2 // MemoryMappedViewStream.cs
5 // Zoltan Varga (vargaz@gmail.com)
7 // Copyright (C) 2009, Novell, Inc (http://www.novell.com)
9 // Permission is hereby granted, free of charge, to any person obtaining
10 // a copy of this software and associated documentation files (the
11 // "Software"), to deal in the Software without restriction, including
12 // without limitation the rights to use, copy, modify, merge, publish,
13 // distribute, sublicense, and/or sell copies of the Software, and to
14 // permit persons to whom the Software is furnished to do so, subject to
15 // the following conditions:
17 // The above copyright notice and this permission notice shall be
18 // included in all copies or substantial portions of the Software.
20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
33 using Mono.Unix.Native;
35 namespace System.IO.MemoryMappedFiles
37 public sealed class MemoryMappedViewStream : UnmanagedMemoryStream {
45 internal MemoryMappedViewStream (FileStream file, long offset, long size, MemoryMappedFileAccess access) {
46 monitor = new Object ();
47 if (Environment.OSVersion.Platform < PlatformID.Unix)
48 throw new NotImplementedException ("Not implemented on windows.");
50 CreateStreamPosix (file, offset, size, access);
53 unsafe void CreateStreamPosix (FileStream file, long offset, long size, MemoryMappedFileAccess access) {
55 pagesize = Syscall.getpagesize ();
57 long fsize = file.Length;
59 if (size == 0 || size > fsize)
63 long real_offset = offset & ~(pagesize - 1);
65 int offset_diff = (int)(offset - real_offset);
67 // FIXME: Need to determine the unix fd for the file, Handle is only
68 // equal to it by accident
69 mmap_size = (ulong)size;
70 mmap_addr = Syscall.mmap (IntPtr.Zero, mmap_size, MmapProts.PROT_READ, MmapFlags.MAP_SHARED, (int)file.Handle, real_offset);
71 if (mmap_addr == (IntPtr)(-1))
72 throw new IOException ("mmap failed for " + file + "(" + offset + ", " + size + ")");
77 case MemoryMappedFileAccess.ReadWrite:
78 faccess = FileAccess.ReadWrite;
80 case MemoryMappedFileAccess.Read:
81 faccess = FileAccess.Read;
83 case MemoryMappedFileAccess.Write:
84 faccess = FileAccess.Write;
87 throw new NotImplementedException ("access mode " + access + " not supported.");
89 Initialize ((byte*)mmap_addr + offset_diff, size, size, faccess);
92 protected override void Dispose (bool disposing)
94 base.Dispose (disposing);
96 if (mmap_addr != (IntPtr)(-1)) {
97 int err = Syscall.munmap (mmap_addr, mmap_size);
99 /* This shouldn't happen */
100 throw new IOException ("munmap failed for address " + mmap_addr + ", size=" + mmap_size);
101 mmap_addr = (IntPtr)(-1);