ea8c7ac7d0
This is a greatly pared down version of the full gdb-4.12, all the config stuff has been removed and the supporting libraries have been stripped to a minimum. This is a 1.1.5 only port, I'll do a more complete port for 2.0 which will have all the config stuff and will install the gnu support libraries as system libraries like we do for readline. There wasn't much point for 1.1.5 since only gdb would use them so I went for saving space instead. For 2.0 I'll config all the other gnu tools to use them as well.
145 lines
4.4 KiB
C
145 lines
4.4 KiB
C
/* Support for an sbrk-like function that uses mmap.
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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 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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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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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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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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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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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., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#if defined(HAVE_MMAP)
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#include <stdio.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#ifndef SEEK_SET
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#define SEEK_SET 0
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#endif
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#include "mmalloc.h"
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extern int munmap PARAMS ((caddr_t, size_t)); /* Not in any header file */
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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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elsewhere, not clutter up this file with lots of kluges to try to figure
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it out. */
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static size_t pagesize;
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extern int getpagesize PARAMS ((void));
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#define PAGE_ALIGN(addr) (caddr_t) (((long)(addr) + pagesize - 1) & \
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~(pagesize - 1))
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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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like sbrk(), but using mmap(). */
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PTR
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__mmalloc_mmap_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 = NULL;
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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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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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char buf = 0; /* Single byte to write to extend mapped file */
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if (pagesize == 0)
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{
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pagesize = getpagesize ();
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}
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if (size == 0)
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{
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/* Just return the current "break" value. */
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result = mdp -> breakval;
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}
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else if (size < 0)
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{
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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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then do nothing, and return NULL. Otherwise, deallocate the
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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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{
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result = (PTR) mdp -> breakval;
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mdp -> breakval += size;
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moveto = PAGE_ALIGN (mdp -> breakval);
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munmap (moveto, (size_t) (mdp -> top - moveto));
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mdp -> top = moveto;
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}
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}
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else
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{
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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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if (mdp -> fd < 0)
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{
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result = NULL;
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}
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else if (mdp -> breakval + size > mdp -> top)
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{
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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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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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to extend a file. */
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moveto = PAGE_ALIGN (mdp -> breakval + size);
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mapbytes = moveto - mdp -> top;
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foffset = mdp -> top - mdp -> base;
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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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write (mdp -> fd, &buf, 1);
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mapto = mmap (mdp -> top, mapbytes, PROT_READ | PROT_WRITE,
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MAP_SHARED | MAP_FIXED, mdp -> fd, foffset);
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if (mapto == mdp -> top)
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{
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mdp -> top = moveto;
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result = (PTR) mdp -> breakval;
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mdp -> breakval += size;
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}
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}
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else
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{
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result = (PTR) mdp -> breakval;
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mdp -> breakval += size;
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}
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}
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return (result);
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}
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PTR
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__mmalloc_remap_core (mdp)
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struct mdesc *mdp;
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{
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caddr_t base;
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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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PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED,
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mdp -> fd, 0);
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return ((PTR) base);
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}
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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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static char ansi_c_idiots = 69;
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#endif /* defined(HAVE_MMAP) */
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