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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/mach/hurd/brk.c
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initial import
Diffstat (limited to 'sysdeps/mach/hurd/brk.c')
-rw-r--r--sysdeps/mach/hurd/brk.c130
1 files changed, 130 insertions, 0 deletions
diff --git a/sysdeps/mach/hurd/brk.c b/sysdeps/mach/hurd/brk.c
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+++ b/sysdeps/mach/hurd/brk.c
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+/* Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
+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., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <ansidecl.h>
+#include <errno.h>
+#include <hurd.h>
+#include <hurd/resource.h>
+#include <cthreads.h> /* For `struct mutex'. */
+
+
+/* Initial maximum size of the data segment (32MB, which is arbitrary). */
+#define DATA_SIZE (32 * 1024 * 1024)
+
+
+/* Up to the page including this address is allocated from the kernel.
+ This address is the data resource limit. */
+vm_address_t _hurd_data_end;
+
+/* Up to this address is actually available to the user.
+ Pages beyond the one containing this address allow no access. */
+vm_address_t _hurd_brk;
+
+struct mutex _hurd_brk_lock;
+
+extern int __data_start, _end;
+
+
+/* Set the end of the process's data space to INADDR.
+ Return 0 if successful, -1 if not. */
+int
+DEFUN(__brk, (inaddr), PTR inaddr)
+{
+ int ret;
+ HURD_CRITICAL_BEGIN;
+ __mutex_lock (&_hurd_brk_lock);
+ ret = _hurd_set_brk ((vm_address_t) inaddr);
+ __mutex_unlock (&_hurd_brk_lock);
+ HURD_CRITICAL_END;
+ return ret;
+}
+weak_alias (__brk, brk)
+
+
+int
+_hurd_set_brk (vm_address_t addr)
+{
+ error_t err;
+ vm_address_t pagend = round_page (addr);
+ vm_address_t pagebrk = round_page (_hurd_brk);
+ long int rlimit;
+
+ if (pagend <= pagebrk)
+ {
+ if (pagend < pagebrk)
+ /* Make that memory inaccessible. */
+ __vm_protect (__mach_task_self (), pagend, pagebrk - pagend,
+ 0, VM_PROT_NONE);
+ _hurd_brk = addr;
+ return 0;
+ }
+
+ __mutex_lock (&_hurd_rlimit_lock);
+ rlimit = _hurd_rlimits[RLIMIT_DATA].rlim_cur;
+ __mutex_unlock (&_hurd_rlimit_lock);
+
+ if (addr - (vm_address_t) &__data_start > rlimit)
+ {
+ /* Need to increase the resource limit. */
+ errno = ENOMEM;
+ return -1;
+ }
+
+ /* Make the memory accessible. */
+ if (err = __vm_protect (__mach_task_self (), pagebrk, pagend - pagebrk,
+ 0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE))
+ {
+ errno = err;
+ return -1;
+ }
+
+ _hurd_brk = addr;
+ return 0;
+}
+
+static void
+init_brk (void)
+{
+ vm_address_t pagend;
+
+ __mutex_init (&_hurd_brk_lock);
+
+ /* If _hurd_brk is already set, don't change it. The assumption is that
+ it was set in a previous run before something like Emacs's unexec was
+ called and dumped all the data up to the break at that point. */
+ if (_hurd_brk == 0)
+ _hurd_brk = (vm_address_t) &_end;
+
+ pagend = round_page (_hurd_brk);
+
+ _hurd_data_end = (vm_address_t) &__data_start + DATA_SIZE;
+
+ if (pagend < _hurd_data_end)
+ {
+ /* We use vm_map to allocate and change permissions atomically. */
+ if (__vm_map (__mach_task_self (), &pagend, _hurd_data_end - pagend,
+ 0, 0, MACH_PORT_NULL, 0, 0,
+ 0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE,
+ VM_INHERIT_COPY))
+ /* Couldn't allocate the memory. The break will be very short. */
+ _hurd_data_end = pagend;
+ }
+
+ (void) &init_brk; /* Avoid ``defined but not used'' warning. */
+}
+text_set_element (_hurd_preinit_hook, init_brk);