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libstdc++: Avoid intercepting exception in ostream::write 

Currently if ostream::write fails and sets badbit and that causes an
exception, we will catch the exception, set badbit again, and rethrow
the exception.

This change delays setting badbit until after the try-catch block, so
that if it causes an exception we don't need to catch and rethrow it.

This removes the last remaining use of _M_write, so it can be made
private (or removed entirely for versioned namespace builds, where ABI
compatibility is not required). All other uses of _M_write were replaced
by calls to __ostream_insert, so make _M_write use that too.

libstdc++-v3/ChangeLog:

	* include/bits/ostream.tcc (basic_ostream::write): Call sputn
	directly instead of using _M_write. Do setstate(__err) all
	outside the try-catch block.
	* include/std/ostream (basic_ostream::_M_write): Declare
	private. Use __ostream_insert. Do not define for the versioned
	namespace.
This commit is contained in:
Jonathan Wakely 2021-06-25 18:31:23 +01:00
parent f8c5b542f6
commit 4a52cf2eb9
2 changed files with 14 additions and 14 deletions
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8
libstdc++-v3/include/bits/ostream.tcc
View File

@ -192,8 +192,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
sentry __cerb(*this);
if (__cerb)
{
ios_base::iostate __err = ios_base::goodbit;
__try
{ _M_write(__s, __n); }
{
if (this->rdbuf()->sputn(__s, __n) != __n)
__err = ios_base::badbit;
}
__catch(__cxxabiv1::__forced_unwind&)
{
this->_M_setstate(ios_base::badbit);
@ -201,6 +205,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
__catch(...)
{ this->_M_setstate(ios_base::badbit); }
if (__err)
this->setstate(ios_base::badbit);
}
return *this;
}

20
libstdc++-v3/include/std/ostream
View File

@ -308,19 +308,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__ostream_type&
put(char_type __c);
/**
* @brief Core write functionality, without sentry.
* @param __s The array to insert.
* @param __n Maximum number of characters to insert.
*/
void
_M_write(const char_type* __s, streamsize __n)
{
const streamsize __put = this->rdbuf()->sputn(__s, __n);
if (__put != __n)
this->setstate(ios_base::badbit);
}
/**
* @brief Character string insertion.
* @param __s The array to insert.
@ -419,6 +406,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ValueT>
__ostream_type&
_M_insert(_ValueT __v);
private:
#if !_GLIBCXX_INLINE_VERSION
void
_M_write(const char_type* __s, streamsize __n)
{ std::__ostream_insert(*this, __s, __n); }
#endif
};
/**