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/* Copyright (C) 2008-2016 Peter Palotas, Jeffrey Jangli, Alexandr Normuradov
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Security;
namespace Alphaleonis.Win32.Filesystem
{
public static partial class File
{
#region Public Methods
/// <summary>Determines whether the specified file exists.</summary>
/// <remarks>
/// <para>MSDN: .NET 3.5+: Trailing spaces are removed from the end of the
/// <paramref name="path"/> parameter before checking whether the directory exists.</para>
/// <para>The Exists method returns <see langword="false"/> if any error occurs while trying to
/// determine if the specified file exists.</para>
/// <para>This can occur in situations that raise exceptions such as passing a file name with
/// invalid characters or too many characters, a failing or missing disk, or if the caller does not have permission to read the
/// file.</para>
/// <para>The Exists method should not be used for path validation,
/// this method merely checks if the file specified in path exists.</para>
/// <para>Passing an invalid path to Exists returns false.</para>
/// <para>Be aware that another process can potentially do something with the file in
/// between the time you call the Exists method and perform another operation on the file, such as Delete.</para>
/// </remarks>
/// <param name="path">The file to check.</param>
/// <returns>
/// Returns <see langword="true"/> if the caller has the required permissions and
/// <paramref name="path"/> contains the name of an existing file; otherwise,
/// <see langword="false"/>
/// </returns>
[SecurityCritical]
public static bool Exists(string path)
{
return ExistsCore(false, null, path, PathFormat.RelativePath);
}
/// <summary>[AlphaFS] Determines whether the specified file exists.</summary>
/// <remarks>
/// <para>MSDN: .NET 3.5+: Trailing spaces are removed from the end of the
/// <paramref name="path"/> parameter before checking whether the directory exists.</para>
/// <para>The Exists method returns <see langword="false"/> if any error occurs while trying to
/// determine if the specified file exists.</para>
/// <para>This can occur in situations that raise exceptions such as passing a file name with
/// invalid characters or too many characters,</para>
/// <para>a failing or missing disk, or if the caller does not have permission to read the
/// file.</para>
/// <para>The Exists method should not be used for path validation, this method merely checks
/// if the file specified in path exists.</para>
/// <para>Passing an invalid path to Exists returns false.</para>
/// <para>Be aware that another process can potentially do something with the file in
/// between the time you call the Exists method and perform another operation on the file, such
/// as Delete.</para>
/// </remarks>
/// <param name="path">The file to check.</param>
/// <param name="pathFormat">Indicates the format of the path parameter(s).</param>
/// <returns>
/// <para>Returns <see langword="true"/> if the caller has the required permissions and
/// <paramref name="path"/> contains the name of an existing file; otherwise,
/// <see langword="false"/></para>
/// </returns>
[SecurityCritical]
public static bool Exists(string path, PathFormat pathFormat)
{
return ExistsCore(false, null, path, pathFormat);
}
#region Transactional
/// <summary>
/// [AlphaFS] Determines whether the specified file exists.
/// </summary>
/// <remarks>
/// <para>MSDN: .NET 3.5+: Trailing spaces are removed from the end of the
/// <paramref name="path"/> parameter before checking whether the directory exists.</para>
/// <para>The Exists method returns <see langword="false"/> if any error occurs while trying to
/// determine if the specified file exists.</para>
/// <para>This can occur in situations that raise exceptions such as passing a file name with
/// invalid characters or too many characters,</para>
/// <para>a failing or missing disk, or if the caller does not have permission to read the
/// file.</para>
/// <para>The Exists method should not be used for path validation,</para>
/// <para>this method merely checks if the file specified in path exists.</para>
/// <para>Passing an invalid path to Exists returns false.</para>
/// <para>Be aware that another process can potentially do something with the file in
/// between</para>
/// <para>the time you call the Exists method and perform another operation on the file, such
/// as Delete.</para>
/// </remarks>
/// <param name="transaction">The transaction.</param>
/// <param name="path">The file to check.</param>
/// <returns>
/// <para>Returns <see langword="true"/> if the caller has the required permissions</para>
/// <para>and <paramref name="path"/> contains the name of an existing file; otherwise,
/// <see langword="false"/></para>
/// </returns>
[SecurityCritical]
public static bool ExistsTransacted(KernelTransaction transaction, string path)
{
return ExistsCore(false, transaction, path, PathFormat.RelativePath);
}
/// <summary>
/// [AlphaFS] Determines whether the specified file exists.
/// </summary>
/// <remarks>
/// <para>MSDN: .NET 3.5+: Trailing spaces are removed from the end of the
/// <paramref name="path"/> parameter before checking whether the directory exists.</para>
/// <para>The Exists method returns <see langword="false"/> if any error occurs while trying to
/// determine if the specified file exists.</para>
/// <para>This can occur in situations that raise exceptions such as passing a file name with
/// invalid characters or too many characters,</para>
/// <para>a failing or missing disk, or if the caller does not have permission to read the
/// file.</para>
/// <para>The Exists method should not be used for path validation,</para>
/// <para>this method merely checks if the file specified in path exists.</para>
/// <para>Passing an invalid path to Exists returns false.</para>
/// <para>Be aware that another process can potentially do something with the file in
/// between</para>
/// <para>the time you call the Exists method and perform another operation on the file, such
/// as Delete.</para>
/// </remarks>
/// <param name="transaction">The transaction.</param>
/// <param name="path">The file to check.</param>
/// <param name="pathFormat">Indicates the format of the path parameter(s).</param>
/// <returns>
/// <para>Returns <see langword="true"/> if the caller has the required permissions</para>
/// <para>and <paramref name="path"/> contains the name of an existing file; otherwise,
/// <see langword="false"/></para>
/// </returns>
[SecurityCritical]
public static bool ExistsTransacted(KernelTransaction transaction, string path, PathFormat pathFormat)
{
return ExistsCore(false, transaction, path, pathFormat);
}
#endregion // Transacted
#endregion
#region Internal Methods
/// <summary>Determines whether the specified file or directory exists.</summary>
/// <remarks>
/// <para>MSDN: .NET 3.5+: Trailing spaces are removed from the end of the <paramref name="path"/> parameter before checking whether
/// the directory exists.</para>
/// <para>The Exists method returns <see langword="false"/> if any error occurs while trying to determine if the specified file
/// exists.</para>
/// <para>This can occur in situations that raise exceptions such as passing a file name with invalid characters or too many characters,
/// </para>
/// <para>a failing or missing disk, or if the caller does not have permission to read the file.</para>
/// <para>The Exists method should not be used for path validation,
/// this method merely checks if the file specified in path exists.</para>
/// <para>Passing an invalid path to Exists returns false.</para>
/// <para>Be aware that another process can potentially do something with the file in between
/// the time you call the Exists method and perform another operation on the file, such as Delete.</para>
/// </remarks>
/// <param name="isFolder">Specifies that <paramref name="path"/> is a file or directory.</param>
/// <param name="transaction">The transaction.</param>
/// <param name="path">The file to check.</param>
/// <param name="pathFormat">Indicates the format of the path parameter(s).</param>
/// <returns>
/// <para>Returns <see langword="true"/> if the caller has the required permissions</para>
/// <para>and <paramref name="path"/> contains the name of an existing file or directory; otherwise, <see langword="false"/></para>
/// </returns>
[SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes")]
[SecurityCritical]
internal static bool ExistsCore(bool isFolder, KernelTransaction transaction, string path, PathFormat pathFormat)
{
// Will be caught later and be thrown as an ArgumentException or ArgumentNullException.
// Let's take a shorter route, preventing an Exception from being thrown altogether.
if (Utils.IsNullOrWhiteSpace(path))
return false;
// DriveInfo.IsReady() will fail.
//
//// After normalizing, check whether path ends in directory separator.
//// Otherwise, FillAttributeInfoCore removes it and we may return a false positive.
//string pathRp = Path.GetRegularPathCore(path, true, false, false, false);
//if (pathRp.Length > 0 && Path.IsDVsc(pathRp[pathRp.Length - 1], false))
// return false;
try
{
string pathLp = Path.GetExtendedLengthPathCore(transaction, path, pathFormat, GetFullPathOptions.TrimEnd | GetFullPathOptions.RemoveTrailingDirectorySeparator | GetFullPathOptions.CheckInvalidPathChars | GetFullPathOptions.ContinueOnNonExist);
var data = new NativeMethods.WIN32_FILE_ATTRIBUTE_DATA();
int dataInitialised = FillAttributeInfoCore(transaction, pathLp, ref data, false, true);
return (dataInitialised == Win32Errors.ERROR_SUCCESS &&
data.dwFileAttributes != (FileAttributes) (-1) &&
(isFolder
? (data.dwFileAttributes & FileAttributes.Directory) != 0
: (data.dwFileAttributes & FileAttributes.Directory) == 0));
}
catch
{
return false;
}
}
#endregion // Internal Methods
}
}