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Copy pathminify.go
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375 lines (328 loc) · 12.1 KB
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// Package minify relates MIME type to minifiers. Several minifiers are provided in the subpackages.
package minify
import (
"bytes"
"errors"
"fmt"
"io"
"log"
"mime"
"net/http"
"net/url"
"os"
"os/exec"
"path"
"regexp"
"strings"
"sync"
"github.com/tdewolff/parse/v2"
"github.com/tdewolff/parse/v2/buffer"
)
// Warning is used to report usage warnings such as using a deprecated feature
var Warning = log.New(os.Stderr, "WARNING: ", 0)
// ErrNotExist is returned when no minifier exists for a given mimetype.
var ErrNotExist = errors.New("minifier does not exist for mimetype")
// ErrClosedWriter is returned when writing to a closed writer.
var ErrClosedWriter = errors.New("write on closed writer") // TODO: DEPRECATED, remove
////////////////////////////////////////////////////////////////
// MinifierFunc is a function that implements Minifer.
type MinifierFunc func(*M, io.Writer, io.Reader, map[string]string) error
// Minify calls f(m, w, r, params)
func (f MinifierFunc) Minify(m *M, w io.Writer, r io.Reader, params map[string]string) error {
return f(m, w, r, params)
}
// Minifier is the interface for minifiers.
// The *M parameter is used for minifying embedded resources, such as JS within HTML.
type Minifier interface {
Minify(*M, io.Writer, io.Reader, map[string]string) error
}
////////////////////////////////////////////////////////////////
type patternMinifier struct {
pattern *regexp.Regexp
Minifier
}
type cmdMinifier struct {
cmd *exec.Cmd
}
var cmdArgExtension = regexp.MustCompile(`^\.[0-9a-zA-Z]+`)
func (c *cmdMinifier) Minify(_ *M, w io.Writer, r io.Reader, _ map[string]string) error {
cmd := &exec.Cmd{}
*cmd = *c.cmd // concurrency safety
var in, out *os.File
for i, arg := range cmd.Args {
if j := strings.Index(arg, "$in"); j != -1 {
var err error
ext := cmdArgExtension.FindString(arg[j+3:])
if in, err = os.CreateTemp("", "minify-in-*"+ext); err != nil {
return err
}
cmd.Args[i] = arg[:j] + in.Name() + arg[j+3+len(ext):]
} else if j := strings.Index(arg, "$out"); j != -1 {
var err error
ext := cmdArgExtension.FindString(arg[j+4:])
if out, err = os.CreateTemp("", "minify-out-*"+ext); err != nil {
return err
}
cmd.Args[i] = arg[:j] + out.Name() + arg[j+4+len(ext):]
}
}
if in == nil {
cmd.Stdin = r
} else if _, err := io.Copy(in, r); err != nil {
return err
}
if out == nil {
cmd.Stdout = w
} else {
defer io.Copy(w, out)
}
stderr := &bytes.Buffer{}
cmd.Stderr = stderr
err := cmd.Run()
if _, ok := err.(*exec.ExitError); ok {
if stderr.Len() != 0 {
err = fmt.Errorf("%s", stderr.String())
}
err = fmt.Errorf("command %s failed: %w", cmd.Path, err)
}
return err
}
////////////////////////////////////////////////////////////////
// M holds a map of mimetype => function to allow recursive minifier calls of the minifier functions.
type M struct {
mutex sync.RWMutex
literal map[string]Minifier
pattern []patternMinifier
URL *url.URL
}
// New returns a new M.
func New() *M {
return &M{
sync.RWMutex{},
map[string]Minifier{},
[]patternMinifier{},
nil,
}
}
// Add adds a minifier to the mimetype => function map (unsafe for concurrent use).
func (m *M) Add(mimetype string, minifier Minifier) {
m.mutex.Lock()
m.literal[mimetype] = minifier
m.mutex.Unlock()
}
// AddFunc adds a minify function to the mimetype => function map (unsafe for concurrent use).
func (m *M) AddFunc(mimetype string, minifier MinifierFunc) {
m.mutex.Lock()
m.literal[mimetype] = minifier
m.mutex.Unlock()
}
// AddRegexp adds a minifier to the mimetype => function map (unsafe for concurrent use).
func (m *M) AddRegexp(pattern *regexp.Regexp, minifier Minifier) {
m.mutex.Lock()
m.pattern = append(m.pattern, patternMinifier{pattern, minifier})
m.mutex.Unlock()
}
// AddFuncRegexp adds a minify function to the mimetype => function map (unsafe for concurrent use).
func (m *M) AddFuncRegexp(pattern *regexp.Regexp, minifier MinifierFunc) {
m.mutex.Lock()
m.pattern = append(m.pattern, patternMinifier{pattern, minifier})
m.mutex.Unlock()
}
// AddCmd adds a minify function to the mimetype => function map (unsafe for concurrent use) that executes a command to process the minification.
// It allows the use of external tools like ClosureCompiler, UglifyCSS, etc. for a specific mimetype.
func (m *M) AddCmd(mimetype string, cmd *exec.Cmd) {
m.mutex.Lock()
m.literal[mimetype] = &cmdMinifier{cmd}
m.mutex.Unlock()
}
// AddCmdRegexp adds a minify function to the mimetype => function map (unsafe for concurrent use) that executes a command to process the minification.
// It allows the use of external tools like ClosureCompiler, UglifyCSS, etc. for a specific mimetype regular expression.
func (m *M) AddCmdRegexp(pattern *regexp.Regexp, cmd *exec.Cmd) {
m.mutex.Lock()
m.pattern = append(m.pattern, patternMinifier{pattern, &cmdMinifier{cmd}})
m.mutex.Unlock()
}
// Match returns the pattern and minifier that gets matched with the mediatype.
// It returns nil when no matching minifier exists.
// It has the same matching algorithm as Minify.
func (m *M) Match(mediatype string) (string, map[string]string, MinifierFunc) {
m.mutex.RLock()
defer m.mutex.RUnlock()
mimetype, params := parse.Mediatype([]byte(mediatype))
if minifier, ok := m.literal[string(mimetype)]; ok { // string conversion is optimized away
return string(mimetype), params, minifier.Minify
}
for _, minifier := range m.pattern {
if minifier.pattern.Match(mimetype) {
return minifier.pattern.String(), params, minifier.Minify
}
}
return string(mimetype), params, nil
}
// Minify minifies the content of a Reader and writes it to a Writer (safe for concurrent use).
// An error is returned when no such mimetype exists (ErrNotExist) or when an error occurred in the minifier function.
// Mediatype may take the form of 'text/plain', 'text/*', '*/*' or 'text/plain; charset=UTF-8; version=2.0'.
func (m *M) Minify(mediatype string, w io.Writer, r io.Reader) error {
mimetype, params := parse.Mediatype([]byte(mediatype))
return m.MinifyMimetype(mimetype, w, r, params)
}
// MinifyMimetype minifies the content of a Reader and writes it to a Writer (safe for concurrent use).
// It is a lower level version of Minify and requires the mediatype to be split up into mimetype and parameters.
// It is mostly used internally by minifiers because it is faster (no need to convert a byte-slice to string and vice versa).
func (m *M) MinifyMimetype(mimetype []byte, w io.Writer, r io.Reader, params map[string]string) error {
m.mutex.RLock()
defer m.mutex.RUnlock()
if minifier, ok := m.literal[string(mimetype)]; ok { // string conversion is optimized away
return minifier.Minify(m, w, r, params)
}
for _, minifier := range m.pattern {
if minifier.pattern.Match(mimetype) {
return minifier.Minify(m, w, r, params)
}
}
return ErrNotExist
}
// Bytes minifies an array of bytes (safe for concurrent use). When an error occurs it return the original array and the error.
// It returns an error when no such mimetype exists (ErrNotExist) or any error occurred in the minifier function.
func (m *M) Bytes(mediatype string, v []byte) ([]byte, error) {
out := buffer.NewWriter(make([]byte, 0, len(v)))
if err := m.Minify(mediatype, out, buffer.NewReader(v)); err != nil {
return v, err
}
return out.Bytes(), nil
}
// String minifies a string (safe for concurrent use). When an error occurs it return the original string and the error.
// It returns an error when no such mimetype exists (ErrNotExist) or any error occurred in the minifier function.
func (m *M) String(mediatype string, v string) (string, error) {
out := buffer.NewWriter(make([]byte, 0, len(v)))
if err := m.Minify(mediatype, out, buffer.NewReader([]byte(v))); err != nil {
return v, err
}
return string(out.Bytes()), nil
}
// Reader wraps a Reader interface and minifies the stream.
// Errors from the minifier are returned by the reader.
func (m *M) Reader(mediatype string, r io.Reader) io.Reader {
pr, pw := io.Pipe()
go func() {
if err := m.Minify(mediatype, pw, r); err != nil {
pw.CloseWithError(err)
} else {
pw.Close()
}
}()
return pr
}
// writer makes sure that errors from the minifier are passed down through Close (can be blocking).
type writer struct {
io.WriteCloser
wg sync.WaitGroup
closed bool
err error
}
// Close must be called when writing has finished. It returns the error from the minifier.
func (z *writer) Close() error {
if z.closed {
return nil
}
z.closed = true
err := z.WriteCloser.Close()
z.wg.Wait()
if z.err == nil {
return err
}
return z.err
}
// Writer wraps a Writer interface and minifies the stream.
// Errors from the minifier are returned by Close on the writer.
// The writer must be closed explicitly.
func (m *M) Writer(mediatype string, w io.Writer) io.WriteCloser {
pr, pw := io.Pipe()
z := &writer{pw, sync.WaitGroup{}, false, nil}
z.wg.Add(1)
go func() {
defer z.wg.Done()
defer pr.Close()
if err := m.Minify(mediatype, w, pr); err != nil {
z.err = err
}
}()
return z
}
// responseWriter wraps an http.ResponseWriter and makes sure that errors from the minifier are passed down through Close (can be blocking).
// All writes to the response writer are intercepted and minified on the fly.
// http.ResponseWriter loses all functionality such as Pusher, Hijacker, Flusher, ...
type responseWriter struct {
http.ResponseWriter
z io.Writer
m *M
mediatype string
}
// WriteHeader intercepts any header writes and removes the Content-Length header.
func (w *responseWriter) WriteHeader(status int) {
w.ResponseWriter.Header().Del("Content-Length")
w.ResponseWriter.WriteHeader(status)
}
// Write intercepts any writes to the response writer.
// The first write will extract the Content-Type as the mediatype. Otherwise it falls back to the RequestURI extension.
func (w *responseWriter) Write(b []byte) (int, error) {
if w.z == nil {
// first write
if mediatype := w.ResponseWriter.Header().Get("Content-Type"); mediatype != "" {
w.mediatype = mediatype
}
if _, params, minifier := w.m.Match(w.mediatype); minifier != nil {
pr, pw := io.Pipe()
z := &writer{pw, sync.WaitGroup{}, false, nil}
z.wg.Add(1)
go func() {
defer z.wg.Done()
defer pr.Close()
if err := minifier(w.m, w.ResponseWriter, pr, params); err != nil {
z.err = err
}
}()
w.z = z
} else {
w.z = w.ResponseWriter
}
}
return w.z.Write(b)
}
// Close must be called when writing has finished. It returns the error from the minifier.
func (w *responseWriter) Close() error {
if closer, ok := w.z.(interface{ Close() error }); ok {
return closer.Close()
}
return nil
}
// ResponseWriter minifies any writes to the http.ResponseWriter.
// http.ResponseWriter loses all functionality such as Pusher, Hijacker, Flusher, ...
// Minification might be slower than just sending the original file! Caching is advised.
func (m *M) ResponseWriter(w http.ResponseWriter, r *http.Request) *responseWriter {
mediatype := mime.TypeByExtension(path.Ext(r.RequestURI))
return &responseWriter{w, nil, m, mediatype}
}
// Middleware provides a middleware function that minifies content on the fly by intercepting writes to http.ResponseWriter.
// http.ResponseWriter loses all functionality such as Pusher, Hijacker, Flusher, ...
// Minification might be slower than just sending the original file! Caching is advised.
func (m *M) Middleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
mw := m.ResponseWriter(w, r)
next.ServeHTTP(mw, r)
mw.Close()
})
}
// MiddlewareWithError provides a middleware function that minifies content on the fly by intercepting writes to http.ResponseWriter. The error function allows handling minification errors.
// http.ResponseWriter loses all functionality such as Pusher, Hijacker, Flusher, ...
// Minification might be slower than just sending the original file! Caching is advised.
func (m *M) MiddlewareWithError(next http.Handler, errorFunc func(w http.ResponseWriter, r *http.Request, err error)) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
mw := m.ResponseWriter(w, r)
next.ServeHTTP(mw, r)
if err := mw.Close(); err != nil {
errorFunc(w, r, err)
return
}
})
}