Files
clang-p2996/libcxx/src/ios.cpp
Louis Dionne 7232a84e68 [libc++] Avoid UB in the no-exceptions mode in a few places
Summary:
A few places in the library seem to behave unexpectedly when the library
is compiled or used with exceptions disabled. For example, not throwing
an exception when a pointer is NULL can lead us to dereference the pointer
later on, which is UB. This patch fixes such occurences.

It's hard to tell whether there are other places where the no-exceptions
mode misbehaves like this, because the replacement for throwing an
exception does not always seem to be abort()ing, but at least this
patch will improve the situation somewhat.

See http://lists.llvm.org/pipermail/libcxx-dev/2019-January/000172.html

Reviewers: mclow.lists, EricWF

Subscribers: christof, jkorous, dexonsmith, libcxx-commits

Differential Revision: https://reviews.llvm.org/D57761

llvm-svn: 353850
2019-02-12 16:06:02 +00:00

458 lines
13 KiB
C++

//===-------------------------- ios.cpp -----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "__config"
#include "ios"
#include <stdlib.h>
#include "__locale"
#include "algorithm"
#include "include/config_elast.h"
#include "istream"
#include "limits"
#include "memory"
#include "new"
#include "streambuf"
#include "string"
#include "__undef_macros"
_LIBCPP_BEGIN_NAMESPACE_STD
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<char>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<wchar_t>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<char>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<wchar_t>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<char>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<wchar_t>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<char>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<wchar_t>;
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_iostream<char>;
class _LIBCPP_HIDDEN __iostream_category
: public __do_message
{
public:
virtual const char* name() const _NOEXCEPT;
virtual string message(int ev) const;
};
const char*
__iostream_category::name() const _NOEXCEPT
{
return "iostream";
}
string
__iostream_category::message(int ev) const
{
if (ev != static_cast<int>(io_errc::stream)
#ifdef _LIBCPP_ELAST
&& ev <= _LIBCPP_ELAST
#endif // _LIBCPP_ELAST
)
return __do_message::message(ev);
return string("unspecified iostream_category error");
}
const error_category&
iostream_category() _NOEXCEPT
{
static __iostream_category s;
return s;
}
// ios_base::failure
ios_base::failure::failure(const string& msg, const error_code& ec)
: system_error(ec, msg)
{
}
ios_base::failure::failure(const char* msg, const error_code& ec)
: system_error(ec, msg)
{
}
ios_base::failure::~failure() throw()
{
}
// ios_base locale
const ios_base::fmtflags ios_base::boolalpha;
const ios_base::fmtflags ios_base::dec;
const ios_base::fmtflags ios_base::fixed;
const ios_base::fmtflags ios_base::hex;
const ios_base::fmtflags ios_base::internal;
const ios_base::fmtflags ios_base::left;
const ios_base::fmtflags ios_base::oct;
const ios_base::fmtflags ios_base::right;
const ios_base::fmtflags ios_base::scientific;
const ios_base::fmtflags ios_base::showbase;
const ios_base::fmtflags ios_base::showpoint;
const ios_base::fmtflags ios_base::showpos;
const ios_base::fmtflags ios_base::skipws;
const ios_base::fmtflags ios_base::unitbuf;
const ios_base::fmtflags ios_base::uppercase;
const ios_base::fmtflags ios_base::adjustfield;
const ios_base::fmtflags ios_base::basefield;
const ios_base::fmtflags ios_base::floatfield;
const ios_base::iostate ios_base::badbit;
const ios_base::iostate ios_base::eofbit;
const ios_base::iostate ios_base::failbit;
const ios_base::iostate ios_base::goodbit;
const ios_base::openmode ios_base::app;
const ios_base::openmode ios_base::ate;
const ios_base::openmode ios_base::binary;
const ios_base::openmode ios_base::in;
const ios_base::openmode ios_base::out;
const ios_base::openmode ios_base::trunc;
void
ios_base::__call_callbacks(event ev)
{
for (size_t i = __event_size_; i;)
{
--i;
__fn_[i](ev, *this, __index_[i]);
}
}
// locale
locale
ios_base::imbue(const locale& newloc)
{
static_assert(sizeof(locale) == sizeof(__loc_), "");
locale& loc_storage = *reinterpret_cast<locale*>(&__loc_);
locale oldloc = loc_storage;
loc_storage = newloc;
__call_callbacks(imbue_event);
return oldloc;
}
locale
ios_base::getloc() const
{
const locale& loc_storage = *reinterpret_cast<const locale*>(&__loc_);
return loc_storage;
}
// xalloc
#if defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
atomic<int> ios_base::__xindex_ = ATOMIC_VAR_INIT(0);
#else
int ios_base::__xindex_ = 0;
#endif
template <typename _Tp>
static size_t __ios_new_cap(size_t __req_size, size_t __current_cap)
{ // Precondition: __req_size > __current_cap
const size_t mx = std::numeric_limits<size_t>::max() / sizeof(_Tp);
if (__req_size < mx/2)
return _VSTD::max(2 * __current_cap, __req_size);
else
return mx;
}
int
ios_base::xalloc()
{
return __xindex_++;
}
long&
ios_base::iword(int index)
{
size_t req_size = static_cast<size_t>(index)+1;
if (req_size > __iarray_cap_)
{
size_t newcap = __ios_new_cap<long>(req_size, __iarray_cap_);
long* iarray = static_cast<long*>(realloc(__iarray_, newcap * sizeof(long)));
if (iarray == 0)
{
setstate(badbit);
static long error;
error = 0;
return error;
}
__iarray_ = iarray;
for (long* p = __iarray_ + __iarray_size_; p < __iarray_ + newcap; ++p)
*p = 0;
__iarray_cap_ = newcap;
}
__iarray_size_ = max<size_t>(__iarray_size_, req_size);
return __iarray_[index];
}
void*&
ios_base::pword(int index)
{
size_t req_size = static_cast<size_t>(index)+1;
if (req_size > __parray_cap_)
{
size_t newcap = __ios_new_cap<void *>(req_size, __iarray_cap_);
void** parray = static_cast<void**>(realloc(__parray_, newcap * sizeof(void *)));
if (parray == 0)
{
setstate(badbit);
static void* error;
error = 0;
return error;
}
__parray_ = parray;
for (void** p = __parray_ + __parray_size_; p < __parray_ + newcap; ++p)
*p = 0;
__parray_cap_ = newcap;
}
__parray_size_ = max<size_t>(__parray_size_, req_size);
return __parray_[index];
}
// register_callback
void
ios_base::register_callback(event_callback fn, int index)
{
size_t req_size = __event_size_ + 1;
if (req_size > __event_cap_)
{
size_t newcap = __ios_new_cap<event_callback>(req_size, __event_cap_);
event_callback* fns = static_cast<event_callback*>(realloc(__fn_, newcap * sizeof(event_callback)));
if (fns == 0)
setstate(badbit);
__fn_ = fns;
int* indxs = static_cast<int *>(realloc(__index_, newcap * sizeof(int)));
if (indxs == 0)
setstate(badbit);
__index_ = indxs;
__event_cap_ = newcap;
}
__fn_[__event_size_] = fn;
__index_[__event_size_] = index;
++__event_size_;
}
ios_base::~ios_base()
{
__call_callbacks(erase_event);
locale& loc_storage = *reinterpret_cast<locale*>(&__loc_);
loc_storage.~locale();
free(__fn_);
free(__index_);
free(__iarray_);
free(__parray_);
}
// iostate
void
ios_base::clear(iostate state)
{
if (__rdbuf_)
__rdstate_ = state;
else
__rdstate_ = state | badbit;
if (((state | (__rdbuf_ ? goodbit : badbit)) & __exceptions_) != 0)
__throw_failure("ios_base::clear");
}
// init
void
ios_base::init(void* sb)
{
__rdbuf_ = sb;
__rdstate_ = __rdbuf_ ? goodbit : badbit;
__exceptions_ = goodbit;
__fmtflags_ = skipws | dec;
__width_ = 0;
__precision_ = 6;
__fn_ = 0;
__index_ = 0;
__event_size_ = 0;
__event_cap_ = 0;
__iarray_ = 0;
__iarray_size_ = 0;
__iarray_cap_ = 0;
__parray_ = 0;
__parray_size_ = 0;
__parray_cap_ = 0;
::new(&__loc_) locale;
}
void
ios_base::copyfmt(const ios_base& rhs)
{
// If we can't acquire the needed resources, throw bad_alloc (can't set badbit)
// Don't alter *this until all needed resources are acquired
unique_ptr<event_callback, void (*)(void*)> new_callbacks(0, free);
unique_ptr<int, void (*)(void*)> new_ints(0, free);
unique_ptr<long, void (*)(void*)> new_longs(0, free);
unique_ptr<void*, void (*)(void*)> new_pointers(0, free);
if (__event_cap_ < rhs.__event_size_)
{
size_t newesize = sizeof(event_callback) * rhs.__event_size_;
new_callbacks.reset(static_cast<event_callback*>(malloc(newesize)));
if (!new_callbacks)
__throw_bad_alloc();
size_t newisize = sizeof(int) * rhs.__event_size_;
new_ints.reset(static_cast<int *>(malloc(newisize)));
if (!new_ints)
__throw_bad_alloc();
}
if (__iarray_cap_ < rhs.__iarray_size_)
{
size_t newsize = sizeof(long) * rhs.__iarray_size_;
new_longs.reset(static_cast<long*>(malloc(newsize)));
if (!new_longs)
__throw_bad_alloc();
}
if (__parray_cap_ < rhs.__parray_size_)
{
size_t newsize = sizeof(void*) * rhs.__parray_size_;
new_pointers.reset(static_cast<void**>(malloc(newsize)));
if (!new_pointers)
__throw_bad_alloc();
}
// Got everything we need. Copy everything but __rdstate_, __rdbuf_ and __exceptions_
__fmtflags_ = rhs.__fmtflags_;
__precision_ = rhs.__precision_;
__width_ = rhs.__width_;
locale& lhs_loc = *reinterpret_cast<locale*>(&__loc_);
const locale& rhs_loc = *reinterpret_cast<const locale*>(&rhs.__loc_);
lhs_loc = rhs_loc;
if (__event_cap_ < rhs.__event_size_)
{
free(__fn_);
__fn_ = new_callbacks.release();
free(__index_);
__index_ = new_ints.release();
__event_cap_ = rhs.__event_size_;
}
for (__event_size_ = 0; __event_size_ < rhs.__event_size_; ++__event_size_)
{
__fn_[__event_size_] = rhs.__fn_[__event_size_];
__index_[__event_size_] = rhs.__index_[__event_size_];
}
if (__iarray_cap_ < rhs.__iarray_size_)
{
free(__iarray_);
__iarray_ = new_longs.release();
__iarray_cap_ = rhs.__iarray_size_;
}
for (__iarray_size_ = 0; __iarray_size_ < rhs.__iarray_size_; ++__iarray_size_)
__iarray_[__iarray_size_] = rhs.__iarray_[__iarray_size_];
if (__parray_cap_ < rhs.__parray_size_)
{
free(__parray_);
__parray_ = new_pointers.release();
__parray_cap_ = rhs.__parray_size_;
}
for (__parray_size_ = 0; __parray_size_ < rhs.__parray_size_; ++__parray_size_)
__parray_[__parray_size_] = rhs.__parray_[__parray_size_];
}
void
ios_base::move(ios_base& rhs)
{
// *this is uninitialized
__fmtflags_ = rhs.__fmtflags_;
__precision_ = rhs.__precision_;
__width_ = rhs.__width_;
__rdstate_ = rhs.__rdstate_;
__exceptions_ = rhs.__exceptions_;
__rdbuf_ = 0;
locale& rhs_loc = *reinterpret_cast<locale*>(&rhs.__loc_);
::new(&__loc_) locale(rhs_loc);
__fn_ = rhs.__fn_;
rhs.__fn_ = 0;
__index_ = rhs.__index_;
rhs.__index_ = 0;
__event_size_ = rhs.__event_size_;
rhs.__event_size_ = 0;
__event_cap_ = rhs.__event_cap_;
rhs.__event_cap_ = 0;
__iarray_ = rhs.__iarray_;
rhs.__iarray_ = 0;
__iarray_size_ = rhs.__iarray_size_;
rhs.__iarray_size_ = 0;
__iarray_cap_ = rhs.__iarray_cap_;
rhs.__iarray_cap_ = 0;
__parray_ = rhs.__parray_;
rhs.__parray_ = 0;
__parray_size_ = rhs.__parray_size_;
rhs.__parray_size_ = 0;
__parray_cap_ = rhs.__parray_cap_;
rhs.__parray_cap_ = 0;
}
void
ios_base::swap(ios_base& rhs) _NOEXCEPT
{
_VSTD::swap(__fmtflags_, rhs.__fmtflags_);
_VSTD::swap(__precision_, rhs.__precision_);
_VSTD::swap(__width_, rhs.__width_);
_VSTD::swap(__rdstate_, rhs.__rdstate_);
_VSTD::swap(__exceptions_, rhs.__exceptions_);
locale& lhs_loc = *reinterpret_cast<locale*>(&__loc_);
locale& rhs_loc = *reinterpret_cast<locale*>(&rhs.__loc_);
_VSTD::swap(lhs_loc, rhs_loc);
_VSTD::swap(__fn_, rhs.__fn_);
_VSTD::swap(__index_, rhs.__index_);
_VSTD::swap(__event_size_, rhs.__event_size_);
_VSTD::swap(__event_cap_, rhs.__event_cap_);
_VSTD::swap(__iarray_, rhs.__iarray_);
_VSTD::swap(__iarray_size_, rhs.__iarray_size_);
_VSTD::swap(__iarray_cap_, rhs.__iarray_cap_);
_VSTD::swap(__parray_, rhs.__parray_);
_VSTD::swap(__parray_size_, rhs.__parray_size_);
_VSTD::swap(__parray_cap_, rhs.__parray_cap_);
}
void
ios_base::__set_badbit_and_consider_rethrow()
{
__rdstate_ |= badbit;
#ifndef _LIBCPP_NO_EXCEPTIONS
if (__exceptions_ & badbit)
throw;
#endif // _LIBCPP_NO_EXCEPTIONS
}
void
ios_base::__set_failbit_and_consider_rethrow()
{
__rdstate_ |= failbit;
#ifndef _LIBCPP_NO_EXCEPTIONS
if (__exceptions_ & failbit)
throw;
#endif // _LIBCPP_NO_EXCEPTIONS
}
bool
ios_base::sync_with_stdio(bool sync)
{
static bool previous_state = true;
bool r = previous_state;
previous_state = sync;
return r;
}
_LIBCPP_END_NAMESPACE_STD