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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2017 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package osutil
import (
"bufio"
"bytes"
"fmt"
"io"
"os"
"strings"
"github.com/snapcore/snapd/osutil/sys"
)
// MountProfile represents an array of mount entries.
type MountProfile struct {
Entries []MountEntry
}
// LoadMountProfile loads a mount profile from a given file.
//
// The file may be absent, in such case an empty profile is returned without errors.
func LoadMountProfile(fname string) (*MountProfile, error) {
f, err := os.Open(fname)
if err != nil && os.IsNotExist(err) {
return &MountProfile{}, nil
}
if err != nil {
return nil, err
}
defer f.Close()
return ReadMountProfile(f)
}
// LoadMountProfileText loads a mount profile from a given string.
func LoadMountProfileText(fstab string) (*MountProfile, error) {
return ReadMountProfile(strings.NewReader(fstab))
}
func SaveMountProfileText(p *MountProfile) (string, error) {
var buf bytes.Buffer
_, err := p.WriteTo(&buf)
if err != nil {
return "", err
}
return buf.String(), nil
}
// Save saves a mount profile (fstab-like) to a given file.
// The profile is saved with an atomic write+rename+sync operation.
// If you don't want to alter the uid and gid of the created file, pass
// osutil.NoChown.
func SaveMountProfile(p *MountProfile, fname string, uid sys.UserID, gid sys.GroupID) error {
var buf bytes.Buffer
if _, err := p.WriteTo(&buf); err != nil {
return err
}
return AtomicWriteFileChown(fname, buf.Bytes(), 0644, AtomicWriteFlags(0), uid, gid)
}
// ReadMountProfile reads and parses a mount profile.
//
// The supported format is described by fstab(5).
func ReadMountProfile(reader io.Reader) (*MountProfile, error) {
var p MountProfile
scanner := bufio.NewScanner(reader)
for scanner.Scan() {
s := scanner.Text()
s = strings.TrimSpace(s)
// Skip lines that only contain a comment, that is, those that start
// with the '#' character (ignoring leading spaces). This specifically
// allows us to parse '#' inside individual fields, which the fstab(5)
// specification allows.
if strings.IndexByte(s, '#') == 0 {
continue
}
// Skip lines that are totally empty
if s == "" {
continue
}
entry, err := ParseMountEntry(s)
if err != nil {
return nil, err
}
p.Entries = append(p.Entries, entry)
}
if err := scanner.Err(); err != nil {
return nil, err
}
return &p, nil
}
// WriteTo writes a mount profile to the given writer.
//
// The supported format is described by fstab(5).
// Note that there is no support for comments.
func (p *MountProfile) WriteTo(writer io.Writer) (int64, error) {
var written int64
for i := range p.Entries {
var n int
var err error
if n, err = fmt.Fprintf(writer, "%s\n", p.Entries[i]); err != nil {
return written, err
}
written += int64(n)
}
return written, nil
}
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