5 files changed, 28 insertions, 0 deletions
diff --git a/lib/tsan/rtl/tsan_interceptors.cc b/lib/tsan/rtl/tsan_interceptors.cc
index 81b859510..25dfe9c01 100644
--- a/lib/tsan/rtl/tsan_interceptors.cc
+++ b/lib/tsan/rtl/tsan_interceptors.cc
@@ -403,6 +403,11 @@ TSAN_INTERCEPTOR(void, cfree, void *p) {
   user_free(thr, pc, p);
 }
 
+TSAN_INTERCEPTOR(uptr, malloc_usable_size, void *p) {
+  SCOPED_INTERCEPTOR_RAW(malloc_usable_size, p);
+  return user_alloc_usable_size(thr, pc, p);
+}
+
 #define OPERATOR_NEW_BODY(mangled_name) \
   if (cur_thread()->in_symbolizer) \
     return __libc_malloc(size); \
diff --git a/lib/tsan/rtl/tsan_mman.cc b/lib/tsan/rtl/tsan_mman.cc
index 7ddcee2a9..fb324834e 100644
--- a/lib/tsan/rtl/tsan_mman.cc
+++ b/lib/tsan/rtl/tsan_mman.cc
@@ -127,6 +127,14 @@ void *user_realloc(ThreadState *thr, uptr pc, void *p, uptr sz) {
   return p2;
 }
 
+uptr user_alloc_usable_size(ThreadState *thr, uptr pc, void *p) {
+  CHECK_GT(thr->in_rtl, 0);
+  if (p == 0)
+    return 0;
+  MBlock *b = (MBlock*)allocator()->GetMetaData(p);
+  return (b) ? b->size : 0;
+}
+
 MBlock *user_mblock(ThreadState *thr, void *p) {
   CHECK_NE(p, (void*)0);
   Allocator *a = allocator();
diff --git a/lib/tsan/rtl/tsan_mman.h b/lib/tsan/rtl/tsan_mman.h
index dc31acd75..4a9240f66 100644
--- a/lib/tsan/rtl/tsan_mman.h
+++ b/lib/tsan/rtl/tsan_mman.h
@@ -31,6 +31,7 @@ void *user_alloc(ThreadState *thr, uptr pc, uptr sz,
 void user_free(ThreadState *thr, uptr pc, void *p);
 void *user_realloc(ThreadState *thr, uptr pc, void *p, uptr sz);
 void *user_alloc_aligned(ThreadState *thr, uptr pc, uptr sz, uptr align);
+uptr user_alloc_usable_size(ThreadState *thr, uptr pc, void *p);
 // Given the pointer p into a valid allocated block,
 // returns the descriptor of the block.
 MBlock *user_mblock(ThreadState *thr, void *p);
diff --git a/lib/tsan/rtl/tsan_stat.h b/lib/tsan/rtl/tsan_stat.h
index 0b4ef832d..e4362b034 100644
--- a/lib/tsan/rtl/tsan_stat.h
+++ b/lib/tsan/rtl/tsan_stat.h
@@ -102,6 +102,7 @@ enum StatType {
   StatInt_realloc,
   StatInt_free,
   StatInt_cfree,
+  StatInt_malloc_usable_size,
   StatInt_mmap,
   StatInt_mmap64,
   StatInt_munmap,
diff --git a/lib/tsan/tests/unit/tsan_mman_test.cc b/lib/tsan/tests/unit/tsan_mman_test.cc
index af813a2ca..ecbe874a0 100644
--- a/lib/tsan/tests/unit/tsan_mman_test.cc
+++ b/lib/tsan/tests/unit/tsan_mman_test.cc
@@ -117,6 +117,19 @@ TEST(Mman, UserRealloc) {
   }
 }
 
+TEST(Mman, UsableSize) {
+  ScopedInRtl in_rtl;
+  ThreadState *thr = cur_thread();
+  uptr pc = 0;
+  char *p = (char*)user_alloc(thr, pc, 10);
+  char *p2 = (char*)user_alloc(thr, pc, 20);
+  EXPECT_EQ(0U, user_alloc_usable_size(thr, pc, NULL));
+  EXPECT_EQ(10U, user_alloc_usable_size(thr, pc, p));
+  EXPECT_EQ(20U, user_alloc_usable_size(thr, pc, p2));
+  user_free(thr, pc, p);
+  user_free(thr, pc, p2);
+}
+
 TEST(Mman, Stats) {
   ScopedInRtl in_rtl;
   ThreadState *thr = cur_thread();