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package asset
import (
"bytes"
"compress/gzip"
"errors"
"fmt"
"io"
"io/fs"
"strings"
"github.com/omeid/go-tarfs"
)
type archiveLoader struct {
loader Loader
}
// NewArchiveLoader wraps an existing Loader in order to support extracting
// files from within an archive file asset.
//
// For example, loading the path `foo.tgz/foo/bar.jpg` will call
// `Load("foo.tgz")`, load that archive into memory, and serve the file
// `./foo/bar.jpg` from within the archive.
func NewArchiveLoader(loader Loader) Loader {
return &archiveLoader{loader: loader}
}
func (l *archiveLoader) Load(path string, into io.Writer, opts LoadOpts) error {
id, subPath, ok := strings.Cut(strings.TrimPrefix(path, "/"), "/")
if !ok {
return l.loader.Load(path, into, opts)
}
var isGzipped bool
switch {
case strings.HasSuffix(id, ".tar.gz"),
strings.HasSuffix(id, ".tgz"):
isGzipped = true
case strings.HasSuffix(id, ".tar"):
// ok
default:
// unsupported
return l.loader.Load(path, into, opts)
}
buf := new(bytes.Buffer)
if err := l.loader.Load(id, buf, opts); err != nil {
return fmt.Errorf("loading archive into buffer: %w", err)
}
var (
from io.Reader = buf
err error
)
if isGzipped {
if from, err = gzip.NewReader(from); err != nil {
return fmt.Errorf("decompressing archive asset with id %q: %w", id, err)
}
}
tarFS, err := tarfs.New(from)
if err != nil {
return fmt.Errorf("reading archive asset with id %q as fs: %w", id, err)
}
f, err := tarFS.Open(subPath)
if errors.Is(err, fs.ErrExist) {
return ErrNotFound
} else if err != nil {
return fmt.Errorf(
"opening path %q from archive asset with id %q as fs: %w",
subPath, id, err,
)
}
defer f.Close()
if _, err = io.Copy(into, f); err != nil {
return fmt.Errorf(
"reading %q from archive asset with id %q as fs: %w",
subPath, id, err,
)
}
return nil
}
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