rclone/lib/file/file_windows.go

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//+build windows
package file
import (
"os"
"syscall"
)
// OpenFile is the generalized open call; most users will use Open or Create
// instead. It opens the named file with specified flag (O_RDONLY etc.) and
// perm (before umask), if applicable. If successful, methods on the returned
// File can be used for I/O. If there is an error, it will be of type
// *PathError.
//
// Under both Unix and Windows this will allow open files to be
// renamed and or deleted.
func OpenFile(path string, mode int, perm os.FileMode) (*os.File, error) {
// This code copied from syscall_windows.go in the go source and then
// modified to support renaming and deleting open files by adding
// FILE_SHARE_DELETE.
//
// https://docs.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-createfilea#file_share_delete
if len(path) == 0 {
return nil, syscall.ERROR_FILE_NOT_FOUND
}
pathp, err := syscall.UTF16PtrFromString(path)
if err != nil {
return nil, err
}
var access uint32
switch mode & (syscall.O_RDONLY | syscall.O_WRONLY | syscall.O_RDWR) {
case syscall.O_RDONLY:
access = syscall.GENERIC_READ
case syscall.O_WRONLY:
access = syscall.GENERIC_WRITE
case syscall.O_RDWR:
access = syscall.GENERIC_READ | syscall.GENERIC_WRITE
}
if mode&syscall.O_CREAT != 0 {
access |= syscall.GENERIC_WRITE
}
if mode&syscall.O_APPEND != 0 {
access &^= syscall.GENERIC_WRITE
access |= syscall.FILE_APPEND_DATA
}
sharemode := uint32(syscall.FILE_SHARE_READ | syscall.FILE_SHARE_WRITE | syscall.FILE_SHARE_DELETE)
var createmode uint32
switch {
case mode&(syscall.O_CREAT|syscall.O_EXCL) == (syscall.O_CREAT | syscall.O_EXCL):
createmode = syscall.CREATE_NEW
case mode&(syscall.O_CREAT|syscall.O_TRUNC) == (syscall.O_CREAT | syscall.O_TRUNC):
createmode = syscall.CREATE_ALWAYS
case mode&syscall.O_CREAT == syscall.O_CREAT:
createmode = syscall.OPEN_ALWAYS
case mode&syscall.O_TRUNC == syscall.O_TRUNC:
createmode = syscall.TRUNCATE_EXISTING
default:
createmode = syscall.OPEN_EXISTING
}
h, e := syscall.CreateFile(pathp, access, sharemode, nil, createmode, syscall.FILE_ATTRIBUTE_NORMAL, 0)
if e != nil {
return nil, e
}
return os.NewFile(uintptr(h), path), nil
}