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Tar: restore directory permissions while extracting. (#72078)
* Tar: restore directory permissions while extracting. * PR feedback. * On Windows, as on Unix: don't set group/other write permission by default. * Fix Windows compilation. * Fix Windows compilation II. * Update test for Windows. * Fix test WindowsFileMode value. * Remove branch. * Apply suggestions from code review Co-authored-by: Eric Erhardt <[email protected]> * Add back DefaultWindowsMode. * Fix build failure in TarWriter due to DefaultWindowsMode usage. * Fix DefaultWindowsMode. * Apply suggestions from code review Co-authored-by: Carlos Sanchez <[email protected]> Co-authored-by: Eric Erhardt <[email protected]> Co-authored-by: Carlos Sanchez <[email protected]>
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149 changes: 149 additions & 0 deletions
149
src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarHelpers.Unix.cs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,149 @@ | ||
| // Licensed to the .NET Foundation under one or more agreements. | ||
| // The .NET Foundation licenses this file to you under the MIT license. | ||
|
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| using System.Collections.Generic; | ||
| using System.IO; | ||
| using System.Diagnostics; | ||
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| namespace System.Formats.Tar | ||
| { | ||
| internal static partial class TarHelpers | ||
| { | ||
| private static readonly Lazy<UnixFileMode> s_umask = new Lazy<UnixFileMode>(DetermineUMask); | ||
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| private static UnixFileMode DetermineUMask() | ||
| { | ||
| // To determine the umask, we'll create a file with full permissions and see | ||
| // what gets filtered out. | ||
| // note: only the owner of a file, and root can change file permissions. | ||
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| const UnixFileMode OwnershipPermissions = | ||
| UnixFileMode.UserRead | UnixFileMode.UserWrite | UnixFileMode.UserExecute | | ||
| UnixFileMode.GroupRead | UnixFileMode.GroupWrite | UnixFileMode.GroupExecute | | ||
| UnixFileMode.OtherRead | UnixFileMode.OtherWrite | UnixFileMode.OtherExecute; | ||
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| string filename = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName()); | ||
| FileStreamOptions options = new() | ||
| { | ||
| Mode = FileMode.CreateNew, | ||
| UnixCreateMode = OwnershipPermissions, | ||
| Options = FileOptions.DeleteOnClose, | ||
| Access = FileAccess.Write, | ||
| BufferSize = 0 | ||
| }; | ||
| using var fs = new FileStream(filename, options); | ||
| UnixFileMode actual = File.GetUnixFileMode(fs.SafeFileHandle); | ||
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| return OwnershipPermissions & ~actual; | ||
| } | ||
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| private sealed class ReverseStringComparer : IComparer<string> | ||
| { | ||
| public int Compare (string? x, string? y) | ||
| => StringComparer.Ordinal.Compare(y, x); | ||
| } | ||
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| private static readonly ReverseStringComparer s_reverseStringComparer = new(); | ||
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| private static UnixFileMode UMask => s_umask.Value; | ||
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| /* | ||
| Tar files are usually ordered: parent directories come before their child entries. | ||
| They may be unordered. In that case we need to create parent directories before | ||
| we know the proper permissions for these directories. | ||
| We create these directories with restrictive permissions. If we encounter an entry for | ||
| the directory later, we store the mode to apply it later. | ||
| If the archive doesn't have an entry for the parent directory, we use the default mask. | ||
| The pending modes to be applied are tracked through a reverse-sorted dictionary. | ||
| The reverse order is needed to apply permissions to children before their parent. | ||
| Otherwise we may apply a restrictive mask to the parent, that prevents us from | ||
| changing a child. | ||
| */ | ||
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| internal static SortedDictionary<string, UnixFileMode>? CreatePendingModesDictionary() | ||
| => new SortedDictionary<string, UnixFileMode>(s_reverseStringComparer); | ||
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| internal static void CreateDirectory(string fullPath, UnixFileMode? mode, bool overwriteMetadata, SortedDictionary<string, UnixFileMode>? pendingModes) | ||
| { | ||
| // Restrictive mask for creating the missing parent directories while extracting. | ||
| const UnixFileMode ExtractPermissions = UnixFileMode.UserRead | UnixFileMode.UserWrite | UnixFileMode.UserExecute; | ||
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| Debug.Assert(pendingModes is not null); | ||
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| if (Directory.Exists(fullPath)) | ||
| { | ||
| // Apply permissions to an existing directory when we're overwriting metadata | ||
| // or the directory was created as a missing parent (stored in pendingModes). | ||
| if (mode.HasValue) | ||
| { | ||
| bool hasExtractPermissions = (mode.Value & ExtractPermissions) == ExtractPermissions; | ||
| if (hasExtractPermissions) | ||
| { | ||
| bool removed = pendingModes.Remove(fullPath); | ||
| if (overwriteMetadata || removed) | ||
| { | ||
| UnixFileMode umask = UMask; | ||
| File.SetUnixFileMode(fullPath, mode.Value & ~umask); | ||
| } | ||
| } | ||
| else if (overwriteMetadata || pendingModes.ContainsKey(fullPath)) | ||
| { | ||
| pendingModes[fullPath] = mode.Value; | ||
| } | ||
| } | ||
| return; | ||
| } | ||
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| if (mode.HasValue) | ||
| { | ||
| // Ensure we have sufficient permissions to extract in the directory. | ||
| if ((mode.Value & ExtractPermissions) != ExtractPermissions) | ||
| { | ||
| pendingModes[fullPath] = mode.Value; | ||
| mode = ExtractPermissions; | ||
| } | ||
| } | ||
| else | ||
| { | ||
| pendingModes.Add(fullPath, DefaultDirectoryMode); | ||
| mode = ExtractPermissions; | ||
| } | ||
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| string parentDir = Path.GetDirectoryName(fullPath)!; | ||
| string rootDir = Path.GetPathRoot(parentDir)!; | ||
| bool hasMissingParents = false; | ||
| for (string dir = parentDir; dir != rootDir && !Directory.Exists(dir); dir = Path.GetDirectoryName(dir)!) | ||
| { | ||
| pendingModes.Add(dir, DefaultDirectoryMode); | ||
| hasMissingParents = true; | ||
| } | ||
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| if (hasMissingParents) | ||
| { | ||
| Directory.CreateDirectory(parentDir, ExtractPermissions); | ||
| } | ||
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| Directory.CreateDirectory(fullPath, mode.Value); | ||
| } | ||
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| internal static void SetPendingModes(SortedDictionary<string, UnixFileMode>? pendingModes) | ||
| { | ||
| Debug.Assert(pendingModes is not null); | ||
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| if (pendingModes.Count == 0) | ||
| { | ||
| return; | ||
| } | ||
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| UnixFileMode umask = UMask; | ||
| foreach (KeyValuePair<string, UnixFileMode> dir in pendingModes) | ||
| { | ||
| File.SetUnixFileMode(dir.Key, dir.Value & ~umask); | ||
| } | ||
| } | ||
| } | ||
| } |
22 changes: 22 additions & 0 deletions
22
src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarHelpers.Windows.cs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,22 @@ | ||
| // Licensed to the .NET Foundation under one or more agreements. | ||
| // The .NET Foundation licenses this file to you under the MIT license. | ||
|
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| using System.Collections.Generic; | ||
| using System.IO; | ||
| using System.Text; | ||
| using System.Diagnostics; | ||
|
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| namespace System.Formats.Tar | ||
| { | ||
| internal static partial class TarHelpers | ||
| { | ||
| internal static SortedDictionary<string, UnixFileMode>? CreatePendingModesDictionary() | ||
| => null; | ||
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| internal static void CreateDirectory(string fullPath, UnixFileMode? mode, bool overwriteMetadata, SortedDictionary<string, UnixFileMode>? pendingModes) | ||
| => Directory.CreateDirectory(fullPath); | ||
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| internal static void SetPendingModes(SortedDictionary<string, UnixFileMode>? pendingModes) | ||
| => Debug.Assert(pendingModes is null); | ||
| } | ||
| } |
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