ZipFile UnixCreateSetsPermissionsInExternalAttributes test fails on Apple OSes (#69583)

* ZipFile UnixCreateSetsPermissionsInExternalAttributes test fails on Apple OSes

There are scenarios where chmod succeeds, but the OS clears certain bits, like S_ISGID and S_ISUID. When this happens, the ZipFile tests fail because the .zip file doesn't contain the expected ExternalAttributes.

To fix this, read the file mode after calling chmod, and update the expected file mode so the tests still pass.

Fix #68293
Fix #60581

* Fix the tests to expect the correct file name

Author: eerhardt

src/libraries/System.IO.Compression.ZipFile/tests/ZipFile.Unix.cs

@@ -12,26 +12,21 @@ namespace System.IO.Compression.Tests
     public partial class ZipFile_Unix : ZipFileTestBase
     {
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/68293", TestPlatforms.OSX)]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/60581", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
         public void UnixCreateSetsPermissionsInExternalAttributes()
         {
             // '7600' tests that S_ISUID, S_ISGID, and S_ISVTX bits get preserved in ExternalAttributes
             string[] testPermissions = new[] { "777", "755", "644", "600", "7600" };
 
             using (var tempFolder = new TempDirectory(Path.Combine(GetTestFilePath(), "testFolder")))
             {
-                foreach (string permission in testPermissions)
-                {
-                    CreateFile(tempFolder.Path, permission);
-                }
+                string[] expectedPermissions = CreateFiles(tempFolder.Path, testPermissions);
 
                 string archivePath = GetTestFilePath();
                 ZipFile.CreateFromDirectory(tempFolder.Path, archivePath);
 
                 using (ZipArchive archive = ZipFile.OpenRead(archivePath))
                 {
-                    Assert.Equal(5, archive.Entries.Count);
+                    Assert.Equal(expectedPermissions.Length, archive.Entries.Count);
 
                     foreach (ZipArchiveEntry entry in archive.Entries)
                     {
@@ -50,7 +45,7 @@ void EnsureExternalAttributes(string permissions, ZipArchiveEntry entry)
                 {
                     ZipFile.ExtractToDirectory(archivePath, extractFolder.Path);
 
-                    foreach (string permission in testPermissions)
+                    foreach (string permission in expectedPermissions)
                     {
                         string filename = Path.Combine(extractFolder.Path, permission + ".txt");
                         Assert.True(File.Exists(filename));
@@ -96,12 +91,38 @@ public void UnixExtractSetsFilePermissionsFromExternalAttributes()
             }
         }
 
-        private static void CreateFile(string folderPath, string permissions)
+        private static string[] CreateFiles(string folderPath, string[] testPermissions)
         {
-            string filename = Path.Combine(folderPath, $"{permissions}.txt");
-            File.WriteAllText(filename, "contents");
+            string[] expectedPermissions = new string[testPermissions.Length];
+
+            for (int i = 0; i < testPermissions.Length; i++)
+            {
+                string permissions =  testPermissions[i];
+                string filename = Path.Combine(folderPath, $"{permissions}.txt");
+                File.WriteAllText(filename, "contents");
+
+                Assert.Equal(0, Interop.Sys.ChMod(filename, Convert.ToInt32(permissions, 8)));
+
+                // In some environments, the file mode may be modified by the OS.
+                // See the Rationale section of https://linux.die.net/man/3/chmod.
 
-            Assert.Equal(0, Interop.Sys.ChMod(filename, Convert.ToInt32(permissions, 8)));
+                // To workaround this, read the file mode back, and if it has changed, update the file name
+                // since the name is used to compare the file mode.
+                Interop.Sys.FileStatus status;
+                Assert.Equal(0, Interop.Sys.Stat(filename, out status));
+                string updatedPermissions = Convert.ToString(status.Mode & 0xFFF, 8);
+                if (updatedPermissions != permissions)
+                {
+                    string newFileName = Path.Combine(folderPath, $"{updatedPermissions}.txt");
+                    File.Move(filename, newFileName);
+
+                    permissions = updatedPermissions;
+                }
+
+                expectedPermissions[i] = permissions;
+            }
+
+            return expectedPermissions;
         }
 
         private static void EnsureFilePermissions(string filename, string permissions)