mime/quotedprintable: create the package

This commit creates the mime/quotedprintable package. It moves and
exports the QP reader of mime/internal/quotedprintable.

The code is almost unchanged to preserve the commit history.

Updates #4943

Change-Id: I4b7b5a2a40a4c84346d42e4cdd2c11a91b28f9e3
Reviewed-on: https://go-review.googlesource.com/5940
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/go/build/deps_test.go

@@ -311,7 +311,7 @@ var pkgDeps = map[string][]string{
 	"crypto/x509/pkix": {"L4", "CRYPTO-MATH"},
 
 	// Simple net+crypto-aware packages.
-	"mime/multipart": {"L4", "OS", "mime", "crypto/rand", "net/textproto", "mime/internal/quotedprintable"},
+	"mime/multipart": {"L4", "OS", "mime", "crypto/rand", "net/textproto", "mime/quotedprintable"},
 	"net/smtp":       {"L4", "CRYPTO", "NET", "crypto/tls"},
 
 	// HTTP, kingpin of dependencies.

src/mime/multipart/multipart.go

@@ -19,7 +19,7 @@ import (
 	"io"
 	"io/ioutil"
 	"mime"
-	"mime/internal/quotedprintable"
+	"mime/quotedprintable"
 	"net/textproto"
 )
 

src/mime/quotedprintable/reader.go

@@ -2,12 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// The file define a quoted-printable decoder, as specified in RFC 2045.
-// Deviations:
-// 1. in addition to "=\r\n", "=\n" is also treated as soft line break.
-// 2. it will pass through a '\r' or '\n' not preceded by '=', consistent
-//    with other broken QP encoders & decoders.
-
+// Package quotedprintable implements quoted-printable encoding as specified by
+// RFC 2045.
 package quotedprintable
 
 import (
@@ -17,14 +13,19 @@ import (
 	"io"
 )
 
-type qpReader struct {
+// Deviations from RFC 2045:
+// 1. in addition to "=\r\n", "=\n" is also treated as soft line break.
+// 2. it will pass through a '\r' or '\n' not preceded by '=', consistent
+//    with other broken QP encoders & decoders.
+type reader struct {
 	br   *bufio.Reader
 	rerr error  // last read error
 	line []byte // to be consumed before more of br
 }
 
+// NewReader returns a quoted-printable reader, decoding from r.
 func NewReader(r io.Reader) io.Reader {
-	return &qpReader{
+	return &reader{
 		br: bufio.NewReader(r),
 	}
 }
@@ -36,10 +37,10 @@ func fromHex(b byte) (byte, error) {
 	case b >= 'A' && b <= 'F':
 		return b - 'A' + 10, nil
 	}
-	return 0, fmt.Errorf("multipart: invalid quoted-printable hex byte 0x%02x", b)
+	return 0, fmt.Errorf("quotedprintable: invalid hex byte 0x%02x", b)
 }
 
-func (q *qpReader) readHexByte(v []byte) (b byte, err error) {
+func (q *reader) readHexByte(v []byte) (b byte, err error) {
 	if len(v) < 2 {
 		return 0, io.ErrUnexpectedEOF
 	}
@@ -67,7 +68,7 @@ var (
 	softSuffix = []byte("=")
 )
 
-func (q *qpReader) Read(p []byte) (n int, err error) {
+func (q *reader) Read(p []byte) (n int, err error) {
 	for len(p) > 0 {
 		if len(q.line) == 0 {
 			if q.rerr != nil {
@@ -84,7 +85,7 @@ func (q *qpReader) Read(p []byte) (n int, err error) {
 				rightStripped := wholeLine[len(q.line):]
 				q.line = q.line[:len(q.line)-1]
 				if !bytes.HasPrefix(rightStripped, lf) && !bytes.HasPrefix(rightStripped, crlf) {
-					q.rerr = fmt.Errorf("multipart: invalid bytes after =: %q", rightStripped)
+					q.rerr = fmt.Errorf("quotedprintable: invalid bytes after =: %q", rightStripped)
 				}
 			} else if hasLF {
 				if hasCR {
@@ -107,7 +108,7 @@ func (q *qpReader) Read(p []byte) (n int, err error) {
 		case b == '\t' || b == '\r' || b == '\n':
 			break
 		case b < ' ' || b > '~':
-			return n, fmt.Errorf("multipart: invalid unescaped byte 0x%02x in quoted-printable body", b)
+			return n, fmt.Errorf("quotedprintable: invalid unescaped byte 0x%02x in body", b)
 		}
 		p[0] = b
 		p = p[1:]

src/mime/quotedprintable/reader_test.go

@@ -19,7 +19,7 @@ import (
 	"time"
 )
 
-func TestQuotedPrintable(t *testing.T) {
+func TestReader(t *testing.T) {
 	tests := []struct {
 		in, want string
 		err      interface{}
@@ -30,14 +30,14 @@ func TestQuotedPrintable(t *testing.T) {
 		{in: "foo bar=\n", want: "foo bar"},
 		{in: "foo bar\n", want: "foo bar\n"}, // somewhat lax.
 		{in: "foo bar=0", want: "foo bar", err: io.ErrUnexpectedEOF},
-		{in: "foo bar=ab", want: "foo bar", err: "multipart: invalid quoted-printable hex byte 0x61"},
+		{in: "foo bar=ab", want: "foo bar", err: "quotedprintable: invalid hex byte 0x61"},
 		{in: "foo bar=0D=0A", want: "foo bar\r\n"},
 		{in: " A B        \r\n C ", want: " A B\r\n C"},
 		{in: " A B =\r\n C ", want: " A B  C"},
 		{in: " A B =\n C ", want: " A B  C"}, // lax. treating LF as CRLF
 		{in: "foo=\nbar", want: "foobar"},
-		{in: "foo\x00bar", want: "foo", err: "multipart: invalid unescaped byte 0x00 in quoted-printable body"},
-		{in: "foo bar\xff", want: "foo bar", err: "multipart: invalid unescaped byte 0xff in quoted-printable body"},
+		{in: "foo\x00bar", want: "foo", err: "quotedprintable: invalid unescaped byte 0x00 in body"},
+		{in: "foo bar\xff", want: "foo bar", err: "quotedprintable: invalid unescaped byte 0xff in body"},
 
 		// Equal sign.
 		{in: "=3D30\n", want: "=30\n"},
@@ -56,8 +56,8 @@ func TestQuotedPrintable(t *testing.T) {
 		// Different types of soft line-breaks.
 		{in: "foo=\r\nbar", want: "foobar"},
 		{in: "foo=\nbar", want: "foobar"},
-		{in: "foo=\rbar", want: "foo", err: "multipart: invalid quoted-printable hex byte 0x0d"},
-		{in: "foo=\r\r\r \nbar", want: "foo", err: `multipart: invalid bytes after =: "\r\r\r \n"`},
+		{in: "foo=\rbar", want: "foo", err: "quotedprintable: invalid hex byte 0x0d"},
+		{in: "foo=\r\r\r \nbar", want: "foo", err: `quotedprintable: invalid bytes after =: "\r\r\r \n"`},
 
 		// Example from RFC 2045:
 		{in: "Now's the time =\n" + "for all folk to come=\n" + " to the aid of their country.",
@@ -101,7 +101,7 @@ var useQprint = flag.Bool("qprint", false, "Compare against the 'qprint' program
 
 var badSoftRx = regexp.MustCompile(`=([^\r\n]+?\n)|([^\r\n]+$)|(\r$)|(\r[^\n]+\n)|( \r\n)`)
 
-func TestQPExhaustive(t *testing.T) {
+func TestExhaustive(t *testing.T) {
 	if *useQprint {
 		_, err := exec.LookPath("qprint")
 		if err != nil {
@@ -123,7 +123,7 @@ func TestQPExhaustive(t *testing.T) {
 				errStr = "invalid bytes after ="
 			}
 			res[errStr]++
-			if strings.Contains(errStr, "invalid quoted-printable hex byte ") {
+			if strings.Contains(errStr, "invalid hex byte ") {
 				if strings.HasSuffix(errStr, "0x20") && (strings.Contains(s, "=0 ") || strings.Contains(s, "=A ") || strings.Contains(s, "= ")) {
 					return
 				}
@@ -193,10 +193,10 @@ func TestQPExhaustive(t *testing.T) {
 	got := strings.Join(outcomes, "\n")
 	want := `OK: 21576
 invalid bytes after =: 3397
-multipart: invalid quoted-printable hex byte 0x0a: 1400
-multipart: invalid quoted-printable hex byte 0x0d: 2700
-multipart: invalid quoted-printable hex byte 0x20: 2490
-multipart: invalid quoted-printable hex byte 0x3d: 440
+quotedprintable: invalid hex byte 0x0a: 1400
+quotedprintable: invalid hex byte 0x0d: 2700
+quotedprintable: invalid hex byte 0x20: 2490
+quotedprintable: invalid hex byte 0x3d: 440
 unexpected EOF: 3122`
 	if got != want {
 		t.Errorf("Got:\n%s\nWant:\n%s", got, want)