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#pragma once
/// @file Aliases and wrapper functions that are transparently GC-enabled
/// if Lix is compiled with BoehmGC enabled.
#include <cstddef>
#include <cstring>
#include <list>
#include <map>
#include <new>
#include <string_view>
#include <vector>
#include "checked-arithmetic.hh"
#if HAVE_BOEHMGC
#include <functional> // std::less
#include <utility> // std::pair
#define GC_INCLUDE_NEW
#include <gc/gc.h>
#include <gc/gc_allocator.h>
#include <gc/gc_cpp.h>
/// calloc, transparently GC-enabled.
#define LIX_GC_CALLOC(size) GC_MALLOC(size)
/// strdup, transaprently GC-enabled.
#define LIX_GC_STRDUP(str) GC_STRDUP(str)
/// Atomic GC malloc() with GC enabled, or regular malloc() otherwise.
#define LIX_GC_MALLOC_ATOMIC(size) GC_MALLOC_ATOMIC(size)
namespace nix
{
/// Alias for std::map which uses BoehmGC's allocator conditional on this Lix
/// build having GC enabled.
template<typename KeyT, typename ValueT>
using GcMap = std::map<
KeyT,
ValueT,
std::less<KeyT>,
traceable_allocator<std::pair<KeyT const, ValueT>>
>;
/// Alias for std::vector which uses BoehmGC's allocator conditional on this Lix
/// build having GC enabled.
template<typename ItemT>
using GcVector = std::vector<ItemT, traceable_allocator<ItemT>>;
/// Alias for std::list which uses BoehmGC's allocator conditional on this Lix
/// build having GC enabled.
template<typename ItemT>
using GcList = std::list<ItemT, traceable_allocator<ItemT>>;
}
#else
#include <cstdlib>
/// calloc, transparently GC-enabled.
#define LIX_GC_CALLOC(size) calloc(size, 1)
/// strdup, transparently GC-enabled.
#define LIX_GC_STRDUP(str) strdup(str)
/// Atomic GC malloc() with GC enabled, or regular malloc() otherwise.
/// The returned memory must never contain pointers.
#define LIX_GC_MALLOC_ATOMIC(size) malloc(size)
namespace nix
{
/// Alias for std::map which uses BoehmGC's allocator conditional on this Lix
/// build having GC enabled.
template<typename KeyT, typename ValueT>
using GcMap = std::map<KeyT, ValueT>;
/// Alias for std::vector which uses BoehmGC's allocator conditional on this Lix
/// build having GC enabled.
template<typename ItemT>
using GcVector = std::vector<ItemT>;
/// Alias for std::list which uses BoehmGC's allocator conditional on this Lix
/// build having GC enabled.
template<typename ItemT>
using GcList = std::list<ItemT>;
}
#endif
namespace nix
{
[[gnu::always_inline]]
inline void * gcAllocBytes(size_t n)
{
// Note: various places expect the allocated memory to be zero.
// Hence: calloc().
void * ptr = LIX_GC_CALLOC(n);
if (ptr == nullptr) {
throw std::bad_alloc();
}
return ptr;
}
/// Typed, safe wrapper around calloc() (transparently GC-enabled). Allocates
/// enough for the requested count of the specified type. Also checks for
/// nullptr (and throws @ref std::bad_alloc), and casts the void pointer to
/// a pointer of the specified type, for type-convenient goodness.
template<typename T>
[[gnu::always_inline]]
inline T * gcAllocType(size_t howMany = 1)
{
// NOTE: size_t * size_t, which can definitely overflow.
// Unsigned integer overflow is definitely a bug, but isn't undefined
// behavior, so we can just check if we overflowed after the fact.
// However, people can and do request zero sized allocations, so we need
// to check that neither of our multiplicands were zero before complaining
// about it.
// NOLINTNEXTLINE(bugprone-sizeof-expression): yeah we only seem to alloc pointers with this. the calculation *is* correct though!
auto checkedSz = checked::Checked<size_t>(howMany) * sizeof(T);
size_t sz = checkedSz.valueWrapping();
if (checkedSz.overflowed()) {
// Congrats, you done did an overflow.
throw std::bad_alloc();
}
return static_cast<T *>(gcAllocBytes(sz));
}
/// GC-transparently allocates a buffer for a C-string of @ref size *bytes*,
/// meaning you should include the size needed by the NUL terminator in the
/// passed size. Memory allocated with this function must never contain other
/// pointers.
inline char * gcAllocString(size_t size)
{
char * cstr = static_cast<char *>(LIX_GC_MALLOC_ATOMIC(size));
if (cstr == nullptr) {
throw std::bad_alloc();
}
return cstr;
}
/// Returns a C-string copied from @ref toCopyFrom, or a single, static empty
/// string if @ref toCopyFrom is also empty.
char const * gcCopyStringIfNeeded(std::string_view toCopyFrom);
}
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