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|
package zip
import (
"archive/zip"
"context"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"sync"
log "github.com/sirupsen/logrus"
"gitlab.com/gitlab-org/gitlab-pages/internal/httprange"
"gitlab.com/gitlab-org/gitlab-pages/internal/vfs"
)
const (
dirPrefix = "public/"
maxSymlinkSize = 256
)
var (
errNotSymlink = errors.New("not a symlink")
errSymlinkSize = errors.New("symlink too long")
)
// zipArchive implements the vfs.Root interface.
// It represents a zip archive saving all its files int memory.
// It holds an httprange.Resource that can be read with httprange.RangedReader in chunks.
type zipArchive struct {
path string
once sync.Once
done chan struct{}
resource *httprange.Resource
reader *httprange.RangedReader
archive *zip.Reader
err error
files map[string]*zip.File
}
func newArchive(path string) *zipArchive {
return &zipArchive{
path: path,
done: make(chan struct{}),
files: make(map[string]*zip.File),
}
}
func (a *zipArchive) openArchive(ctx context.Context) error {
a.once.Do(func() {
a.readArchive(ctx)
})
// wait for readArchive to be done or return when the context is canceled
select {
case <-a.done:
return a.err
case <-ctx.Done():
err := ctx.Err()
log.WithError(err).Traceln("open zip archive timed out")
return err
}
}
func (a *zipArchive) readArchive(ctx context.Context) {
defer close(a.done)
a.resource, a.err = httprange.NewResource(ctx, a.path)
if a.err != nil {
return
}
// load all archive files into memory using a cached ranged reader
a.reader = httprange.NewRangedReader(a.resource)
a.reader.WithCachedReader(func() {
a.archive, a.err = zip.NewReader(a.reader, a.resource.Size)
})
if a.archive != nil {
for _, file := range a.archive.File {
if !strings.HasPrefix(file.Name, dirPrefix) {
continue
}
a.files[file.Name] = file
}
// recycle memory
a.archive.File = nil
}
}
func (a *zipArchive) findFile(name string) *zip.File {
name = filepath.Join(dirPrefix, name)
if file := a.files[name]; file != nil {
return file
}
if dir := a.files[name+"/"]; dir != nil {
return dir
}
return nil
}
// Open finds the file by name inside the zipArchive and returns a reader that can be served by the VFS
func (a *zipArchive) Open(ctx context.Context, name string) (vfs.File, error) {
file := a.findFile(name)
if file == nil {
return nil, os.ErrNotExist
}
dataOffset, err := file.DataOffset()
if err != nil {
return nil, err
}
// only read from dataOffset up to the size of the compressed file
reader := a.reader.SectionReader(dataOffset, int64(file.CompressedSize64))
switch file.Method {
case zip.Deflate:
return newDeflateReader(reader), nil
case zip.Store:
return reader, nil
default:
return nil, fmt.Errorf("unsupported compression method: %x", file.Method)
}
}
// Lstat finds the file by name inside the zipArchive and returns its FileInfo
func (a *zipArchive) Lstat(ctx context.Context, name string) (os.FileInfo, error) {
file := a.findFile(name)
if file == nil {
return nil, os.ErrNotExist
}
return file.FileInfo(), nil
}
// ReadLink finds the file by name inside the zipArchive and returns the contents of the symlink
func (a *zipArchive) Readlink(ctx context.Context, name string) (string, error) {
file := a.findFile(name)
if file == nil {
return "", os.ErrNotExist
}
if file.FileInfo().Mode()&os.ModeSymlink != os.ModeSymlink {
return "", errNotSymlink
}
rc, err := file.Open()
if err != nil {
return "", err
}
defer rc.Close()
symlink := make([]byte, maxSymlinkSize+1)
// read up to len(symlink) bytes from the link file
n, err := io.ReadFull(rc, symlink)
if err != nil && err != io.ErrUnexpectedEOF {
// if err == io.ErrUnexpectedEOF the link is smaller than len(symlink) so it's OK to not return it
return "", err
}
// return errSymlinkSize if the number of bytes read from the link is too big
if n > maxSymlinkSize {
return "", errSymlinkSize
}
// only return the n bytes read from the link
return string(symlink[:n]), nil
}
// close no-op: everything can be recycled by the GC
func (a *zipArchive) close() {}
|
