sysdeps/mach/hurd/mmap.c

   1 /* Copyright (C) 1994, 1995, 1996, 1997 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 (caddr_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 caddr_t
  35 __mmap (caddr_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   pageoff = offset & (vm_page_size - 1);
  44   offset &= ~(vm_page_size - 1);
  45
  46   mapaddr = (vm_address_t) addr;
  47   if (flags & MAP_FIXED)
  48     {
  49       /* A specific address is requested.  It need not be page-aligned;
  50          it just needs to be congruent with the object offset.  */
  51       if ((mapaddr & (vm_page_size - 1)) != pageoff)
  52         return (caddr_t) (long int) __hurd_fail (EINVAL);
  53       else
  54         /* We will add back PAGEOFF after mapping.  */
  55         mapaddr -= pageoff;
  56     }
  57
  58   vmprot = VM_PROT_NONE;
  59   if (prot & PROT_READ)
  60     vmprot |= VM_PROT_READ;
  61   if (prot & PROT_WRITE)
  62     vmprot |= VM_PROT_WRITE;
  63   if (prot & PROT_EXEC)
  64     vmprot |= VM_PROT_EXECUTE;
  65
  66   switch (flags & MAP_TYPE)
  67     {
  68     default:
  69       return (caddr_t) (long int) __hurd_fail (EINVAL);
  70
  71     case MAP_ANON:
  72       memobj = MACH_PORT_NULL;
  73       break;
  74
  75     case MAP_FILE:
  76     case 0:                     /* Allow, e.g., just MAP_SHARED.  */
  77       {
  78         mach_port_t robj, wobj;
  79         if (err = HURD_DPORT_USE (fd, __io_map (port, &robj, &wobj)))
  80           return (caddr_t) (long int) __hurd_dfail (fd, err);
  81         switch (prot & (PROT_READ|PROT_WRITE))
  82           {
  83           case PROT_READ:
  84             memobj = robj;
  85             if (wobj != MACH_PORT_NULL)
  86               __mach_port_deallocate (__mach_task_self (), wobj);
  87             break;
  88           case PROT_WRITE:
  89             memobj = wobj;
  90             if (robj != MACH_PORT_NULL)
  91               __mach_port_deallocate (__mach_task_self (), robj);
  92             break;
  93           case PROT_READ|PROT_WRITE:
  94             if (robj == wobj)
  95               {
  96                 memobj = wobj;
  97                 /* Remove extra reference.  */
  98                 __mach_port_deallocate (__mach_task_self (), memobj);
  99               }
 100             else if (wobj == MACH_PORT_NULL && /* Not writable by mapping.  */
 101                      !(flags & MAP_SHARED))
 102               /* The file can only be mapped for reading.  Since we are
 103                  making a private mapping, we will never try to write the
 104                  object anyway, so we don't care.  */
 105               memobj = robj;
 106             else
 107               {
 108                 __mach_port_deallocate (__mach_task_self (), wobj);
 109                 return (caddr_t) (long int) __hurd_fail (EACCES);
 110               }
 111             break;
 112           }
 113         break;
 114         /* XXX handle MAP_NOEXTEND */
 115       }
 116     }
 117
 118   /* XXX handle MAP_INHERIT */
 119
 120   err = __vm_map (__mach_task_self (),
 121                   &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 122                   ! (flags & MAP_FIXED),
 123                   memobj, (vm_offset_t) offset,
 124                   ! (flags & MAP_SHARED),
 125                   vmprot, VM_PROT_ALL,
 126                   (flags & MAP_SHARED) ? VM_INHERIT_SHARE : VM_INHERIT_COPY);
 127
 128   if (err == KERN_NO_SPACE && (flags & MAP_FIXED))
 129     {
 130       /* XXX this is not atomic as it is in unix! */
 131       /* The region is already allocated; deallocate it first.  */
 132       err = __vm_deallocate (__mach_task_self (), mapaddr, len);
 133       if (! err)
 134         err = __vm_map (__mach_task_self (),
 135                         &mapaddr, (vm_size_t) len, (vm_address_t) 0,
 136                         0, memobj, (vm_offset_t) offset,
 137                         ! (flags & MAP_SHARED),
 138                         vmprot, VM_PROT_ALL,
 139                         (flags & MAP_SHARED) ? VM_INHERIT_SHARE
 140                         : VM_INHERIT_COPY);
 141     }
 142
 143   if (memobj != MACH_PORT_NULL)
 144     __mach_port_deallocate (__mach_task_self (), memobj);
 145
 146   if (err)
 147     return (caddr_t) (long int) __hurd_fail (err);
 148
 149   /* Adjust the mapping address for the offset-within-page.  */
 150   mapaddr += pageoff;
 151
 152   return (caddr_t) mapaddr;
 153 }
 154
 155 weak_alias (__mmap, mmap)