sysdeps/mach/hurd/mmap.c

   1 /* Copyright (C) 1994, 1995, 1996, 1997, 1999 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <sys/types.h>
  20 #include <sys/mman.h>
  21 #include <errno.h>
  22 #include <hurd.h>
  23 #include <hurd/fd.h>
  24
  25 /* Map addresses starting near ADDR and extending for LEN bytes.  from
  26    OFFSET into the file FD describes according to PROT and FLAGS.  If ADDR
  27    is nonzero, it is the desired mapping address.  If the MAP_FIXED bit is
  28    set in FLAGS, the mapping will be at ADDR exactly (which must be
  29    page-aligned); otherwise the system chooses a convenient nearby address.
  30    The return value is the actual mapping address chosen or (__ptr_t) -1
  31    for errors (in which case `errno' is set).  A successful `mmap' call
  32    deallocates any previous mapping for the affected region.  */
  33
  34 __ptr_t
  35 __mmap (__ptr_t addr, size_t len, int prot, int flags, int fd, off_t offset)
  36 {
  37   error_t err;
  38   vm_prot_t vmprot;
  39   memory_object_t memobj;
  40   vm_address_t mapaddr;
  41   vm_size_t pageoff;
  42
  43   mapaddr = (vm_address_t) addr;
  44
  45   if ((flags & (MAP_TYPE|MAP_INHERIT)) == MAP_ANON
  46       && prot == (PROT_READ|PROT_WRITE)) /* cf VM_PROT_DEFAULT */
  47     {
  48       /* vm_allocate has (a little) less overhead in the kernel too.  */
  49       err = __vm_allocate (__mach_task_self (), &mapaddr, len,
  50                            !(flags & MAP_FIXED));
  51
  52       if (err == KERN_NO_SPACE && (flags & MAP_FIXED))
  53         {
  54           /* XXX this is not atomic as it is in unix! */
  55           /* The region is already allocated; deallocate it first.  */
  56           err = __vm_deallocate (__mach_task_self (), mapaddr, len);
  57           if (!err)
  58             err = __vm_allocate (__mach_task_self (), &mapaddr, len, 0);
  59         }
  60
  61       return err ? (__ptr_t) (long int) __hurd_fail (err) : (__ptr_t) mapaddr;
  62     }
  63
  64   pageoff = offset & (vm_page_size - 1);
  65   offset &= ~(vm_page_size - 1);
  66
  67   if (flags & MAP_FIXED)
  68     {
  69       /* A specific address is requested.  It need not be page-aligned;
  70          it just needs to be congruent with the object offset.  */
  71       if ((mapaddr & (vm_page_size - 1)) != pageoff)
  72         return (__ptr_t) (long int) __hurd_fail (EINVAL);
  73       else
  74         /* We will add back PAGEOFF after mapping.  */
  75         mapaddr -= pageoff;
  76     }
  77
  78   vmprot = VM_PROT_NONE;
  79   if (prot & PROT_READ)
  80     vmprot |= VM_PROT_READ;
  81   if (prot & PROT_WRITE)
  82     vmprot |= VM_PROT_WRITE;
  83   if (prot & PROT_EXEC)
  84     vmprot |= VM_PROT_EXECUTE;
  85
  86   switch (flags & MAP_TYPE)
  87     {
  88     default:
  89       return (__ptr_t) (long int) __hurd_fail (EINVAL);
  90
  91     case MAP_ANON:
  92       memobj = MACH_PORT_NULL;
  93       break;
  94
  95     case MAP_FILE:
  96     case 0:                     /* Allow, e.g., just MAP_SHARED.  */
  97       {
  98         mach_port_t robj, wobj;
  99         if (err = HURD_DPORT_USE (fd, __io_map (port, &robj, &wobj)))
 100           return (__ptr_t) (long int) __hurd_dfail (fd, err);
 101         switch (prot & (PROT_READ|PROT_WRITE))
 102           {
 103           case PROT_READ:
 104             memobj = robj;
 105             if (wobj != MACH_PORT_NULL)
 106               __mach_port_deallocate (__mach_task_self (), wobj);
 107             break;
 108           case PROT_WRITE:
 109             memobj = wobj;
 110             if (robj != MACH_PORT_NULL)
 111               __mach_port_deallocate (__mach_task_self (), robj);
 112             break;
 113           case PROT_READ|PROT_WRITE:
 114             if (robj == wobj)
 115               {
 116                 memobj = wobj;
 117                 /* Remove extra reference.  */
 118                 __mach_port_deallocate (__mach_task_self (), memobj);
 119               }
 120             else if (wobj == MACH_PORT_NULL && /* Not writable by mapping.  */
 121                      !(flags & MAP_SHARED))
 122               /* The file can only be mapped for reading.  Since we are
 123                  making a private mapping, we will never try to write the
 124                  object anyway, so we don't care.  */
 125               memobj = robj;
 126             else
 127               {
 128                 __mach_port_deallocate (__mach_task_self (), wobj);
 129                 return (__ptr_t) (long int) __hurd_fail (EACCES);
 130               }
 131             break;
 132           }
 133         break;
 134         /* XXX handle MAP_NOEXTEND */
 135       }
 136     }
 137
 138   /* XXX handle MAP_INHERIT */
 139
 140   err = __vm_map (__mach_task_self (),
 141                   &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 142                   ! (flags & MAP_FIXED),
 143                   memobj, (vm_offset_t) offset,
 144                   ! (flags & MAP_SHARED),
 145                   vmprot, VM_PROT_ALL,
 146                   (flags & MAP_SHARED) ? VM_INHERIT_SHARE : VM_INHERIT_COPY);
 147
 148   if (err == KERN_NO_SPACE && (flags & MAP_FIXED))
 149     {
 150       /* XXX this is not atomic as it is in unix! */
 151       /* The region is already allocated; deallocate it first.  */
 152       err = __vm_deallocate (__mach_task_self (), mapaddr, len);
 153       if (! err)
 154         err = __vm_map (__mach_task_self (),
 155                         &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 156                         0, memobj, (vm_offset_t) offset,
 157                         ! (flags & MAP_SHARED),
 158                         vmprot, VM_PROT_ALL,
 159                         (flags & MAP_SHARED) ? VM_INHERIT_SHARE
 160                         : VM_INHERIT_COPY);
 161     }
 162
 163   if (memobj != MACH_PORT_NULL)
 164     __mach_port_deallocate (__mach_task_self (), memobj);
 165
 166   if (err)
 167     return (__ptr_t) (long int) __hurd_fail (err);
 168
 169   /* Adjust the mapping address for the offset-within-page.  */
 170   mapaddr += pageoff;
 171
 172   return (__ptr_t) mapaddr;
 173 }
 174
 175 weak_alias (__mmap, mmap)