* Remove Size() method and size field from lock.LockedFile * WriteTo method of fsMeta and uploadsV1 now takes concrete type *lock.LockedFile
173 lines
4.4 KiB
Go
173 lines
4.4 KiB
Go
// +build windows
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/*
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* Minio Cloud Storage, (C) 2016 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package lock
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import (
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"errors"
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"os"
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"syscall"
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"unsafe"
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)
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var (
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modkernel32 = syscall.NewLazyDLL("kernel32.dll")
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procLockFileEx = modkernel32.NewProc("LockFileEx")
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errLocked = errors.New("The process cannot access the file because another process has locked a portion of the file.")
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)
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const (
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// see https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382(v=vs.85).aspx
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errLockViolation syscall.Errno = 0x21
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)
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// LockedOpenFile - initializes a new lock and protects
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// the file from concurrent access.
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func LockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
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f, err := open(path, flag, perm)
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if err != nil {
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return nil, err
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}
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if err = lockFile(syscall.Handle(f.Fd()), 0); err != nil {
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f.Close()
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return nil, err
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}
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st, err := os.Stat(path)
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if err != nil {
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f.Close()
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return nil, err
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}
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if st.IsDir() {
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f.Close()
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return nil, &os.PathError{
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Op: "open",
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Path: path,
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Err: syscall.EISDIR,
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}
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}
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return &LockedFile{File: f}, nil
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}
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func makeInheritSa() *syscall.SecurityAttributes {
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var sa syscall.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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// perm param is ignored, on windows file perms/NT acls
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// are not octet combinations. Providing access to NT
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// acls is out of scope here.
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func open(path string, flag int, perm os.FileMode) (*os.File, error) {
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if path == "" {
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return nil, syscall.ERROR_FILE_NOT_FOUND
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}
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pathp, err := syscall.UTF16PtrFromString(path)
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if err != nil {
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return nil, err
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}
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var access uint32
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switch flag {
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case syscall.O_RDONLY:
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access = syscall.GENERIC_READ
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case syscall.O_WRONLY:
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access = syscall.GENERIC_WRITE
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case syscall.O_RDWR:
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access = syscall.GENERIC_READ | syscall.GENERIC_WRITE
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case syscall.O_RDWR | syscall.O_CREAT:
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access = syscall.GENERIC_ALL
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case syscall.O_WRONLY | syscall.O_CREAT:
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access = syscall.GENERIC_ALL
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}
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if flag&syscall.O_APPEND != 0 {
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access &^= syscall.GENERIC_WRITE
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access |= syscall.FILE_APPEND_DATA
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}
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var sa *syscall.SecurityAttributes
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if flag&syscall.O_CLOEXEC == 0 {
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sa = makeInheritSa()
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}
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var createflag uint32
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switch {
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case flag&(syscall.O_CREAT|syscall.O_EXCL) == (syscall.O_CREAT | syscall.O_EXCL):
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createflag = syscall.CREATE_NEW
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case flag&(syscall.O_CREAT|syscall.O_TRUNC) == (syscall.O_CREAT | syscall.O_TRUNC):
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createflag = syscall.CREATE_ALWAYS
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case flag&syscall.O_CREAT == syscall.O_CREAT:
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createflag = syscall.OPEN_ALWAYS
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case flag&syscall.O_TRUNC == syscall.O_TRUNC:
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createflag = syscall.TRUNCATE_EXISTING
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default:
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createflag = syscall.OPEN_EXISTING
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}
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shareflag := uint32(syscall.FILE_SHARE_READ | syscall.FILE_SHARE_WRITE | syscall.FILE_SHARE_DELETE)
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accessAttr := uint32(syscall.FILE_ATTRIBUTE_NORMAL | 0x80000000)
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fd, err := syscall.CreateFile(pathp, access, shareflag, sa, createflag, accessAttr, 0)
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if err != nil {
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return nil, err
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}
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return os.NewFile(uintptr(fd), path), nil
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}
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func lockFile(fd syscall.Handle, flags uint32) error {
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// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
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var flag uint32 = 2 // Lockfile exlusive.
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flag |= flags
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if fd == syscall.InvalidHandle {
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return nil
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}
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err := lockFileEx(fd, flag, 1, 0, &syscall.Overlapped{})
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if err == nil {
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return nil
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} else if err.Error() == errLocked.Error() {
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return errors.New("lock already acquired")
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} else if err != errLockViolation {
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return err
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}
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return nil
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}
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func lockFileEx(h syscall.Handle, flags, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
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var reserved = uint32(0)
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r1, _, e1 := syscall.Syscall6(procLockFileEx.Addr(), 6, uintptr(h), uintptr(flags), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)))
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if r1 == 0 {
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if e1 != 0 {
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err = error(e1)
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} else {
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err = syscall.EINVAL
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}
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}
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return
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}
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