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aix: make ctype_inline.h thread-safe and avoid _OBJ_DATA char subscript.

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g++.dg/warn/Wstringop-overflow-6.C tests for a bogus overflow warning in
system headers.  This testcase was generating a -Wchar-subscript warning
on AIX because ctype_inline.h was subscripting AIX _OBJ_DATA using a char.
The _M_table case cast the subscript to unsigned char, but the _OBJ_DATA
case did not.

The investigation also exposed that AIX has added a thread-safe variant
of access to __lc_type that had not been applied to the libstdc++
implementation.

This patch casts the subscript to unsigned char and adds the THREAD_SAFE
variant.  libstdc++ always is compiled with pthreads, but it is good
to make the situation explicit and to document the appropriate usage.

Bootstrapped on powerpc-ibm-aix7.2.3.0.

libstdc++-v3/ChangeLog:

	* config/os/aix/ctype_inline.h (bool ctype<char>:: is): Cast
	_OBJ_DATA subscript to unsigned char. Add _THREAD_SAFE access to
	__lc_type.
	(const char* ctype<char>:: is): Same.
This commit is contained in:
David Edelsohn 2021-01-19 22:24:08 -05:00
parent 842afc4e28
commit fb39c4fe44
1 changed files with 10 additions and 2 deletions
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12
libstdc++-v3/config/os/aix/ctype_inline.h
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@ -45,7 +45,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
if(_M_table)
return _M_table[static_cast<unsigned char>(__c)] & __m;
else
return __OBJ_DATA(__lc_ctype)->mask[__c] & __m;
#ifdef _THREAD_SAFE
return __OBJ_DATA((*__lc_ctype_ptr))->mask[static_cast<unsigned char>(__c)] & __m;
#else
return __OBJ_DATA(__lc_ctype)->mask[static_cast<unsigned char>(__c)] & __m;
#endif
}
const char*
@ -57,7 +61,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*__vec++ = _M_table[static_cast<unsigned char>(*__low++)];
else
while (__low < __high)
*__vec++ = __OBJ_DATA(__lc_ctype)->mask[*__low++];
#ifdef _THREAD_SAFE
*__vec++ = __OBJ_DATA((*__lc_ctype_ptr))->mask[static_cast<unsigned char>(*__low++)];
#else
*__vec++ = __OBJ_DATA(__lc_ctype)->mask[static_cast<unsigned char>(*__low++)];
#endif
return __high;
}