[njs] Fixed regexp compilation of patterns with escaped '[' characters.

[noreply at nginx.com]

details:   https://github.com/nginx/njs/commit/17124c81d84cfed13e47791893aa301681994db4
branches:  master
commit:    17124c81d84cfed13e47791893aa301681994db4
user:      Dmitry Volyntsev <xeioex at nginx.com>
date:      Mon, 30 Jun 2025 18:30:03 -0700
description:
Fixed regexp compilation of patterns with escaped '[' characters.

This fixes #934 issue on Github.

---
 external/njs_regex.c     | 27 +++++++++++++++++++++++++++
 src/test/njs_unit_test.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/external/njs_regex.c b/external/njs_regex.c
index a118666b..a0decefd 100644
--- a/external/njs_regex.c
+++ b/external/njs_regex.c
@@ -114,6 +114,11 @@ njs_regex_escape(njs_mp_t *mp, njs_str_t *text)
 
     for (p = start; p < end; p++) {
         switch (*p) {
+        case '\\':
+            p += 1;
+
+            break;
+
         case '[':
             if (p + 1 < end && p[1] == ']') {
                 p += 1;
@@ -122,6 +127,11 @@ njs_regex_escape(njs_mp_t *mp, njs_str_t *text)
             } else if (p + 2 < end && p[1] == '^' && p[2] == ']') {
                 p += 2;
                 anychars += 1;
+
+            } else {
+                while (p < end && *p != ']') {
+                    p += 1;
+                }
             }
 
             break;
@@ -146,6 +156,15 @@ njs_regex_escape(njs_mp_t *mp, njs_str_t *text)
     for (p = start; p < end; p++) {
 
         switch (*p) {
+        case '\\':
+            *dst++ = *p;
+            if (p + 1 < end) {
+                p += 1;
+                *dst++ = *p;
+            }
+
+            continue;
+
         case '[':
             if (p + 1 < end && p[1] == ']') {
                 p += 1;
@@ -156,6 +175,14 @@ njs_regex_escape(njs_mp_t *mp, njs_str_t *text)
                 p += 2;
                 dst = njs_cpymem(dst, "[\\s\\S]", 6);
                 continue;
+
+            } else {
+                *dst++ = *p;
+                while (p < end && *p != ']') {
+                    *dst++ = *p++;
+                }
+
+                continue;
             }
         }
 
diff --git a/src/test/njs_unit_test.c b/src/test/njs_unit_test.c
index 3d466b96..01ff08d4 100644
--- a/src/test/njs_unit_test.c
+++ b/src/test/njs_unit_test.c
@@ -11969,6 +11969,48 @@ static njs_unit_test_t  njs_test[] =
     { njs_str("/[]a/.test('a')"),
       njs_str("false") },
 
+    { njs_str("/[#[]/.test('[')"),
+      njs_str("true") },
+
+    { njs_str("/[\\s[]/.test('[')"),
+      njs_str("true") },
+
+    { njs_str("/[#[^]/.test('[')"),
+      njs_str("true") },
+
+    { njs_str("/[#\\[]/.test('[')"),
+      njs_str("true") },
+
+    { njs_str("/[\\[^]/.test('[')"),
+      njs_str("true") },
+
+    { njs_str("/[^]abc]/.test('#abc]')"),
+      njs_str("true") },
+
+    { njs_str("/[[^]abc]/.test('[abc]')"),
+      njs_str("true") },
+
+    { njs_str("/[[^]abc]/.test('^abc]')"),
+      njs_str("true") },
+
+    { njs_str("/[]/.test('[]')"),
+      njs_str("false") },
+
+    { njs_str("/[[]/.test('[')"),
+      njs_str("true") },
+
+    { njs_str("/\\[]/.test('[]')"),
+      njs_str("true") },
+
+    { njs_str("/[]abc]/.test('abc]')"),
+      njs_str("false") },
+
+    { njs_str("/abc]/.test('abc]')"),
+      njs_str("true") },
+
+    { njs_str("/\\\\\\[]/.test('\\\\[]')"),
+      njs_str("true") },
+
 #ifdef NJS_HAVE_PCRE2
     { njs_str("/[]*a/.test('a')"),
       njs_str("true") },