github.com/gaukas/wazerofs@v0.1.0/sysfs/file_windows.go (about)

     1  package sysfs
     2  
     3  import (
     4  	"errors"
     5  	"syscall"
     6  	"unsafe"
     7  
     8  	"github.com/tetratelabs/wazero/experimental/sys"
     9  )
    10  
    11  const (
    12  	nonBlockingFileReadSupported  = true
    13  	nonBlockingFileWriteSupported = false
    14  
    15  	_ERROR_IO_INCOMPLETE = syscall.Errno(996)
    16  )
    17  
    18  var kernel32 = syscall.NewLazyDLL("kernel32.dll")
    19  
    20  // procPeekNamedPipe is the syscall.LazyProc in kernel32 for PeekNamedPipe
    21  var (
    22  	// procPeekNamedPipe is the syscall.LazyProc in kernel32 for PeekNamedPipe
    23  	procPeekNamedPipe = kernel32.NewProc("PeekNamedPipe")
    24  	// procGetOverlappedResult is the syscall.LazyProc in kernel32 for GetOverlappedResult
    25  	procGetOverlappedResult = kernel32.NewProc("GetOverlappedResult")
    26  	// procCreateEventW is the syscall.LazyProc in kernel32 for CreateEventW
    27  	procCreateEventW = kernel32.NewProc("CreateEventW")
    28  )
    29  
    30  // readFd returns ENOSYS on unsupported platforms.
    31  //
    32  // PeekNamedPipe: https://learn.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-peeknamedpipe
    33  // "GetFileType can assist in determining what device type the handle refers to. A console handle presents as FILE_TYPE_CHAR."
    34  // https://learn.microsoft.com/en-us/windows/console/console-handles
    35  func readFd(fd uintptr, buf []byte) (int, sys.Errno) {
    36  	handle := syscall.Handle(fd)
    37  	fileType, err := syscall.GetFileType(handle)
    38  	if err != nil {
    39  		return 0, sys.UnwrapOSError(err)
    40  	}
    41  	if fileType&syscall.FILE_TYPE_CHAR == 0 {
    42  		return -1, sys.ENOSYS
    43  	}
    44  	n, errno := peekNamedPipe(handle)
    45  	if errno == syscall.ERROR_BROKEN_PIPE {
    46  		return 0, 0
    47  	}
    48  	if n == 0 {
    49  		return -1, sys.EAGAIN
    50  	}
    51  	un, err := syscall.Read(handle, buf[0:n])
    52  	return un, sys.UnwrapOSError(err)
    53  }
    54  
    55  func writeFd(fd uintptr, buf []byte) (int, sys.Errno) {
    56  	return -1, sys.ENOSYS
    57  }
    58  
    59  func writeSocket(fd uintptr, buf []byte) (int, sys.Errno) {
    60  	var done uint32
    61  	var overlapped syscall.Overlapped
    62  	errno := syscall.WriteFile(syscall.Handle(fd), buf, &done, &overlapped)
    63  	if errors.Is(errno, syscall.ERROR_IO_PENDING) {
    64  		errno = syscall.EAGAIN
    65  	}
    66  	return int(done), sys.UnwrapOSError(errno)
    67  }
    68  
    69  // peekNamedPipe partially exposes PeekNamedPipe from the Win32 API
    70  // see https://learn.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-peeknamedpipe
    71  func peekNamedPipe(handle syscall.Handle) (uint32, syscall.Errno) {
    72  	var totalBytesAvail uint32
    73  	totalBytesPtr := unsafe.Pointer(&totalBytesAvail)
    74  	_, _, errno := syscall.SyscallN(
    75  		procPeekNamedPipe.Addr(),
    76  		uintptr(handle),        // [in]            HANDLE  hNamedPipe,
    77  		0,                      // [out, optional] LPVOID  lpBuffer,
    78  		0,                      // [in]            DWORD   nBufferSize,
    79  		0,                      // [out, optional] LPDWORD lpBytesRead
    80  		uintptr(totalBytesPtr), // [out, optional] LPDWORD lpTotalBytesAvail,
    81  		0)                      // [out, optional] LPDWORD lpBytesLeftThisMessage
    82  	return totalBytesAvail, errno
    83  }
    84  
    85  func rmdir(path string) sys.Errno {
    86  	err := syscall.Rmdir(path)
    87  	return sys.UnwrapOSError(err)
    88  }
    89  
    90  func getOverlappedResult(handle syscall.Handle, overlapped *syscall.Overlapped, wait bool) (uint32, syscall.Errno) {
    91  	var totalBytesAvail uint32
    92  	var bwait uintptr
    93  	if wait {
    94  		bwait = 0xFFFFFFFF
    95  	}
    96  	totalBytesPtr := unsafe.Pointer(&totalBytesAvail)
    97  	_, _, errno := syscall.SyscallN(
    98  		procGetOverlappedResult.Addr(),
    99  		uintptr(handle),                     // [in]  HANDLE       hFile,
   100  		uintptr(unsafe.Pointer(overlapped)), // [in]  LPOVERLAPPED lpOverlapped,
   101  		uintptr(totalBytesPtr),              // [out] LPDWORD      lpNumberOfBytesTransferred,
   102  		bwait)                               // [in]  BOOL         bWait
   103  	return totalBytesAvail, errno
   104  }
   105  
   106  func createEventW(lpEventAttributes *syscall.SecurityAttributes, bManualReset bool, bInitialState bool, lpName *uint16) (uintptr, syscall.Errno) {
   107  	var manualReset uintptr
   108  	var initialState uintptr
   109  	if bManualReset {
   110  		manualReset = 1
   111  	}
   112  	if bInitialState {
   113  		initialState = 1
   114  	}
   115  	handle, _, errno := syscall.SyscallN(
   116  		procCreateEventW.Addr(),
   117  		uintptr(unsafe.Pointer(lpEventAttributes)), // [in]     LPSECURITY_ATTRIBUTES lpEventAttributes,
   118  		manualReset,                     // [in]     BOOL                  bManualReset,
   119  		initialState,                    // [in]     BOOL                  bInitialState,
   120  		uintptr(unsafe.Pointer(lpName)), // [in, opt]LPCWSTR               lpName,
   121  	)
   122  
   123  	return handle, errno
   124  }