Handle escaping in Unix file enumeration (#20784)

* Handle escaping in Unix file enumeration

We try and align with Windows, so we'll escape out [ and /.

Adds a bunch of tests and issues for other cases that we don't
match Windows behavior.

* Clarify comments, move one case

For completeness I ran everything through RtlIsNameInExpression to
validate the "correct" results. I've commented appropriately.

I moved one test to the "normal" block that I misplaced.

* Optimize the escaping a bit

* Improve perf further

* Whoops, miscopied

* More feedback

Author: JeremyKuhne

src/System.IO.FileSystem/src/System/IO/UnixFileSystem.cs

@@ -504,6 +504,21 @@ internal FileSystemEnumerable(
                         }
                         searchPattern = searchPattern.Substring(lastSlash + 1);
                     }
+
+                    // Typically we shouldn't see either of these cases, an upfront check is much faster
+                    foreach (char c in searchPattern)
+                    {
+                        if (c == '\\' || c == '[')
+                        {
+                            // We need to escape any escape characters in the search pattern
+                            searchPattern = searchPattern.Replace(@"\", @"\\");
+
+                            // And then escape '[' to prevent it being picked up as a wildcard
+                            searchPattern = searchPattern.Replace(@"[", @"\[");
+                            break;
+                        }
+                    }
+
                     string fullPath = Path.GetFullPath(userPath);
 
                     // Store everything for the enumerator
@@ -638,6 +653,7 @@ private static string NormalizeSearchPattern(string searchPattern)
                 {
                     searchPattern += "*";
                 }
+
                 return searchPattern;
             }
 

src/System.IO.FileSystem/tests/Directory/GetFileSystemEntries_str.cs

@@ -20,6 +20,17 @@ public virtual string[] GetEntries(string dirName)
             return Directory.GetFileSystemEntries(dirName);
         }
 
+        /// <summary>
+        /// Create a file at the given path or directory if GetEntries doesn't return files
+        /// </summary>
+        protected void CreateItem(string path)
+        {
+            if (TestFiles)
+                File.WriteAllText(path, path);
+            else
+                Directory.CreateDirectory(path);
+        }
+
         #endregion
 
         #region UniversalTests