From: Lucian Grijincu <lucian@fb.com>
Date: Thu, 19 May 2016 08:14:49 +0000 (-0700)
Subject: folly: FBString: avoid ubsan in assert
X-Git-Tag: 2016.07.26~216
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=4d78cf49cefb03bd8b376fa2061e5cbe7ee41746;p=folly.git

folly: FBString: avoid ubsan in assert

Summary:
```
buck-out/gen/folly/__default_headers__#default,headers/folly/FBString.h:365:7: runtime error: null pointer passed as argument 2, which is declared to never be null
third-party-buck/build/glibc/include/string.h:70:33: note: nonnull attribute specified here
    #0 0x433a39 in _ZZN5folly13fbstring_coreIcEC1EPKcmbENKUlvE_clEv ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////buck-out/gen/folly/__default_headers__#default,headers/folly/FBString.h:365:7
    #1 0x4335a9 in _ZN5folly14ScopeGuardImplIZNS_13fbstring_coreIcEC1EPKcmbEUlvE_E7executeEv ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////buck-out/gen/folly/__default_headers__#default,headers/folly/ScopeGuard.h:153:29
    #2 0x4335a9 in _ZN5folly14ScopeGuardImplIZNS_13fbstring_coreIcEC1EPKcmbEUlvE_ED2Ev ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////buck-out/gen/folly/__default_headers__#default,headers/folly/ScopeGuard.h:130
    #3 0x4335a9 in folly::fbstring_core<char>::fbstring_core(char const*, unsigned long, bool) ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////buck-out/gen/folly/__default_headers__#default,headers/folly/FBString.h:427
    #4 0x4353fa in folly::basic_fbstring<char, std::char_traits<char>, std::allocator<char>, folly::fbstring_core<char> >::basic_fbstring(char const*, unsigned long, std::allocator<char> const&) ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////buck-out/gen/folly/__default_headers__#default,headers/folly/FBString.h:1038:9
```

Reviewed By: Gownta

Differential Revision: D3321266

fbshipit-source-id: 28d5aef16e91a98066a1de6bab95403fbc63eaab
---

diff --git a/folly/FBString.h b/folly/FBString.h
index 4f0d3231..346d23c4 100644
--- a/folly/FBString.h
+++ b/folly/FBString.h
@@ -362,7 +362,7 @@ public:
 #ifndef _LIBSTDCXX_FBSTRING
     SCOPE_EXIT {
       assert(this->size() == size);
-      assert(memcmp(this->data(), data, size * sizeof(Char)) == 0);
+      assert(size == 0 || memcmp(this->data(), data, size * sizeof(Char)) == 0);
     };
 #endif
 #endif