIVATE_OR_SHARED (mdp), mdp -> fd, foffset);
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MAP_PRIVATE_OR_SHARED (mdp), mdp -> fd, foffset);
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if (mapto != (caddr_t) -1)
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if (mapto != (caddr_t) -1)
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{
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{
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mdp -> base = mdp -> breakval = mapto;
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mdp -> base = mdp -> breakval = mapto;
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mdp -> top = mdp -> base + mapbytes;
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mdp -> top = mdp -> base + mapbytes;
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result = (PTR) mdp -> breakval;
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result = (PTR) mdp -> breakval;
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mdp -> breakval += size;
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mdp -> breakval += size;
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}
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}
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}
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}
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else
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else
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{
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{
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mapto = mmap (mdp -> top, mapbytes, PROT_READ | PROT_WRITE,
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mapto = mmap (mdp -> top, mapbytes, PROT_READ | PROT_WRITE,
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MAP_PRIVATE_OR_SHARED (mdp) | MAP_FIXED, mdp -> fd,
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MAP_PRIVATE_OR_SHARED (mdp) | MAP_FIXED, mdp -> fd,
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foffset);
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foffset);
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if (mapto == mdp -> top)
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if (mapto == mdp -> top)
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{
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{
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mdp -> top = moveto;
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mdp -> top = moveto;
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result = (PTR) mdp -> breakval;
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result = (PTR) mdp -> breakval;
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mdp -> breakval += size;
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mdp -> breakval += size;
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}
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}
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}
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}
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}
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}
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else
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else
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{
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{
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result = (PTR) mdp -> breakval;
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result = (PTR) mdp -> breakval;
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mdp -> breakval += size;
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mdp -> breakval += size;
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}
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}
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}
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}
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return (result);
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return (result);
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}
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}
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PTR
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PTR
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__mmalloc_remap_core (mdp)
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__mmalloc_remap_core (mdp)
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struct mdesc *mdp;
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struct mdesc *mdp;
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{
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{
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caddr_t base;
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caddr_t base;
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/* FIXME: Quick hack, needs error checking and other attention. */
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/* FIXME: Quick hack, needs error checking and other attention. */
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base = mmap (mdp -> base, mdp -> top - mdp -> base,
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base = mmap (mdp -> base, mdp -> top - mdp -> base,
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PROT_READ | PROT_WRITE, MAP_PRIVATE_OR_SHARED (mdp) | MAP_FIXED,
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PROT_READ | PROT_WRITE, MAP_PRIVATE_OR_SHARED (mdp) | MAP_FIXED,
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mdp -> fd, 0);
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mdp -> fd, 0);
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return ((PTR) base);
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return ((PTR) base);
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}
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}
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PTR
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PTR
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mmalloc_findbase (size)
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mmalloc_findbase (size)
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int size;
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int size;
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{
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{
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int fd;
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int fd;
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int flags;
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int flags;
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caddr_t base = NULL;
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caddr_t base = NULL;
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#ifdef MAP_ANONYMOUS
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#ifdef MAP_ANONYMOUS
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flags = MAP_PRIVATE | MAP_ANONYMOUS;
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flags = MAP_PRIVATE | MAP_ANONYMOUS;
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fd = -1;
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fd = -1;
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#else
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#else
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#ifdef MAP_FILE
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#ifdef MAP_FILE
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flags = MAP_PRIVATE | MAP_FILE;
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flags = MAP_PRIVATE | MAP_FILE;
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#else
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#else
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flags = MAP_PRIVATE;
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flags = MAP_PRIVATE;
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#endif
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#endif
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fd = open ("/dev/zero", O_RDWR);
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fd = open ("/dev/zero", O_RDWR);
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if (fd != -1)
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if (fd != -1)
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{
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{
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return ((PTR) NULL);
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return ((PTR) NULL);
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}
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}
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#endif
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#endif
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base = mmap (0, size, PROT_READ | PROT_WRITE, flags, fd, 0);
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base = mmap (0, size, PROT_READ | PROT_WRITE, flags, fd, 0);
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if (base != (caddr_t) -1)
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if (base != (caddr_t) -1)
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{
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{
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munmap (base, (size_t) size);
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munmap (base, (size_t) size);
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}
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}
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if (fd != -1)
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if (fd != -1)
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{
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{
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close (fd);
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close (fd);
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}
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}
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if (base == 0)
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if (base == 0)
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{
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{
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/* Don't allow mapping at address zero. We use that value
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/* Don't allow mapping at address zero. We use that value
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to signal an error return, and besides, it is useful to
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to signal an error return, and besides, it is useful to
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catch NULL pointers if it is unmapped. Instead start
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catch NULL pointers if it is unmapped. Instead start
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at the next page boundary. */
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at the next page boundary. */
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base = (caddr_t) getpagesize ();
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base = (caddr_t) getpagesize ();
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}
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}
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else if (base == (caddr_t) -1)
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else if (base == (caddr_t) -1)
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{
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{
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base = NULL;
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base = NULL;
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}
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}
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return ((PTR) base);
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return ((PTR) base);
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}
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}
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#else /* defined(HAVE_MMAP) */
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#else /* defined(HAVE_MMAP) */
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/* Prevent "empty translation unit" warnings from the idiots at X3J11. */
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/* Prevent "empty translation unit" warnings from the idiots at X3J11. */
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static char ansi_c_idiots = 69;
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static char ansi_c_idiots = 69;
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#endif /* defined(HAVE_MMAP) */
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#endif /* defined(HAVE_MMAP) */
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