77 lines
2.3 KiB
Go
77 lines
2.3 KiB
Go
//go:build windows && !go1.26
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package sequential
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import (
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"os"
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"unsafe"
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"golang.org/x/sys/windows"
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)
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func openFileSequential(name string, flag int, _ os.FileMode) (file *os.File, err error) {
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if name == "" {
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return nil, &os.PathError{Op: "open", Path: name, Err: windows.ERROR_FILE_NOT_FOUND}
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}
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r, e := openSequential(name, flag|windows.O_CLOEXEC)
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if e != nil {
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return nil, &os.PathError{Op: "open", Path: name, Err: e}
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}
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return os.NewFile(uintptr(r), name), nil
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}
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func makeInheritSa() *windows.SecurityAttributes {
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var sa windows.SecurityAttributes
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sa.Length = uint32(unsafe.Sizeof(sa))
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sa.InheritHandle = 1
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return &sa
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}
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func openSequential(path string, mode int) (fd windows.Handle, err error) {
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if len(path) == 0 {
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return windows.InvalidHandle, windows.ERROR_FILE_NOT_FOUND
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}
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pathp, err := windows.UTF16PtrFromString(path)
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if err != nil {
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return windows.InvalidHandle, err
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}
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var access uint32
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switch mode & (windows.O_RDONLY | windows.O_WRONLY | windows.O_RDWR) {
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case windows.O_RDONLY:
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access = windows.GENERIC_READ
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case windows.O_WRONLY:
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access = windows.GENERIC_WRITE
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case windows.O_RDWR:
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access = windows.GENERIC_READ | windows.GENERIC_WRITE
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}
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if mode&windows.O_CREAT != 0 {
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access |= windows.GENERIC_WRITE
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}
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if mode&windows.O_APPEND != 0 {
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access &^= windows.GENERIC_WRITE
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access |= windows.FILE_APPEND_DATA
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}
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sharemode := uint32(windows.FILE_SHARE_READ | windows.FILE_SHARE_WRITE)
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var sa *windows.SecurityAttributes
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if mode&windows.O_CLOEXEC == 0 {
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sa = makeInheritSa()
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}
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var createmode uint32
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switch {
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case mode&(windows.O_CREAT|windows.O_EXCL) == (windows.O_CREAT | windows.O_EXCL):
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createmode = windows.CREATE_NEW
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case mode&(windows.O_CREAT|windows.O_TRUNC) == (windows.O_CREAT | windows.O_TRUNC):
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createmode = windows.CREATE_ALWAYS
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case mode&windows.O_CREAT == windows.O_CREAT:
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createmode = windows.OPEN_ALWAYS
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case mode&windows.O_TRUNC == windows.O_TRUNC:
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createmode = windows.TRUNCATE_EXISTING
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default:
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createmode = windows.OPEN_EXISTING
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}
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// Use FILE_FLAG_SEQUENTIAL_SCAN rather than FILE_ATTRIBUTE_NORMAL as implemented in golang.
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// https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea#FILE_FLAG_SEQUENTIAL_SCAN
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h, e := windows.CreateFile(pathp, access, sharemode, sa, createmode, windows.FILE_FLAG_SEQUENTIAL_SCAN, 0)
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return h, e
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}
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