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-rw-r--r--boost/context/fiber_ucontext.hpp515
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diff --git a/boost/context/fiber_ucontext.hpp b/boost/context/fiber_ucontext.hpp
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+
+// Copyright Oliver Kowalke 2017.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_CONTEXT_FIBER_H
+#define BOOST_CONTEXT_FIBER_H
+
+#include <boost/predef.h>
+#if BOOST_OS_MACOS
+#define _XOPEN_SOURCE 600
+#endif
+
+extern "C" {
+#include <ucontext.h>
+}
+
+#include <boost/context/detail/config.hpp>
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <functional>
+#include <memory>
+#include <ostream>
+#include <system_error>
+#include <tuple>
+#include <utility>
+
+#include <boost/assert.hpp>
+#include <boost/config.hpp>
+
+#include <boost/context/detail/disable_overload.hpp>
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+#include <boost/context/detail/exchange.hpp>
+#endif
+#include <boost/context/detail/externc.hpp>
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+#include <boost/context/detail/invoke.hpp>
+#endif
+#include <boost/context/fixedsize_stack.hpp>
+#include <boost/context/flags.hpp>
+#include <boost/context/preallocated.hpp>
+#if defined(BOOST_USE_SEGMENTED_STACKS)
+#include <boost/context/segmented_stack.hpp>
+#endif
+#include <boost/context/stack_context.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+namespace context {
+namespace detail {
+
+// tampoline function
+// entered if the execution context
+// is resumed for the first time
+template< typename Record >
+static void fiber_entry_func( void * data) noexcept {
+ Record * record = static_cast< Record * >( data);
+ BOOST_ASSERT( nullptr != record);
+ // start execution of toplevel context-function
+ record->run();
+}
+
+struct BOOST_CONTEXT_DECL fiber_activation_record {
+ ucontext_t uctx{};
+ stack_context sctx{};
+ bool main_ctx{ true };
+ fiber_activation_record * from{ nullptr };
+ std::function< fiber_activation_record*(fiber_activation_record*&) > ontop{};
+ bool terminated{ false };
+ bool force_unwind{ false };
+#if defined(BOOST_USE_ASAN)
+ void * fake_stack{ nullptr };
+ void * stack_bottom{ nullptr };
+ std::size_t stack_size{ 0 };
+#endif
+
+ static fiber_activation_record *& current() noexcept;
+
+ // used for toplevel-context
+ // (e.g. main context, thread-entry context)
+ fiber_activation_record() {
+ if ( BOOST_UNLIKELY( 0 != ::getcontext( & uctx) ) ) {
+ throw std::system_error(
+ std::error_code( errno, std::system_category() ),
+ "getcontext() failed");
+ }
+ }
+
+ fiber_activation_record( stack_context sctx_) noexcept :
+ sctx( sctx_ ),
+ main_ctx( false ) {
+ }
+
+ virtual ~fiber_activation_record() {
+ }
+
+ fiber_activation_record( fiber_activation_record const&) = delete;
+ fiber_activation_record & operator=( fiber_activation_record const&) = delete;
+
+ bool is_main_context() const noexcept {
+ return main_ctx;
+ }
+
+ fiber_activation_record * resume() {
+ from = current();
+ // store `this` in static, thread local pointer
+ // `this` will become the active (running) context
+ current() = this;
+#if defined(BOOST_USE_SEGMENTED_STACKS)
+ // adjust segmented stack properties
+ __splitstack_getcontext( from->sctx.segments_ctx);
+ __splitstack_setcontext( sctx.segments_ctx);
+#endif
+#if defined(BOOST_USE_ASAN)
+ if ( terminated) {
+ __sanitizer_start_switch_fiber( nullptr, stack_bottom, stack_size);
+ } else {
+ __sanitizer_start_switch_fiber( & from->fake_stack, stack_bottom, stack_size);
+ }
+#endif
+ // context switch from parent context to `this`-context
+ ::swapcontext( & from->uctx, & uctx);
+#if defined(BOOST_USE_ASAN)
+ __sanitizer_finish_switch_fiber( current()->fake_stack,
+ (const void **) & current()->from->stack_bottom,
+ & current()->from->stack_size);
+#endif
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ return exchange( current()->from, nullptr);
+#else
+ return std::exchange( current()->from, nullptr);
+#endif
+ }
+
+ template< typename Ctx, typename Fn >
+ fiber_activation_record * resume_with( Fn && fn) {
+ from = current();
+ // store `this` in static, thread local pointer
+ // `this` will become the active (running) context
+ // returned by fiber::current()
+ current() = this;
+#if defined(BOOST_NO_CXX14_GENERIC_LAMBDAS)
+ current()->ontop = std::bind(
+ [](typename std::decay< Fn >::type & fn, fiber_activation_record *& ptr){
+ Ctx c{ ptr };
+ c = fn( std::move( c) );
+ if ( ! c) {
+ ptr = nullptr;
+ }
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ return exchange( c.ptr_, nullptr);
+#else
+ return std::exchange( c.ptr_, nullptr);
+#endif
+ },
+ std::forward< Fn >( fn),
+ std::placeholders::_1);
+#else
+ current()->ontop = [fn=std::forward<Fn>(fn)](fiber_activation_record *& ptr){
+ Ctx c{ ptr };
+ c = fn( std::move( c) );
+ if ( ! c) {
+ ptr = nullptr;
+ }
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ return exchange( c.ptr_, nullptr);
+#else
+ return std::exchange( c.ptr_, nullptr);
+#endif
+ };
+#endif
+#if defined(BOOST_USE_SEGMENTED_STACKS)
+ // adjust segmented stack properties
+ __splitstack_getcontext( from->sctx.segments_ctx);
+ __splitstack_setcontext( sctx.segments_ctx);
+#endif
+#if defined(BOOST_USE_ASAN)
+ __sanitizer_start_switch_fiber( & from->fake_stack, stack_bottom, stack_size);
+#endif
+ // context switch from parent context to `this`-context
+ ::swapcontext( & from->uctx, & uctx);
+#if defined(BOOST_USE_ASAN)
+ __sanitizer_finish_switch_fiber( current()->fake_stack,
+ (const void **) & current()->from->stack_bottom,
+ & current()->from->stack_size);
+#endif
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ return exchange( current()->from, nullptr);
+#else
+ return std::exchange( current()->from, nullptr);
+#endif
+ }
+
+ virtual void deallocate() noexcept {
+ }
+};
+
+struct BOOST_CONTEXT_DECL fiber_activation_record_initializer {
+ fiber_activation_record_initializer() noexcept;
+ ~fiber_activation_record_initializer();
+};
+
+struct forced_unwind {
+ fiber_activation_record * from{ nullptr };
+
+ forced_unwind( fiber_activation_record * from_) noexcept :
+ from{ from_ } {
+ }
+};
+
+template< typename Ctx, typename StackAlloc, typename Fn >
+class fiber_capture_record : public fiber_activation_record {
+private:
+ typename std::decay< StackAlloc >::type salloc_;
+ typename std::decay< Fn >::type fn_;
+
+ static void destroy( fiber_capture_record * p) noexcept {
+ typename std::decay< StackAlloc >::type salloc = std::move( p->salloc_);
+ stack_context sctx = p->sctx;
+ // deallocate activation record
+ p->~fiber_capture_record();
+ // destroy stack with stack allocator
+ salloc.deallocate( sctx);
+ }
+
+public:
+ fiber_capture_record( stack_context sctx, StackAlloc && salloc, Fn && fn) noexcept :
+ fiber_activation_record{ sctx },
+ salloc_{ std::forward< StackAlloc >( salloc) },
+ fn_( std::forward< Fn >( fn) ) {
+ }
+
+ void deallocate() noexcept override final {
+ BOOST_ASSERT( main_ctx || ( ! main_ctx && terminated) );
+ destroy( this);
+ }
+
+ void run() {
+#if defined(BOOST_USE_ASAN)
+ __sanitizer_finish_switch_fiber( fake_stack,
+ (const void **) & from->stack_bottom,
+ & from->stack_size);
+#endif
+ Ctx c{ from };
+ try {
+ // invoke context-function
+#if defined(BOOST_NO_CXX17_STD_INVOKE)
+ c = boost::context::detail::invoke( fn_, std::move( c) );
+#else
+ c = std::invoke( fn_, std::move( c) );
+#endif
+ } catch ( forced_unwind const& ex) {
+ c = Ctx{ ex.from };
+ }
+ // this context has finished its task
+ from = nullptr;
+ ontop = nullptr;
+ terminated = true;
+ force_unwind = false;
+ std::move( c).resume();
+ BOOST_ASSERT_MSG( false, "fiber already terminated");
+ }
+};
+
+template< typename Ctx, typename StackAlloc, typename Fn >
+static fiber_activation_record * create_fiber1( StackAlloc && salloc, Fn && fn) {
+ typedef fiber_capture_record< Ctx, StackAlloc, Fn > capture_t;
+
+ auto sctx = salloc.allocate();
+ // reserve space for control structure
+ void * storage = reinterpret_cast< void * >(
+ ( reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
+ & ~ static_cast< uintptr_t >( 0xff) );
+ // placment new for control structure on context stack
+ capture_t * record = new ( storage) capture_t{
+ sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
+ // stack bottom
+ void * stack_bottom = reinterpret_cast< void * >(
+ reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sctx.size) );
+ // create user-context
+ if ( BOOST_UNLIKELY( 0 != ::getcontext( & record->uctx) ) ) {
+ throw std::system_error(
+ std::error_code( errno, std::system_category() ),
+ "getcontext() failed");
+ }
+ record->uctx.uc_stack.ss_sp = stack_bottom;
+ // 64byte gap between control structure and stack top
+ record->uctx.uc_stack.ss_size = reinterpret_cast< uintptr_t >( storage) -
+ reinterpret_cast< uintptr_t >( stack_bottom) - static_cast< uintptr_t >( 64);
+ record->uctx.uc_link = nullptr;
+ ::makecontext( & record->uctx, ( void (*)() ) & fiber_entry_func< capture_t >, 1, record);
+#if defined(BOOST_USE_ASAN)
+ record->stack_bottom = record->uctx.uc_stack.ss_sp;
+ record->stack_size = record->uctx.uc_stack.ss_size;
+#endif
+ return record;
+}
+
+template< typename Ctx, typename StackAlloc, typename Fn >
+static fiber_activation_record * create_fiber2( preallocated palloc, StackAlloc && salloc, Fn && fn) {
+ typedef fiber_capture_record< Ctx, StackAlloc, Fn > capture_t;
+
+ // reserve space for control structure
+ void * storage = reinterpret_cast< void * >(
+ ( reinterpret_cast< uintptr_t >( palloc.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
+ & ~ static_cast< uintptr_t >( 0xff) );
+ // placment new for control structure on context stack
+ capture_t * record = new ( storage) capture_t{
+ palloc.sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
+ // stack bottom
+ void * stack_bottom = reinterpret_cast< void * >(
+ reinterpret_cast< uintptr_t >( palloc.sctx.sp) - static_cast< uintptr_t >( palloc.sctx.size) );
+ // create user-context
+ if ( BOOST_UNLIKELY( 0 != ::getcontext( & record->uctx) ) ) {
+ throw std::system_error(
+ std::error_code( errno, std::system_category() ),
+ "getcontext() failed");
+ }
+ record->uctx.uc_stack.ss_sp = stack_bottom;
+ // 64byte gap between control structure and stack top
+ record->uctx.uc_stack.ss_size = reinterpret_cast< uintptr_t >( storage) -
+ reinterpret_cast< uintptr_t >( stack_bottom) - static_cast< uintptr_t >( 64);
+ record->uctx.uc_link = nullptr;
+ ::makecontext( & record->uctx, ( void (*)() ) & fiber_entry_func< capture_t >, 1, record);
+#if defined(BOOST_USE_ASAN)
+ record->stack_bottom = record->uctx.uc_stack.ss_sp;
+ record->stack_size = record->uctx.uc_stack.ss_size;
+#endif
+ return record;
+}
+
+}
+
+class BOOST_CONTEXT_DECL fiber {
+private:
+ friend struct detail::fiber_activation_record;
+
+ template< typename Ctx, typename StackAlloc, typename Fn >
+ friend class detail::fiber_capture_record;
+
+ template< typename Ctx, typename StackAlloc, typename Fn >
+ friend detail::fiber_activation_record * detail::create_fiber1( StackAlloc &&, Fn &&);
+
+ template< typename Ctx, typename StackAlloc, typename Fn >
+ friend detail::fiber_activation_record * detail::create_fiber2( preallocated, StackAlloc &&, Fn &&);
+
+ template< typename StackAlloc, typename Fn >
+ friend fiber
+ callcc( std::allocator_arg_t, StackAlloc &&, Fn &&);
+
+ template< typename StackAlloc, typename Fn >
+ friend fiber
+ callcc( std::allocator_arg_t, preallocated, StackAlloc &&, Fn &&);
+
+ detail::fiber_activation_record * ptr_{ nullptr };
+
+ fiber( detail::fiber_activation_record * ptr) noexcept :
+ ptr_{ ptr } {
+ }
+
+public:
+ fiber() = default;
+
+ template< typename Fn, typename = detail::disable_overload< fiber, Fn > >
+ fiber( Fn && fn) :
+ fiber{
+ std::allocator_arg,
+#if defined(BOOST_USE_SEGMENTED_STACKS)
+ segmented_stack(),
+#else
+ fixedsize_stack(),
+#endif
+ std::forward< Fn >( fn) } {
+ }
+
+ template< typename StackAlloc, typename Fn >
+ fiber( std::allocator_arg_t, StackAlloc && salloc, Fn && fn) :
+ ptr_{ detail::create_fiber1< fiber >(
+ std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) } {
+ }
+
+ template< typename StackAlloc, typename Fn >
+ fiber( std::allocator_arg_t, preallocated palloc, StackAlloc && salloc, Fn && fn) :
+ ptr_{ detail::create_fiber2< fiber >(
+ palloc, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) } {
+ }
+
+ ~fiber() {
+ if ( BOOST_UNLIKELY( nullptr != ptr_) && ! ptr_->main_ctx) {
+ if ( BOOST_LIKELY( ! ptr_->terminated) ) {
+ ptr_->force_unwind = true;
+ ptr_->resume();
+ BOOST_ASSERT( ptr_->terminated);
+ }
+ ptr_->deallocate();
+ }
+ }
+
+ fiber( fiber const&) = delete;
+ fiber & operator=( fiber const&) = delete;
+
+ fiber( fiber && other) noexcept {
+ swap( other);
+ }
+
+ fiber & operator=( fiber && other) noexcept {
+ if ( BOOST_LIKELY( this != & other) ) {
+ fiber tmp = std::move( other);
+ swap( tmp);
+ }
+ return * this;
+ }
+
+ fiber resume() && {
+ BOOST_ASSERT( nullptr != ptr_);
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ detail::fiber_activation_record * ptr = detail::exchange( ptr_, nullptr)->resume();
+#else
+ detail::fiber_activation_record * ptr = std::exchange( ptr_, nullptr)->resume();
+#endif
+ if ( BOOST_UNLIKELY( detail::fiber_activation_record::current()->force_unwind) ) {
+ throw detail::forced_unwind{ ptr};
+ } else if ( BOOST_UNLIKELY( nullptr != detail::fiber_activation_record::current()->ontop) ) {
+ ptr = detail::fiber_activation_record::current()->ontop( ptr);
+ detail::fiber_activation_record::current()->ontop = nullptr;
+ }
+ return { ptr };
+ }
+
+ template< typename Fn >
+ fiber resume_with( Fn && fn) && {
+ BOOST_ASSERT( nullptr != ptr_);
+#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
+ detail::fiber_activation_record * ptr =
+ detail::exchange( ptr_, nullptr)->resume_with< fiber >( std::forward< Fn >( fn) );
+#else
+ detail::fiber_activation_record * ptr =
+ std::exchange( ptr_, nullptr)->resume_with< fiber >( std::forward< Fn >( fn) );
+#endif
+ if ( BOOST_UNLIKELY( detail::fiber_activation_record::current()->force_unwind) ) {
+ throw detail::forced_unwind{ ptr};
+ } else if ( BOOST_UNLIKELY( nullptr != detail::fiber_activation_record::current()->ontop) ) {
+ ptr = detail::fiber_activation_record::current()->ontop( ptr);
+ detail::fiber_activation_record::current()->ontop = nullptr;
+ }
+ return { ptr };
+ }
+
+ explicit operator bool() const noexcept {
+ return nullptr != ptr_ && ! ptr_->terminated;
+ }
+
+ bool operator!() const noexcept {
+ return nullptr == ptr_ || ptr_->terminated;
+ }
+
+ bool operator==( fiber const& other) const noexcept {
+ return ptr_ == other.ptr_;
+ }
+
+ bool operator!=( fiber const& other) const noexcept {
+ return ptr_ != other.ptr_;
+ }
+
+ bool operator<( fiber const& other) const noexcept {
+ return ptr_ < other.ptr_;
+ }
+
+ bool operator>( fiber const& other) const noexcept {
+ return other.ptr_ < ptr_;
+ }
+
+ bool operator<=( fiber const& other) const noexcept {
+ return ! ( * this > other);
+ }
+
+ bool operator>=( fiber const& other) const noexcept {
+ return ! ( * this < other);
+ }
+
+ template< typename charT, class traitsT >
+ friend std::basic_ostream< charT, traitsT > &
+ operator<<( std::basic_ostream< charT, traitsT > & os, fiber const& other) {
+ if ( nullptr != other.ptr_) {
+ return os << other.ptr_;
+ } else {
+ return os << "{not-a-context}";
+ }
+ }
+
+ void swap( fiber & other) noexcept {
+ std::swap( ptr_, other.ptr_);
+ }
+};
+
+inline
+void swap( fiber & l, fiber & r) noexcept {
+ l.swap( r);
+}
+
+}}
+
+#ifdef BOOST_HAS_ABI_HEADERS
+# include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_CONTEXT_FIBER_H