我最近需要枚举一个整个文件系统,寻找特定类型的文件进行审计.由于对要扫描的文件系统的权限有限,这导致我遇到了几个例外.其中最流行的是
UnauthorizedAccessException,对我的懊恼,PathTooLongException.
这些通常不会是一个问题,除了它们使IEnumerable无效,阻止我无法完成扫描.
解决方法
为了解决这个问题,我创建了一个替换文件系统枚举器.虽然它可能不完美,但它执行得相当快,并且陷入了我遇到的两个例外.它会找到与传递给它的搜索模式匹配的任何目录或文件.
// This code is public domain
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using log4net;
public class FileSystemEnumerable : IEnumerable<FileSystemInfo>
{
private ILog _logger = LogManager.GetLogger(typeof(FileSystemEnumerable));
private readonly DirectoryInfo _root;
private readonly IList<string> _patterns;
private readonly SearchOption _option;
public FileSystemEnumerable(DirectoryInfo root,string pattern,SearchOption option)
{
_root = root;
_patterns = new List<string> { pattern };
_option = option;
}
public FileSystemEnumerable(DirectoryInfo root,IList<string> patterns,SearchOption option)
{
_root = root;
_patterns = patterns;
_option = option;
}
public IEnumerator<FileSystemInfo> GetEnumerator()
{
if (_root == null || !_root.Exists) yield break;
IEnumerable<FileSystemInfo> matches = new List<FileSystemInfo>();
try
{
_logger.DebugFormat("Attempting to enumerate '{0}'",_root.FullName);
foreach (var pattern in _patterns)
{
_logger.DebugFormat("Using pattern '{0}'",pattern);
matches = matches.Concat(_root.EnumerateDirectories(pattern,SearchOption.TopDirectoryOnly))
.Concat(_root.EnumerateFiles(pattern,SearchOption.TopDirectoryOnly));
}
}
catch (UnauthorizedAccessException)
{
_logger.WarnFormat("Unable to access '{0}'. Skipping...",_root.FullName);
yield break;
}
catch (PathTooLongException ptle)
{
_logger.Warn(string.Format(@"Could not process path '{0}\{1}'.",_root.Parent.FullName,_root.Name),ptle);
yield break;
} catch (System.IO.IOException e)
{
// "The symbolic link cannot be followed because its type is disabled."
// "The specified network name is no longer available."
_logger.Warn(string.Format(@"Could not process path (check SymlinkEvaluation rules)'{0}\{1}'.",e);
yield break;
}
_logger.DebugFormat("Returning all objects that match the pattern(s) '{0}'",string.Join(",",_patterns));
foreach (var file in matches)
{
yield return file;
}
if (_option == SearchOption.AllDirectories)
{
_logger.DebugFormat("Enumerating all child directories.");
foreach (var dir in _root.EnumerateDirectories("*",SearchOption.TopDirectoryOnly))
{
_logger.DebugFormat("Enumerating '{0}'",dir.FullName);
var fileSystemInfos = new FileSystemEnumerable(dir,_patterns,_option);
foreach (var match in fileSystemInfos)
{
yield return match;
}
}
}
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
}
用法相当简单.
//This code is public domain var root = new DirectoryInfo(@"c:\wherever"); var searchPattern = @"*.txt"; var searchOption = SearchOption.AllDirectories; var enumerable = new FileSystemEnumerable(root,searchPattern,searchOption);
人们可以自由使用它,如果他们觉得有用.
