file_access.go

/*
Copyright 2023 NVIDIA CORPORATION &

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

//nolint:gomnd
package sriovnet

import (
	"io"
	"os"
	"strconv"
	"strings"
	"syscall"
)

type fileObject struct {
	Path string
	File *os.File
}

func (attrib *fileObject) Exists() bool {
	return fileExists(attrib.Path)
}

func (attrib *fileObject) Open() (err error) {
	attrib.File, err = os.OpenFile(attrib.Path, os.O_RDWR|syscall.O_NONBLOCK, 0660)
	return err
}

func (attrib *fileObject) OpenRO() (err error) {
	attrib.File, err = os.OpenFile(attrib.Path, os.O_RDONLY, 0444)
	return err
}

func (attrib *fileObject) OpenWO() (err error) {
	attrib.File, err = os.OpenFile(attrib.Path, os.O_WRONLY, 0444)
	return err
}

func (attrib *fileObject) Close() (err error) {
	err = attrib.File.Close()
	attrib.File = nil
	return err
}

func (attrib *fileObject) Read() (str string, err error) {
	if attrib.File == nil {
		err = attrib.OpenRO()
		if err != nil {
			return
		}
		defer func() {
			e := attrib.Close()
			if err == nil {
				err = e
			}
		}()
	}
	_, err = attrib.File.Seek(0, io.SeekStart)
	if err != nil {
		return "", err
	}
	data, err := io.ReadAll(attrib.File)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

func (attrib *fileObject) Write(value string) (err error) {
	if attrib.File == nil {
		err = attrib.OpenWO()
		if err != nil {
			return
		}
		defer func() {
			e := attrib.Close()
			if err == nil {
				err = e
			}
		}()
	}
	_, err = attrib.File.Seek(0, io.SeekStart)
	if err != nil {
		return err
	}
	_, err = attrib.File.WriteString(value)
	return err
}

func (attrib *fileObject) ReadInt() (value int, err error) {
	s, err := attrib.Read()
	if err != nil {
		return 0, err
	}
	s = strings.Trim(s, "\n")
	value, err = strconv.Atoi(s)
	if err != nil {
		return 0, err
	}

	return value, err
}

func (attrib *fileObject) WriteInt(value int) (err error) {
	return attrib.Write(strconv.Itoa(value))
}

func lsFilesWithPrefix(dir, filePrefix string, ignoreDir bool) ([]string, error) {
	var desiredFiles []string

	f, err := os.Open(dir)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	fileInfos, err := f.Readdir(-1)
	if err != nil {
		return nil, err
	}

	for i := range fileInfos {
		if ignoreDir && fileInfos[i].IsDir() {
			continue
		}

		if filePrefix == "" ||
			strings.Contains(fileInfos[i].Name(), filePrefix) {
			desiredFiles = append(desiredFiles, fileInfos[i].Name())
		}
	}
	return desiredFiles, nil
}

func dirExists(dirname string) bool {
	info, err := os.Stat(dirname)
	return err == nil && info.IsDir()
}

func fileExists(dirname string) bool {
	info, err := os.Stat(dirname)
	return err == nil && !info.IsDir()
}