wings/server/filesystem/decompress.go

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package filesystem
import (
"archive/tar"
"archive/zip"
"compress/gzip"
"fmt"
"github.com/mholt/archiver/v3"
"github.com/pkg/errors"
"os"
"path/filepath"
"reflect"
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"strings"
"sync/atomic"
)
// Look through a given archive and determine if decompressing it would put the server over
// its allocated disk space limit.
func (fs *Filesystem) SpaceAvailableForDecompression(dir string, file string) (bool, error) {
// Don't waste time trying to determine this if we know the server will have the space for
// it since there is no limit.
if fs.MaxDisk() <= 0 {
return true, nil
}
source, err := fs.SafePath(filepath.Join(dir, file))
if err != nil {
return false, err
}
// Get the cached size in a parallel process so that if it is not cached we are not
// waiting an unnecessary amount of time on this call.
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dirSize, err := fs.DiskUsage(false)
var size int64
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// Walk over the archive and figure out just how large the final output would be from unarchiving it.
err = archiver.Walk(source, func(f archiver.File) error {
if atomic.AddInt64(&size, f.Size())+dirSize > fs.MaxDisk() {
return ErrNotEnoughDiskSpace
}
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return nil
})
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if err != nil {
if strings.HasPrefix(err.Error(), "format ") {
return false, ErrUnknownArchiveFormat
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}
return false, err
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}
return true, err
}
// Decompress a file in a given directory by using the archiver tool to infer the file
// type and go from there. This will walk over all of the files within the given archive
// and ensure that there is not a zip-slip attack being attempted by validating that the
// final path is within the server data directory.
func (fs *Filesystem) DecompressFile(dir string, file string) error {
source, err := fs.SafePath(filepath.Join(dir, file))
if err != nil {
return err
}
// Make sure the file exists basically.
if _, err := os.Stat(source); err != nil {
return err
}
// Walk over all of the files spinning up an additional go-routine for each file we've encountered
// and then extract that file from the archive and write it to the disk. If any part of this process
// encounters an error the entire process will be stopped.
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err = archiver.Walk(source, func(f archiver.File) error {
// Don't waste time with directories, we don't need to create them if they have no contents, and
// we will ensure the directory exists when opening the file for writing anyways.
if f.IsDir() {
return nil
}
var name string
switch s := f.Sys().(type) {
case *tar.Header:
name = s.Name
case *gzip.Header:
name = s.Name
case *zip.FileHeader:
name = s.Name
default:
return errors.New(fmt.Sprintf("could not parse underlying data source with type %s", reflect.TypeOf(s).String()))
}
p, err := fs.SafePath(filepath.Join(dir, name))
if err != nil {
return errors.WithMessage(err, "failed to generate a safe path to server file")
}
return errors.WithMessage(fs.Writefile(p, f), "could not extract file from archive")
})
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if err != nil {
if strings.HasPrefix(err.Error(), "format ") {
return ErrUnknownArchiveFormat
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}
return err
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}
return nil
}