wings/server/filesystem/decompress.go
2021-01-16 11:48:30 -08:00

112 lines
3.3 KiB
Go

package filesystem
import (
"archive/tar"
"archive/zip"
"compress/gzip"
"fmt"
"os"
"path/filepath"
"reflect"
"strings"
"sync/atomic"
"emperror.dev/errors"
"github.com/mholt/archiver/v3"
)
// SpaceAvailableForDecompression looks through a given archive and determines
// if decompressing it would put the server over its allocated disk space limit.
func (fs *Filesystem) SpaceAvailableForDecompression(dir string, file string) 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 nil
}
source, err := fs.SafePath(filepath.Join(dir, file))
if err != nil {
return 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.
dirSize, err := fs.DiskUsage(false)
var size int64
// 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 &Error{code: ErrCodeDiskSpace}
}
return nil
})
if err != nil {
if strings.HasPrefix(err.Error(), "format ") {
return &Error{code: ErrCodeUnknownArchive}
}
return err
}
return err
}
// DecompressFile will 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
}
// Ensure that the source archive actually exists on the system.
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.
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 &Error{
code: ErrCodeUnknownError,
resolved: filepath.Join(dir, f.Name()),
err: errors.New(fmt.Sprintf("could not parse underlying data source with type: %s", reflect.TypeOf(s).String())),
}
}
p := filepath.Join(dir, name)
// If it is ignored, just don't do anything with the file and skip over it.
if err := fs.IsIgnored(p); err != nil {
return nil
}
if err := fs.Writefile(p, f); err != nil {
return &Error{code: ErrCodeUnknownError, err: err, resolved: source}
}
return nil
})
if err != nil {
if strings.HasPrefix(err.Error(), "format ") {
return &Error{code: ErrCodeUnknownArchive}
}
return err
}
return nil
}