Poison non-POD memset & non-trivially-copyable memcpy/memmove
This patch catches invalid initialization of non-POD types with memset, at compile time. This is what I used to catch the problems fixed by the previous patches in the series: $ make -k 2>&1 | grep "deleted function" src/gdb/breakpoint.c:951:53: error: use of deleted function ‘void* memset(T*, int, size_t) [with T = bp_location; <template-parameter-1-2> = void; size_t = long unsigned int]’ src/gdb/breakpoint.c:7325:32: error: use of deleted function ‘void* memset(T*, int, size_t) [with T = bp_location; <template-parameter-1-2> = void; size_t = long unsigned int]’ src/gdb/btrace.c:1153:42: error: use of deleted function ‘void* memset(T*, int, size_t) [with T = btrace_insn; <template-parameter-1-2> = void; size_t = long unsigned int]’ ... gdb/ChangeLog: 2017-04-25 Pedro Alves <palves@redhat.com> * common/common-defs.h: Include "common/poison.h". * common/function-view.h: (Not, Or, Requires): Move to traits.h and adjust. * common/poison.h: New file. * common/traits.h: Include <type_traits>. (Not, Or, Requires): New, moved from common/function-view.h.
This commit is contained in:
Pedro Alves
parent
16c4d54a71
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b0b92aeb38
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@ -1,3 +1,12 @@
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2017-04-25 Pedro Alves <palves@redhat.com>
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* common/common-defs.h: Include "common/poison.h".
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* common/function-view.h: (Not, Or, Requires): Move to traits.h
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and adjust.
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* common/poison.h: New file.
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* common/traits.h: Include <type_traits>.
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(Not, Or, Requires): New, moved from common/function-view.h.
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2017-04-25 Pedro Alves <palves@redhat.com>
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* breakpoint.h (struct breakpoint): In-class initialize all
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@ -82,6 +82,7 @@
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#include "common-debug.h"
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#include "cleanups.h"
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#include "common-exceptions.h"
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#include "common/poison.h"
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#define EXTERN_C extern "C"
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#define EXTERN_C_PUSH extern "C" {
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@ -153,34 +153,6 @@
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namespace gdb {
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namespace traits {
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/* A few trait helpers. */
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template<typename Predicate>
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struct Not : public std::integral_constant<bool, !Predicate::value>
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{};
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template<typename...>
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struct Or;
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template<>
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struct Or<> : public std::false_type
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{};
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template<typename B1>
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struct Or<B1> : public B1
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{};
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template<typename B1, typename B2>
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struct Or<B1, B2>
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: public std::conditional<B1::value, B1, B2>::type
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{};
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template<typename B1,typename B2,typename B3, typename... Bn>
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struct Or<B1, B2, B3, Bn...>
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: public std::conditional<B1::value, B1, Or<B2, B3, Bn...>>::type
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{};
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} /* namespace traits */
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namespace fv_detail {
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/* Bits shared by all function_view instantiations that do not depend
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on the template parameters. */
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@ -209,9 +181,9 @@ class function_view<Res (Args...)>
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{
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template<typename From, typename To>
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using CompatibleReturnType
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= traits::Or<std::is_void<To>,
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std::is_same<From, To>,
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std::is_convertible<From, To>>;
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= Or<std::is_void<To>,
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std::is_same<From, To>,
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std::is_convertible<From, To>>;
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/* True if Func can be called with Args, and either the result is
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Res, convertible to Res or Res is void. */
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@ -227,10 +199,6 @@ class function_view<Res (Args...)>
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: std::is_same<function_view, typename std::decay<Callable>::type>
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{};
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/* Helper to make SFINAE logic easier to read. */
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template<typename Condition>
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using Requires = typename std::enable_if<Condition::value, void>::type;
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public:
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/* NULL by default. */
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@ -248,7 +216,7 @@ class function_view<Res (Args...)>
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compatible. */
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template
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<typename Callable,
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typename = Requires<traits::Not<IsFunctionView<Callable>>>,
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typename = Requires<Not<IsFunctionView<Callable>>>,
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typename = Requires<IsCompatibleCallable<Callable>>>
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function_view (Callable &&callable) noexcept
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{
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@ -0,0 +1,83 @@
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/* Poison symbols at compile time.
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef COMMON_POISON_H
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#define COMMON_POISON_H
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#include "traits.h"
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/* Poison memset of non-POD types. The idea is catching invalid
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initialization of non-POD structs that is easy to be introduced as
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side effect of refactoring. For example, say this:
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struct S { VEC(foo_s) *m_data; };
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is converted to this at some point:
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struct S {
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S() { m_data.reserve (10); }
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std::vector<foo> m_data;
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};
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and old code was initializing S objects like this:
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struct S s;
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memset (&s, 0, sizeof (S)); // whoops, now wipes vector.
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Declaring memset as deleted for non-POD types makes the memset above
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be a compile-time error. */
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/* Helper for SFINAE. True if "T *" is memsettable. I.e., if T is
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either void, or POD. */
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template<typename T>
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struct IsMemsettable
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: gdb::Or<std::is_void<T>,
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std::is_pod<T>>
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{};
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template <typename T,
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typename = gdb::Requires<gdb::Not<IsMemsettable<T>>>>
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void *memset (T *s, int c, size_t n) = delete;
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/* Similarly, poison memcpy and memmove of non trivially-copyable
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types, which is undefined. */
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/* True if "T *" is relocatable. I.e., copyable with memcpy/memmove.
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I.e., T is either trivially copyable, or void. */
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template<typename T>
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struct IsRelocatable
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: gdb::Or<std::is_void<T>,
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std::is_trivially_copyable<T>>
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{};
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/* True if both source and destination are relocatable. */
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template <typename D, typename S>
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using BothAreRelocatable
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= gdb::And<IsRelocatable<D>, IsRelocatable<S>>;
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template <typename D, typename S,
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typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
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void *memcpy (D *dest, const S *src, size_t n) = delete;
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template <typename D, typename S,
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typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
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void *memmove (D *dest, const S *src, size_t n) = delete;
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#endif /* COMMON_POISON_H */
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@ -32,7 +32,32 @@ template<typename... Ts>
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using void_t = typename make_void<Ts...>::type;
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/* A few trait helpers, mainly stolen from libstdc++. Uppercase
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because "and" is a keyword. */
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because "and/or", etc. are reserved keywords. */
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template<typename Predicate>
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struct Not : public std::integral_constant<bool, !Predicate::value>
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{};
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template<typename...>
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struct Or;
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template<>
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struct Or<> : public std::false_type
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{};
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template<typename B1>
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struct Or<B1> : public B1
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{};
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template<typename B1, typename B2>
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struct Or<B1, B2>
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: public std::conditional<B1::value, B1, B2>::type
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{};
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template<typename B1,typename B2,typename B3, typename... Bn>
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struct Or<B1, B2, B3, Bn...>
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: public std::conditional<B1::value, B1, Or<B2, B3, Bn...>>::type
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{};
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template<typename...>
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struct And;
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@ -55,6 +80,9 @@ struct And<B1, B2, B3, Bn...>
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: public std::conditional<B1::value, And<B2, B3, Bn...>, B1>::type
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{};
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/* Concepts-light-like helper to make SFINAE logic easier to read. */
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template<typename Condition>
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using Requires = typename std::enable_if<Condition::value, void>::type;
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}
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#endif /* COMMON_TRAITS_H */
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