Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / IO / IsolatedStorage / IsolatedStorageFileStream.cs / 1305376 / IsolatedStorageFileStream.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== /*============================================================ * * Class: IsolatedStorageFileStream // //[....] * * * Purpose: Provides access to files using the same interface as FileStream * * Date: Feb 18, 2000 * ===========================================================*/ namespace System.IO.IsolatedStorage { using System; using System.IO; using Microsoft.Win32; using Microsoft.Win32.SafeHandles; using System.Security; using System.Security.Permissions; using System.Threading; using System.Runtime.CompilerServices; using System.Runtime.InteropServices; using System.Runtime.Versioning; using System.Diagnostics.Contracts; [System.Runtime.InteropServices.ComVisible(true)] public class IsolatedStorageFileStream : FileStream { private const int s_BlockSize = 1024; // Should be a power of 2! // see usage before // changing this constant #if !FEATURE_PAL private const String s_BackSlash = "\\"; #else // s_BackSlash is initialized in the contructor with Path.DirectorySeparatorChar private readonly String s_BackSlash; #endif // !FEATURE_PAL private FileStream m_fs; private IsolatedStorageFile m_isf; private String m_GivenPath; private String m_FullPath; private bool m_OwnedStore; private IsolatedStorageFileStream() {} #if !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.AppDomain | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly, ResourceScope.AppDomain | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode) : this(path, mode, (mode == FileMode.Append ? FileAccess.Write : FileAccess.ReadWrite), FileShare.None, null) { } #endif // !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.Machine | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, IsolatedStorageFile isf) : this(path, mode, (mode == FileMode.Append ? FileAccess.Write : FileAccess.ReadWrite), FileShare.None, isf) { } #if !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.AppDomain | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly, ResourceScope.AppDomain | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access) : this(path, mode, access, access == FileAccess.Read? FileShare.Read: FileShare.None, DefaultBufferSize, null) { } #endif // !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.Machine | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, IsolatedStorageFile isf) : this(path, mode, access, access == FileAccess.Read? FileShare.Read: FileShare.None, DefaultBufferSize, isf) { } #if !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.AppDomain | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly, ResourceScope.AppDomain | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, FileShare share) : this(path, mode, access, share, DefaultBufferSize, null) { } #endif // !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.Machine | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, FileShare share, IsolatedStorageFile isf) : this(path, mode, access, share, DefaultBufferSize, isf) { } #if !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.AppDomain | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly, ResourceScope.AppDomain | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, FileShare share, int bufferSize) : this(path, mode, access, share, bufferSize, null) { } #endif // !FEATURE_ISOSTORE_LIGHT // If the isolated storage file is null, then we default to using a file // that is scoped by user, appdomain, and assembly. [System.Security.SecuritySafeCritical] // auto-generated [ResourceExposure(ResourceScope.Machine | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, FileShare share, int bufferSize, IsolatedStorageFile isf) { if (path == null) throw new ArgumentNullException("path"); Contract.EndContractBlock(); #if FEATURE_PAL if (s_BackSlash == null) s_BackSlash = new String(System.IO.Path.DirectorySeparatorChar,1); #endif // FEATURE_PAL if ((path.Length == 0) || path.Equals(s_BackSlash)) throw new ArgumentException( Environment.GetResourceString( "IsolatedStorage_Path")); ulong oldFileSize=0, newFileSize; bool fNewFile = false, fLock=false; if (isf == null) { #if FEATURE_ISOSTORE_LIGHT throw new ArgumentNullException("isf"); #else // !FEATURE_ISOSTORE_LIGHT m_OwnedStore = true; isf = IsolatedStorageFile.GetUserStoreForDomain(); #endif // !FEATURE_ISOSTORE_LIGHT } if (isf.Disposed) throw new ObjectDisposedException(null, Environment.GetResourceString("IsolatedStorage_StoreNotOpen")); m_isf = isf; FileIOPermission fiop = new FileIOPermission(FileIOPermissionAccess.AllAccess, m_isf.RootDirectory); fiop.Assert(); fiop.PermitOnly(); m_GivenPath = path; m_FullPath = m_isf.GetFullPath(m_GivenPath); RuntimeHelpers.PrepareConstrainedRegions(); try { // for finally Unlocking locked store // Cache the old file size if the file size could change // Also find if we are going to create a new file. switch (mode) { case FileMode.CreateNew: // Assume new file #if FEATURE_ISOSTORE_LIGHT // We are going to call Reserve so we need to lock the store. m_isf.Lock(ref fLock); #endif fNewFile = true; break; case FileMode.Create: // Check for New file & Unreserve case FileMode.OpenOrCreate: // Check for new file case FileMode.Truncate: // Unreserve old file size case FileMode.Append: // Check for new file m_isf.Lock(ref fLock); // oldFileSize needs to be // protected try { #if FEATURE_ISOSTORE_LIGHT oldFileSize = IsolatedStorageFile.RoundToBlockSize((ulong)(new FileInfo(m_FullPath).Length)); #else oldFileSize = IsolatedStorageFile.RoundToBlockSize((ulong)LongPathFile.GetLength(m_FullPath)); #endif } catch (FileNotFoundException) { fNewFile = true; } catch { } break; case FileMode.Open: // Open existing, else exception break; default: throw new ArgumentException( Environment.GetResourceString( "IsolatedStorage_FileOpenMode")); } if (fNewFile) m_isf.ReserveOneBlock(); try { #if FEATURE_ISOSTORE_LIGHT m_fs = new FileStream(m_FullPath, mode, access, share, bufferSize, FileOptions.None, m_GivenPath, true); #else m_fs = new FileStream(m_FullPath, mode, access, share, bufferSize, FileOptions.None, m_GivenPath, true, true); #endif } catch { if (fNewFile) m_isf.UnreserveOneBlock(); #if FEATURE_ISOSTORE_LIGHT // IsoStore generally does not let arbitrary exceptions flow out: a // IsolatedStorageException is thrown instead (see examples in IsolatedStorageFile.cs // Keeping this scoped to coreclr just because changing the exception type thrown is a // breaking change and that should not be introduced into the desktop without deliberation. throw new IsolatedStorageException(Environment.GetResourceString("IsolatedStorage_Operation_ISFS")); #else throw; #endif // FEATURE_ISOSTORE_LIGHT } // make adjustment to the Reserve / Unreserve state if ((fNewFile == false) && ((mode == FileMode.Truncate) || (mode == FileMode.Create))) { newFileSize = IsolatedStorageFile.RoundToBlockSize((ulong)m_fs.Length); if (oldFileSize > newFileSize) m_isf.Unreserve(oldFileSize - newFileSize); else if (newFileSize > oldFileSize) // Can this happen ? m_isf.Reserve(newFileSize - oldFileSize); } } finally { if (fLock) m_isf.Unlock(); } CodeAccessPermission.RevertAll(); } #if false public IsolatedStorageFileStream(IntPtr handle, FileAccess access) : this(handle, access, true, false, DefaultBufferSize) { } public IsolatedStorageFileStream(IntPtr handle, FileAccess access, bool ownsHandle) : this(handle, access, ownsHandle, false, DefaultBufferSize) { } public IsolatedStorageFileStream(IntPtr handle, FileAccess access, bool ownsHandle, bool isAsync) : this(handle, access, ownsHandle, isAsync, DefaultBufferSize) { } [SecurityPermissionAttribute(SecurityAction.Demand, Flags=SecurityPermissionFlag.UnmanagedCode)] public IsolatedStorageFileStream(IntPtr handle, FileAccess access, bool ownsHandle, bool isAsync, int bufferSize) { NotPermittedError(); } #endif public override bool CanRead { [Pure] get { return m_fs.CanRead; } } public override bool CanWrite { [Pure] get { return m_fs.CanWrite; } } public override bool CanSeek { [Pure] get { return m_fs.CanSeek; } } public override bool IsAsync { get { return m_fs.IsAsync; } } public override long Length { get { return m_fs.Length; } } public override long Position { get { return m_fs.Position; } set { if (value < 0) { throw new ArgumentOutOfRangeException("value", Environment.GetResourceString( "ArgumentOutOfRange_NeedNonNegNum")); } Contract.EndContractBlock(); Seek(value, SeekOrigin.Begin); } } #if false unsafe private static void AsyncFSCallback(uint errorCode, uint numBytes, NativeOverlapped* pOverlapped) { NotPermittedError(); } #endif protected override void Dispose(bool disposing) { try { if (disposing) { try { if (m_fs != null) m_fs.Close(); } finally { if (m_OwnedStore && m_isf != null) m_isf.Close(); } } } finally { base.Dispose(disposing); } } public override void Flush() { m_fs.Flush(); } public override void Flush(Boolean flushToDisk) { m_fs.Flush(flushToDisk); } [Obsolete("This property has been deprecated. Please use IsolatedStorageFileStream's SafeFileHandle property instead. http://go.microsoft.com/fwlink/?linkid=14202")] public override IntPtr Handle { [System.Security.SecurityCritical] // auto-generated_required [SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags=SecurityPermissionFlag.UnmanagedCode)] get { NotPermittedError(); return Win32Native.INVALID_HANDLE_VALUE; } } public override SafeFileHandle SafeFileHandle { [System.Security.SecurityCritical] // auto-generated_required [SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags=SecurityPermissionFlag.UnmanagedCode)] get { NotPermittedError(); return null; } } [System.Security.SecuritySafeCritical] // auto-generated public override void SetLength(long value) { if (value < 0) throw new ArgumentOutOfRangeException("value", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum")); Contract.EndContractBlock(); bool locked = false; RuntimeHelpers.PrepareConstrainedRegions(); try { m_isf.Lock(ref locked); // oldLen needs to be protected ulong oldLen = (ulong)m_fs.Length; ulong newLen = (ulong)value; // Reserve before the operation. m_isf.Reserve(oldLen, newLen); try { ZeroInit(oldLen, newLen); m_fs.SetLength(value); } catch { // Undo the reserve m_isf.UndoReserveOperation(oldLen, newLen); throw; } // Unreserve if this operation reduced the file size. if (oldLen > newLen) { // params oldlen, newlength reversed on purpose. m_isf.UndoReserveOperation(newLen, oldLen); } } finally { if (locked) m_isf.Unlock(); } } // 0 out the allocated disk so that // untrusted apps won't be able to read garbage, which // is a security hole, if allowed. // This may not be necessary in some file systems ? private void ZeroInit(ulong oldLen, ulong newLen) { if (oldLen >= newLen) return; ulong rem = newLen - oldLen; byte[] buffer = new byte[s_BlockSize]; // buffer is zero inited // here by the runtime // memory allocator. // back up the current position. long pos = m_fs.Position; m_fs.Seek((long)oldLen, SeekOrigin.Begin); // If we have a small number of bytes to write, do that and // we are done. if (rem <= (ulong)s_BlockSize) { m_fs.Write(buffer, 0, (int)rem); m_fs.Position = pos; return; } // Block write is better than writing a byte in a loop // or all bytes. The number of bytes to write could // be very large. // Align to block size // allign = s_BlockSize - (int)(oldLen % s_BlockSize); // Converting % to & operation since s_BlockSize is a power of 2 int allign = s_BlockSize - (int)(oldLen & ((ulong)s_BlockSize - 1)); /* this will never happen since we already handled this case leaving this code here for documentation if ((ulong)allign > rem) allign = (int)rem; */ m_fs.Write(buffer, 0, allign); rem -= (ulong)allign; int nBlocks = (int)(rem / s_BlockSize); // Write out one block at a time. for (int i=0; i[....] * * * Purpose: Provides access to files using the same interface as FileStream * * Date: Feb 18, 2000 * ===========================================================*/ namespace System.IO.IsolatedStorage { using System; using System.IO; using Microsoft.Win32; using Microsoft.Win32.SafeHandles; using System.Security; using System.Security.Permissions; using System.Threading; using System.Runtime.CompilerServices; using System.Runtime.InteropServices; using System.Runtime.Versioning; using System.Diagnostics.Contracts; [System.Runtime.InteropServices.ComVisible(true)] public class IsolatedStorageFileStream : FileStream { private const int s_BlockSize = 1024; // Should be a power of 2! // see usage before // changing this constant #if !FEATURE_PAL private const String s_BackSlash = "\\"; #else // s_BackSlash is initialized in the contructor with Path.DirectorySeparatorChar private readonly String s_BackSlash; #endif // !FEATURE_PAL private FileStream m_fs; private IsolatedStorageFile m_isf; private String m_GivenPath; private String m_FullPath; private bool m_OwnedStore; private IsolatedStorageFileStream() {} #if !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.AppDomain | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly, ResourceScope.AppDomain | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode) : this(path, mode, (mode == FileMode.Append ? FileAccess.Write : FileAccess.ReadWrite), FileShare.None, null) { } #endif // !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.Machine | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, IsolatedStorageFile isf) : this(path, mode, (mode == FileMode.Append ? FileAccess.Write : FileAccess.ReadWrite), FileShare.None, isf) { } #if !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.AppDomain | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly, ResourceScope.AppDomain | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access) : this(path, mode, access, access == FileAccess.Read? FileShare.Read: FileShare.None, DefaultBufferSize, null) { } #endif // !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.Machine | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, IsolatedStorageFile isf) : this(path, mode, access, access == FileAccess.Read? FileShare.Read: FileShare.None, DefaultBufferSize, isf) { } #if !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.AppDomain | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly, ResourceScope.AppDomain | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, FileShare share) : this(path, mode, access, share, DefaultBufferSize, null) { } #endif // !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.Machine | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, FileShare share, IsolatedStorageFile isf) : this(path, mode, access, share, DefaultBufferSize, isf) { } #if !FEATURE_ISOSTORE_LIGHT [ResourceExposure(ResourceScope.AppDomain | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly, ResourceScope.AppDomain | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, FileShare share, int bufferSize) : this(path, mode, access, share, bufferSize, null) { } #endif // !FEATURE_ISOSTORE_LIGHT // If the isolated storage file is null, then we default to using a file // that is scoped by user, appdomain, and assembly. [System.Security.SecuritySafeCritical] // auto-generated [ResourceExposure(ResourceScope.Machine | ResourceScope.Assembly)] [ResourceConsumption(ResourceScope.Machine | ResourceScope.Assembly)] public IsolatedStorageFileStream(String path, FileMode mode, FileAccess access, FileShare share, int bufferSize, IsolatedStorageFile isf) { if (path == null) throw new ArgumentNullException("path"); Contract.EndContractBlock(); #if FEATURE_PAL if (s_BackSlash == null) s_BackSlash = new String(System.IO.Path.DirectorySeparatorChar,1); #endif // FEATURE_PAL if ((path.Length == 0) || path.Equals(s_BackSlash)) throw new ArgumentException( Environment.GetResourceString( "IsolatedStorage_Path")); ulong oldFileSize=0, newFileSize; bool fNewFile = false, fLock=false; if (isf == null) { #if FEATURE_ISOSTORE_LIGHT throw new ArgumentNullException("isf"); #else // !FEATURE_ISOSTORE_LIGHT m_OwnedStore = true; isf = IsolatedStorageFile.GetUserStoreForDomain(); #endif // !FEATURE_ISOSTORE_LIGHT } if (isf.Disposed) throw new ObjectDisposedException(null, Environment.GetResourceString("IsolatedStorage_StoreNotOpen")); m_isf = isf; FileIOPermission fiop = new FileIOPermission(FileIOPermissionAccess.AllAccess, m_isf.RootDirectory); fiop.Assert(); fiop.PermitOnly(); m_GivenPath = path; m_FullPath = m_isf.GetFullPath(m_GivenPath); RuntimeHelpers.PrepareConstrainedRegions(); try { // for finally Unlocking locked store // Cache the old file size if the file size could change // Also find if we are going to create a new file. switch (mode) { case FileMode.CreateNew: // Assume new file #if FEATURE_ISOSTORE_LIGHT // We are going to call Reserve so we need to lock the store. m_isf.Lock(ref fLock); #endif fNewFile = true; break; case FileMode.Create: // Check for New file & Unreserve case FileMode.OpenOrCreate: // Check for new file case FileMode.Truncate: // Unreserve old file size case FileMode.Append: // Check for new file m_isf.Lock(ref fLock); // oldFileSize needs to be // protected try { #if FEATURE_ISOSTORE_LIGHT oldFileSize = IsolatedStorageFile.RoundToBlockSize((ulong)(new FileInfo(m_FullPath).Length)); #else oldFileSize = IsolatedStorageFile.RoundToBlockSize((ulong)LongPathFile.GetLength(m_FullPath)); #endif } catch (FileNotFoundException) { fNewFile = true; } catch { } break; case FileMode.Open: // Open existing, else exception break; default: throw new ArgumentException( Environment.GetResourceString( "IsolatedStorage_FileOpenMode")); } if (fNewFile) m_isf.ReserveOneBlock(); try { #if FEATURE_ISOSTORE_LIGHT m_fs = new FileStream(m_FullPath, mode, access, share, bufferSize, FileOptions.None, m_GivenPath, true); #else m_fs = new FileStream(m_FullPath, mode, access, share, bufferSize, FileOptions.None, m_GivenPath, true, true); #endif } catch { if (fNewFile) m_isf.UnreserveOneBlock(); #if FEATURE_ISOSTORE_LIGHT // IsoStore generally does not let arbitrary exceptions flow out: a // IsolatedStorageException is thrown instead (see examples in IsolatedStorageFile.cs // Keeping this scoped to coreclr just because changing the exception type thrown is a // breaking change and that should not be introduced into the desktop without deliberation. throw new IsolatedStorageException(Environment.GetResourceString("IsolatedStorage_Operation_ISFS")); #else throw; #endif // FEATURE_ISOSTORE_LIGHT } // make adjustment to the Reserve / Unreserve state if ((fNewFile == false) && ((mode == FileMode.Truncate) || (mode == FileMode.Create))) { newFileSize = IsolatedStorageFile.RoundToBlockSize((ulong)m_fs.Length); if (oldFileSize > newFileSize) m_isf.Unreserve(oldFileSize - newFileSize); else if (newFileSize > oldFileSize) // Can this happen ? m_isf.Reserve(newFileSize - oldFileSize); } } finally { if (fLock) m_isf.Unlock(); } CodeAccessPermission.RevertAll(); } #if false public IsolatedStorageFileStream(IntPtr handle, FileAccess access) : this(handle, access, true, false, DefaultBufferSize) { } public IsolatedStorageFileStream(IntPtr handle, FileAccess access, bool ownsHandle) : this(handle, access, ownsHandle, false, DefaultBufferSize) { } public IsolatedStorageFileStream(IntPtr handle, FileAccess access, bool ownsHandle, bool isAsync) : this(handle, access, ownsHandle, isAsync, DefaultBufferSize) { } [SecurityPermissionAttribute(SecurityAction.Demand, Flags=SecurityPermissionFlag.UnmanagedCode)] public IsolatedStorageFileStream(IntPtr handle, FileAccess access, bool ownsHandle, bool isAsync, int bufferSize) { NotPermittedError(); } #endif public override bool CanRead { [Pure] get { return m_fs.CanRead; } } public override bool CanWrite { [Pure] get { return m_fs.CanWrite; } } public override bool CanSeek { [Pure] get { return m_fs.CanSeek; } } public override bool IsAsync { get { return m_fs.IsAsync; } } public override long Length { get { return m_fs.Length; } } public override long Position { get { return m_fs.Position; } set { if (value < 0) { throw new ArgumentOutOfRangeException("value", Environment.GetResourceString( "ArgumentOutOfRange_NeedNonNegNum")); } Contract.EndContractBlock(); Seek(value, SeekOrigin.Begin); } } #if false unsafe private static void AsyncFSCallback(uint errorCode, uint numBytes, NativeOverlapped* pOverlapped) { NotPermittedError(); } #endif protected override void Dispose(bool disposing) { try { if (disposing) { try { if (m_fs != null) m_fs.Close(); } finally { if (m_OwnedStore && m_isf != null) m_isf.Close(); } } } finally { base.Dispose(disposing); } } public override void Flush() { m_fs.Flush(); } public override void Flush(Boolean flushToDisk) { m_fs.Flush(flushToDisk); } [Obsolete("This property has been deprecated. Please use IsolatedStorageFileStream's SafeFileHandle property instead. http://go.microsoft.com/fwlink/?linkid=14202")] public override IntPtr Handle { [System.Security.SecurityCritical] // auto-generated_required [SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags=SecurityPermissionFlag.UnmanagedCode)] get { NotPermittedError(); return Win32Native.INVALID_HANDLE_VALUE; } } public override SafeFileHandle SafeFileHandle { [System.Security.SecurityCritical] // auto-generated_required [SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags=SecurityPermissionFlag.UnmanagedCode)] get { NotPermittedError(); return null; } } [System.Security.SecuritySafeCritical] // auto-generated public override void SetLength(long value) { if (value < 0) throw new ArgumentOutOfRangeException("value", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum")); Contract.EndContractBlock(); bool locked = false; RuntimeHelpers.PrepareConstrainedRegions(); try { m_isf.Lock(ref locked); // oldLen needs to be protected ulong oldLen = (ulong)m_fs.Length; ulong newLen = (ulong)value; // Reserve before the operation. m_isf.Reserve(oldLen, newLen); try { ZeroInit(oldLen, newLen); m_fs.SetLength(value); } catch { // Undo the reserve m_isf.UndoReserveOperation(oldLen, newLen); throw; } // Unreserve if this operation reduced the file size. if (oldLen > newLen) { // params oldlen, newlength reversed on purpose. m_isf.UndoReserveOperation(newLen, oldLen); } } finally { if (locked) m_isf.Unlock(); } } // 0 out the allocated disk so that // untrusted apps won't be able to read garbage, which // is a security hole, if allowed. // This may not be necessary in some file systems ? private void ZeroInit(ulong oldLen, ulong newLen) { if (oldLen >= newLen) return; ulong rem = newLen - oldLen; byte[] buffer = new byte[s_BlockSize]; // buffer is zero inited // here by the runtime // memory allocator. // back up the current position. long pos = m_fs.Position; m_fs.Seek((long)oldLen, SeekOrigin.Begin); // If we have a small number of bytes to write, do that and // we are done. if (rem <= (ulong)s_BlockSize) { m_fs.Write(buffer, 0, (int)rem); m_fs.Position = pos; return; } // Block write is better than writing a byte in a loop // or all bytes. The number of bytes to write could // be very large. // Align to block size // allign = s_BlockSize - (int)(oldLen % s_BlockSize); // Converting % to & operation since s_BlockSize is a power of 2 int allign = s_BlockSize - (int)(oldLen & ((ulong)s_BlockSize - 1)); /* this will never happen since we already handled this case leaving this code here for documentation if ((ulong)allign > rem) allign = (int)rem; */ m_fs.Write(buffer, 0, allign); rem -= (ulong)allign; int nBlocks = (int)(rem / s_BlockSize); // Write out one block at a time. for (int i=0; i
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