go-ethereum/core/rawdb/freezer_utils.go

121 lines
3.4 KiB
Go

// Copyright 2022 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rawdb
import (
"io"
"io/ioutil"
"os"
"path/filepath"
)
// copyFrom copies data from 'srcPath' at offset 'offset' into 'destPath'.
// The 'destPath' is created if it doesn't exist, otherwise it is overwritten.
// Before the copy is executed, there is a callback can be registered to
// manipulate the dest file.
// It is perfectly valid to have destPath == srcPath.
func copyFrom(srcPath, destPath string, offset uint64, before func(f *os.File) error) error {
// Create a temp file in the same dir where we want it to wind up
f, err := ioutil.TempFile(filepath.Dir(destPath), "*")
if err != nil {
return err
}
fname := f.Name()
// Clean up the leftover file
defer func() {
if f != nil {
f.Close()
}
os.Remove(fname)
}()
// Apply the given function if it's not nil before we copy
// the content from the src.
if before != nil {
if err := before(f); err != nil {
return err
}
}
// Open the source file
src, err := os.Open(srcPath)
if err != nil {
return err
}
if _, err = src.Seek(int64(offset), 0); err != nil {
src.Close()
return err
}
// io.Copy uses 32K buffer internally.
_, err = io.Copy(f, src)
if err != nil {
src.Close()
return err
}
// Rename the temporary file to the specified dest name.
// src may be same as dest, so needs to be closed before
// we do the final move.
src.Close()
if err := f.Close(); err != nil {
return err
}
f = nil
if err := os.Rename(fname, destPath); err != nil {
return err
}
return nil
}
// openFreezerFileForAppend opens a freezer table file and seeks to the end
func openFreezerFileForAppend(filename string) (*os.File, error) {
// Open the file without the O_APPEND flag
// because it has differing behaviour during Truncate operations
// on different OS's
file, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE, 0644)
if err != nil {
return nil, err
}
// Seek to end for append
if _, err = file.Seek(0, io.SeekEnd); err != nil {
return nil, err
}
return file, nil
}
// openFreezerFileForReadOnly opens a freezer table file for read only access
func openFreezerFileForReadOnly(filename string) (*os.File, error) {
return os.OpenFile(filename, os.O_RDONLY, 0644)
}
// openFreezerFileTruncated opens a freezer table making sure it is truncated
func openFreezerFileTruncated(filename string) (*os.File, error) {
return os.OpenFile(filename, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
}
// truncateFreezerFile resizes a freezer table file and seeks to the end
func truncateFreezerFile(file *os.File, size int64) error {
if err := file.Truncate(size); err != nil {
return err
}
// Seek to end for append
if _, err := file.Seek(0, io.SeekEnd); err != nil {
return err
}
return nil
}