wings/server/filesystem/archive.go

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package filesystem
import (
"archive/tar"
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"io"
"io/fs"
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"os"
"path/filepath"
"strings"
"sync"
"emperror.dev/errors"
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"github.com/apex/log"
"github.com/juju/ratelimit"
"github.com/karrick/godirwalk"
"github.com/klauspost/pgzip"
ignore "github.com/sabhiram/go-gitignore"
"github.com/pterodactyl/wings/config"
)
const memory = 4 * 1024
var pool = sync.Pool{
New: func() interface{} {
b := make([]byte, memory)
return b
},
}
type Archive struct {
// BasePath is the absolute path to create the archive from where Files and Ignore are
// relative to.
BasePath string
// Ignore is a gitignore string (most likely read from a file) of files to ignore
// from the archive.
Ignore string
// Files specifies the files to archive, this takes priority over the Ignore option, if
// unspecified, all files in the BasePath will be archived unless Ignore is set.
Files []string
}
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// Create creates an archive at dst with all of the files defined in the
// included files struct.
func (a *Archive) Create(dst string) error {
f, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return err
}
defer f.Close()
// Select a writer based off of the WriteLimit configuration option. If there is no
// write limit, use the file as the writer.
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var writer io.Writer
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if writeLimit := int64(config.Get().System.Backups.WriteLimit * 1024 * 1024); writeLimit > 0 {
// Token bucket with a capacity of "writeLimit" MiB, adding "writeLimit" MiB/s
// and then wrap the file writer with the token bucket limiter.
writer = ratelimit.Writer(f, ratelimit.NewBucketWithRate(float64(writeLimit), writeLimit))
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} else {
writer = f
}
// Create a new gzip writer around the file.
gw, _ := pgzip.NewWriterLevel(writer, pgzip.BestSpeed)
_ = gw.SetConcurrency(1<<20, 1)
defer gw.Close()
// Create a new tar writer around the gzip writer.
tw := tar.NewWriter(gw)
defer tw.Close()
// Configure godirwalk.
options := &godirwalk.Options{
FollowSymbolicLinks: false,
Unsorted: true,
Callback: a.callback(tw),
}
// If we're specifically looking for only certain files, or have requested
// that certain files be ignored we'll update the callback function to reflect
// that request.
if len(a.Files) == 0 && len(a.Ignore) > 0 {
i := ignore.CompileIgnoreLines(strings.Split(a.Ignore, "\n")...)
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options.Callback = a.callback(tw, func(_ string, rp string) error {
if i.MatchesPath(rp) {
return godirwalk.SkipThis
}
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return nil
})
} else if len(a.Files) > 0 {
options.Callback = a.withFilesCallback(tw)
}
// Recursively walk the path we are archiving.
return godirwalk.Walk(a.BasePath, options)
}
// Callback function used to determine if a given file should be included in the archive
// being generated.
func (a *Archive) callback(tw *tar.Writer, opts ...func(path string, relative string) error) func(path string, de *godirwalk.Dirent) error {
return func(path string, de *godirwalk.Dirent) error {
// Skip directories because we walking them recursively.
if de.IsDir() {
return nil
}
relative := filepath.ToSlash(strings.TrimPrefix(path, a.BasePath+string(filepath.Separator)))
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// Call the additional options passed to this callback function. If any of them return
// a non-nil error we will exit immediately.
for _, opt := range opts {
if err := opt(path, relative); err != nil {
return err
}
}
// Add the file to the archive, if it is nested in a directory,
// the directory will be automatically "created" in the archive.
return a.addToArchive(path, relative, tw)
}
}
// Pushes only files defined in the Files key to the final archive.
func (a *Archive) withFilesCallback(tw *tar.Writer) func(path string, de *godirwalk.Dirent) error {
return a.callback(tw, func(p string, rp string) error {
for _, f := range a.Files {
// If the given doesn't match, or doesn't have the same prefix continue
// to the next item in the loop.
if p != f && !strings.HasPrefix(p, f) {
continue
}
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// Once we have a match return a nil value here so that the loop stops and the
// call to this function will correctly include the file in the archive. If there
// are no matches we'll never make it to this line, and the final error returned
// will be the godirwalk.SkipThis error.
return nil
}
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return godirwalk.SkipThis
})
}
// Adds a given file path to the final archive being created.
func (a *Archive) addToArchive(p string, rp string, w *tar.Writer) error {
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// Lstat the file, this will give us the same information as Stat except that it will not
// follow a symlink to it's target automatically. This is important to avoid including
// files that exist outside the server root unintentionally in the backup.
s, err := os.Lstat(p)
if err != nil {
if os.IsNotExist(err) {
return nil
}
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return errors.WrapIff(err, "failed executing os.Lstat on '%s'", rp)
}
// Skip socket files as they are unsupported by archive/tar.
// Error will come from tar#FileInfoHeader: "archive/tar: sockets not supported"
if s.Mode()&fs.ModeSocket != 0 {
return nil
}
// Resolve the symlink target if the file is a symlink.
var target string
if s.Mode()&fs.ModeSymlink != 0 {
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// Read the target of the symlink. If there are any errors we will dump them out to
// the logs, but we're not going to stop the backup. There are far too many cases of
// symlinks causing all sorts of unnecessary pain in this process. Sucks to suck if
// it doesn't work.
target, err = os.Readlink(s.Name())
if err != nil {
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// Ignore the not exist errors specifically, since theres nothing important about that.
if !os.IsNotExist(err) {
log.WithField("path", rp).WithField("readlink_err", err.Error()).Warn("failed reading symlink for target path; skipping...")
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}
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return nil
}
}
// Get the tar FileInfoHeader in order to add the file to the archive.
header, err := tar.FileInfoHeader(s, filepath.ToSlash(target))
if err != nil {
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return errors.WrapIff(err, "failed to get tar#FileInfoHeader for '%s'", rp)
}
// Fix the header name if the file is not a symlink.
if s.Mode()&fs.ModeSymlink == 0 {
header.Name = rp
}
// Write the tar FileInfoHeader to the archive.
if err := w.WriteHeader(header); err != nil {
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return errors.WrapIff(err, "failed to write tar#FileInfoHeader for '%s'", rp)
}
// If the size of the file is less than 1 (most likely for symlinks), skip writing the file.
if header.Size < 1 {
return nil
}
// If the buffer size is larger than the file size, create a smaller buffer to hold the file.
var buf []byte
if header.Size < memory {
buf = make([]byte, header.Size)
} else {
// Get a fixed-size buffer from the pool to save on allocations.
buf = pool.Get().([]byte)
defer func() {
buf = make([]byte, memory)
pool.Put(buf)
}()
}
// Open the file.
f, err := os.Open(p)
if err != nil {
if os.IsNotExist(err) {
return nil
}
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return errors.WrapIff(err, "failed to open '%s' for copying", header.Name)
}
defer f.Close()
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// Copy the file's contents to the archive using our buffer.
if _, err := io.CopyBuffer(w, io.LimitReader(f, header.Size), buf); err != nil {
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return errors.WrapIff(err, "failed to copy '%s' to archive", header.Name)
}
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return nil
}