folly/.../ExceptionTracerLib.cpp: provide less DOF fodder (avoid heap use-after-free)

[folly.git] / folly / experimental / BitVectorCoding.h

diff --git a/folly/experimental/BitVectorCoding.h b/folly/experimental/BitVectorCoding.h
index 874a5d271d09338417f880ff1b7b62f6b684f69b..a7f711c24a26de8a2fdae2c2305de320d76a5b3e 100644 (file)
--- a/folly/experimental/BitVectorCoding.h
+++ b/folly/experimental/BitVectorCoding.h
@@ -29,10 +29,6 @@
 #include <folly/experimental/Select64.h>
 #include <glog/logging.h>
 
-#ifndef __GNUC__
-#error BitVectorCoding.h requires GCC
-#endif
-
 #if !FOLLY_X64
 #error BitVectorCoding.h requires x86_64
 #endif
@@ -129,7 +125,7 @@ struct BitVectorEncoder {
         reinterpret_cast<folly::Unaligned<uint64_t>*>(block), inner);
 
     if (skipQuantum != 0) {
-      size_t nextSkipPointerSize = value / (skipQuantum ?: 1);
+      size_t nextSkipPointerSize = value / skipQuantum;
       while (skipPointersSize_ < nextSkipPointerSize) {
         auto pos = skipPointersSize_++;
         folly::storeUnaligned<SkipValueType>(
@@ -138,8 +134,8 @@ struct BitVectorEncoder {
     }
 
     if (forwardQuantum != 0) {
-      if (size_ != 0 && (size_ % (forwardQuantum ?: 1) == 0)) {
-        const auto pos = size_ / (forwardQuantum ?: 1) - 1;
+      if (size_ != 0 && (size_ % forwardQuantum == 0)) {
+        const auto pos = size_ / forwardQuantum - 1;
         folly::storeUnaligned<SkipValueType>(
             forwardPointers_ + pos * sizeof(SkipValueType), value);
       }
@@ -183,11 +179,11 @@ struct BitVectorEncoder<Value, SkipValue, kSkipQuantum, kForwardQuantum>::
     layout.bits = bitVectorSizeInBytes;
 
     if (skipQuantum != 0) {
-      size_t numSkipPointers = upperBound / (skipQuantum ?: 1);
+      size_t numSkipPointers = upperBound / skipQuantum;
       layout.skipPointers = numSkipPointers * sizeof(SkipValueType);
     }
     if (forwardQuantum != 0) {
-      size_t numForwardPointers = size / (forwardQuantum ?: 1);
+      size_t numForwardPointers = size / forwardQuantum;
       layout.forwardPointers = numForwardPointers * sizeof(SkipValueType);
     }
 
@@ -304,15 +300,12 @@ class BitVectorReader {
 
     // Use forward pointer.
     if (Encoder::forwardQuantum > 0 && n > Encoder::forwardQuantum) {
-      // Workaround to avoid 'division by zero' compile-time error.
-      constexpr size_t q = Encoder::forwardQuantum ?: 1;
-
-      const size_t steps = position_ / q;
+      const size_t steps = position_ / Encoder::forwardQuantum;
       const size_t dest = folly::loadUnaligned<SkipValueType>(
           forwardPointers_ + (steps - 1) * sizeof(SkipValueType));
 
       reposition(dest);
-      n = position_ + 1 - steps * q;
+      n = position_ + 1 - steps * Encoder::forwardQuantum;
       // Correct inner_ will be set at the end.
     }
 
@@ -353,8 +346,8 @@ class BitVectorReader {
 
     if (Encoder::skipQuantum > 0 && v - value_ > Encoder::skipQuantum) {
       size_t q = v / Encoder::skipQuantum;
-      position_ = folly::loadUnaligned<SkipValueType>(
-                      skipPointers_ + (q - 1) * sizeof(SkipValueType)) - 1;
+      position_ = size_t(folly::loadUnaligned<SkipValueType>(
+                      skipPointers_ + (q - 1) * sizeof(SkipValueType))) - 1;
 
       reposition(q * Encoder::skipQuantum);
     }