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// Copyright (C) 2019-2024 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
package libgoal
import (
"fmt"
"io"
"os"
)
type locker interface {
tryRLock(fd *os.File) error
tryLock(fd *os.File) error
unlock(fd *os.File) error
}
func newLockedFile(path string) (*lockedFile, error) {
locker, err := makeLocker()
if err != nil {
return nil, err
}
return &lockedFile{
path: path,
locker: locker,
}, nil
}
// lockedFile implementation
// It a platform-agnostic with appropriate locker implementation.
// Each platform needs own specific `newLockedFile`
type lockedFile struct {
path string
locker locker
}
func (f *lockedFile) read() (bytes []byte, err error) {
fd, err := os.Open(f.path)
if err != nil {
return
}
defer func() {
err2 := fd.Close()
if err2 != nil {
err = err2
}
}()
err = f.locker.tryRLock(fd)
if err != nil {
err = fmt.Errorf("Can't acquire read lock for %s: %s", f.path, err.Error())
return
}
defer func() {
err2 := f.locker.unlock(fd)
if err2 != nil {
err = fmt.Errorf("Can't unlock for %s: %s", f.path, err2.Error())
}
}()
bytes, err = io.ReadAll(fd)
return
}
func (f *lockedFile) write(data []byte, perm os.FileMode) (err error) {
fd, err := os.OpenFile(f.path, os.O_WRONLY|os.O_CREATE, perm)
if err != nil {
return
}
defer func() {
err2 := fd.Close()
if err2 != nil {
err = err2
}
}()
err = f.locker.tryLock(fd)
if err != nil {
return fmt.Errorf("Can't acquire lock for %s: %s", f.path, err.Error())
}
defer func() {
err2 := f.locker.unlock(fd)
if err2 != nil {
err = fmt.Errorf("Can't unlock for %s: %s", f.path, err2.Error())
}
}()
err = fd.Truncate(0)
if err != nil {
return
}
_, err = fd.Write(data)
return
}
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