62 lines
2.0 KiB
Go
62 lines
2.0 KiB
Go
package sysfs
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import (
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"syscall"
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"unsafe"
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"github.com/tetratelabs/wazero/internal/platform"
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)
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const NonBlockingFileIoSupported = true
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var kernel32 = syscall.NewLazyDLL("kernel32.dll")
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// procPeekNamedPipe is the syscall.LazyProc in kernel32 for PeekNamedPipe
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var procPeekNamedPipe = kernel32.NewProc("PeekNamedPipe")
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// readFd returns ENOSYS on unsupported platforms.
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//
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// PeekNamedPipe: https://learn.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-peeknamedpipe
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// "GetFileType can assist in determining what device type the handle refers to. A console handle presents as FILE_TYPE_CHAR."
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// https://learn.microsoft.com/en-us/windows/console/console-handles
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func readFd(fd uintptr, buf []byte) (int, syscall.Errno) {
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handle := syscall.Handle(fd)
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fileType, err := syscall.GetFileType(syscall.Stdin)
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if err != nil {
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return 0, platform.UnwrapOSError(err)
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}
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if fileType&syscall.FILE_TYPE_CHAR == 0 {
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return -1, syscall.ENOSYS
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}
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n, err := peekNamedPipe(handle)
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if err != nil {
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errno := platform.UnwrapOSError(err)
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if errno == syscall.ERROR_BROKEN_PIPE {
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return 0, 0
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}
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}
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if n == 0 {
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return -1, syscall.EAGAIN
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}
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un, err := syscall.Read(handle, buf[0:n])
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return un, platform.UnwrapOSError(err)
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}
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// peekNamedPipe partially exposes PeekNamedPipe from the Win32 API
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// see https://learn.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-peeknamedpipe
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func peekNamedPipe(handle syscall.Handle) (uint32, error) {
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var totalBytesAvail uint32
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totalBytesPtr := unsafe.Pointer(&totalBytesAvail)
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_, _, err := procPeekNamedPipe.Call(
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uintptr(handle), // [in] HANDLE hNamedPipe,
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0, // [out, optional] LPVOID lpBuffer,
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0, // [in] DWORD nBufferSize,
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0, // [out, optional] LPDWORD lpBytesRead
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uintptr(totalBytesPtr), // [out, optional] LPDWORD lpTotalBytesAvail,
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0) // [out, optional] LPDWORD lpBytesLeftThisMessage
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if err == syscall.Errno(0) {
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return totalBytesAvail, nil
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}
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return totalBytesAvail, err
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}
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