From 926182d851584bc8200f66ebe0b4d88f2c49def7 Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Thu, 14 Dec 2023 19:13:22 +0000
Subject: [PATCH] Fix an issue with expr_match

---
 osscan.cc                |  8 ++++----
 tests/expr_match_test.cc | 16 +++++++++++-----
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/osscan.cc b/osscan.cc
index 18967765b..3198ad6f3 100644
--- a/osscan.cc
+++ b/osscan.cc
@@ -308,17 +308,17 @@ bool expr_match(const char *val, size_t vlen, const char *expr, size_t explen, b
   }
 
   p = expr;
-  const char *p_end = p + explen;
+  const char * const p_end = p + explen;
 
   do {
     const char *nest = NULL; // where the [] nested expr starts
     const char *subval = val; // portion of val after previous nest and before the next one
     size_t sublen; // length of subval not subject to nested matching
     q = strchr_p(p, p_end, '|');
+    nest = strchr_p(p, q ? q : p_end, '[');
 
     // if we're already in a nested expr, we skip this and just match as usual.
-    if (do_nested) {
-      nest = strchr_p(p, p_end, '[');
+    if (do_nested && nest) {
       // As long as we keep finding nested portions, e.g. M[>500]ST11W[1-5]
       while (nest) {
         q1 = strchr_p(nest, p_end, ']');
@@ -343,7 +343,7 @@ bool expr_match(const char *val, size_t vlen, const char *expr, size_t explen, b
         //fprintf(stderr, "nest: %-.*s cmp %-.*s\n", nlen, subval, q1 - nest, nest);
         if (nlen > 0 && expr_match(subval, nlen, nest, q1 - nest, false)) {
           subval += nlen;
-          nest = strchr_p(p, p_end, '[');
+          nest = strchr_p(p, q ? q : p_end, '[');
         }
         else {
           goto next_expr;
diff --git a/tests/expr_match_test.cc b/tests/expr_match_test.cc
index b92f21fd1..142037536 100644
--- a/tests/expr_match_test.cc
+++ b/tests/expr_match_test.cc
@@ -181,6 +181,7 @@ const struct expr_test tests[] = {
   {"01", "A", false},
   {"001", "A", false},
   {"0001", "A", false},
+  {"M5B4NNSNW5|M5B4NNSNW7|M5B4NNSNWA", "M5B4NNSNW7", true},
   {"", "", true}
 };
 
@@ -188,17 +189,22 @@ int main(int argc, char **argv)
 {
   size_t num_tests = sizeof(tests) / sizeof(expr_test);
   size_t num_fail = 0;
+  size_t num_run = 0;
   for (size_t i=0; i < num_tests; i++) {
     const char *val = tests[i].val;
     const char *expr = tests[i].expr;
     bool expected = tests[i].result;
+    int nested = strchr(expr, '[') ? 1 : 0;
     std::cout << i << '\r';
-    if (expected != expr_match(val, 0, expr, 0, strchr(expr, '['))) {
-      std::cout << "FAIL test " << i << ": " << val <<
-      (expected ? " nomatch " : " badmatch ") << expr << std::endl;
-      num_fail++;
+    for (int n = 1; n >= nested; n--)  {
+      num_run++;
+      if (expected != expr_match(val, 0, expr, 0, n)) {
+        std::cout << "FAIL test " << i << ": " << val <<
+          (expected ? " nomatch " : " badmatch ") << expr << std::endl;
+        num_fail++;
+      }
     }
   }
-  std::cout << "Ran " << num_tests << " tests. " << num_fail << " failures." << std::endl;
+  std::cout << "Ran " << num_run << " tests. " << num_fail << " failures." << std::endl;
   return num_fail;
 }