third_party/protobuf: Update to HEAD (83d681ee2c)

third_party/protobuf/src/google/protobuf/arena.cc

Index: third_party/protobuf/src/google/protobuf/arena.cc
diff --git a/third_party/protobuf/src/google/protobuf/arena.cc b/third_party/protobuf/src/google/protobuf/arena.cc
index 613e5897144151967594abc84da94bc610cb0ce2..21fd1be61ca2d6e99cd9d70859263a38903d42ce 100755
--- a/third_party/protobuf/src/google/protobuf/arena.cc
+++ b/third_party/protobuf/src/google/protobuf/arena.cc
@@ -30,10 +30,13 @@
 
 #include <google/protobuf/arena.h>
 
+#include <algorithm>
+#include <limits>
+
 
 #ifdef ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
-#endif
+#endif  // ADDRESS_SANITIZER
 
 namespace google {
 namespace protobuf {
@@ -125,26 +128,20 @@ Arena::Block* Arena::NewBlock(void* me, Block* my_last_block, size_t n,
   } else {
     size = start_block_size;
   }
-  if (n > size - kHeaderSize) {
-    // TODO(sanjay): Check if n + kHeaderSize would overflow
-    size = kHeaderSize + n;
-  }
+  // Verify that n + kHeaderSize won't overflow.
+  GOOGLE_CHECK_LE(n, std::numeric_limits<size_t>::max() - kHeaderSize);
+  size = std::max(size, kHeaderSize + n);
 
   Block* b = reinterpret_cast<Block*>(options_.block_alloc(size));
   b->pos = kHeaderSize + n;
   b->size = size;
-  if (b->avail() == 0) {
-    // Do not attempt to reuse this block.
-    b->owner = NULL;
-  } else {
-    b->owner = me;
-  }
+  b->owner = me;
 #ifdef ADDRESS_SANITIZER
   // Poison the rest of the block for ASAN. It was unpoisoned by the underlying
   // malloc but it's not yet usable until we return it as part of an allocation.
   ASAN_POISON_MEMORY_REGION(
       reinterpret_cast<char*>(b) + b->pos, b->size - b->pos);
-#endif
+#endif  // ADDRESS_SANITIZER
   return b;
 }
 
@@ -208,7 +205,7 @@ void* Arena::AllocFromBlock(Block* b, size_t n) {
   b->pos = p + n;
 #ifdef ADDRESS_SANITIZER
   ASAN_UNPOISON_MEMORY_REGION(reinterpret_cast<char*>(b) + p, n);
-#endif
+#endif  // ADDRESS_SANITIZER
   return reinterpret_cast<char*>(b) + p;
 }
 
@@ -223,9 +220,7 @@ void* Arena::SlowAlloc(size_t n) {
   }
   b = NewBlock(me, b, n, options_.start_block_size, options_.max_block_size);
   AddBlock(b);
-  if (b->owner == me) {  // If this block can be reused (see NewBlock()).
-    SetThreadCacheBlock(b);
-  }
+  SetThreadCacheBlock(b);
   return reinterpret_cast<char*>(b) + kHeaderSize;
 }
 
@@ -249,7 +244,7 @@ uint64 Arena::SpaceUsed() const {
   return space_used;
 }
 
-pair<uint64, uint64> Arena::SpaceAllocatedAndUsed() const {
+std::pair<uint64, uint64> Arena::SpaceAllocatedAndUsed() const {
   uint64 allocated = 0;
   uint64 used = 0;
 
@@ -270,9 +265,19 @@ uint64 Arena::FreeBlocks() {
     space_allocated += (b->size);
     Block* next = b->next;
     if (next != NULL) {
+#ifdef ADDRESS_SANITIZER
+      // This memory was provided by the underlying allocator as unpoisoned, so
+      // return it in an unpoisoned state.
+      ASAN_UNPOISON_MEMORY_REGION(reinterpret_cast<char*>(b), b->size);
+#endif  // ADDRESS_SANITIZER
       options_.block_dealloc(b, b->size);
     } else {
       if (owns_first_block_) {
+#ifdef ADDRESS_SANITIZER
+        // This memory was provided by the underlying allocator as unpoisoned,
+        // so return it in an unpoisoned state.
+        ASAN_UNPOISON_MEMORY_REGION(reinterpret_cast<char*>(b), b->size);
+#endif  // ADDRESS_SANITIZER
         options_.block_dealloc(b, b->size);
       } else {
         // User passed in the first block, skip free'ing the memory.