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Diffstat (limited to 'hugofs/hashing_fs.go')
-rw-r--r-- | hugofs/hashing_fs.go | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/hugofs/hashing_fs.go b/hugofs/hashing_fs.go new file mode 100644 index 000000000..94a50b960 --- /dev/null +++ b/hugofs/hashing_fs.go @@ -0,0 +1,92 @@ +// Copyright 2019 The Hugo Authors. All rights reserved. +// +// 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 hugofs + +import ( + "crypto/md5" + "encoding/hex" + "hash" + "os" + + "github.com/spf13/afero" +) + +var ( + _ afero.Fs = (*md5HashingFs)(nil) +) + +// FileHashReceiver will receive the filename an the content's MD5 sum on file close. +type FileHashReceiver interface { + OnFileClose(name, md5sum string) +} + +type md5HashingFs struct { + afero.Fs + hashReceiver FileHashReceiver +} + +// NewHashingFs creates a new filesystem that will receive MD5 checksums of +// any written file content on Close. Note that this is probably not a good +// idea for "full build" situations, but when doing fast render mode, the amount +// of files published is low, and it would be really nice to know exactly which +// of these files where actually changed. +// Note that this will only work for file operations that use the io.Writer +// to write content to file, but that is fine for the "publish content" use case. +func NewHashingFs(delegate afero.Fs, hashReceiver FileHashReceiver) afero.Fs { + return &md5HashingFs{Fs: delegate, hashReceiver: hashReceiver} +} + +func (fs *md5HashingFs) Create(name string) (afero.File, error) { + f, err := fs.Fs.Create(name) + if err == nil { + f = fs.wrapFile(f) + } + return f, err +} + +func (fs *md5HashingFs) OpenFile(name string, flag int, perm os.FileMode) (afero.File, error) { + f, err := fs.Fs.OpenFile(name, flag, perm) + if err == nil && isWrite(flag) { + f = fs.wrapFile(f) + } + return f, err +} + +func (fs *md5HashingFs) wrapFile(f afero.File) afero.File { + return &hashingFile{File: f, h: md5.New(), hashReceiver: fs.hashReceiver} +} + +func (fs *md5HashingFs) Name() string { + return "md5HashingFs" +} + +type hashingFile struct { + hashReceiver FileHashReceiver + h hash.Hash + afero.File +} + +func (h *hashingFile) Write(p []byte) (n int, err error) { + n, err = h.File.Write(p) + if err != nil { + return + } + return h.h.Write(p) +} + +func (h *hashingFile) Close() error { + sum := hex.EncodeToString(h.h.Sum(nil)) + h.hashReceiver.OnFileClose(h.Name(), sum) + return h.File.Close() +} |