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client/pkg/fileutil: use golang.org/x/sys/windows for FileLockEx

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Use the FileLockEx wrapper and the corresponding LOCKFILE_* and error
constants from the golang.org/x/sys/windows package rather than
implementing these in the fileutil package.
This commit is contained in:
Tobias Klauser 2021-06-25 14:44:30 +02:00
parent dcf60888bc
commit c3fe63a658
1 changed files with 9 additions and 37 deletions
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46
client/pkg/fileutil/lock_windows.go
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@ -22,31 +22,18 @@ import (
"fmt" "fmt"
"os" "os"
"syscall" "syscall"
"unsafe"
"golang.org/x/sys/windows"
) )
var ( var errLocked = errors.New("the process cannot access the file because another process has locked a portion of the file")
modkernel32 = syscall.NewLazyDLL("kernel32.dll")
procLockFileEx = modkernel32.NewProc("LockFileEx")
errLocked = errors.New("the process cannot access the file because another process has locked a portion of the file")
)
const (
// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
LOCKFILE_EXCLUSIVE_LOCK = 2
LOCKFILE_FAIL_IMMEDIATELY = 1
// see https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382(v=vs.85).aspx
errLockViolation syscall.Errno = 0x21
)
func TryLockFile(path string, flag int, perm os.FileMode) (*LockedFile, error) { func TryLockFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
f, err := open(path, flag, perm) f, err := open(path, flag, perm)
if err != nil { if err != nil {
return nil, err return nil, err
} }
if err := lockFile(syscall.Handle(f.Fd()), LOCKFILE_FAIL_IMMEDIATELY); err != nil { if err := lockFile(windows.Handle(f.Fd()), windows.LOCKFILE_FAIL_IMMEDIATELY); err != nil {
f.Close() f.Close()
return nil, err return nil, err
} }
@ -58,7 +45,7 @@ func LockFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
if err != nil { if err != nil {
return nil, err return nil, err
} }
if err := lockFile(syscall.Handle(f.Fd()), 0); err != nil { if err := lockFile(windows.Handle(f.Fd()), 0); err != nil {
f.Close() f.Close()
return nil, err return nil, err
} }
@ -95,32 +82,17 @@ func open(path string, flag int, perm os.FileMode) (*os.File, error) {
return os.NewFile(uintptr(fd), path), nil return os.NewFile(uintptr(fd), path), nil
} }
func lockFile(fd syscall.Handle, flags uint32) error { func lockFile(fd windows.Handle, flags uint32) error {
var flag uint32 = LOCKFILE_EXCLUSIVE_LOCK if fd == windows.InvalidHandle {
flag |= flags
if fd == syscall.InvalidHandle {
return nil return nil
} }
err := lockFileEx(fd, flag, 1, 0, &syscall.Overlapped{}) err := windows.LockFileEx(fd, flags|windows.LOCKFILE_EXCLUSIVE_LOCK, 0, 1, 0, &windows.Overlapped{})
if err == nil { if err == nil {
return nil return nil
} else if err.Error() == errLocked.Error() { } else if err.Error() == errLocked.Error() {
return ErrLocked return ErrLocked
} else if err != errLockViolation { } else if err != windows.ERROR_LOCK_VIOLATION {
return err return err
} }
return nil return nil
} }
func lockFileEx(h syscall.Handle, flags, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
var reserved uint32 = 0
r1, _, e1 := syscall.Syscall6(procLockFileEx.Addr(), 6, uintptr(h), uintptr(flags), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)))
if r1 == 0 {
if e1 != 0 {
err = error(e1)
} else {
err = syscall.EINVAL
}
}
return err
}