github.com/olivere/camlistore@v0.0.0-20140121221811-1b7ac2da0199/server/camlistored/ui/closure/closure.go (about)

     1  /*
     2  Copyright 2013 Google Inc.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8  	http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package closure
    18  
    19  import (
    20  	"archive/zip"
    21  	"bytes"
    22  	"errors"
    23  	"fmt"
    24  	"io"
    25  	"io/ioutil"
    26  	"net/http"
    27  	"os"
    28  	"path"
    29  	"strings"
    30  	"sync"
    31  	"time"
    32  )
    33  
    34  // ZipData is either the empty string (when compiling with "go get",
    35  // or the devcam server), or is initialized to a base64-encoded zip file
    36  // of the Closure library (when using make.go, which puts an extra
    37  // file in this package containing an init function to set ZipData).
    38  var ZipData string
    39  var ZipModTime time.Time
    40  
    41  func FileSystem() (http.FileSystem, error) {
    42  	if ZipData == "" {
    43  		return nil, os.ErrNotExist
    44  	}
    45  	zr, err := zip.NewReader(strings.NewReader(ZipData), int64(len(ZipData)))
    46  	if err != nil {
    47  		return nil, err
    48  	}
    49  	m := make(map[string]*fileInfo)
    50  	for _, zf := range zr.File {
    51  		if !strings.HasPrefix(zf.Name, "closure/") {
    52  			continue
    53  		}
    54  		fi, err := newFileInfo(zf)
    55  		if err != nil {
    56  			return nil, fmt.Errorf("Error reading zip file %q: %v", zf.Name, err)
    57  		}
    58  		m[strings.TrimPrefix(zf.Name, "closure")] = fi
    59  	}
    60  	return &fs{zr, m}, nil
    61  
    62  }
    63  
    64  type fs struct {
    65  	zr *zip.Reader
    66  	m  map[string]*fileInfo // keyed by what Open gets. see Open's comment.
    67  }
    68  
    69  var nopCloser = ioutil.NopCloser(nil)
    70  
    71  // Open is called with names like "/goog/base.js", but the zip contains Files named like "closure/goog/base.js".
    72  func (s *fs) Open(name string) (http.File, error) {
    73  	fi, ok := s.m[name]
    74  	if !ok {
    75  		return nil, os.ErrNotExist
    76  	}
    77  	return &file{fileInfo: fi}, nil
    78  }
    79  
    80  // a file is an http.File, wrapping a *fileInfo with a lazily-constructed SectionReader.
    81  type file struct {
    82  	*fileInfo
    83  	once sync.Once // for making the SectionReader
    84  	sr   *io.SectionReader
    85  }
    86  
    87  func (f *file) Read(p []byte) (n int, err error) {
    88  	f.once.Do(f.initReader)
    89  	return f.sr.Read(p)
    90  }
    91  
    92  func (f *file) Seek(offset int64, whence int) (ret int64, err error) {
    93  	f.once.Do(f.initReader)
    94  	return f.sr.Seek(offset, whence)
    95  }
    96  
    97  func (f *file) initReader() {
    98  	f.sr = io.NewSectionReader(f.fileInfo.ra, 0, f.Size())
    99  }
   100  
   101  func newFileInfo(zf *zip.File) (*fileInfo, error) {
   102  	rc, err := zf.Open()
   103  	if err != nil {
   104  		return nil, err
   105  	}
   106  	all, err := ioutil.ReadAll(rc)
   107  	if err != nil {
   108  		return nil, err
   109  	}
   110  	rc.Close()
   111  	return &fileInfo{
   112  		fullName: zf.Name,
   113  		regdata:  all,
   114  		Closer:   nopCloser,
   115  		ra:       bytes.NewReader(all),
   116  	}, nil
   117  }
   118  
   119  type fileInfo struct {
   120  	fullName string
   121  	regdata  []byte      // non-nil if regular file
   122  	ra       io.ReaderAt // over regdata
   123  	io.Closer
   124  }
   125  
   126  func (f *fileInfo) IsDir() bool                { return f.regdata == nil }
   127  func (f *fileInfo) Size() int64                { return int64(len(f.regdata)) }
   128  func (f *fileInfo) ModTime() time.Time         { return ZipModTime }
   129  func (f *fileInfo) Name() string               { return path.Base(f.fullName) }
   130  func (f *fileInfo) Stat() (os.FileInfo, error) { return f, nil }
   131  func (f *fileInfo) Sys() interface{}           { return nil }
   132  
   133  func (f *fileInfo) Readdir(count int) ([]os.FileInfo, error) {
   134  	// TODO: implement.
   135  	return nil, errors.New("TODO")
   136  }
   137  
   138  func (f *fileInfo) Mode() os.FileMode {
   139  	if f.IsDir() {
   140  		return 0755 | os.ModeDir
   141  	}
   142  	return 0644
   143  }