From 9145984972756c8b17f7edaf4d6e2391cb3fef65 Mon Sep 17 00:00:00 2001
From: Taco de Wolff <tacodewolff@gmail.com>
Date: Sun, 14 May 2023 19:24:43 -0400
Subject: [PATCH] JS: use literal NULL instead of escaped zero in strings,
 fixes #577

---
 js/js_test.go |  9 +++++----
 js/util.go    | 13 +++++++------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/js/js_test.go b/js/js_test.go
index 909266ac85..4ea670efea 100644
--- a/js/js_test.go
+++ b/js/js_test.go
@@ -149,9 +149,9 @@ func TestJS(t *testing.T) {
 		{`0,"string\t\f\v\bstring"`, "0,\"string\t\f\v\bstring\""},
 		{`0,"string\a\c\'string"`, `0,"stringac'string"`},
 		{`0,"string\∀string"`, `0,"string∀string"`},
-		{`0,"string\0\uFFFFstring"`, `0,"string\0\uFFFFstring"`},
-		{`0,"string\x00\x55\x0A\x0D\x22\x27string"`, `0,"string\0U\n\r\"'string"`},
-		{`0,"string\000\12\015\042\47\411string"`, `0,"string\0\n\r\"'!1string"`},
+		{`0,"string\0\uFFFFstring"`, "0,\"string\x00\\uFFFFstring\""},
+		{`0,"string\x00\x55\x0A\x0D\x22\x27string"`, "0,\"string\x00U\\n\\r\\\"'string\""},
+		{`0,"string\000\12\015\042\47\411string"`, "0,\"string\x00\\n\\r\\\"'!1string\""},
 		{"0,'string\\n\\rstring'", "0,`string\n\rstring`"},
 		{"0,'string\\\r\nstring\\\nstring\\\rstring\\\u2028string\\\u2029string'", `0,"stringstringstringstringstringstring"`},
 		{`0,"str1ng" + "str2ng"`, `0,"str1ngstr2ng"`},
@@ -793,7 +793,8 @@ func TestJS(t *testing.T) {
 		{`var a=5;({});var b=class{c(){3}}`, `var b,a=5;({},b=class{c(){3}})`},                                                                             // #494
 		{`({});a={b(){3}}`, `({},a={b(){3}})`},                                                                                                             // #494
 		{`export default function Foo(){a}Foo.prototype.bar=b`, `export default function Foo(){a}Foo.prototype.bar=b`},                                     // #525
-		{`(e=1,e=2)`, `e=1,e=2`}, // #528
+		{`(e=1,e=2)`, `e=1,e=2`},            // #528
+		{`"\x00\x31 \0"`, "\"\x001 \x00\""}, // #577
 	}
 
 	m := minify.New()
diff --git a/js/util.go b/js/util.go
index c7e603cc51..585f32ef1d 100644
--- a/js/util.go
+++ b/js/util.go
@@ -981,12 +981,12 @@ func replaceEscapes(b []byte, quote byte, prefix, suffix int) []byte {
 	for i := prefix; i < len(b)-suffix; i++ {
 		if c := b[i]; c == '\\' {
 			c = b[i+1]
-			if c == quote || c == '\\' || c == 'u' || c == '0' && (i+2 == len(b)-1 || b[i+2] < '0' || '7' < b[i+2]) || quote != '`' && (c == 'n' || c == 'r') {
+			if c == quote || c == '\\' || c == 'u' || quote != '`' && (c == 'n' || c == 'r') {
 				// keep escape sequence
 				i++
 				continue
 			}
-			n := 1
+			n := 1 // number of characters to skip
 			if c == '\n' || c == '\r' || c == 0xE2 && i+3 < len(b)-1 && b[i+2] == 0x80 && (b[i+3] == 0xA8 || b[i+3] == 0xA9) {
 				// line continuations
 				if c == 0xE2 {
@@ -1001,10 +1001,8 @@ func replaceEscapes(b []byte, quote byte, prefix, suffix int) []byte {
 					// hexadecimal escapes
 					_, _ = hex.Decode(b[i+3:i+4:i+4], b[i+2:i+4])
 					n = 3
-					if b[i+3] == 0 || b[i+3] == '\\' || b[i+3] == quote || b[i+3] == '\n' || b[i+3] == '\r' {
-						if b[i+3] == 0 {
-							b[i+3] = '0'
-						} else if b[i+3] == '\n' {
+					if b[i+3] == '\\' || b[i+3] == quote || b[i+3] == '\n' || b[i+3] == '\r' {
+						if b[i+3] == '\n' {
 							b[i+3] = 'n'
 						} else if b[i+3] == '\r' {
 							b[i+3] = 'r'
@@ -1016,6 +1014,9 @@ func replaceEscapes(b []byte, quote byte, prefix, suffix int) []byte {
 					i++
 					continue
 				}
+			} else if c == '0' && (i+2 == len(b)-1 || b[i+2] < '0' || '7' < b[i+2]) {
+				// \0 (NULL)
+				b[i+1] = '\x00'
 			} else if '0' <= c && c <= '7' {
 				// octal escapes (legacy), \0 already handled
 				num := c - '0'