--- /dev/null
+/* Support for an sbrk-like function that uses mmap.
+ 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. */
+
+#if defined(HAVE_MMAP)
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h> /* Prototypes for lseek */
+#endif
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+
+#ifndef SEEK_SET
+#define SEEK_SET 0
+#endif
+
+#include "mmprivate.h"
+
+/* Cache the pagesize for the current host machine. Note that if the host
+ does not readily provide a getpagesize() function, we need to emulate it
+ elsewhere, not clutter up this file with lots of kluges to try to figure
+ it out. */
+
+static size_t pagesize;
+#if NEED_DECLARATION_GETPAGESIZE
+extern int getpagesize PARAMS ((void));
+#endif
+
+#define PAGE_ALIGN(addr) (PTR) (((long)(addr) + pagesize - 1) & \
+ ~(pagesize - 1))
+
+/* Return MAP_PRIVATE if MDP represents /dev/zero. Otherwise, return
+ MAP_SHARED. */
+
+#define MAP_PRIVATE_OR_SHARED(MDP) ((MDP -> flags & MMALLOC_DEVZERO) \
+ ? MAP_PRIVATE \
+ : MAP_SHARED)
+
+/* Return MAP_ANONYMOUS if MDP uses anonymous mapping. Otherwise, return 0 */
+
+#define MAP_IS_ANONYMOUS(MDP) (((MDP) -> flags & MMALLOC_ANONYMOUS) \
+ ? MAP_ANONYMOUS \
+ : 0)
+
+/* Return -1 if MDP uses anonymous mapping. Otherwise, return MDP->FD */
+#define MAP_ANON_OR_FD(MDP) (((MDP) -> flags & MMALLOC_ANONYMOUS) \
+ ? -1 \
+ : (MDP) -> fd)
+
+/* Get core for the memory region specified by MDP, using SIZE as the
+ amount to either add to or subtract from the existing region. Works
+ like sbrk(), but using mmap(). */
+
+PTR
+__mmalloc_mmap_morecore (mdp, size)
+ struct mdesc *mdp;
+ int size;
+{
+ PTR result = NULL;
+ off_t foffset; /* File offset at which new mapping will start */
+ size_t mapbytes; /* Number of bytes to map */
+ PTR moveto; /* Address where we wish to move "break value" to */
+ PTR mapto; /* Address we actually mapped to */
+ char buf = 0; /* Single byte to write to extend mapped file */
+
+ if (pagesize == 0)
+ pagesize = getpagesize();
+
+ if (size == 0)
+ {
+ /* Just return the current "break" value. */
+ result = mdp -> breakval;
+ }
+ else if (size < 0)
+ {
+ /* We are deallocating memory. If the amount requested would cause
+ us to try to deallocate back past the base of the mmap'd region
+ then do nothing, and return NULL. Otherwise, deallocate the
+ memory and return the old break value. */
+ if (mdp -> breakval + size >= mdp -> base)
+ {
+ result = (PTR) mdp -> breakval;
+ mdp -> breakval += size;
+ moveto = PAGE_ALIGN (mdp -> breakval);
+ munmap (moveto, (size_t) (mdp -> top - moveto) - 1);
+ mdp -> top = moveto;
+ }
+ }
+ else
+ {
+ /* We are allocating memory. Make sure we have an open file
+ descriptor if not working with anonymous memory. */
+ if ( !(mdp->flags & MMALLOC_ANONYMOUS) && mdp -> fd < 0)
+ {
+ result = NULL;
+ }
+ else if (mdp -> breakval + size > mdp -> top)
+ {
+ /* The request would move us past the end of the currently
+ mapped memory, so map in enough more memory to satisfy
+ the request. This means we also have to grow the mapped-to
+ file by an appropriate amount, since mmap cannot be used
+ to extend a file. */
+ moveto = PAGE_ALIGN (mdp -> breakval + size);
+ mapbytes = moveto - mdp -> top;
+ foffset = mdp -> top - mdp -> base;
+
+ if( mdp -> fd > 0){
+ /* FIXME: Test results of lseek() and write() */
+ lseek (mdp -> fd, foffset + mapbytes - 1, SEEK_SET);
+ write (mdp -> fd, &buf, 1);
+ }
+
+ /* Let's call mmap. Note that it is possible that mdp->top
+ is 0. In this case mmap will choose the address for us */
+ mapto = mmap (mdp->top, mapbytes, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE_OR_SHARED(mdp) | MAP_IS_ANONYMOUS(mdp) | MAP_FIXED,
+ MAP_ANON_OR_FD(mdp), foffset);
+
+ if (mapto != (PTR) -1){
+
+ if(mdp -> top == 0)
+ mdp -> base = mdp -> breakval = mapto;
+
+ mdp -> top = PAGE_ALIGN (mdp -> breakval + size);
+ result = (PTR) mdp -> breakval;
+ mdp -> breakval += size;
+ }
+ }
+ else
+ {
+ result = (PTR) mdp -> breakval;
+ mdp -> breakval += size;
+ }
+ }
+ return (result);
+}
+
+PTR
+__mmalloc_remap_core (mdp)
+ struct mdesc *mdp;
+{
+ PTR base;
+
+ /* FIXME: Quick hack, needs error checking and other attention. */
+
+ base = mmap (mdp -> base, mdp -> top - mdp -> base,
+ PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE_OR_SHARED (mdp) | MAP_FIXED,
+ mdp -> fd, 0);
+ return ((PTR) base);
+}
+
+PTR
+mmalloc_findbase (size)
+ int size;
+{
+ int fd;
+ int flags;
+ PTR base = NULL;
+
+#ifdef MAP_ANONYMOUS
+ flags = MAP_PRIVATE | MAP_ANONYMOUS;
+ fd = -1;
+#else
+#ifdef MAP_FILE
+ flags = MAP_PRIVATE | MAP_FILE;
+#else
+ flags = MAP_PRIVATE;
+#endif
+ fd = open ("/dev/zero", O_RDWR);
+ if (fd != -1)
+ {
+ return ((PTR) NULL);
+ }
+#endif
+ base = mmap (0, size, PROT_READ | PROT_WRITE, flags, fd, 0);
+ if (base != (PTR) -1)
+ {
+ munmap (base, (size_t) size);
+ }
+ if (fd != -1)
+ {
+ close (fd);
+ }
+ if (base == 0)
+ {
+ /* Don't allow mapping at address zero. We use that value
+ to signal an error return, and besides, it is useful to
+ catch NULL pointers if it is unmapped. Instead start
+ at the next page boundary. */
+ base = (PTR) getpagesize ();
+ }
+ else if (base == (PTR) -1)
+ {
+ base = NULL;
+ }
+ return ((PTR) base);
+}
+
+#else /* defined(HAVE_MMAP) */
+/* Prevent "empty translation unit" warnings from the idiots at X3J11. */
+static char ansi_c_idiots = 69;
+#endif /* defined(HAVE_MMAP) */
