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Use PosixFileStream for files on POSIX #1855

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Use PosixFileStream for files on POSIX #1855

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86adef5
Use PosixFileStream for files on POSIX
BCSharp Dec 30, 2024
64d0d4a
Improve non-buffering strategy for FileStream
BCSharp Dec 31, 2024
1cf9ac6
Ignore OSException along with IOException
BCSharp Jan 1, 2025
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2 changes: 1 addition & 1 deletion Src/IronPython.Modules/_warnings.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -260,7 +260,7 @@ internal static void showwarning(CodeContext context, object message, PythonType
((TextWriter)file).Write(text);
} // unrecognized file type - warning is lost
}
} catch (IOException) {
} catch (Exception ex) when (ex is IOException or OSException) {
// invalid file - warning is lost
}
}
Expand Down
130 changes: 101 additions & 29 deletions Src/IronPython.Modules/mmap.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Serialization;
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System.Runtime.Serialization is VS trying to be helpful?

using System.Runtime.Versioning;
using System.Text;
using System.Threading;

Expand All @@ -24,6 +26,7 @@
using IronPython.Runtime.Types;

using Microsoft.Scripting.Utils;
using Microsoft.Win32.SafeHandles;

[assembly: PythonModule("mmap", typeof(IronPython.Modules.MmapModule))]
namespace IronPython.Modules {
Expand Down Expand Up @@ -92,6 +95,7 @@ public class MmapDefault : IWeakReferenceable {
private readonly long _offset;
private readonly string _mapName;
private readonly MemoryMappedFileAccess _fileAccess;
private readonly SafeFileHandle _handle; // only used on some POSIX platforms, null otherwise

private volatile bool _isClosed;
private int _refCount = 1;
Expand Down Expand Up @@ -148,46 +152,65 @@ public MmapDefault(CodeContext/*!*/ context, int fileno, long length, string tag

PythonContext pContext = context.LanguageContext;
if (pContext.FileManager.TryGetStreams(fileno, out StreamBox streams)) {
if ((_sourceStream = streams.ReadStream as FileStream) == null) {
throw WindowsError(PythonExceptions._OSError.ERROR_INVALID_HANDLE);
Stream stream = streams.ReadStream;
if (stream is FileStream fs) {
_sourceStream = fs;
} else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX) || RuntimeInformation.IsOSPlatform(OSPlatform.Linux)) {
// use file descriptor
#if NET8_0_OR_GREATER
CheckFileAccess(_fileAccess, stream);
_handle = new SafeFileHandle((IntPtr)fileno, ownsHandle: false);
_file = MemoryMappedFile.CreateFromFile(_handle, _mapName, length, _fileAccess, HandleInheritability.None, leaveOpen: true);
#else
_handle = new SafeFileHandle((IntPtr)fileno, ownsHandle: false);
FileAccess fileAccess = stream.CanWrite ? stream.CanRead ? FileAccess.ReadWrite : FileAccess.Write : FileAccess.Read;
// This may or may not work on Mono, but on Mono streams.ReadStream is FileStream (unless dupped in some cases)
_sourceStream = new FileStream(_handle, fileAccess);
#endif
}
// otherwise leaves _file as null and _sourceStream as null
} else {
throw PythonOps.OSError(PythonExceptions._OSError.ERROR_INVALID_BLOCK, "Bad file descriptor");
}

if (_fileAccess == MemoryMappedFileAccess.ReadWrite && !_sourceStream.CanWrite) {
throw WindowsError(PythonExceptions._OSError.ERROR_ACCESS_DENIED);
}
if (_file is null) {
// create _file form _sourceStream
if (_sourceStream is null) {
throw WindowsError(PythonExceptions._OSError.ERROR_INVALID_HANDLE);
}

CheckFileAccess(_fileAccess, _sourceStream);

if (length == 0) {
length = _sourceStream.Length;
if (length == 0) {
throw PythonOps.ValueError("cannot mmap an empty file");
}
if (_offset >= length) {
throw PythonOps.ValueError("mmap offset is greater than file size");
length = _sourceStream.Length;
if (length == 0) {
throw PythonOps.ValueError("cannot mmap an empty file");
}
if (_offset >= length) {
throw PythonOps.ValueError("mmap offset is greater than file size");
}
length -= _offset;
}
length -= _offset;
}

long capacity = checked(_offset + length);
long capacity = checked(_offset + length);

// Enlarge the file as needed.
if (capacity > _sourceStream.Length) {
if (_sourceStream.CanWrite) {
_sourceStream.SetLength(capacity);
} else {
throw WindowsError(PythonExceptions._OSError.ERROR_NOT_ENOUGH_MEMORY);
// Enlarge the file as needed.
if (capacity > _sourceStream.Length) {
if (_sourceStream.CanWrite) {
_sourceStream.SetLength(capacity);
} else {
throw WindowsError(PythonExceptions._OSError.ERROR_NOT_ENOUGH_MEMORY);
}
}
}

_file = CreateFromFile(
_sourceStream,
_mapName,
_sourceStream.Length,
_fileAccess,
HandleInheritability.None,
true);
_file = CreateFromFile(
_sourceStream,
_mapName,
_sourceStream.Length,
_fileAccess,
HandleInheritability.None,
true);
}
}

try {
Expand All @@ -198,7 +221,24 @@ public MmapDefault(CodeContext/*!*/ context, int fileno, long length, string tag
throw;
}
_position = 0L;
}

void CheckFileAccess(MemoryMappedFileAccess mmapAccess, Stream stream) {
bool isValid = mmapAccess switch {
MemoryMappedFileAccess.Read => stream.CanRead,
MemoryMappedFileAccess.ReadWrite => stream.CanRead && stream.CanWrite,
MemoryMappedFileAccess.CopyOnWrite => stream.CanRead,
_ => false
};

if (!isValid) {
if (_handle is not null && _sourceStream is not null) {
_sourceStream.Dispose();
}
throw PythonOps.OSError(PythonExceptions._OSError.ERROR_ACCESS_DENIED, "Invalid access mode");
}
}
} // end of constructor


public object __len__() {
using (new MmapLocker(this)) {
Expand Down Expand Up @@ -325,6 +365,11 @@ private void CloseWorker() {
_view.Flush();
_view.Dispose();
_file.Dispose();
if (_handle is not null) {
// mmap owns _sourceStream too in this case
_sourceStream?.Dispose();
_handle.Dispose();
}
_sourceStream = null;
_view = null;
_file = null;
Expand Down Expand Up @@ -557,6 +602,11 @@ public void resize(long newsize) {
}

if (_sourceStream == null) {
if (_handle is not null && !_handle.IsInvalid
&& (RuntimeInformation.IsOSPlatform(OSPlatform.OSX) || RuntimeInformation.IsOSPlatform(OSPlatform.Linux))) {
// resize on Posix platforms
PythonNT.ftruncateUnix(unchecked((int)_handle.DangerousGetHandle()), newsize);
}
// resizing is not supported without an underlying file
throw WindowsError(PythonExceptions._OSError.ERROR_INVALID_PARAMETER);
}
Expand Down Expand Up @@ -716,6 +766,9 @@ public void seek(long pos, int whence = SEEK_SET) {

public object size() {
using (new MmapLocker(this)) {
if (_handle is not null && (RuntimeInformation.IsOSPlatform(OSPlatform.OSX) || RuntimeInformation.IsOSPlatform(OSPlatform.Linux))) {
return GetFileSizeUnix(_handle);
}
if (_sourceStream == null) return ReturnLong(_view.Capacity);
return ReturnLong(new FileInfo(_sourceStream.Name).Length);
}
Expand Down Expand Up @@ -830,6 +883,25 @@ internal Bytes GetSearchString() {
}
}

[SupportedOSPlatform("linux"), SupportedOSPlatform("macos")]
private static long GetFileSizeUnix(SafeFileHandle handle) {
long size;
if (handle.IsInvalid) {
throw PythonOps.OSError(PythonExceptions._OSError.ERROR_INVALID_HANDLE, "Invalid file handle");
}

if (Mono.Unix.Native.Syscall.fstat((int)handle.DangerousGetHandle(), out Mono.Unix.Native.Stat status) == 0) {
size = status.st_size;
} else {
Mono.Unix.Native.Errno errno = Mono.Unix.Native.Stdlib.GetLastError();
string msg = Mono.Unix.UnixMarshal.GetErrorDescription(errno);
int error = Mono.Unix.Native.NativeConvert.FromErrno(errno);
throw PythonOps.OSError(error, msg);
}

return size;
}

#endregion

#region Synchronization
Expand Down
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