sysdeps/mach/hurd/mmap.c

   1 /* Copyright (C) 1994,1995,1996,1997,1999,2002,2003,2004,2012
   2         Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <sys/types.h>
  21 #include <sys/mman.h>
  22 #include <errno.h>
  23 #include <hurd.h>
  24 #include <hurd/fd.h>
  25
  26 /* Map addresses starting near ADDR and extending for LEN bytes.  from
  27    OFFSET into the file FD describes according to PROT and FLAGS.  If ADDR
  28    is nonzero, it is the desired mapping address.  If the MAP_FIXED bit is
  29    set in FLAGS, the mapping will be at ADDR exactly (which must be
  30    page-aligned); otherwise the system chooses a convenient nearby address.
  31    The return value is the actual mapping address chosen or (__ptr_t) -1
  32    for errors (in which case `errno' is set).  A successful `mmap' call
  33    deallocates any previous mapping for the affected region.  */
  34
  35 __ptr_t
  36 __mmap (__ptr_t addr, size_t len, int prot, int flags, int fd, off_t offset)
  37 {
  38   error_t err;
  39   vm_prot_t vmprot;
  40   memory_object_t memobj;
  41   vm_address_t mapaddr;
  42
  43   mapaddr = (vm_address_t) addr;
  44
  45   /* ADDR and OFFSET must be page-aligned.  */
  46   if ((mapaddr & (vm_page_size - 1)) || (offset & (vm_page_size - 1)))
  47     return (__ptr_t) (long int) __hurd_fail (EINVAL);
  48
  49   if ((flags & (MAP_TYPE|MAP_INHERIT)) == MAP_ANON
  50       && prot == (PROT_READ|PROT_WRITE)) /* cf VM_PROT_DEFAULT */
  51     {
  52       /* vm_allocate has (a little) less overhead in the kernel too.  */
  53       err = __vm_allocate (__mach_task_self (), &mapaddr, len,
  54                            mapaddr == NULL);
  55
  56       if (err == KERN_NO_SPACE)
  57         {
  58           if (flags & MAP_FIXED)
  59             {
  60               /* XXX this is not atomic as it is in unix! */
  61               /* The region is already allocated; deallocate it first.  */
  62               err = __vm_deallocate (__mach_task_self (), mapaddr, len);
  63               if (!err)
  64                 err = __vm_allocate (__mach_task_self (), &mapaddr, len, 0);
  65             }
  66           else if (mapaddr != NULL)
  67             err = __vm_allocate (__mach_task_self (), &mapaddr, len, 1);
  68         }
  69
  70       return err ? (__ptr_t) (long int) __hurd_fail (err) : (__ptr_t) mapaddr;
  71     }
  72
  73   vmprot = VM_PROT_NONE;
  74   if (prot & PROT_READ)
  75     vmprot |= VM_PROT_READ;
  76   if (prot & PROT_WRITE)
  77     vmprot |= VM_PROT_WRITE;
  78   if (prot & PROT_EXEC)
  79     vmprot |= VM_PROT_EXECUTE;
  80
  81   switch (flags & MAP_TYPE)
  82     {
  83     default:
  84       return (__ptr_t) (long int) __hurd_fail (EINVAL);
  85
  86     case MAP_ANON:
  87       memobj = MACH_PORT_NULL;
  88       break;
  89
  90     case MAP_FILE:
  91     case 0:                     /* Allow, e.g., just MAP_SHARED.  */
  92       {
  93         mach_port_t robj, wobj;
  94         if (err = HURD_DPORT_USE (fd, __io_map (port, &robj, &wobj)))
  95           {
  96             if (err == MIG_BAD_ID || err == EOPNOTSUPP || err == ENOSYS)
  97               err = ENODEV;     /* File descriptor doesn't support mmap.  */
  98             return (__ptr_t) (long int) __hurd_dfail (fd, err);
  99           }
 100         switch (prot & (PROT_READ|PROT_WRITE))
 101           {
 102           case PROT_READ:
 103             memobj = robj;
 104             if (wobj != MACH_PORT_NULL)
 105               __mach_port_deallocate (__mach_task_self (), wobj);
 106             break;
 107           case PROT_WRITE:
 108             memobj = wobj;
 109             if (robj != MACH_PORT_NULL)
 110               __mach_port_deallocate (__mach_task_self (), robj);
 111             break;
 112           case PROT_READ|PROT_WRITE:
 113             if (robj == wobj)
 114               {
 115                 memobj = wobj;
 116                 /* Remove extra reference.  */
 117                 __mach_port_deallocate (__mach_task_self (), memobj);
 118               }
 119             else if (wobj == MACH_PORT_NULL && /* Not writable by mapping.  */
 120                      !(flags & MAP_SHARED))
 121               /* The file can only be mapped for reading.  Since we are
 122                  making a private mapping, we will never try to write the
 123                  object anyway, so we don't care.  */
 124               memobj = robj;
 125             else
 126               {
 127                 __mach_port_deallocate (__mach_task_self (), wobj);
 128                 return (__ptr_t) (long int) __hurd_fail (EACCES);
 129               }
 130             break;
 131           default:              /* impossible */
 132             return 0;
 133           }
 134         break;
 135         /* XXX handle MAP_NOEXTEND */
 136       }
 137     }
 138
 139   /* XXX handle MAP_INHERIT */
 140
 141   err = __vm_map (__mach_task_self (),
 142                   &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 143                   mapaddr == NULL,
 144                   memobj, (vm_offset_t) offset,
 145                   ! (flags & MAP_SHARED),
 146                   vmprot, VM_PROT_ALL,
 147                   (flags & MAP_SHARED) ? VM_INHERIT_SHARE : VM_INHERIT_COPY);
 148
 149   if (err == KERN_NO_SPACE)
 150     {
 151       if (flags & MAP_FIXED)
 152         {
 153           /* XXX this is not atomic as it is in unix! */
 154           /* The region is already allocated; deallocate it first.  */
 155           err = __vm_deallocate (__mach_task_self (), mapaddr, len);
 156           if (! err)
 157             err = __vm_map (__mach_task_self (),
 158                             &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 159                             0, memobj, (vm_offset_t) offset,
 160                             ! (flags & MAP_SHARED),
 161                             vmprot, VM_PROT_ALL,
 162                             (flags & MAP_SHARED) ? VM_INHERIT_SHARE
 163                             : VM_INHERIT_COPY);
 164         }
 165       else if (mapaddr != NULL)
 166         err = __vm_map (__mach_task_self (),
 167                         &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 168                         1, memobj, (vm_offset_t) offset,
 169                         ! (flags & MAP_SHARED),
 170                         vmprot, VM_PROT_ALL,
 171                         (flags & MAP_SHARED) ? VM_INHERIT_SHARE
 172                         : VM_INHERIT_COPY);
 173     }
 174
 175   if (memobj != MACH_PORT_NULL)
 176     __mach_port_deallocate (__mach_task_self (), memobj);
 177
 178   if (err)
 179     return (__ptr_t) (long int) __hurd_fail (err);
 180
 181   return (__ptr_t) mapaddr;
 182 }
 183
 184 weak_alias (__mmap, mmap)