forked from perkeep/perkeep
/
genfileembed.go
228 lines (207 loc) · 4.92 KB
/
genfileembed.go
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/*
Copyright 2012 Google Inc.
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 main
import (
"bytes"
"compress/zlib"
"flag"
"fmt"
"go/parser"
"go/printer"
"go/token"
"io"
"io/ioutil"
"log"
"os"
"path/filepath"
"regexp"
"strings"
)
const (
maxUncompressed = 50 << 10 // 50KB
// Threshold ratio for compression.
// Files which don't compress at least as well are kept uncompressed.
zRatio = 0.5
)
func main() {
flag.Parse()
dir := "."
switch flag.NArg() {
case 0:
case 1:
dir = flag.Arg(0)
if err := os.Chdir(dir); err != nil {
log.Fatalf("chdir(%q) = %v", dir, err)
}
default:
fmt.Fprintf(os.Stderr, "usage: genfileembed [<dir>]\n")
os.Exit(2)
}
pkgName, filePattern, err := parseFileEmbed()
if err != nil {
log.Fatalf("Error parsing %s/fileembed.go: %v", dir, err)
}
for _, fileName := range matchingFiles(filePattern) {
embedName := "zembed_" + fileName + ".go"
fi, err := os.Stat(fileName)
if err != nil {
log.Fatal(err)
}
efi, err := os.Stat(embedName)
if err == nil && !efi.ModTime().Before(fi.ModTime()) {
continue
}
log.Printf("Updating %s (package %s)", filepath.Join(dir, embedName), pkgName)
zb, fileSize := compressFile(fileName)
ratio := float64(len(zb)) / float64(fileSize)
var bs []byte
byteStreamType := ""
if fileSize < maxUncompressed || ratio > zRatio {
byteStreamType = "fileembed.String"
bs, err = ioutil.ReadFile(fileName)
if err != nil {
log.Fatal(err)
}
} else {
byteStreamType = "fileembed.ZlibCompressed"
bs = zb
}
qb := quote(bs) // quoted bytes
var b bytes.Buffer
fmt.Fprintf(&b, "// THIS FILE IS AUTO-GENERATED FROM %s\n", fileName)
fmt.Fprintf(&b, "// DO NOT EDIT.\n")
fmt.Fprintf(&b, "package %s\n\n", pkgName)
fmt.Fprintf(&b, "import \"time\"\n\n")
fmt.Fprintf(&b, "import \"camlistore.org/pkg/fileembed\"\n\n")
fmt.Fprintf(&b, "func init() {\n\tFiles.Add(%q, %d, %s(%s), time.Unix(0, %d));\n}\n",
fileName, fileSize, byteStreamType, qb, fi.ModTime().UnixNano())
// gofmt it
fset := token.NewFileSet()
ast, err := parser.ParseFile(fset, "", b.Bytes(), parser.ParseComments)
if err != nil {
log.Fatal(err)
}
var clean bytes.Buffer
config := &printer.Config{
Mode: printer.TabIndent | printer.UseSpaces,
Tabwidth: 8,
}
err = config.Fprint(&clean, fset, ast)
if err != nil {
log.Fatal(err)
}
if err := ioutil.WriteFile(embedName, clean.Bytes(), 0644); err != nil {
log.Fatal(err)
}
}
}
func compressFile(fileName string) ([]byte, int64) {
var zb bytes.Buffer
f, err := os.Open(fileName)
if err != nil {
log.Fatal(err)
}
defer f.Close()
w := zlib.NewWriter(&zb)
n, err := io.Copy(w, f)
if err != nil {
log.Fatal(err)
}
w.Close()
return zb.Bytes(), n
}
func quote(bs []byte) []byte {
var qb bytes.Buffer
qb.WriteByte('"')
run := 0
for _, b := range bs {
if b == '\n' {
qb.WriteString(`\n`)
}
if b == '\n' || run > 80 {
qb.WriteString("\" +\n\t\"")
run = 0
}
if b == '\n' {
continue
}
run++
if b == '\\' {
qb.WriteString(`\\`)
continue
}
if b == '"' {
qb.WriteString(`\"`)
continue
}
if (b >= 32 && b <= 126) || b == '\t' {
qb.WriteByte(b)
continue
}
fmt.Fprintf(&qb, "\\x%02x", b)
}
qb.WriteByte('"')
return qb.Bytes()
}
func matchingFiles(p *regexp.Regexp) []string {
var f []string
d, err := os.Open(".")
if err != nil {
log.Fatal(err)
}
defer d.Close()
names, err := d.Readdirnames(-1)
if err != nil {
log.Fatal(err)
}
for _, n := range names {
if strings.HasPrefix(n, "zembed_") {
continue
}
if p.MatchString(n) {
f = append(f, n)
}
}
return f
}
func parseFileEmbed() (pkgName string, filePattern *regexp.Regexp, err error) {
fe, err := os.Open("fileembed.go")
if err != nil {
return
}
defer fe.Close()
fs := token.NewFileSet()
astf, err := parser.ParseFile(fs, "fileembed.go", fe, parser.PackageClauseOnly|parser.ParseComments)
if err != nil {
return
}
pkgName = astf.Name.Name
if astf.Doc == nil {
err = fmt.Errorf("no package comment before the %q line", "package "+pkgName)
return
}
pkgComment := astf.Doc.Text()
findPattern := regexp.MustCompile(`(?m)^#fileembed\s+pattern\s+(\S+)\s*$`)
m := findPattern.FindStringSubmatch(pkgComment)
if m == nil {
err = fmt.Errorf("package comment lacks line of form: #fileembed pattern <pattern>")
return
}
pattern := m[1]
filePattern, err = regexp.Compile(pattern)
if err != nil {
err = fmt.Errorf("bad regexp %q: %v", pattern, err)
return
}
return
}