From 3a5042f66aeae484aead80b0e172827fbccc3be1 Mon Sep 17 00:00:00 2001
From: Dmitry Volyntsev <xeioex@nginx.com>
Date: Wed, 22 May 2024 17:26:08 -0700
Subject: [PATCH] Fixed String.prototype.replaceAll() with zero length
 argument.

This fixes #712 issue on Github.
---
 src/njs_string.c         | 15 ++++-----------
 src/njs_string.h         |  4 ++++
 src/test/njs_unit_test.c |  6 ++++++
 3 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/njs_string.c b/src/njs_string.c
index 95514274..54a6ae5a 100644
--- a/src/njs_string.c
+++ b/src/njs_string.c
@@ -1736,7 +1736,9 @@ njs_string_index_of(njs_string_prop_t *string, njs_string_prop_t *search,
         } else {
             /* UTF-8 string. */
 
-            p = njs_string_utf8_offset(string->start, end, index);
+            p = (index < string->length)
+                    ? njs_string_utf8_offset(string->start, end, index)
+                    : end;
             end -= search->size - 1;
 
             while (p < end) {
@@ -3231,7 +3233,6 @@ njs_string_prototype_replace(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
     njs_int_t          ret;
     njs_str_t          str;
     njs_chb_t          chain;
-    njs_bool_t         is_ascii_string;
     njs_value_t        *this, *search, *replace;
     njs_value_t        search_lvalue, replace_lvalue, replacer, value,
                        arguments[3];
@@ -3378,7 +3379,6 @@ njs_string_prototype_replace(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
 
     p_start = string.start;
     increment = s.length != 0 ? s.length : 1;
-    is_ascii_string = njs_is_ascii_string(&string);
 
     do {
         if (func_replace == NULL) {
@@ -3405,14 +3405,7 @@ njs_string_prototype_replace(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
             }
         }
 
-        if (is_ascii_string) {
-            p = string.start + pos;
-
-        } else {
-            p = njs_string_utf8_offset(string.start, string.start + string.size,
-                                       pos);
-        }
-
+        p = njs_string_offset(&string, pos);
         (void) njs_string_prop(&ret_string, &value);
 
         njs_chb_append(&chain, p_start, p - p_start);
diff --git a/src/njs_string.h b/src/njs_string.h
index ef746ae5..a83c406a 100644
--- a/src/njs_string.h
+++ b/src/njs_string.h
@@ -245,6 +245,10 @@ njs_string_offset(njs_string_prop_t *string, int64_t index)
 
     /* UTF-8 string. */
 
+    if (index == (int64_t) string->length) {
+        return string->start + string->size;
+    }
+
     return njs_string_utf8_offset(string->start, string->start + string->size,
                                   index);
 }
diff --git a/src/test/njs_unit_test.c b/src/test/njs_unit_test.c
index d8b4dac6..981404ee 100644
--- a/src/test/njs_unit_test.c
+++ b/src/test/njs_unit_test.c
@@ -8888,6 +8888,12 @@ static njs_unit_test_t  njs_test[] =
     { njs_str("var r = 'αβγ'.replaceAll('', 'X'); [r, r.length]"),
       njs_str("XαXβXγX,7") },
 
+    { njs_str("var r = ''.replaceAll('', 'z'); [r, r.length]"),
+      njs_str("z,1") },
+
+    { njs_str("var r = 'α'.padStart(32).replaceAll('', 'z'); [r, r.length]"),
+      njs_str("z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z zαz,65") },
+
     { njs_str("'abc'.replace('b', (m, o, s) => `|${s}|${o}|${m}|`)"),
       njs_str("a|abc|1|b|c") },
 
-- 
2.47.3