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Implement syscall ioctl #1903

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Merged
merged 3 commits into from
Feb 5, 2025
Merged

Implement syscall ioctl #1903

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fa6799b
Implement syscall `ioctl`
BCSharp Feb 3, 2025
ddd210e
Simplify by avoiding unmanaged memory allocation
BCSharp Feb 4, 2025
42244b4
Accept `str` as argument to `fcntl` and `ioctl`
BCSharp Feb 4, 2025
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209 changes: 173 additions & 36 deletions src/core/IronPython.Modules/fcntl.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,11 +5,13 @@
#nullable enable

using System;
using System.Buffers;
using System.Diagnostics;
using System.Numerics;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Text;

using Mono.Unix;
using Mono.Unix.Native;
Expand Down Expand Up @@ -77,15 +79,13 @@ public static object fcntl(int fd, int cmd, [NotNone] Bytes arg) {
public static object fcntl(int fd, int cmd, [Optional] object? arg) {
CheckFileDescriptor(fd);

long data = arg switch {
Missing => 0,
int i => i,
uint ui => ui,
long l => l,
ulong ul => (long)ul,
BigInteger bi => (long)bi,
Extensible<BigInteger> ebi => (long)ebi.Value,
_ => throw PythonOps.TypeErrorForBadInstance("integer argument expected, got {0}", arg)
if (!TryGetInt64(arg, out long data)) {
return arg switch {
Bytes bytes => fcntl(fd, cmd, bytes),
string s => fcntl(fd, cmd, Bytes.Make(Encoding.UTF8.GetBytes(s))),
Extensible<string> es => fcntl(fd, cmd, Bytes.Make(Encoding.UTF8.GetBytes(es.Value))),
_ => throw PythonOps.TypeErrorForBadInstance("integer or bytes argument expected, got {0}", arg)
};
};

if (!NativeConvert.TryToFcntlCommand(cmd, out FcntlCommand fcntlCommand)) {
Expand All @@ -106,47 +106,164 @@ public static object fcntl(int fd, int cmd, [Optional] object? arg) {


[LightThrowing]
public static object fcntl(CodeContext context, object? fd, int cmd, object? arg = null) {
int fileno = GetFileDescriptor(context, fd);
public static object fcntl(CodeContext context, object? fd, int cmd, [Optional] object? arg)
=> fcntl(GetFileDescriptor(context, fd), cmd, arg);

#endregion


#region ioctl

// The actual signature of ioctl is
//
// int ioctl(int, unsigned long, ...)
//
// but .NET, as of Jan 2025, still does not support varargs in P/Invoke [1]
// so as a workaround, nonvararg prototypes are defined for each architecture.
// [1]: https://github.com/dotnet/runtime/issues/48796

#if NET10_0_OR_GREATER
#error Check if this version of .NET supports P/Invoke of variadic functions; if not, change the condition to recheck at next major .NET version
#endif

[DllImport("libc", SetLastError = true, EntryPoint = "ioctl")]
private static extern unsafe int _ioctl(int fd, ulong request, void* arg);
[DllImport("libc", SetLastError = true, EntryPoint = "ioctl")]
private static extern int _ioctl(int fd, ulong request, long arg);

[DllImport("libc", SetLastError = true, EntryPoint = "ioctl")]
private static extern unsafe int _ioctl_arm64(int fd, ulong request,
// pad register arguments (first 8) to force vararg on stack
// ARM: https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#appendix-variable-argument-lists
// Apple: https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms
nint r2, nint r3, nint r4, nint r5, nint r6, nint r7,
void* arg);
[DllImport("libc", SetLastError = true, EntryPoint = "ioctl")]
private static extern int _ioctl_arm64(int fd, ulong request,
nint r2, nint r3, nint r4, nint r5, nint r6, nint r7,
long arg);


// request will be int, uint or BigInteger, and in Python is limited to values that can fit in 32 bits (unchecked)
// long should capture all allowed request values
// return value is int, bytes, or LightException
[LightThrowing]
public static object ioctl(int fd, long request, [NotNone] IBufferProtocol arg, bool mutate_flag = true) {
CheckFileDescriptor(fd);

ulong cmd = unchecked((ulong)request);

if (arg is Bytes bytes) {
return fcntl(fileno, cmd, bytes);
const int defaultBufSize = 1024;
int bufSize;
IPythonBuffer? buf = null;

if (mutate_flag) {
buf = arg.GetBufferNoThrow(BufferFlags.Writable);
}
if (buf is not null) {
bufSize = buf.AsSpan().Length; // check early if buf is indeed writable
} else {
buf = arg.GetBuffer(BufferFlags.Simple);
bufSize = buf.AsReadOnlySpan().Length;
if (bufSize > defaultBufSize) {
buf.Dispose();
throw PythonOps.ValueError("ioctl bytes arg too long");
}
mutate_flag = false; // return a buffer, not integer
}
bool in_place = bufSize > defaultBufSize; // only large buffers are mutated in place

return fcntl(fileno, cmd, arg);
}
#if !NETCOREAPP
throw new PlatformNotSupportedException("ioctl is not supported on Mono");
#else
try {
Debug.Assert(!in_place || mutate_flag); // in_place implies mutate_flag

#endregion
Span<byte> workSpan;
if (in_place) {
workSpan = buf.AsSpan();
} else {
workSpan = new byte[defaultBufSize + 1]; // +1 for extra NUL byte
Debug.Assert(bufSize <= defaultBufSize);
buf.AsReadOnlySpan().CopyTo(workSpan);
}
int result;
Errno errno;
unsafe {
fixed (byte* ptr = workSpan) {
do {
if (RuntimeInformation.ProcessArchitecture == Architecture.Arm64) {
// workaround for Arm64 vararg calling convention (but not for ARM64EC on Windows)
result = _ioctl_arm64(fd, cmd, 0, 0, 0, 0, 0, 0, ptr);
} else {
result = _ioctl(fd, cmd, ptr);
}
} while (UnixMarshal.ShouldRetrySyscall(result, out errno));
}
}

if (result == -1) {
return LightExceptions.Throw(PythonNT.GetOsError(NativeConvert.FromErrno(errno)));
}
if (mutate_flag) {
if (!in_place) {
workSpan.Slice(0, bufSize).CopyTo(buf.AsSpan());
}
return ScriptingRuntimeHelpers.Int32ToObject(result);
} else {
Debug.Assert(!in_place);
byte[] response = new byte[bufSize];
workSpan.Slice(0, bufSize).CopyTo(response);
return Bytes.Make(response);
}
} finally {
buf.Dispose();
}
#endif
}


#region ioctl
[LightThrowing]
public static object ioctl(int fd, long request, [Optional] object? arg, bool mutate_flag = true) {
CheckFileDescriptor(fd);

// supporting fcntl.ioctl(fileno, termios.TIOCGWINSZ, buf)
// where buf = array.array('h', [0, 0, 0, 0])
public static object ioctl(CodeContext context, int fd, int cmd, [NotNone] IBufferProtocol arg, int mutate_flag = 1) {
if (cmd == PythonTermios.TIOCGWINSZ) {
using IPythonBuffer buf = arg.GetBuffer();
if (!TryGetInt64(arg, out long data)) {
return arg switch {
IBufferProtocol bp => ioctl(fd, request, bp),
string s => ioctl(fd, request, Bytes.Make(Encoding.UTF8.GetBytes(s))),
Extensible<string> es => ioctl(fd, request, Bytes.Make(Encoding.UTF8.GetBytes(es.Value))),
_ => throw PythonOps.TypeErrorForBadInstance("integer or a bytes-like argument expected, got {0}", arg)
};
};

Span<short> winsize = stackalloc short[4];
winsize[0] = (short)Console.WindowHeight;
winsize[1] = (short)Console.WindowWidth;
winsize[2] = (short)Console.BufferHeight; // buffer height and width are not accurate on macOS
winsize[3] = (short)Console.BufferWidth;
Span<byte> payload = MemoryMarshal.Cast<short, byte>(winsize);
ulong cmd = unchecked((ulong)request);

if (buf.IsReadOnly || mutate_flag == 0) {
byte[] res = buf.ToArray();
payload.Slice(0, Math.Min(payload.Length, res.Length)).CopyTo(res);
return Bytes.Make(res);
#if !NETCOREAPP
throw new PlatformNotSupportedException("ioctl is not supported on Mono");
#else
int result;
Errno errno;
do {
if (RuntimeInformation.ProcessArchitecture == Architecture.Arm64) {
// workaround for Arm64 vararg calling convention (but not for ARM64EC on Windows)
result = _ioctl_arm64(fd, cmd, 0, 0, 0, 0, 0, 0, data);
} else {
var res = buf.AsSpan();
payload.Slice(0, Math.Min(payload.Length, res.Length)).CopyTo(res);
return 0;
result = _ioctl(fd, cmd, data);
}
} while (UnixMarshal.ShouldRetrySyscall(result, out errno));

if (result == -1) {
return LightExceptions.Throw(PythonNT.GetOsError(NativeConvert.FromErrno(errno)));
}
throw new NotImplementedException($"ioctl: unsupported command {cmd}");
return ScriptingRuntimeHelpers.Int32ToObject(result);
#endif
}


[LightThrowing]
public static object ioctl(CodeContext context, object? fd, long request, [Optional] object? arg, bool mutate_flag = true)
=> ioctl(GetFileDescriptor(context, fd), request, arg, mutate_flag);

#endregion


Expand Down Expand Up @@ -242,6 +359,26 @@ private static void CheckFileDescriptor(int fd) {
}
}


private static bool TryGetInt64(object? obj, out long value) {
int success = 1;
value = obj switch {
Missing => 0,
int i => i,
uint ui => ui,
long l => l,
ulong ul => (long)ul,
BigInteger bi => (long)bi,
Extensible<BigInteger> ebi => (long)ebi.Value,
byte b => b,
sbyte sb => sb,
short s => s,
ushort us => us,
_ => success = 0
};
return success != 0;
}

#endregion


Expand Down