mime/quotedprintable: accept trailing soft line-break at the end of message

Fixes #15486.

Change-Id: Id879dc9acef9232003df9a0f6f54312191374a60
Reviewed-on: https://go-review.googlesource.com/27530
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/mime/quotedprintable/reader.go b/src/mime/quotedprintable/reader.go
index 3bd6833da5fb8f52febec95e49145675b80d23a2..7645777ab2170d34f3bd261b54a082a8b3ceb82a 100644 (file)
--- a/src/mime/quotedprintable/reader.go
+++ b/src/mime/quotedprintable/reader.go
@@ -74,6 +74,9 @@ func (r *Reader) Read(p []byte) (n int, err error) {
        // 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.
+       // 3. it accepts soft line-break (=) at end of message (issue 15486); i.e.
+       //    the final byte read from the underlying reader is allowed to be '=',
+       //    and it will be silently ignored.
        for len(p) > 0 {
                if len(r.line) == 0 {
                        if r.rerr != nil {
@@ -89,7 +92,8 @@ func (r *Reader) Read(p []byte) (n int, err error) {
                        if bytes.HasSuffix(r.line, softSuffix) {
                                rightStripped := wholeLine[len(r.line):]
                                r.line = r.line[:len(r.line)-1]
-                               if !bytes.HasPrefix(rightStripped, lf) && !bytes.HasPrefix(rightStripped, crlf) {
+                               if !bytes.HasPrefix(rightStripped, lf) && !bytes.HasPrefix(rightStripped, crlf) &&
+                                       !(len(rightStripped) == 0 && len(r.line) > 0 && r.rerr == io.EOF) {
                                        r.rerr = fmt.Errorf("quotedprintable: invalid bytes after =: %q", rightStripped)
                                }
                        } else if hasLF {

diff --git a/src/mime/quotedprintable/reader_test.go b/src/mime/quotedprintable/reader_test.go
index e77b2610ec104a083da6a88f63cbf7ea81bbeebb..966f33e6c0efb6ea265188aaa523b06fd72e4a1f 100644 (file)
--- a/src/mime/quotedprintable/reader_test.go
+++ b/src/mime/quotedprintable/reader_test.go
@@ -58,6 +58,9 @@ func TestReader(t *testing.T) {
                {in: "foo=\nbar", want: "foobar"},
                {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"`},
+               // Issue 15486, accept trailing soft line-break at end of input.
+               {in: "foo=", want: "foo"},
+               {in: "=", want: "", err: `quotedprintable: invalid bytes after =: ""`},
 
                // Example from RFC 2045:
                {in: "Now's the time =\n" + "for all folk to come=\n" + " to the aid of their country.",