sysdeps/mach/hurd/mmap.c

   1 /* Copyright (C) 1994-2014 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <sys/types.h>
  19 #include <sys/mman.h>
  20 #include <errno.h>
  21 #include <hurd.h>
  22 #include <hurd/fd.h>
  23
  24 /* Map addresses starting near ADDR and extending for LEN bytes.  from
  25    OFFSET into the file FD describes according to PROT and FLAGS.  If ADDR
  26    is nonzero, it is the desired mapping address.  If the MAP_FIXED bit is
  27    set in FLAGS, the mapping will be at ADDR exactly (which must be
  28    page-aligned); otherwise the system chooses a convenient nearby address.
  29    The return value is the actual mapping address chosen or (__ptr_t) -1
  30    for errors (in which case `errno' is set).  A successful `mmap' call
  31    deallocates any previous mapping for the affected region.  */
  32
  33 __ptr_t
  34 __mmap (__ptr_t addr, size_t len, int prot, int flags, int fd, off_t offset)
  35 {
  36   error_t err;
  37   vm_prot_t vmprot;
  38   memory_object_t memobj;
  39   vm_address_t mapaddr;
  40
  41   mapaddr = (vm_address_t) addr;
  42
  43   /* ADDR and OFFSET must be page-aligned.  */
  44   if ((mapaddr & (vm_page_size - 1)) || (offset & (vm_page_size - 1)))
  45     return (__ptr_t) (long int) __hurd_fail (EINVAL);
  46
  47   if ((flags & (MAP_TYPE|MAP_INHERIT)) == MAP_ANON
  48       && prot == (PROT_READ|PROT_WRITE)) /* cf VM_PROT_DEFAULT */
  49     {
  50       /* vm_allocate has (a little) less overhead in the kernel too.  */
  51       err = __vm_allocate (__mach_task_self (), &mapaddr, len,
  52                            mapaddr == NULL);
  53
  54       if (err == KERN_NO_SPACE)
  55         {
  56           if (flags & MAP_FIXED)
  57             {
  58               /* XXX this is not atomic as it is in unix! */
  59               /* The region is already allocated; deallocate it first.  */
  60               err = __vm_deallocate (__mach_task_self (), mapaddr, len);
  61               if (!err)
  62                 err = __vm_allocate (__mach_task_self (), &mapaddr, len, 0);
  63             }
  64           else if (mapaddr != NULL)
  65             err = __vm_allocate (__mach_task_self (), &mapaddr, len, 1);
  66         }
  67
  68       return err ? (__ptr_t) (long int) __hurd_fail (err) : (__ptr_t) mapaddr;
  69     }
  70
  71   vmprot = VM_PROT_NONE;
  72   if (prot & PROT_READ)
  73     vmprot |= VM_PROT_READ;
  74   if (prot & PROT_WRITE)
  75     vmprot |= VM_PROT_WRITE;
  76   if (prot & PROT_EXEC)
  77     vmprot |= VM_PROT_EXECUTE;
  78
  79   switch (flags & MAP_TYPE)
  80     {
  81     default:
  82       return (__ptr_t) (long int) __hurd_fail (EINVAL);
  83
  84     case MAP_ANON:
  85       memobj = MACH_PORT_NULL;
  86       break;
  87
  88     case MAP_FILE:
  89     case 0:                     /* Allow, e.g., just MAP_SHARED.  */
  90       {
  91         mach_port_t robj, wobj;
  92         if (err = HURD_DPORT_USE (fd, __io_map (port, &robj, &wobj)))
  93           {
  94             if (err == MIG_BAD_ID || err == EOPNOTSUPP || err == ENOSYS)
  95               err = ENODEV;     /* File descriptor doesn't support mmap.  */
  96             return (__ptr_t) (long int) __hurd_dfail (fd, err);
  97           }
  98         switch (prot & (PROT_READ|PROT_WRITE))
  99           {
 100           case PROT_READ:
 101             memobj = robj;
 102             if (wobj != MACH_PORT_NULL)
 103               __mach_port_deallocate (__mach_task_self (), wobj);
 104             break;
 105           case PROT_WRITE:
 106             memobj = wobj;
 107             if (robj != MACH_PORT_NULL)
 108               __mach_port_deallocate (__mach_task_self (), robj);
 109             break;
 110           case PROT_READ|PROT_WRITE:
 111             if (robj == wobj)
 112               {
 113                 memobj = wobj;
 114                 /* Remove extra reference.  */
 115                 __mach_port_deallocate (__mach_task_self (), memobj);
 116               }
 117             else if (wobj == MACH_PORT_NULL && /* Not writable by mapping.  */
 118                      !(flags & MAP_SHARED))
 119               /* The file can only be mapped for reading.  Since we are
 120                  making a private mapping, we will never try to write the
 121                  object anyway, so we don't care.  */
 122               memobj = robj;
 123             else
 124               {
 125                 __mach_port_deallocate (__mach_task_self (), wobj);
 126                 return (__ptr_t) (long int) __hurd_fail (EACCES);
 127               }
 128             break;
 129           default:              /* impossible */
 130             return 0;
 131           }
 132         break;
 133         /* XXX handle MAP_NOEXTEND */
 134       }
 135     }
 136
 137   /* XXX handle MAP_INHERIT */
 138
 139   err = __vm_map (__mach_task_self (),
 140                   &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 141                   mapaddr == NULL,
 142                   memobj, (vm_offset_t) offset,
 143                   ! (flags & MAP_SHARED),
 144                   vmprot, VM_PROT_ALL,
 145                   (flags & MAP_SHARED) ? VM_INHERIT_SHARE : VM_INHERIT_COPY);
 146
 147   if (err == KERN_NO_SPACE)
 148     {
 149       if (flags & MAP_FIXED)
 150         {
 151           /* XXX this is not atomic as it is in unix! */
 152           /* The region is already allocated; deallocate it first.  */
 153           err = __vm_deallocate (__mach_task_self (), mapaddr, len);
 154           if (! err)
 155             err = __vm_map (__mach_task_self (),
 156                             &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 157                             0, memobj, (vm_offset_t) offset,
 158                             ! (flags & MAP_SHARED),
 159                             vmprot, VM_PROT_ALL,
 160                             (flags & MAP_SHARED) ? VM_INHERIT_SHARE
 161                             : VM_INHERIT_COPY);
 162         }
 163       else if (mapaddr != NULL)
 164         err = __vm_map (__mach_task_self (),
 165                         &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 166                         1, memobj, (vm_offset_t) offset,
 167                         ! (flags & MAP_SHARED),
 168                         vmprot, VM_PROT_ALL,
 169                         (flags & MAP_SHARED) ? VM_INHERIT_SHARE
 170                         : VM_INHERIT_COPY);
 171     }
 172
 173   if (memobj != MACH_PORT_NULL)
 174     __mach_port_deallocate (__mach_task_self (), memobj);
 175
 176   if (err)
 177     return (__ptr_t) (long int) __hurd_fail (err);
 178
 179   return (__ptr_t) mapaddr;
 180 }
 181
 182 weak_alias (__mmap, mmap)