From fa376f420ce76daf05ab3fd4ea214c8c238e1aae Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Sat, 15 Feb 2020 10:34:21 +0100
Subject: [PATCH] src: fix -Wmaybe-uninitialized compiler warning
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Turn the `strategy_` method pointer into an enum-based static dispatch.

It's both safer and more secure (no chance of method pointer corruption)
and it helps GCC see that the shift and suffix tables it's complaining
about are unused in single char search mode.

Fixes the following warning:

    ../src/string_search.h:113:30: warning:
    ‘search’ may be used uninitialized in this function [-Wmaybe-uninitialized]
         return (this->*strategy_)(subject, index);

Fixes: https://github.com/nodejs/node/issues/26733
Refs: https://github.com/nodejs/node/pull/31532
Refs: https://github.com/nodejs/node/pull/31798
PR-URL: https://github.com/nodejs/node/pull/31809
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 src/string_search.h | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/src/string_search.h b/src/string_search.h
index b339c355fe168d..3d06f32058f673 100644
--- a/src/string_search.h
+++ b/src/string_search.h
@@ -100,17 +100,29 @@ class StringSearch : private StringSearchBase {
     CHECK_GT(pattern_length, 0);
     if (pattern_length < kBMMinPatternLength) {
       if (pattern_length == 1) {
-        strategy_ = &StringSearch::SingleCharSearch;
+        strategy_ = SearchStrategy::kSingleChar;
         return;
       }
-      strategy_ = &StringSearch::LinearSearch;
+      strategy_ = SearchStrategy::kLinear;
       return;
     }
-    strategy_ = &StringSearch::InitialSearch;
+    strategy_ = SearchStrategy::kInitial;
   }
 
   size_t Search(Vector subject, size_t index) {
-    return (this->*strategy_)(subject, index);
+    switch (strategy_) {
+      case kBoyerMooreHorspool:
+        return BoyerMooreHorspoolSearch(subject, index);
+      case kBoyerMoore:
+        return BoyerMooreSearch(subject, index);
+      case kInitial:
+        return InitialSearch(subject, index);
+      case kLinear:
+        return LinearSearch(subject, index);
+      case kSingleChar:
+        return SingleCharSearch(subject, index);
+    }
+    UNREACHABLE();
   }
 
   static inline int AlphabetSize() {
@@ -149,10 +161,17 @@ class StringSearch : private StringSearchBase {
     return bad_char_occurrence[equiv_class];
   }
 
+  enum SearchStrategy {
+    kBoyerMooreHorspool,
+    kBoyerMoore,
+    kInitial,
+    kLinear,
+    kSingleChar,
+  };
+
   // The pattern to search for.
   Vector pattern_;
-  // Pointer to implementation of the search.
-  SearchFunction strategy_;
+  SearchStrategy strategy_;
   // Cache value of Max(0, pattern_length() - kBMMaxShift)
   size_t start_;
 };
@@ -476,7 +495,7 @@ size_t StringSearch<Char>::BoyerMooreHorspoolSearch(
     badness += (pattern_length - j) - last_char_shift;
     if (badness > 0) {
       PopulateBoyerMooreTable();
-      strategy_ = &StringSearch::BoyerMooreSearch;
+      strategy_ = SearchStrategy::kBoyerMoore;
       return BoyerMooreSearch(subject, index);
     }
   }
@@ -548,7 +567,7 @@ size_t StringSearch<Char>::InitialSearch(
       badness += j;
     } else {
       PopulateBoyerMooreHorspoolTable();
-      strategy_ = &StringSearch::BoyerMooreHorspoolSearch;
+      strategy_ = SearchStrategy::kBoyerMooreHorspool;
       return BoyerMooreHorspoolSearch(subject, i);
     }
   }