From ab0d686b9bb43a02f8d74c5e881782ab4e94e30b Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Sat, 18 Feb 2023 12:53:05 -0700
Subject: jsonparse: Have PushReadBarrier reject trailing whitespace

---
 internal/jsonparse/parse.go | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

(limited to 'internal/jsonparse')

diff --git a/internal/jsonparse/parse.go b/internal/jsonparse/parse.go
index 06efc8c..1c35533 100644
--- a/internal/jsonparse/parse.go
+++ b/internal/jsonparse/parse.go
@@ -324,7 +324,8 @@ type Parser struct {
 }
 
 type barrier struct {
-	stack []RuneType
+	allowWS bool
+	stack   []RuneType
 }
 
 func (par *Parser) init() {
@@ -387,9 +388,10 @@ func (par *Parser) Reset() {
 }
 
 // PushReadBarrier causes the parser to emit EOF once the end of the
-// element that is started by the current top-of-stack is reached,
-// until this is un-done with PopBarrier.  It essentially turns the
-// parser in to a sub-parser.
+// element that is started by the current top-of-stack is reached
+// (which means that it will reject whitespace between the end of the
+// element and EOF), until this is un-done with PopBarrier.  It
+// essentially turns the parser in to a sub-parser.
 //
 // PushReadBarrier may only be called at the beginning of an element,
 // whether that be
@@ -424,14 +426,16 @@ func (par *Parser) PushReadBarrier() {
 	}
 	// Actually push.
 	par.barriers = append(par.barriers, barrier{
-		stack: par.stack[:len(par.stack)-1],
+		allowWS: false,
+		stack:   par.stack[:len(par.stack)-1],
 	})
 	par.stack = []RuneType{curState}
 }
 
 // PushWriteBarrier causes the parser to emit EOF once the end of the
-// about-to-start element is reached, until this is un-done with
-// PopBarrier.  It essentially turns the parser in to a sub-parser.
+// about-to-start element is reached and any trailing whitespace has
+// been exhausted, until this is un-done with PopBarrier.  It
+// essentially turns the parser in to a sub-parser.
 //
 // PushWriteBarrier may only be called at the places where an element
 // of any type may start:
@@ -451,13 +455,15 @@ func (par *Parser) PushWriteBarrier() {
 	case runeTypeAny:
 		par.popState()
 		par.barriers = append(par.barriers, barrier{
-			stack: par.stack,
+			allowWS: true,
+			stack:   par.stack,
 		})
 		par.stack = []RuneType{runeTypeAny}
 	case RuneTypeArrayBeg:
 		par.replaceState(RuneTypeArrayComma)
 		par.barriers = append(par.barriers, barrier{
-			stack: par.stack,
+			allowWS: true,
+			stack:   par.stack,
 		})
 		par.stack = []RuneType{runeTypeAny}
 	default:
@@ -541,16 +547,17 @@ func (par *Parser) HandleRune(c rune) (RuneType, error) {
 	}
 	par.init()
 	if len(par.stack) == 0 {
-		switch c {
-		case 0x0020, 0x000A, 0x000D, 0x0009:
-			return RuneTypeSpace, nil
-		default:
-			if len(par.barriers) > 0 {
-				return RuneTypeEOF, nil
-			} else {
-				return RuneTypeError, fmt.Errorf("invalid character %q after top-level value", c)
+		if len(par.barriers) == 0 || par.barriers[len(par.barriers)-1].allowWS {
+			switch c {
+			case 0x0020, 0x000A, 0x000D, 0x0009:
+				return RuneTypeSpace, nil
 			}
 		}
+		if len(par.barriers) > 0 {
+			return RuneTypeEOF, nil
+		} else {
+			return RuneTypeError, fmt.Errorf("invalid character %q after top-level value", c)
+		}
 	}
 	switch par.stack[len(par.stack)-1] {
 	// any /////////////////////////////////////////////////////////////////////////////////////
-- 
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