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#include <cpptrace/cpptrace.hpp>
#define CPPTRACE_DONT_PREPARE_UNWIND_INTERCEPTOR_ON
#include <cpptrace/from_current.hpp>
#include <system_error>
#include <typeinfo>
#include "platform/platform.hpp"
#include "utils/microfmt.hpp"
#ifndef _MSC_VER
#include <string.h>
#if IS_WINDOWS
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#else
#include <sys/mman.h>
#include <unistd.h>
#if IS_APPLE
#include <mach/mach.h>
#ifdef HAS_MACH_VM
#include <mach/mach_vm.h>
#endif
#else
#include <fstream>
#include <ios>
#endif
#endif
#endif
namespace cpptrace {
namespace detail {
thread_local lazy_trace_holder current_exception_trace;
CPPTRACE_FORCE_NO_INLINE void collect_current_trace(std::size_t skip) {
current_exception_trace = lazy_trace_holder(cpptrace::generate_raw_trace(skip + 1));
}
#ifndef _MSC_VER
// set only once by do_prepare_unwind_interceptor
char (*intercept_unwind_handler)(std::size_t) = nullptr;
CPPTRACE_FORCE_NO_INLINE
bool intercept_unwind(const std::type_info*, const std::type_info*, void**, unsigned) {
if(intercept_unwind_handler) {
intercept_unwind_handler(1);
}
return false;
}
CPPTRACE_FORCE_NO_INLINE
bool unconditional_exception_unwind_interceptor(const std::type_info*, const std::type_info*, void**, unsigned) {
collect_current_trace(1);
return false;
}
using do_catch_fn = decltype(intercept_unwind);
unwind_interceptor::~unwind_interceptor() = default;
unconditional_unwind_interceptor::~unconditional_unwind_interceptor() = default;
#if IS_LIBSTDCXX
constexpr size_t vtable_size = 11;
#elif IS_LIBCXX
constexpr size_t vtable_size = 10;
#else
#warning "Cpptrace from_current: Unrecognized C++ standard library, from_current() won't be supported"
constexpr size_t vtable_size = 0;
#endif
#if IS_WINDOWS
int get_page_size() {
SYSTEM_INFO info;
GetSystemInfo(&info);
return info.dwPageSize;
}
constexpr auto memory_readonly = PAGE_READONLY;
constexpr auto memory_readwrite = PAGE_READWRITE;
int mprotect_page_and_return_old_protections(void* page, int page_size, int protections) {
DWORD old_protections;
if(!VirtualProtect(page, page_size, protections, &old_protections)) {
throw std::runtime_error(
microfmt::format(
"VirtualProtect call failed: {}",
std::system_error(GetLastError(), std::system_category()).what()
)
);
}
return old_protections;
}
void mprotect_page(void* page, int page_size, int protections) {
mprotect_page_and_return_old_protections(page, page_size, protections);
}
void* allocate_page(int page_size) {
auto page = VirtualAlloc(nullptr, page_size, MEM_COMMIT | MEM_RESERVE, memory_readwrite);
if(!page) {
throw std::runtime_error(
microfmt::format(
"VirtualAlloc call failed: {}",
std::system_error(GetLastError(), std::system_category()).what()
)
);
}
return page;
}
#else
int get_page_size() {
#if defined(_SC_PAGESIZE)
return sysconf(_SC_PAGESIZE);
#else
return getpagesize();
#endif
}
constexpr auto memory_readonly = PROT_READ;
constexpr auto memory_readwrite = PROT_READ | PROT_WRITE;
#if IS_APPLE
int get_page_protections(void* page) {
// https://stackoverflow.com/a/12627784/15675011
#ifdef HAS_MACH_VM
mach_vm_size_t vmsize;
mach_vm_address_t address = (mach_vm_address_t)page;
#else
vm_size_t vmsize;
vm_address_t address = (vm_address_t)page;
#endif
vm_region_basic_info_data_t info;
mach_msg_type_number_t info_count =
sizeof(size_t) == 8 ? VM_REGION_BASIC_INFO_COUNT_64 : VM_REGION_BASIC_INFO_COUNT;
memory_object_name_t object;
kern_return_t status =
#ifdef HAS_MACH_VM
mach_vm_region
#else
vm_region_64
#endif
(
mach_task_self(),
&address,
&vmsize,
VM_REGION_BASIC_INFO,
(vm_region_info_t)&info,
&info_count,
&object
);
if(status == KERN_INVALID_ADDRESS) {
throw std::runtime_error("vm_region failed with KERN_INVALID_ADDRESS");
}
int perms = 0;
if(info.protection & VM_PROT_READ) {
perms |= PROT_READ;
}
if(info.protection & VM_PROT_WRITE) {
perms |= PROT_WRITE;
}
if(info.protection & VM_PROT_EXECUTE) {
perms |= PROT_EXEC;
}
return perms;
}
#else
int get_page_protections(void* page) {
auto page_addr = reinterpret_cast<uintptr_t>(page);
std::ifstream stream("/proc/self/maps");
stream>>std::hex;
while(!stream.eof()) {
uintptr_t start;
uintptr_t stop;
stream>>start;
stream.ignore(1); // dash
stream>>stop;
if(stream.eof()) {
break;
}
if(stream.fail()) {
throw std::runtime_error("Failure reading /proc/self/maps");
}
if(page_addr >= start && page_addr < stop) {
stream.ignore(1); // space
char r, w, x; // there's a private/shared flag after these but we don't need it
stream>>r>>w>>x;
if(stream.fail() || stream.eof()) {
throw std::runtime_error("Failure reading /proc/self/maps");
}
int perms = 0;
if(r == 'r') {
perms |= PROT_READ;
}
if(w == 'w') {
perms |= PROT_WRITE;
}
if(x == 'x') {
perms |= PROT_EXEC;
}
// std::cerr<<"--parsed: "<<std::hex<<start<<" "<<stop<<" "<<r<<w<<x<<std::endl;
return perms;
}
stream.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
}
throw std::runtime_error("Failed to find mapping with page in /proc/self/maps");
}
#endif
void mprotect_page(void* page, int page_size, int protections) {
if(mprotect(page, page_size, protections) != 0) {
throw std::runtime_error(microfmt::format("mprotect call failed: {}", strerror(errno)));
}
}
int mprotect_page_and_return_old_protections(void* page, int page_size, int protections) {
auto old_protections = get_page_protections(page);
mprotect_page(page, page_size, protections);
return old_protections;
}
void* allocate_page(int page_size) {
auto page = mmap(nullptr, page_size, memory_readwrite, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if(page == MAP_FAILED) {
throw std::runtime_error(microfmt::format("mmap call failed: {}", strerror(errno)));
}
return page;
}
#endif
void perform_typeinfo_surgery(const std::type_info& info, do_catch_fn* do_catch_function) {
if(vtable_size == 0) { // set to zero if we don't know what standard library we're working with
return;
}
void* type_info_pointer = const_cast<void*>(static_cast<const void*>(&info));
void* type_info_vtable_pointer = *static_cast<void**>(type_info_pointer);
// the type info vtable pointer points to two pointers inside the vtable, adjust it back
type_info_vtable_pointer = static_cast<void*>(static_cast<void**>(type_info_vtable_pointer) - 2);
// for libstdc++ the class type info vtable looks like
// 0x7ffff7f89d18 <_ZTVN10__cxxabiv117__class_type_infoE>: 0x0000000000000000 0x00007ffff7f89d00
// [offset ][typeinfo pointer ]
// 0x7ffff7f89d28 <_ZTVN10__cxxabiv117__class_type_infoE+16>: 0x00007ffff7dd65a0 0x00007ffff7dd65c0
// [base destructor ][deleting dtor ]
// 0x7ffff7f89d38 <_ZTVN10__cxxabiv117__class_type_infoE+32>: 0x00007ffff7dd8f10 0x00007ffff7dd8f10
// [__is_pointer_p ][__is_function_p ]
// 0x7ffff7f89d48 <_ZTVN10__cxxabiv117__class_type_infoE+48>: 0x00007ffff7dd6640 0x00007ffff7dd6500
// [__do_catch ][__do_upcast ]
// 0x7ffff7f89d58 <_ZTVN10__cxxabiv117__class_type_infoE+64>: 0x00007ffff7dd65e0 0x00007ffff7dd66d0
// [__do_upcast ][__do_dyncast ]
// 0x7ffff7f89d68 <_ZTVN10__cxxabiv117__class_type_infoE+80>: 0x00007ffff7dd6580 0x00007ffff7f8abe8
// [__do_find_public_src][other ]
// In libc++ the layout is
// [offset ][typeinfo pointer ]
// [base destructor ][deleting dtor ]
// [noop1 ][noop2 ]
// [can_catch ][search_above_dst ]
// [search_below_dst ][has_unambiguous_public_base]
// Relevant documentation/implementation:
// https://itanium-cxx-abi.github.io/cxx-abi/abi.html
// libstdc++
// https://github.com/gcc-mirror/gcc/blob/b13e34699c7d27e561fcfe1b66ced1e50e69976f/libstdc%252B%252B-v3/libsupc%252B%252B/typeinfo
// https://github.com/gcc-mirror/gcc/blob/b13e34699c7d27e561fcfe1b66ced1e50e69976f/libstdc%252B%252B-v3/libsupc%252B%252B/class_type_info.cc
// libc++
// https://github.com/llvm/llvm-project/blob/648f4d0658ab00cf1e95330c8811aaea9481a274/libcxx/include/typeinfo
// https://github.com/llvm/llvm-project/blob/648f4d0658ab00cf1e95330c8811aaea9481a274/libcxxabi/src/private_typeinfo.h
// shouldn't be anything other than 4096 but out of an abundance of caution
auto page_size = get_page_size();
if(page_size <= 0 && (page_size & (page_size - 1)) != 0) {
throw std::runtime_error(
microfmt::format("getpagesize() is not a power of 2 greater than zero (was {})", page_size)
);
}
// allocate a page for the new vtable so it can be made read-only later
// the OS cleans this up, no cleanup done here for it
void* new_vtable_page = allocate_page(page_size);
// make our own copy of the vtable
memcpy(new_vtable_page, type_info_vtable_pointer, vtable_size * sizeof(void*));
// ninja in the custom __do_catch interceptor
auto new_vtable = static_cast<void**>(new_vtable_page);
new_vtable[6] = reinterpret_cast<void*>(do_catch_function);
// make the page read-only
mprotect_page(new_vtable_page, page_size, memory_readonly);
// make the vtable pointer for unwind_interceptor's type_info point to the new vtable
auto type_info_addr = reinterpret_cast<uintptr_t>(type_info_pointer);
auto page_addr = type_info_addr & ~(page_size - 1);
// make sure the memory we're going to set is within the page
if(type_info_addr - page_addr + sizeof(void*) > static_cast<unsigned>(page_size)) {
throw std::runtime_error("pointer crosses page boundaries");
}
auto old_protections = mprotect_page_and_return_old_protections(
reinterpret_cast<void*>(page_addr),
page_size,
memory_readwrite
);
*static_cast<void**>(type_info_pointer) = static_cast<void*>(new_vtable + 2);
mprotect_page(reinterpret_cast<void*>(page_addr), page_size, old_protections);
}
void do_prepare_unwind_interceptor(char(*intercept_unwind_handler)(std::size_t)) {
static bool did_prepare = false;
if(!did_prepare) {
cpptrace::detail::intercept_unwind_handler = intercept_unwind_handler;
try {
perform_typeinfo_surgery(typeid(cpptrace::detail::unwind_interceptor), intercept_unwind);
perform_typeinfo_surgery(
typeid(cpptrace::detail::unconditional_unwind_interceptor),
unconditional_exception_unwind_interceptor
);
} catch(std::exception& e) {
std::fprintf(
stderr,
"Cpptrace: Exception occurred while preparing from_current support: %s\n",
e.what()
);
} catch(...) {
std::fprintf(stderr, "Cpptrace: Unknown exception occurred while preparing from_current support\n");
}
did_prepare = true;
}
}
#endif
}
const raw_trace& raw_trace_from_current_exception() {
return detail::current_exception_trace.get_raw_trace();
}
const stacktrace& from_current_exception() {
return detail::current_exception_trace.get_resolved_trace();
}
}