squirrel.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#include "../stdafx.h"
#include "../debug.h"
#include "squirrel_std.hpp"
#include "../error_func.h"
#include "../fileio_func.h"
#include "../string_func.h"
#include "script_fatalerror.hpp"
#include "../settings_type.h"
#include <sqstdaux.h>
#include <../squirrel/sqpcheader.h>
#include <../squirrel/sqvm.h>
#include "../core/math_func.hpp"
#include "../core/string_consumer.hpp"
 
#include "../safeguards.h"
 
/*
 * If changing the call paths into the scripting engine, define this symbol to enable full debugging of allocations.
 * This lets you track whether the allocator context is being switched correctly in all call paths.
#define SCRIPT_DEBUG_ALLOCATIONS
 */
 
struct ScriptAllocator {
  friend class Squirrel;
 
private:
  std::allocator<uint8_t> allocator;
  size_t allocated_size = 0; 
  size_t allocation_limit; 
  bool error_thrown = false;
 
  static const size_t SAFE_LIMIT = 0x8000000; 
 
#ifdef SCRIPT_DEBUG_ALLOCATIONS
  std::map<void *, size_t> allocations;
#endif

  void CheckAllocationAllowed(size_t requested_size)
  {
    /* When an error has been thrown, we are allocating just a bit of memory for the stack trace. */
    if (this->error_thrown) return;
 
    if (this->allocated_size + requested_size <= this->allocation_limit) return;
 
    /* Do not allow allocating more than the allocation limit. */
    this->error_thrown = true;
    std::string msg = fmt::format("Maximum memory allocation exceeded by {} bytes when allocating {} bytes",
      this->allocated_size + requested_size - this->allocation_limit, requested_size);
    throw Script_FatalError(msg);
  }

  void *DoAlloc(SQUnsignedInteger requested_size)
  {
    try {
      void *p = this->allocator.allocate(requested_size);
      assert(p != nullptr);
      this->allocated_size += requested_size;
 
#ifdef SCRIPT_DEBUG_ALLOCATIONS
      assert(this->allocations.find(p) == this->allocations.end());
      this->allocations[p] = requested_size;
#endif
      return p;
    } catch (const std::bad_alloc &) {
      /* The OS did not have enough memory to allocate the object, regardless of the
       * limit imposed by OpenTTD on the amount of memory that may be allocated. */
      if (this->error_thrown) {
        /* The allocation is called in the error handling of a memory allocation
         * failure, then not being able to allocate that small amount of memory
         * means there is no other choice than to bug out completely. */
        FatalError("Out of memory. Cannot allocate {} bytes", requested_size);
      }
 
      this->error_thrown = true;
      std::string msg = fmt::format("Out of memory. Cannot allocate {} bytes", requested_size);
      throw Script_FatalError(msg);
    }
  }
 
public:
  size_t GetAllocatedSize() const { return this->allocated_size; }
 
  void CheckLimit() const
  {
    if (this->allocated_size > this->allocation_limit) throw Script_FatalError("Maximum memory allocation exceeded");
  }
 
  void Reset()
  {
    assert(this->allocated_size == 0);
    this->error_thrown = false;
  }
 
  void *Malloc(SQUnsignedInteger size)
  {
    this->CheckAllocationAllowed(size);
    return this->DoAlloc(size);
  }
 
  void *Realloc(void *p, SQUnsignedInteger oldsize, SQUnsignedInteger size)
  {
    if (p == nullptr) {
      return this->Malloc(size);
    }
    if (size == 0) {
      this->Free(p, oldsize);
      return nullptr;
    }
 
    this->CheckAllocationAllowed(size - oldsize);
 
    void *new_p = this->DoAlloc(size);
    std::copy_n(static_cast<std::byte *>(p), std::min(oldsize, size), static_cast<std::byte *>(new_p));
    this->Free(p, oldsize);
 
    return new_p;
  }
 
  void Free(void *p, SQUnsignedInteger size)
  {
    if (p == nullptr) return;
    this->allocator.deallocate(reinterpret_cast<uint8_t*>(p), size);
    this->allocated_size -= size;
 
#ifdef SCRIPT_DEBUG_ALLOCATIONS
    assert(this->allocations.at(p) == size);
    this->allocations.erase(p);
#endif
  }
 
  ScriptAllocator()
  {
    this->allocation_limit = static_cast<size_t>(_settings_game.script.script_max_memory_megabytes) << 20;
    if (this->allocation_limit == 0) this->allocation_limit = SAFE_LIMIT; // in case the setting is somehow zero
  }

  ~ScriptAllocator()
  {
#ifdef SCRIPT_DEBUG_ALLOCATIONS
    assert(this->allocations.empty());
#endif
  }
};
 
ScriptAllocator *_squirrel_allocator = nullptr;
 
void *sq_vm_malloc(SQUnsignedInteger size) { return _squirrel_allocator->Malloc(size); }
void *sq_vm_realloc(void *p, SQUnsignedInteger oldsize, SQUnsignedInteger size) { return _squirrel_allocator->Realloc(p, oldsize, size); }
void sq_vm_free(void *p, SQUnsignedInteger size) { _squirrel_allocator->Free(p, size); }
 
size_t Squirrel::GetAllocatedMemory() const noexcept
{
  assert(this->allocator != nullptr);
  return this->allocator->GetAllocatedSize();
}
 
 
void Squirrel::CompileError(HSQUIRRELVM vm, std::string_view desc, std::string_view source, SQInteger line, SQInteger column)
{
  std::string msg = fmt::format("Error {}:{}/{}: {}", source, line, column, desc);
 
  /* Check if we have a custom print function */
  Squirrel *engine = (Squirrel *)sq_getforeignptr(vm);
  engine->crashed = true;
  SQPrintFunc *func = engine->print_func;
  if (func == nullptr) {
    Debug(Facility::Misc, Severity::Critical, "[Squirrel] Compile error: {}", msg);
  } else {
    (*func)(true, msg);
  }
}
 
void Squirrel::ErrorPrintFunc(HSQUIRRELVM vm, std::string_view s)
{
  /* Check if we have a custom print function */
  SQPrintFunc *func = ((Squirrel *)sq_getforeignptr(vm))->print_func;
  if (func == nullptr) {
    fmt::print(stderr, "{}", s);
  } else {
    (*func)(true, s);
  }
}
 
void Squirrel::RunError(HSQUIRRELVM vm, std::string_view error)
{
  /* Set the print function to something that prints to stderr */
  SQPRINTFUNCTION pf = sq_getprintfunc(vm);
  sq_setprintfunc(vm, &Squirrel::ErrorPrintFunc);
 
  /* Check if we have a custom print function */
  std::string msg = fmt::format("Your script made an error: {}\n", error);
  Squirrel *engine = (Squirrel *)sq_getforeignptr(vm);
  SQPrintFunc *func = engine->print_func;
  if (func == nullptr) {
    fmt::print(stderr, "{}", msg);
  } else {
    (*func)(true, msg);
  }
 
  /* Print below the error the stack, so the users knows what is happening */
  sqstd_printcallstack(vm);
  /* Reset the old print function */
  sq_setprintfunc(vm, pf);
}
 
SQInteger Squirrel::_RunError(HSQUIRRELVM vm)
{
  std::string_view view;
 
  if (sq_gettop(vm) >= 1) {
    if (SQ_SUCCEEDED(sq_getstring(vm, -1, view))) {
      Squirrel::RunError(vm, view);
      return 0;
    }
  }
 
  Squirrel::RunError(vm, "unknown error");
  return 0;
}
 
void Squirrel::PrintFunc(HSQUIRRELVM vm, std::string_view s)
{
  /* Check if we have a custom print function */
  SQPrintFunc *func = ((Squirrel *)sq_getforeignptr(vm))->print_func;
  if (func == nullptr) {
    fmt::print("{}", s);
  } else {
    (*func)(false, s);
  }
}
 
void Squirrel::AddMethod(std::string_view method_name, SQFUNCTION proc, std::string_view params, void *userdata, int size, bool suspendable)
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_pushstring(this->vm, fmt::format("{1}{0}{1}", method_name, suspendable ? "@" : ""));
 
  if (size != 0) {
    void *ptr = sq_newuserdata(vm, size);
    std::copy_n(static_cast<std::byte *>(userdata), size, static_cast<std::byte *>(ptr));
  }
 
  sq_newclosure(this->vm, proc, size != 0 ? 1 : 0);
  if (!params.empty()) sq_setparamscheck(this->vm, params.size(), params);
  sq_setnativeclosurename(this->vm, -1, method_name);
  sq_newslot(this->vm, -3, SQFalse);
 
  if (suspendable) {
    std::string squirrel_script = fmt::format(
      "function {0}(...)\n"
      "{{\n"
      "    local args = [this];\n"
      "    for(local i = 0; i < vargc; i++) args.push(vargv[i]);\n"
      "    while(this[\"@{0}@\"].acall(args)); \n"
      "}}\n"
      "return {0};\n", method_name);
 
    sq_pushstring(this->vm, method_name);
    if (SQ_FAILED(sq_compilebuffer(this->vm, squirrel_script, method_name, SQTrue))) NOT_REACHED();
    sq_pushroottable(this->vm);
    if (SQ_FAILED(sq_call(this->vm, 1, SQTrue, SQTrue))) NOT_REACHED();
    sq_remove(this->vm, -2);
    sq_newslot(this->vm, -3, SQFalse);
  }
}
 
void Squirrel::AddConst(std::string_view var_name, SQInteger value)
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_pushstring(this->vm, var_name);
  sq_pushinteger(this->vm, value);
  sq_newslot(this->vm, -3, SQTrue);
}
 
void Squirrel::AddConst(std::string_view var_name, bool value)
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_pushstring(this->vm, var_name);
  sq_pushbool(this->vm, value);
  sq_newslot(this->vm, -3, SQTrue);
}
 
void Squirrel::AddClassBegin(std::string_view class_name)
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_pushroottable(this->vm);
  sq_pushstring(this->vm, class_name);
  sq_newclass(this->vm, SQFalse);
}
 
void Squirrel::AddClassBegin(std::string_view class_name, std::string_view parent_class)
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_pushroottable(this->vm);
  sq_pushstring(this->vm, class_name);
  sq_pushstring(this->vm, parent_class);
  if (SQ_FAILED(sq_get(this->vm, -3))) {
    Debug(Facility::Misc, Severity::Critical, "[squirrel] Failed to initialize class '{}' based on parent class '{}'", class_name, parent_class);
    Debug(Facility::Misc, Severity::Critical, "[squirrel] Make sure that '{}' exists before trying to define '{}'", parent_class, class_name);
    return;
  }
  sq_newclass(this->vm, SQTrue);
}
 
void Squirrel::AddClassEnd()
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_newslot(vm, -3, SQFalse);
  sq_pop(vm, 1);
}
 
void Squirrel::AddScopedEnumBegin(std::string_view enum_name)
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_pushstring(this->vm, enum_name);
  sq_newclass(this->vm, SQFalse);
}
 
void Squirrel::AddScopedEnumEnd()
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_newslot(vm, -3, SQFalse);
}
 
bool Squirrel::MethodExists(HSQOBJECT instance, std::string_view method_name)
{
  assert(!this->crashed);
  ScriptAllocatorScope alloc_scope(this);
 
  int top = sq_gettop(this->vm);
  /* Go to the instance-root */
  sq_pushobject(this->vm, instance);
  /* Find the function-name inside the script */
  sq_pushstring(this->vm, method_name);
  if (SQ_FAILED(sq_get(this->vm, -2))) {
    sq_settop(this->vm, top);
    return false;
  }
  sq_settop(this->vm, top);
  return true;
}
 
bool Squirrel::Resume(int suspend)
{
  assert(!this->crashed);
  ScriptAllocatorScope alloc_scope(this);
 
  /* Did we use more operations than we should have in the
   * previous tick? If so, subtract that from the current run. */
  if (this->overdrawn_ops > 0 && suspend > 0) {
    this->overdrawn_ops -= suspend;
    /* Do we need to wait even more? */
    if (this->overdrawn_ops >= 0) return true;
 
    /* We can now only run whatever is "left". */
    suspend = -this->overdrawn_ops;
  }
 
  this->crashed = !sq_resumecatch(this->vm, suspend);
  this->overdrawn_ops = -this->vm->_ops_till_suspend;
  this->allocator->CheckLimit();
  return this->vm->_suspended != 0;
}
 
void Squirrel::ResumeError()
{
  assert(!this->crashed);
  ScriptAllocatorScope alloc_scope(this);
  sq_resumeerror(this->vm);
}
 
void Squirrel::CollectGarbage()
{
  ScriptAllocatorScope alloc_scope(this);
  sq_collectgarbage(this->vm);
}
 
bool Squirrel::CallMethod(HSQOBJECT instance, std::string_view method_name, HSQOBJECT *ret, int suspend)
{
  assert(!this->crashed);
  ScriptAllocatorScope alloc_scope(this);
  this->allocator->CheckLimit();
 
  /* Store the stack-location for the return value. We need to
   * restore this after saving or the stack will be corrupted
   * if we're in the middle of a DoCommand. */
  SQInteger last_target = this->vm->_suspended_target;
  /* Store the current top */
  int top = sq_gettop(this->vm);
  /* Go to the instance-root */
  sq_pushobject(this->vm, instance);
  /* Find the function-name inside the script */
  sq_pushstring(this->vm, method_name);
  if (SQ_FAILED(sq_get(this->vm, -2))) {
    Debug(Facility::Misc, Severity::Critical, "[squirrel] Could not find '{}' in the class", method_name);
    sq_settop(this->vm, top);
    return false;
  }
  /* Call the method */
  sq_pushobject(this->vm, instance);
  if (SQ_FAILED(sq_call(this->vm, 1, ret == nullptr ? SQFalse : SQTrue, SQTrue, suspend))) return false;
  if (ret != nullptr) sq_getstackobj(vm, -1, ret);
  /* Reset the top, but don't do so for the script main function, as we need
   *  a correct stack when resuming. */
  if (suspend == -1 || !this->IsSuspended()) sq_settop(this->vm, top);
  /* Restore the return-value location. */
  this->vm->_suspended_target = last_target;
 
  return true;
}
 
bool Squirrel::CallStringMethod(HSQOBJECT instance, std::string_view method_name, std::string *res, int suspend)
{
  HSQOBJECT ret;
  if (!this->CallMethod(instance, method_name, &ret, suspend)) return false;
 
  auto str = ObjectToString(&ret);
  if (!str.has_value()) return false;
 
  *res = StrMakeValid(*str);
  return true;
}
 
bool Squirrel::CallIntegerMethod(HSQOBJECT instance, std::string_view method_name, int *res, int suspend)
{
  HSQOBJECT ret;
  if (!this->CallMethod(instance, method_name, &ret, suspend)) return false;
  if (ret._type != OT_INTEGER) return false;
  *res = ObjectToInteger(&ret);
  return true;
}
 
bool Squirrel::CallBoolMethod(HSQOBJECT instance, std::string_view method_name, bool *res, int suspend)
{
  HSQOBJECT ret;
  if (!this->CallMethod(instance, method_name, &ret, suspend)) return false;
  if (ret._type != OT_BOOL) return false;
  *res = ObjectToBool(&ret);
  return true;
}
 
/* static */ bool Squirrel::CreateClassInstanceVM(HSQUIRRELVM vm, const std::string &class_name, void *real_instance, HSQOBJECT *instance, SQRELEASEHOOK release_hook, bool prepend_API_name)
{
  Squirrel *engine = (Squirrel *)sq_getforeignptr(vm);
 
  int oldtop = sq_gettop(vm);
 
  /* First, find the class */
  sq_pushroottable(vm);
 
  if (prepend_API_name) {
    std::string prepended_class_name = fmt::format("{}{}", engine->GetAPIName(), class_name);
    sq_pushstring(vm, prepended_class_name);
  } else {
    sq_pushstring(vm, class_name);
  }
 
  if (SQ_FAILED(sq_get(vm, -2))) {
    Debug(Facility::Misc, Severity::Critical, "[squirrel] Failed to find class by the name '{}{}'", prepend_API_name ? engine->GetAPIName() : "", class_name);
    sq_settop(vm, oldtop);
    return false;
  }
 
  /* Create the instance */
  if (SQ_FAILED(sq_createinstance(vm, -1))) {
    Debug(Facility::Misc, Severity::Critical, "[squirrel] Failed to create instance for class '{}{}'", prepend_API_name ? engine->GetAPIName() : "", class_name);
    sq_settop(vm, oldtop);
    return false;
  }
 
  if (instance != nullptr) {
    /* Find our instance */
    sq_getstackobj(vm, -1, instance);
    /* Add a reference to it, so it survives for ever */
    sq_addref(vm, instance);
  }
  sq_remove(vm, -2); // Class-name
  sq_remove(vm, -2); // Root-table
 
  /* Store it in the class */
  sq_setinstanceup(vm, -1, real_instance);
  if (release_hook != nullptr) sq_setreleasehook(vm, -1, release_hook);
 
  if (instance != nullptr) sq_settop(vm, oldtop);
 
  return true;
}
 
bool Squirrel::CreateClassInstance(const std::string &class_name, void *real_instance, HSQOBJECT *instance)
{
  ScriptAllocatorScope alloc_scope(this);
  return Squirrel::CreateClassInstanceVM(this->vm, class_name, real_instance, instance, nullptr);
}
 
/* static */ SQUserPointer Squirrel::GetRealInstance(HSQUIRRELVM vm, int index, std::string_view tag)
{
  if (index < 0) index += sq_gettop(vm) + 1;
  Squirrel *engine = static_cast<Squirrel *>(sq_getforeignptr(vm));
  std::string class_name = fmt::format("{}{}", engine->GetAPIName(), tag);
  sq_pushroottable(vm);
  sq_pushstring(vm, class_name);
  sq_get(vm, -2);
  sq_push(vm, index);
  if (sq_instanceof(vm) == SQTrue) {
    sq_pop(vm, 3);
    SQUserPointer ptr = nullptr;
    if (SQ_SUCCEEDED(sq_getinstanceup(vm, index, &ptr, nullptr))) return ptr;
  }
  throw sq_throwerror(vm, fmt::format("parameter {} has an invalid type ; expected: '{}'", index - 1, class_name));
}
 
Squirrel::Squirrel(std::string_view api_name) :
  api_name(api_name), allocator(std::make_unique<ScriptAllocator>())
{
  this->Initialize();
}
 
void Squirrel::Initialize()
{
  ScriptAllocatorScope alloc_scope(this);
 
  this->global_pointer = nullptr;
  this->print_func = nullptr;
  this->crashed = false;
  this->overdrawn_ops = 0;
  this->vm = sq_open(1024);
 
  /* Handle compile-errors ourself, so we can display it nicely */
  sq_setcompilererrorhandler(this->vm, &Squirrel::CompileError);
  sq_notifyallexceptions(this->vm, IsVisibleSeverity(Facility::Script, Severity::Debug2));
  /* Set a good print-function */
  sq_setprintfunc(this->vm, &Squirrel::PrintFunc);
  /* Handle runtime-errors ourself, so we can display it nicely */
  sq_newclosure(this->vm, &Squirrel::_RunError, 0);
  sq_seterrorhandler(this->vm);
 
  /* Set the foreign pointer, so we can always find this instance from within the VM */
  sq_setforeignptr(this->vm, this);
 
  sq_pushroottable(this->vm);
  squirrel_register_global_std(*this);
 
  /* Set consts table as delegate of root table, so consts/enums defined via require() are accessible */
  sq_pushconsttable(this->vm);
  sq_setdelegate(this->vm, -2);
}
 
class SQFile {
private:
  FileHandle file;
  size_t size;
  size_t pos;
  std::string buffer;
  StringConsumer consumer;
 
  size_t ReadInternal(std::span<char> buf)
  {
    size_t count = buf.size();
    if (this->pos + count > this->size) {
      count = this->size - this->pos;
    }
    if (count > 0) count = fread(buf.data(), 1, count, this->file);
    this->pos += count;
    return count;
  }
 
public:
  SQFile(FileHandle file, size_t size) : file(std::move(file)), size(size), pos(0), consumer(buffer) {}
 
  StringConsumer &GetConsumer(size_t min_size = 64)
  {
    if (this->consumer.GetBytesLeft() < min_size && this->pos < this->size) {
      this->buffer.erase(0, this->consumer.GetBytesRead());
 
      size_t buffer_size = this->buffer.size();
      size_t read_size = Align(min_size - buffer_size, 4096); // read pages of 4096 bytes
      /* TODO C++23: use std::string::resize_and_overwrite() */
      this->buffer.resize(buffer_size + read_size);
      auto dest = std::span(this->buffer.data(), this->buffer.size()).subspan(buffer_size);
      buffer_size += this->ReadInternal(dest);
      this->buffer.resize(buffer_size);
 
      this->consumer = StringConsumer(this->buffer);
    }
    return this->consumer;
  }
 
  size_t Read(void *buf, size_t max_size)
  {
    std::span<char> dest(reinterpret_cast<char *>(buf), max_size);
 
    auto view = this->consumer.Read(max_size);
    std::copy(view.data(), view.data() + view.size(), dest.data());
    size_t result_size = view.size();
 
    if (result_size < max_size) {
      assert(!this->consumer.AnyBytesLeft());
      result_size += this->ReadInternal(dest.subspan(result_size));
    }
 
    return result_size;
  }
};
 
static char32_t _io_file_lexfeed_ASCII(SQUserPointer file)
{
  StringConsumer &consumer = reinterpret_cast<SQFile *>(file)->GetConsumer();
  return consumer.TryReadUint8().value_or(0); // read as unsigned, otherwise integer promotion breaks it
}
 
static char32_t _io_file_lexfeed_UTF8(SQUserPointer file)
{
  StringConsumer &consumer = reinterpret_cast<SQFile *>(file)->GetConsumer();
  return consumer.AnyBytesLeft() ? consumer.ReadUtf8(-1) : 0;
}
 
static SQInteger _io_file_read(SQUserPointer file, SQUserPointer buf, SQInteger size)
{
  SQInteger ret = reinterpret_cast<SQFile *>(file)->Read(buf, size);
  if (ret == 0) return -1;
  return ret;
}
 
SQRESULT Squirrel::LoadFile(HSQUIRRELVM vm, const std::string &filename, SQBool printerror)
{
  ScriptAllocatorScope alloc_scope(this);
 
  std::optional<FileHandle> file = std::nullopt;
  size_t size;
  if (this->GetAPIName().starts_with("AI")) {
    file = FioFOpenFile(filename, "rb", Subdirectory::Ai, &size);
    if (!file.has_value()) file = FioFOpenFile(filename, "rb", Subdirectory::AiLibrary, &size);
  } else if (this->GetAPIName().starts_with("GS")) {
    file = FioFOpenFile(filename, "rb", Subdirectory::Gs, &size);
    if (!file.has_value()) file = FioFOpenFile(filename, "rb", Subdirectory::GsLibrary, &size);
  } else {
    NOT_REACHED();
  }
 
  if (!file.has_value()) {
    return sq_throwerror(vm, "cannot open the file");
  }
  unsigned short bom = 0;
  if (size >= 2) {
    if (fread(&bom, 1, sizeof(bom), *file) != sizeof(bom)) return sq_throwerror(vm, "cannot read the file");;
  }
 
  SQLEXREADFUNC func;
  switch (bom) {
    case SQ_BYTECODE_STREAM_TAG: { // BYTECODE
      if (fseek(*file, -2, SEEK_CUR) < 0) {
        return sq_throwerror(vm, "cannot seek the file");
      }
 
      SQFile f(std::move(*file), size);
      if (SQ_SUCCEEDED(sq_readclosure(vm, _io_file_read, &f))) {
        return SQ_OK;
      }
      return sq_throwerror(vm, "Couldn't read bytecode");
    }
    case 0xBBEF:   // UTF-8
    case 0xEFBB: { // UTF-8 on big-endian machine
      /* Similarly, check the file is actually big enough to finish checking BOM */
      if (size < 3) {
        return sq_throwerror(vm, "I/O error");
      }
      unsigned char uc;
      if (fread(&uc, 1, sizeof(uc), *file) != sizeof(uc) || uc != 0xBF) {
        return sq_throwerror(vm, "Unrecognized encoding");
      }
      func = _io_file_lexfeed_UTF8;
      size -= 3; // Skip BOM
      break;
    }
    default: // ASCII
      func = _io_file_lexfeed_ASCII;
      /* Account for when we might not have fread'd earlier */
      if (size >= 2 && fseek(*file, -2, SEEK_CUR) < 0) {
        return sq_throwerror(vm, "cannot seek the file");
      }
      break;
  }
 
  SQFile f(std::move(*file), size);
  if (SQ_SUCCEEDED(sq_compile(vm, func, &f, filename.c_str(), printerror))) {
    return SQ_OK;
  }
  return SQ_ERROR;
}
 
bool Squirrel::LoadScript(HSQUIRRELVM vm, const std::string &script, bool in_root)
{
  ScriptAllocatorScope alloc_scope(this);
 
  /* Make sure we are always in the root-table */
  if (in_root) sq_pushroottable(vm);
 
  SQInteger ops_left = vm->_ops_till_suspend;
  /* Load and run the script */
  if (SQ_SUCCEEDED(LoadFile(vm, script, SQTrue))) {
    sq_push(vm, -2);
    if (SQ_SUCCEEDED(sq_call(vm, 1, SQFalse, SQTrue, 100000))) {
      sq_pop(vm, 1);
      /* After compiling the file we want to reset the amount of opcodes. */
      vm->_ops_till_suspend = ops_left;
      return true;
    }
  }
 
  vm->_ops_till_suspend = ops_left;
  Debug(Facility::Misc, Severity::Critical, "[squirrel] Failed to compile '{}'", script);
  return false;
}
 
bool Squirrel::LoadScript(const std::string &script)
{
  return LoadScript(this->vm, script);
}

Squirrel::~Squirrel()
{
  this->Uninitialize();
}
 
void Squirrel::Uninitialize()
{
  ScriptAllocatorScope alloc_scope(this);
 
  /* Remove the delegation */
  sq_pushroottable(this->vm);
  sq_pushnull(this->vm);
  sq_setdelegate(this->vm, -2);
  sq_pop(this->vm, 1);
 
  /* Clean up the stuff */
  sq_pop(this->vm, 1);
  sq_close(this->vm);
 
  /* Reset memory allocation errors. */
  this->allocator->Reset();
}
 
void Squirrel::Reset()
{
  this->Uninitialize();
  this->Initialize();
}
 
void Squirrel::InsertResult(bool result)
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_pushbool(this->vm, result);
  if (this->IsSuspended()) { // Called before resuming a suspended script?
    vm->GetAt(vm->_stackbase + vm->_suspended_target) = vm->GetUp(-1);
    vm->Pop();
  }
}
 
void Squirrel::InsertResult(int result)
{
  ScriptAllocatorScope alloc_scope(this);
 
  sq_pushinteger(this->vm, result);
  if (this->IsSuspended()) { // Called before resuming a suspended script?
    vm->GetAt(vm->_stackbase + vm->_suspended_target) = vm->GetUp(-1);
    vm->Pop();
  }
}
 
/* static */ void Squirrel::DecreaseOps(HSQUIRRELVM vm, int ops)
{
  vm->DecreaseOps(ops);
}
 
bool Squirrel::IsSuspended()
{
  return this->vm->_suspended != 0;
}
 
bool Squirrel::HasScriptCrashed()
{
  return this->crashed;
}
 
void Squirrel::CrashOccurred()
{
  this->crashed = true;
}
 
bool Squirrel::CanSuspend()
{
  ScriptAllocatorScope alloc_scope(this);
  return sq_can_suspend(this->vm);
}
 
SQInteger Squirrel::GetOpsTillSuspend()
{
  return this->vm->_ops_till_suspend;
}
 
void Squirrel::IncreaseAllocatedSize(size_t bytes)
{
  _squirrel_allocator->CheckAllocationAllowed(bytes);
  _squirrel_allocator->allocated_size += bytes;
}
 
void Squirrel::DecreaseAllocatedSize(size_t bytes)
{
  _squirrel_allocator->allocated_size -= bytes;
}