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Correct and expand errno mapping to Python exeptions
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@BCSharp
BCSharp committed Jan 13, 2025
1 parent 314cccd commit 6de1e81
Showing 1 changed file with 69 additions and 28 deletions.
97 changes: 69 additions & 28 deletions Src/IronPython/Runtime/Exceptions/PythonExceptions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -127,7 +127,7 @@ public partial class _OSError {
errno = WinErrorToErrno(winerror);
}
}
cls = ErrnoToPythonType(ErrnoToErrorEnum(errno));
cls = ErrorEnumToPythonType(ErrnoToErrorEnum(errno));
}
return Activator.CreateInstance(cls.UnderlyingSystemType, cls);
}
Expand Down Expand Up @@ -180,6 +180,13 @@ public override void __init__(params object[] args) {
base.__init__(args);
}

// This enum is used solely for the purpose of mapping errno values to Python exception types.
// The values are based on errno codes but do not exactly match them;
// they are selected such that it is possible to algorithmically map them from true platform-dependent errno values.
// The subset of codes is chosen that is sufficient for mapping all relevant Python exceptions.
// Because it is an enum, it can be used in switch statements and expressions, simplifying the code
// over using actual errno values (which are not always compile-time constants) while keeping it readable.
// In a way it is subset-equivalent to Mono.Unix.Native.Errno, but it is not dependent on Mono.Posix assembly.
private enum Error {
UNSPECIFIED = -1,
EPERM = 1,
Expand Down Expand Up @@ -212,15 +219,17 @@ private enum Error {
WSAECONNREFUSED = 10061,
}

// Not all input errno values are mapped to existing constants of Error.
// This is suffcient since all values that are not listed as Error constants are mapped to OSError.
private static Error ErrnoToErrorEnum(int errno) {
if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX)) {
if (errno == 11) return Error.UNSPECIFIED; // EAGAIN on Linux/Windows but EDEADLK on OSX, which is not being remapped
if (errno >= 35) errno += 10000; // add WSABASEERR to map to Windows error range
if (errno >= 35) errno += WSABASEERR; // add WSABASEERR to map to Windows error range
}
return (Error)errno;
}

private static PythonType ErrnoToPythonType(Error errno) {
private static PythonType ErrorEnumToPythonType(Error errno) {
var res = errno switch {
Error.EPERM => PermissionError,
Error.ENOENT => FileNotFoundError,
Expand Down Expand Up @@ -264,9 +273,12 @@ private static PythonType ErrnoToPythonType(Error errno) {
return res ?? OSError;
}

// Values of the Errno codes below are identical with values defined in PythonErrno in IronPython.Modules.dll.
// They provide platform-independent errno codes to be used in this assembly.

/// <summary>
/// Provides a subset of platform-independent errno codes to be used in this assembly.
/// </summary>
/// <remarks>
/// Values of the Errno codes defined here are identical with values defined in PythonErrno in IronPython.Modules.dll.
/// </remarks>
internal static class Errno {

#region Generated Common Errno Codes
Expand Down Expand Up @@ -407,6 +419,7 @@ internal static class Errno {
internal const int ERROR_NESTING_NOT_ALLOWED = 215;
internal const int ERROR_NO_DATA = 232;
internal const int ERROR_DIRECTORY = 267;
internal const int ERROR_NO_UNICODE_TRANSLATION = 1113;
internal const int ERROR_NOT_ENOUGH_QUOTA = 1816;

// These map to POSIX errno 22 and are added by hand as needed.
Expand All @@ -415,14 +428,20 @@ internal static class Errno {
internal const int ERROR_FILE_INVALID = 1006;
internal const int ERROR_MAPPED_ALIGNMENT = 1132;

// Some Winsock error codes are errno values.
internal const int WSABASEERR = 10000;
internal const int WSAEINTR = WSABASEERR + 4;
internal const int WSAEBADF = WSABASEERR + 9;
internal const int WSAEACCES = WSABASEERR + 13;
internal const int WSAEFAULT = WSABASEERR + 14;
internal const int WSAEINVAL = WSABASEERR + 22;
internal const int WSAEMFILE = WSABASEERR + 24;

// See also errmap.h in CPython
internal static int WinErrorToErrno(int winerror) {
int errno = winerror;
if (winerror < 10000) {
if (winerror < WSABASEERR) {
switch (winerror) {
case ERROR_BROKEN_PIPE:
case ERROR_NO_DATA:
errno = 32;
break;
case ERROR_FILE_NOT_FOUND:
case ERROR_PATH_NOT_FOUND:
case ERROR_INVALID_DRIVE:
Expand All @@ -431,10 +450,10 @@ internal static int WinErrorToErrno(int winerror) {
case ERROR_BAD_NET_NAME:
case ERROR_BAD_PATHNAME:
case ERROR_FILENAME_EXCED_RANGE:
errno = 2;
errno = Errno.ENOENT;
break;
case ERROR_BAD_ENVIRONMENT:
errno = 7;
errno = Errno.E2BIG;
break;
case ERROR_BAD_FORMAT:
case ERROR_INVALID_STARTING_CODESEG:
Expand All @@ -452,27 +471,27 @@ internal static int WinErrorToErrno(int winerror) {
case ERROR_RING2SEG_MUST_BE_MOVABLE:
case ERROR_RELOC_CHAIN_XEEDS_SEGLIM:
case ERROR_INFLOOP_IN_RELOC_CHAIN:
errno = 8;
errno = Errno.ENOEXEC;
break;
case ERROR_INVALID_HANDLE:
case ERROR_INVALID_TARGET_HANDLE:
case ERROR_DIRECT_ACCESS_HANDLE:
errno = 9;
errno = Errno.EBADF;
break;
case ERROR_WAIT_NO_CHILDREN:
case ERROR_CHILD_NOT_COMPLETE:
errno = 10;
errno = Errno.ECHILD;
break;
case ERROR_NO_PROC_SLOTS:
case ERROR_MAX_THRDS_REACHED:
case ERROR_NESTING_NOT_ALLOWED:
errno = 11;
errno = Errno.EAGAIN;
break;
case ERROR_ARENA_TRASHED:
case ERROR_NOT_ENOUGH_MEMORY:
case ERROR_INVALID_BLOCK:
case ERROR_NOT_ENOUGH_QUOTA:
errno = 12;
errno = Errno.ENOMEM;
break;
case ERROR_ACCESS_DENIED:
case ERROR_CURRENT_DIRECTORY:
Expand Down Expand Up @@ -500,29 +519,51 @@ internal static int WinErrorToErrno(int winerror) {
case ERROR_SEEK_ON_DEVICE:
case ERROR_NOT_LOCKED:
case ERROR_LOCK_FAILED:
errno = 13;
case 35: // undefined
errno = Errno.EACCES;
break;
case ERROR_FILE_EXISTS:
case ERROR_ALREADY_EXISTS:
errno = 17;
errno = Errno.EEXIST;
break;
case ERROR_NOT_SAME_DEVICE:
errno = 18;
errno = Errno.EXDEV;
break;
case ERROR_DIRECTORY:
errno = 20;
break;
case ERROR_DIR_NOT_EMPTY:
errno = 41;
errno = Errno.ENOTDIR;
break;
case ERROR_TOO_MANY_OPEN_FILES:
errno = 24;
errno = Errno.EMFILE;
break;
case ERROR_DISK_FULL:
errno = 28;
errno = Errno.ENOSPC;
break;
case ERROR_BROKEN_PIPE:
case ERROR_NO_DATA:
errno = Errno.EPIPE;
break;
case ERROR_DIR_NOT_EMPTY: // ENOTEMPTY
errno = Errno.ENOTEMPTY;
break;
case ERROR_NO_UNICODE_TRANSLATION: // EILSEQ
errno = Errno.EILSEQ;
break;
default:
errno = Errno.EINVAL;
break;
}
} else if (winerror < 12000) { // Winsock error codes are 10000-11999
switch (winerror) {
case WSAEINTR:
case WSAEBADF:
case WSAEACCES:
case WSAEFAULT:
case WSAEINVAL:
case WSAEMFILE:
errno = winerror - WSABASEERR;
break;
default:
errno = 22;
errno = winerror;
break;
}
}
Expand Down

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