| // Copyright 2021 The Prometheus Authors |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package assets |
| |
| import ( |
| "compress/gzip" |
| "embed" |
| "io" |
| "io/fs" |
| "time" |
| ) |
| |
| const ( |
| gzipSuffix = ".gz" |
| ) |
| |
| type FileSystem struct { |
| embed embed.FS |
| } |
| |
| func New(fs embed.FS) FileSystem { |
| return FileSystem{fs} |
| } |
| |
| // Open implements the fs.FS interface. |
| func (compressed FileSystem) Open(path string) (fs.File, error) { |
| // If we have the file in our embed FS, just return that as it could be a dir. |
| var f fs.File |
| if f, err := compressed.embed.Open(path); err == nil { |
| return f, nil |
| } |
| |
| f, err := compressed.embed.Open(path + gzipSuffix) |
| if err != nil { |
| return f, err |
| } |
| // Read the decompressed content into a buffer. |
| gr, err := gzip.NewReader(f) |
| if err != nil { |
| return f, err |
| } |
| defer gr.Close() |
| |
| c, err := io.ReadAll(gr) |
| if err != nil { |
| return f, err |
| } |
| // Wrap everything in our custom File. |
| return &File{file: f, content: c}, nil |
| } |
| |
| type File struct { |
| // The underlying file. |
| file fs.File |
| // The decrompressed content, needed to return an accurate size. |
| content []byte |
| // Offset for calls to Read(). |
| offset int |
| } |
| |
| // Stat implements the fs.File interface. |
| func (f File) Stat() (fs.FileInfo, error) { |
| stat, err := f.file.Stat() |
| if err != nil { |
| return stat, err |
| } |
| return FileInfo{stat, int64(len(f.content))}, nil |
| } |
| |
| // Read implements the fs.File interface. |
| func (f *File) Read(buf []byte) (int, error) { |
| if len(buf) > len(f.content)-f.offset { |
| buf = buf[0:len(f.content[f.offset:])] |
| } |
| n := copy(buf, f.content[f.offset:]) |
| if n == len(f.content)-f.offset { |
| return n, io.EOF |
| } |
| f.offset += n |
| return n, nil |
| } |
| |
| // Close implements the fs.File interface. |
| func (f File) Close() error { |
| return f.file.Close() |
| } |
| |
| type FileInfo struct { |
| fi fs.FileInfo |
| actualSize int64 |
| } |
| |
| // Name implements the fs.FileInfo interface. |
| func (fi FileInfo) Name() string { |
| name := fi.fi.Name() |
| return name[:len(name)-len(gzipSuffix)] |
| } |
| |
| // Size implements the fs.FileInfo interface. |
| func (fi FileInfo) Size() int64 { return fi.actualSize } |
| |
| // Mode implements the fs.FileInfo interface. |
| func (fi FileInfo) Mode() fs.FileMode { return fi.fi.Mode() } |
| |
| // ModTime implements the fs.FileInfo interface. |
| func (fi FileInfo) ModTime() time.Time { return fi.fi.ModTime() } |
| |
| // IsDir implements the fs.FileInfo interface. |
| func (fi FileInfo) IsDir() bool { return fi.fi.IsDir() } |
| |
| // Sys implements the fs.FileInfo interface. |
| func (fi FileInfo) Sys() interface{} { return nil } |