diff options
| author | Jonathan Wakely <jwakely@redhat.com> | 2023-03-28 11:12:58 +0100 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2023-03-28 21:12:18 +0100 |
| commit | cb6f663f9d79d7134ae6ecaff9a25342c40aeb5d (patch) | |
| tree | 7a187ca513f93f6dc064e062b94e0a2c57430558 | |
| parent | bf78b43873b0b7e8f9a430df38749b8b61f9c9b8 (diff) | |
| download | gcc-cb6f663f9d79d7134ae6ecaff9a25342c40aeb5d.zip gcc-cb6f663f9d79d7134ae6ecaff9a25342c40aeb5d.tar.gz gcc-cb6f663f9d79d7134ae6ecaff9a25342c40aeb5d.tar.bz2 | |
libstdc++: More fixes for null pointers used with std::char_traits
The std::char_traits member functions require that [p,p+n) is a valid
range, which is true for p==nullptr iff n==0. But we must not call
memcpy, memset etc, in that case, as they require non-null pointers even
when n==0.
This std::char_traits<char> and std::char_traits<wchar_t> explicit
specializations are already correct, but the primary template has some
bugs.
libstdc++-v3/ChangeLog:
* include/bits/char_traits.h (char_traits::copy): Return without
using memcpy if n==0.
(char_traits::assign): Likewise for memset.
| -rw-r--r-- | libstdc++-v3/include/bits/char_traits.h | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/libstdc++-v3/include/bits/char_traits.h b/libstdc++-v3/include/bits/char_traits.h index cfc7d0f..68ed827 100644 --- a/libstdc++-v3/include/bits/char_traits.h +++ b/libstdc++-v3/include/bits/char_traits.h @@ -263,6 +263,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION char_traits<_CharT>:: copy(char_type* __s1, const char_type* __s2, std::size_t __n) { + if (__n == 0) + return __s1; #if __cplusplus >= 202002L if (std::__is_constant_evaluated()) { @@ -271,7 +273,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION return __s1; } #endif - __builtin_memcpy(__s1, __s2, __n * sizeof(char_type)); return __s1; } @@ -293,9 +294,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION if _GLIBCXX17_CONSTEXPR (sizeof(_CharT) == 1 && __is_trivial(_CharT)) { - unsigned char __c; - __builtin_memcpy(&__c, __builtin_addressof(__a), 1); - __builtin_memset(__s, __c, __n); + if (__n) + { + unsigned char __c; + __builtin_memcpy(&__c, __builtin_addressof(__a), 1); + __builtin_memset(__s, __c, __n); + } } else { |