/src/testdir/tests/capi/luaL_loadbuffer_proto/serializer.cc

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/*
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2022, Tarantool AUTHORS, please see AUTHORS file.
 */
#include "serializer.h"

#include <stack>
#include <string>

/**
* If control flow reaches the point of the unreachable(), the program is
* undefined. It is useful in situations where the compiler cannot deduce
* the unreachability of the code.
*/
#if __has_builtin(__builtin_unreachable) || defined(__GNUC__)
#  define unreachable() (assert(0), __builtin_unreachable())
#else
#  define unreachable() (assert(0))
#endif

using namespace lua_grammar;

extern char preamble_lua[];

#define PROTO_TOSTRING(TYPE, VAR_NAME) \
  std::string TYPE##ToString(const TYPE & (VAR_NAME))

/* PROTO_TOSTRING version for nested (depth=2) protobuf messages. */
#define NESTED_PROTO_TOSTRING(TYPE, VAR_NAME, PARENT_MESSAGE) \
  std::string TYPE##ToString \
  (const PARENT_MESSAGE::TYPE & (VAR_NAME))

namespace luajit_fuzzer {
namespace {

/*
 * The following keywords are reserved and cannot be used as names,
 * see Lua 5.1 Reference Manual, 2.1 – Lexical Conventions.
 */
const std::set<std::string> KReservedLuaKeywords {
  "and",
  "break",
  "do",
  "else",
  "elseif",
  "end",
  "false",
  "for",
  "function",
  "if",
  "in",
  "local",
  "nil",
  "not",
  "or",
  "repeat",
  "return",
  "then",
  "true",
  "until",
  "while",
};

const std::string kCounterNamePrefix = "counter_";
const std::string kNumberWrapperName = "always_number";
const std::string kBinOpWrapperName = "only_numbers_cmp";
const std::string kNotNaNAndNilWrapperName = "not_nan_and_nil";

PROTO_TOSTRING(Block, block);
PROTO_TOSTRING(Chunk, chunk);

PROTO_TOSTRING(Statement, stat);

/** LastStatement and nested types. */
PROTO_TOSTRING(LastStatement, laststat);
NESTED_PROTO_TOSTRING(ReturnOptionalExpressionList, explist, LastStatement);

/**
 * Statement options.
 */

/** AssignmentList and nested types. */
PROTO_TOSTRING(AssignmentList, assignmentlist);
NESTED_PROTO_TOSTRING(VariableList, varlist, AssignmentList);

/** FunctionCall and nested types. */
PROTO_TOSTRING(FunctionCall, call);
NESTED_PROTO_TOSTRING(Args, args, FunctionCall);
NESTED_PROTO_TOSTRING(PrefixArgs, prefixargs, FunctionCall);
NESTED_PROTO_TOSTRING(PrefixNamedArgs, prefixnamedargs, FunctionCall);

/** DoBlock, WhileCycle and RepeatCycle clauses. */
PROTO_TOSTRING(DoBlock, block);
PROTO_TOSTRING(WhileCycle, whilecycle);
PROTO_TOSTRING(RepeatCycle, repeatcycle);

/** IfStatement and nested types. */
PROTO_TOSTRING(IfStatement, statement);
NESTED_PROTO_TOSTRING(ElseIfBlock, elseifblock, IfStatement);

/** ForCycleName and ForCycleList clauses. */
PROTO_TOSTRING(ForCycleName, forcyclename);
PROTO_TOSTRING(ForCycleList, forcyclelist);

/** Function and nested types. */
PROTO_TOSTRING(Function, func);
NESTED_PROTO_TOSTRING(FuncName, funcname, Function);

PROTO_TOSTRING(NameList, namelist);
NESTED_PROTO_TOSTRING(NameListWithEllipsis, namelist, FuncBody);
NESTED_PROTO_TOSTRING(ParList, parlist, FuncBody);

/** LocalFunc and LocalNames clauses. */
PROTO_TOSTRING(LocalFunc, localfunc);
PROTO_TOSTRING(LocalNames, localnames);

/**
 * Expressions and variables.
 */

/** Expressions clauses. */
PROTO_TOSTRING(ExpressionList, explist);
PROTO_TOSTRING(OptionalExpressionList, explist);
PROTO_TOSTRING(PrefixExpression, prefExpr);

/* Variable and nested types. */
PROTO_TOSTRING(Variable, var);
NESTED_PROTO_TOSTRING(IndexWithExpression, indexexpr, Variable);
NESTED_PROTO_TOSTRING(IndexWithName, indexname, Variable);

/** Expression and nested types. */
PROTO_TOSTRING(Expression, expr);
NESTED_PROTO_TOSTRING(AnonFunc, function, Expression);
NESTED_PROTO_TOSTRING(ExpBinaryOpExp, binary, Expression);
NESTED_PROTO_TOSTRING(UnaryOpExp, unary, Expression);

/**
 * Tables and fields.
 */
PROTO_TOSTRING(TableConstructor, table);
PROTO_TOSTRING(FieldList, fieldlist);
NESTED_PROTO_TOSTRING(FieldWithFieldSep, field, FieldList);

/** Field and nested types. */
PROTO_TOSTRING(Field, field);
NESTED_PROTO_TOSTRING(ExpressionAssignment, assignment, Field);
NESTED_PROTO_TOSTRING(NameAssignment, assignment, Field);
PROTO_TOSTRING(FieldSep, sep);

/** Operators. */
PROTO_TOSTRING(BinaryOperator, op);
PROTO_TOSTRING(UnaryOperator, op);

/** Identifier (Name). */
PROTO_TOSTRING(Name, name);

std::string
NumberWrappedExpressionToString(const Expression &expr)
{
  std::string retval;
  retval += kNumberWrapperName;
  retval += "(";
  retval += ExpressionToString(expr);
  retval += ")";

  return retval;
}

std::string
AllowedIndexExpressionToString(const Expression &expr)
{
  std::string retval;
  retval += kNotNaNAndNilWrapperName;
  retval += "(";
  retval += ExpressionToString(expr);
  retval += ")";
  return retval;
}

/**
 * Class that controls id creation for counters. Basically, a
 * variable wrapper that guarantees variable to be incremented.
 */
class CounterIdProvider {
public:
  /** Returns number of id provided. */
  std::size_t count()
  {
    return id_;
  }

  /** Returns a new id that was not used after last clean(). */
  std::size_t next()
  {
    return id_++;
  }

  /**
   * Cleans history. Should be used to make fuzzer starts
   * independent.
   */
  void clean()
  {
    id_ = 0;
  }

private:
  std::size_t id_ = 0;
};

/** A singleton for counter id provider. */
CounterIdProvider&
GetCounterIdProvider()
{
  static CounterIdProvider provider;
  return provider;
}

std::string
GetCounterName(std::size_t id)
{
  return kCounterNamePrefix + std::to_string(id);
}

/** Returns `<counter_name> = <counter_name> + 1`. */
std::string
GetCounterIncrement(const std::string &counter_name)
{
  std::string retval = counter_name;
  retval += " = ";
  retval += counter_name;
  retval += " + 1;\n";
  return retval;
}

/**
 * Returns `if <counter_name> > kMaxCounterValue then
 * <then_block> end`.
 */
std::string
GetCondition(const std::string &counter_name, const std::string &then_block)
{
  std::string retval = "if ";
  retval += counter_name;
  retval += " > ";
  retval += std::to_string(kMaxCounterValue);
  retval += " then ";
  retval += then_block;
  retval += " end\n";
  return retval;
}

/**
 * Class that registers and provides context during code
 * generation.
 * Used to generate correct Lua code.
 */
class Context {
public:
  enum class BlockType {
    kReturnable,
    kBreakable,
    kReturnableWithVararg,
  };

  void step_in(BlockType type)
  {
    block_stack_.push(type);
    if (block_type_is_returnable_(type)) {
      returnable_stack_.push(type);
    }
  }

  void step_out()
  {
    assert(!block_stack_.empty());
    if (block_type_is_returnable_(block_stack_.top())) {
      assert(!returnable_stack_.empty());
      returnable_stack_.pop();
    }
    block_stack_.pop();
  }

  std::string get_next_block_setup()
  {
    std::size_t id = GetCounterIdProvider().next();
    std::string counter_name = GetCounterName(id);

    return GetCondition(counter_name, get_exit_statement_()) +
           GetCounterIncrement(counter_name);
  }

  bool break_is_possible()
  {
    return !block_stack_.empty() &&
           block_stack_.top() == BlockType::kBreakable;
  }

  bool return_is_possible()
  {
    return !returnable_stack_.empty();
  }

  bool vararg_is_possible()
  {
    return (returnable_stack_.empty() ||
      (!returnable_stack_.empty() &&
       returnable_stack_.top() ==
        BlockType::kReturnableWithVararg));
  }

private:

  bool block_type_is_returnable_(BlockType type)
  {
    switch (type) {
    case BlockType::kBreakable:
      return false;
    case BlockType::kReturnable:
    case BlockType::kReturnableWithVararg:
      return true;
    }
    unreachable();
  }

  std::string get_exit_statement_()
  {
    assert(!block_stack_.empty());
    switch (block_stack_.top()) {
    case BlockType::kBreakable:
      return "break";
    case BlockType::kReturnable:
    case BlockType::kReturnableWithVararg:
      return "return";
    }
    unreachable();
  }

  std::stack<BlockType> block_stack_;
  /*
   * The returnable block can be exited with return from
   * the breakable block within it, but the breakable block
   * cannot be exited with break from the returnable block within
   * it.
   * Valid code:
   * `function foo() while true do return end end`
   * Erroneous code:
   * `while true do function foo() break end end`
   * This stack is used to check if `return` is possible.
   */
  std::stack<BlockType> returnable_stack_;
};

Context&
GetContext()
{
  static Context context;
  return context;
}

/**
 * Block may be placed not only in a cycle, so specially for cycles
 * there is a function that will add a break condition and a
 * counter increment.
 */
std::string
BlockToStringCycleProtected(const Block &block)
{
  std::string retval = GetContext().get_next_block_setup();
  retval += ChunkToString(block.chunk());
  return retval;
}

/**
 * DoBlock may be placed not only in a cycle, so specially for
 * cycles there is a function that will call
 * BlockToStringCycleProtected().
 */
std::string
DoBlockToStringCycleProtected(const DoBlock &block)
{
  std::string retval = "do\n";
  retval += BlockToStringCycleProtected(block.block());
  retval += "end\n";
  return retval;
}

/**
 * FuncBody may contain recursive calls, so for all function bodies,
 * there is a function that adds a return condition and a counter
 * increment.
 */
std::string
FuncBodyToStringReqProtected(const FuncBody &body)
{
  std::string body_str = "( ";
  if (body.has_parlist()) {
    body_str += ParListToString(body.parlist());
  }
  body_str += " )\n\t";

  body_str += GetContext().get_next_block_setup();

  body_str += BlockToString(body.block());
  body_str += "end\n";
  return body_str;
}

bool
FuncBodyHasVararg(const FuncBody &body)
{
  if (!body.has_parlist()) {
    return false;
  }
  const FuncBody::ParList &parlist = body.parlist();
  switch (parlist.parlist_oneof_case()) {
  case FuncBody::ParList::ParlistOneofCase::kNamelist:
    return parlist.namelist().has_ellipsis();
  case FuncBody::ParList::ParlistOneofCase::kEllipsis:
    return true;
  default:
    return parlist.namelist().has_ellipsis();
  }
}

Context::BlockType
GetFuncBodyType(const FuncBody &body)
{
  return FuncBodyHasVararg(body) ?
    Context::BlockType::kReturnableWithVararg :
    Context::BlockType::kReturnable;
}

std::string
ClearIdentifier(const std::string &identifier)
{
  std::string cleared;

  bool has_first_not_digit = false;
  for (char c : identifier) {
    if (has_first_not_digit && (std::iswalnum(c) || c == '_')) {
      cleared += c;
    } else if (std::isalpha(c) || c == '_') {
      has_first_not_digit = true;
      cleared += c;
    } else {
      cleared += '_';
    }
  }
  return cleared;
}

inline std::string
clamp(std::string s, size_t maxSize = kMaxStrLength)
{
  if (s.size() > maxSize)
    s.resize(maxSize);
  return s;
}

inline double
clamp(double number, double upper, double lower)
{
  return number <= lower ? lower :
         number >= upper ? upper : number;
}

inline std::string
ConvertToStringDefault(const std::string &s, bool sanitize = false)
{
  std::string ident = clamp(s);
  if (sanitize)
    ident = ClearIdentifier(ident);
  if (ident.empty())
    ident = std::string(kDefaultIdent);
  return ident;
}

PROTO_TOSTRING(Block, block)
{
  return ChunkToString(block.chunk());
}

PROTO_TOSTRING(Chunk, chunk)
{
  std::string chunk_str;
  for (int i = 0; i < chunk.stat_size(); ++i)
    chunk_str += StatementToString(chunk.stat(i)) + "\n";

  if (chunk.has_laststat())
    chunk_str += LastStatementToString(chunk.laststat()) + "\n";

  return chunk_str;
}

/**
 * LastStatement and nested types.
 */
PROTO_TOSTRING(LastStatement, laststat)
{
  std::string laststat_str;
  using LastStatType = LastStatement::LastOneofCase;
  switch (laststat.last_oneof_case()) {
  case LastStatType::kExplist:
    laststat_str = ReturnOptionalExpressionListToString(
      laststat.explist());
    break;
  case LastStatType::kBreak:
    if (GetContext().break_is_possible()) {
      laststat_str = "break";
    }
    break;
  default:
    /* Chosen as default in order to decrease number of 'break's. */
    laststat_str = ReturnOptionalExpressionListToString(
      laststat.explist());
    break;
  }

  /*
   * Add a semicolon when last statement is not empty
   * to avoid errors like:
   *
   * <preamble.lua>
   * (nil):Name0()
   * (nil)() -- ambiguous syntax (function call x new statement) near '('
   */
  if (!laststat_str.empty())
    laststat_str += "; ";

  return laststat_str;
}

NESTED_PROTO_TOSTRING(ReturnOptionalExpressionList, explist, LastStatement)
{
  if (!GetContext().return_is_possible()) {
    return "";
  }

  std::string explist_str = "return";
  if (explist.has_explist()) {
    explist_str += " " + ExpressionListToString(explist.explist());
    explist_str += " ";
  }
  return explist_str;
}

/**
 * Statement and statement options.
 */
PROTO_TOSTRING(Statement, stat)
{
  std::string stat_str;
  using StatType = Statement::StatOneofCase;
  switch (stat.stat_oneof_case()) {
  case StatType::kList:
    stat_str = AssignmentListToString(stat.list());
    break;
  case StatType::kCall:
    stat_str = FunctionCallToString(stat.call());
    break;
  case StatType::kBlock:
    stat_str = DoBlockToString(stat.block());
    break;
  case StatType::kWhilecycle:
    stat_str = WhileCycleToString(stat.whilecycle());
    break;
  case StatType::kRepeatcycle:
    stat_str = RepeatCycleToString(stat.repeatcycle());
    break;
  case StatType::kIfstat:
    stat_str = IfStatementToString(stat.ifstat());
    break;
  case StatType::kForcyclename:
    stat_str = ForCycleNameToString(stat.forcyclename());
    break;
  case StatType::kForcyclelist:
    stat_str = ForCycleListToString(stat.forcyclelist());
    break;
  case StatType::kFunc:
    stat_str = FunctionToString(stat.func());
    break;
  case StatType::kLocalfunc:
    stat_str = LocalFuncToString(stat.localfunc());
    break;
  case StatType::kLocalnames:
    stat_str = LocalNamesToString(stat.localnames());
    break;
  default:
    /**
     * Chosen arbitrarily more for simplicity.
     * TODO: Choose "more interesting" defaults.
     */
    stat_str = AssignmentListToString(stat.list());
    break;
  }

  /*
   * Always add a semicolon regardless of grammar
   * to avoid errors like:
   *
   * <preamble.lua>
   * (nil):Name0()
   * (nil)() -- ambiguous syntax (function call x new statement) near '('
   */
  stat_str += "; ";

  return stat_str;
}

/**
 * AssignmentList and nested types.
 */
PROTO_TOSTRING(AssignmentList, assignmentlist)
{
  std::string list_str = VariableListToString(assignmentlist.varlist());
  list_str += " = " + ExpressionListToString(assignmentlist.explist());
  return list_str;
}

NESTED_PROTO_TOSTRING(VariableList, varlist, AssignmentList)
{
  std::string varlist_str = VariableToString(varlist.var());
  for (int i = 0; i < varlist.vars_size(); ++i) {
    varlist_str += ", " + VariableToString(varlist.vars(i));
    varlist_str += " ";
  }
  return varlist_str;
}

/**
 * FunctionCall and nested types.
 */
PROTO_TOSTRING(FunctionCall, call)
{
  using FuncCallType = FunctionCall::CallOneofCase;
  switch (call.call_oneof_case()) {
  case FuncCallType::kPrefArgs:
    return PrefixArgsToString(call.prefargs());
  case FuncCallType::kNamedArgs:
    return PrefixNamedArgsToString(call.namedargs());
  default:
    /* Chosen for more variability of generated programs. */
    return PrefixNamedArgsToString(call.namedargs());
  }
}

NESTED_PROTO_TOSTRING(Args, args, FunctionCall)
{
  using ArgsType = FunctionCall::Args::ArgsOneofCase;
  switch (args.args_oneof_case()) {
  case ArgsType::kExplist:
    return "(" + OptionalExpressionListToString(args.explist()) +
           ")";
  case ArgsType::kTableconstructor:
    return TableConstructorToString(args.tableconstructor());
  case ArgsType::kStr:
    return "'" + ConvertToStringDefault(args.str()) + "'";
  default:
    /* For more variability. */
    return TableConstructorToString(args.tableconstructor());
  }
}

NESTED_PROTO_TOSTRING(PrefixArgs, prefixargs, FunctionCall)
{
  std::string prefixargs_str = PrefixExpressionToString(
    prefixargs.prefixexp());
  prefixargs_str += " " + ArgsToString(prefixargs.args());
  return prefixargs_str;
}

NESTED_PROTO_TOSTRING(PrefixNamedArgs, prefixnamedargs, FunctionCall)
{
  std::string predixnamedargs_str = PrefixExpressionToString(
    prefixnamedargs.prefixexp());
  predixnamedargs_str += ":" + NameToString(prefixnamedargs.name());
  predixnamedargs_str += " " + ArgsToString(prefixnamedargs.args());
  return predixnamedargs_str;
}

/**
 * DoBlock clause.
 */
PROTO_TOSTRING(DoBlock, block)
{
  return "do\n" + BlockToString(block.block()) + "end\n";
}

/**
 * WhileCycle clause.
 */
PROTO_TOSTRING(WhileCycle, whilecycle)
{
  GetContext().step_in(Context::BlockType::kBreakable);

  std::string whilecycle_str = "while ";
  whilecycle_str += ExpressionToString(whilecycle.condition());
  whilecycle_str += " ";
  whilecycle_str += DoBlockToStringCycleProtected(whilecycle.doblock());

  GetContext().step_out();
  return whilecycle_str;
}

/**
 * RepeatCycle clause.
 */
PROTO_TOSTRING(RepeatCycle, repeatcycle)
{
  GetContext().step_in(Context::BlockType::kBreakable);

  std::string repeatcycle_str = "repeat\n";
  repeatcycle_str += BlockToStringCycleProtected(repeatcycle.block());
  repeatcycle_str += "until ";
  repeatcycle_str += ExpressionToString(repeatcycle.condition());

  GetContext().step_out();
  return repeatcycle_str;
}

/**
 * IfStatement and nested types.
 */
PROTO_TOSTRING(IfStatement, statement)
{
  std::string statement_str = "if " +
    ExpressionToString(statement.condition());
  statement_str += " then\n\t" + BlockToString(statement.first());

  for (int i = 0; i < statement.clauses_size(); ++i)
    statement_str += ElseIfBlockToString(statement.clauses(i));

  if (statement.has_last())
    statement_str += "else\n\t" + BlockToString(statement.last());

  statement_str += "end\n";
  return statement_str;
}

NESTED_PROTO_TOSTRING(ElseIfBlock, elseifblock, IfStatement)
{
  std::string elseifblock_str = "elseif ";
  elseifblock_str += ExpressionToString(elseifblock.condition());
  elseifblock_str += " then\n\t";
  elseifblock_str += BlockToString(elseifblock.block());
  return elseifblock_str;
}

/**
 * ForCycleName clause.
 * TODO: In 'for i = start, stop, step' construction start, stop, step
 * should be numbers. So results of the corresponding expressions
 * should be number.
 */
PROTO_TOSTRING(ForCycleName, forcyclename)
{
  GetContext().step_in(Context::BlockType::kBreakable);

  std::string forcyclename_str = "for ";
  forcyclename_str += NameToString(forcyclename.name());
  forcyclename_str += " = ";
  forcyclename_str += NumberWrappedExpressionToString(
    forcyclename.startexp());
  forcyclename_str += ", ";
  forcyclename_str += NumberWrappedExpressionToString(
    forcyclename.stopexp());

  if (forcyclename.has_stepexp())
    forcyclename_str += ", " + NumberWrappedExpressionToString(
      forcyclename.stepexp());

  forcyclename_str += " ";
  forcyclename_str += DoBlockToStringCycleProtected(
    forcyclename.doblock());

  GetContext().step_out();
  return forcyclename_str;
}

/**
 * ForCycleList clause.
 */
PROTO_TOSTRING(ForCycleList, forcyclelist)
{
  GetContext().step_in(Context::BlockType::kBreakable);

  std::string forcyclelist_str = "for ";
  forcyclelist_str += NameListToString(forcyclelist.names());
  forcyclelist_str += " in ";
  forcyclelist_str += ExpressionListToString(forcyclelist.expressions());
  forcyclelist_str += " ";
  forcyclelist_str += DoBlockToStringCycleProtected(
    forcyclelist.doblock());

  GetContext().step_out();
  return forcyclelist_str;
}

/**
 * Function and nested types.
 */
PROTO_TOSTRING(Function, func)
{
  GetContext().step_in(GetFuncBodyType(func.body()));

  std::string func_str = "function ";
  func_str += FuncNameToString(func.name());
  func_str += FuncBodyToStringReqProtected(func.body());

  GetContext().step_out();
  return func_str;
}

NESTED_PROTO_TOSTRING(FuncName, funcname, Function)
{
  std::string funcname_str = NameToString(funcname.firstname());

  for (int i = 0; i < funcname.names_size(); ++i)
    funcname_str += "." + NameToString(funcname.names(i));

  if (funcname.has_lastname())
    funcname_str += ":" + NameToString(funcname.lastname());

  return funcname_str;
}

PROTO_TOSTRING(NameList, namelist)
{
  std::string namelist_str = NameToString(namelist.firstname());
  for (int i = 0; i < namelist.names_size(); ++i)
    namelist_str += ", " + NameToString(namelist.names(i));
  return namelist_str;
}

NESTED_PROTO_TOSTRING(NameListWithEllipsis, namelist, FuncBody)
{
  std::string namelist_str = NameListToString(namelist.namelist());
  if (namelist.has_ellipsis())
    namelist_str += ", ...";
  return namelist_str;
}

NESTED_PROTO_TOSTRING(ParList, parlist, FuncBody)
{
  using ParListType = FuncBody::ParList::ParlistOneofCase;
  switch (parlist.parlist_oneof_case()) {
  case ParListType::kNamelist:
    return NameListWithEllipsisToString(parlist.namelist());
  case ParListType::kEllipsis:
    return "...";
  default:
    /* Chosen as default in order to decrease number of ellipses. */
    return NameListWithEllipsisToString(parlist.namelist());
  }
}

/**
 * LocalFunc clause.
 */
PROTO_TOSTRING(LocalFunc, localfunc)
{
  GetContext().step_in(GetFuncBodyType(localfunc.funcbody()));

  std::string localfunc_str = "local function ";
  localfunc_str += NameToString(localfunc.name());
  localfunc_str += " ";
  localfunc_str += FuncBodyToStringReqProtected(localfunc.funcbody());

  GetContext().step_out();
  return localfunc_str;
}

/**
 * LocalNames clause.
 */
PROTO_TOSTRING(LocalNames, localnames)
{
  std::string localnames_str = "local ";
  localnames_str += NameListToString(localnames.namelist());

  if (localnames.has_explist())
    localnames_str += " = " + ExpressionListToString(
      localnames.explist());
  return localnames_str;
}

/**
 * Expressions and variables.
 */

/**
 * Expressions clauses.
 */
PROTO_TOSTRING(ExpressionList, explist)
{
  std::string explist_str;
  for (int i = 0; i < explist.expressions_size(); ++i)
    explist_str += ExpressionToString(explist.expressions(i)) +
        ", ";
  explist_str += ExpressionToString(explist.explast()) + " ";
  return explist_str;
}

PROTO_TOSTRING(OptionalExpressionList, explist)
{
  if (explist.has_explist())
    return ExpressionListToString(explist.explist());
  return "";
}

PROTO_TOSTRING(PrefixExpression, prefixexp)
{
  using PrefExprType = PrefixExpression::PrefixOneofCase;
  switch (prefixexp.prefix_oneof_case()) {
  case PrefExprType::kVar:
    return VariableToString(prefixexp.var());
  case PrefExprType::kFunctioncall:
    return FunctionCallToString(prefixexp.functioncall());
  case PrefExprType::kExp:
    return "(" + ExpressionToString(prefixexp.exp()) + ")";
  default:
    /*
     * Can be generated too nested expressions with other options,
     * though they can be enabled for more variable fuzzing.
     */
    return VariableToString(prefixexp.var());
  }
}

/**
 * Variable and nested types.
 */
PROTO_TOSTRING(Variable, var)
{
  using VarType = Variable::VarOneofCase;
  switch (var.var_oneof_case()) {
  case VarType::kName:
    return NameToString(var.name());
  case VarType::kIndexexpr:
    return IndexWithExpressionToString(var.indexexpr());
  case VarType::kIndexname:
    return IndexWithNameToString(var.indexname());
  default:
    /*
     * Can be generated too nested expressions with other options,
     * though they can be enabled for more variable fuzzing.
     */
    return NameToString(var.name());
  }
}

NESTED_PROTO_TOSTRING(IndexWithExpression, indexexpr, Variable)
{
  std::string indexexpr_str = PrefixExpressionToString(
    indexexpr.prefixexp());
  indexexpr_str += "[" + ExpressionToString(indexexpr.exp()) + "]";
  return indexexpr_str;
}

NESTED_PROTO_TOSTRING(IndexWithName, indexname, Variable)
{
  std::string indexname_str = PrefixExpressionToString(
    indexname.prefixexp());
  std::string idx_str = ConvertToStringDefault(indexname.name(), true);
  /* Prevent using reserved keywords as indices. */
  if (KReservedLuaKeywords.find(idx_str) != KReservedLuaKeywords.end()) {
    idx_str += "_1";
  }
  indexname_str += "." + idx_str;
  return indexname_str;
}

/**
 * Expression and nested types.
 */
PROTO_TOSTRING(Expression, expr)
{
  using ExprType = Expression::ExprOneofCase;
  switch (expr.expr_oneof_case()) {
  case ExprType::kNil:
    return "nil";
  case ExprType::kFalse:
    return "false";
  case ExprType::kTrue:
    return "true";
  case ExprType::kNumber: {
    /* Clamp number between given boundaries. */
    double number = clamp(expr.number(), kMaxNumber, kMinNumber);
    return std::to_string(number);
  }
  case ExprType::kStr:
    return "'" + ConvertToStringDefault(expr.str()) + "'";
  case ExprType::kEllipsis:
    if (GetContext().vararg_is_possible()) {
      return " ... ";
    } else {
      return " nil";
    }
  case ExprType::kFunction:
    return AnonFuncToString(expr.function());
  case ExprType::kPrefixexp:
    return PrefixExpressionToString(expr.prefixexp());
  case ExprType::kTableconstructor:
    return TableConstructorToString(expr.tableconstructor());
  case ExprType::kBinary:
    return ExpBinaryOpExpToString(expr.binary());
  case ExprType::kUnary:
    return UnaryOpExpToString(expr.unary());
  default:
    /**
     * Arbitrary choice.
     * TODO: Choose "more interesting" defaults.
     */
    return "'" + ConvertToStringDefault(expr.str()) + "'";
  }
}

NESTED_PROTO_TOSTRING(AnonFunc, func, Expression)
{
  GetContext().step_in(GetFuncBodyType(func.body()));

  std::string retval = "function ";
  retval += FuncBodyToStringReqProtected(func.body());

  GetContext().step_out();
  return retval;
}

NESTED_PROTO_TOSTRING(ExpBinaryOpExp, binary, Expression)
{
  std::string leftexp_str = ExpressionToString(binary.leftexp());
  std::string binop_str = BinaryOperatorToString(binary.binop());
  std::string rightexp_str = ExpressionToString(binary.rightexp());

  std::string binary_str;
  if (binop_str == "<" ||
      binop_str == ">" ||
      binop_str == "<=" ||
      binop_str == ">=") {
    binary_str = kBinOpWrapperName;
    binary_str += "(" + leftexp_str;
    binary_str += ", '" + binop_str + "', ";
    binary_str += rightexp_str + ")";
    return binary_str;
  }

  binary_str = leftexp_str;
  binary_str += " " + binop_str + " ";
  binary_str += rightexp_str;

  return binary_str;
}

NESTED_PROTO_TOSTRING(UnaryOpExp, unary, Expression)
{
  std::string unary_str = UnaryOperatorToString(unary.unop());
  /*
   * Add a whitespace before an expression with unary minus,
   * otherwise double hyphen comments the following code
   * and it breaks generated programs syntactically.
   */
  unary_str += " " + ExpressionToString(unary.exp());
  return unary_str;
}

/**
 * Tables and fields.
 */
PROTO_TOSTRING(TableConstructor, table)
{
  std::string table_str = " (setmetatable({ ";
  if (table.has_fieldlist())
    table_str += FieldListToString(table.fieldlist());
  table_str += " }, table_mt))()";
  return table_str;
}

PROTO_TOSTRING(FieldList, fieldlist)
{
  std::string fieldlist_str = FieldToString(fieldlist.firstfield());
  for (int i = 0; i < fieldlist.fields_size(); ++i)
    fieldlist_str += FieldWithFieldSepToString(fieldlist.fields(i));
  if (fieldlist.has_lastsep())
    fieldlist_str += FieldSepToString(fieldlist.lastsep());
  return fieldlist_str;
}

NESTED_PROTO_TOSTRING(FieldWithFieldSep, field, FieldList)
{
  std::string field_str = FieldSepToString(field.sep());
  field_str += " " + FieldToString(field.field());
  return field_str;
}

/**
 * Field and nested types.
 */
PROTO_TOSTRING(Field, field)
{
  using FieldType = Field::FieldOneofCase;
  switch (field.field_oneof_case()) {
  case FieldType::kExprassign:
    return ExpressionAssignmentToString(field.exprassign());
  case FieldType::kNamedassign:
    return NameAssignmentToString(field.namedassign());
  case FieldType::kExpression:
    return ExpressionToString(field.expression());
  default:
    /* More common case of using fields. */
    return NameAssignmentToString(field.namedassign());
  }
}

NESTED_PROTO_TOSTRING(ExpressionAssignment, assignment, Field)
{
  /* Prevent error 'table index is nil' and 'table index is NaN'. */
  std::string assignment_str = "[ " +
    AllowedIndexExpressionToString(assignment.key()) + " ]";
  assignment_str += " = " + ExpressionToString(assignment.value());
  return assignment_str;
}

NESTED_PROTO_TOSTRING(NameAssignment, assignment, Field)
{
  std::string assignment_str = NameToString(assignment.name());
  assignment_str += " = " + ExpressionToString(assignment.value());
  return assignment_str;
}

PROTO_TOSTRING(FieldSep, sep)
{
  using FieldSepType = FieldSep::SepOneofCase;
  switch (sep.sep_oneof_case()) {
  case FieldSepType::kComma:
    return ",";
  case FieldSepType::kSemicolon:
    return ";";
  default:
    return ",";
  }
}

/**
 * Operators.
 */
PROTO_TOSTRING(BinaryOperator, op)
{
  using BinopType = BinaryOperator::BinaryOneofCase;
  switch (op.binary_oneof_case()) {
  case BinopType::kAdd:
    return "+";
  case BinopType::kSub:
    return "-";
  case BinopType::kMult:
    return "*";
  case BinopType::kDiv:
    return "/";
#if LUA_VERSION_NUM >= 503
  case BinopType::kIDiv:
    return "//";
#endif
  case BinopType::kExp:
    return "^";
  case BinopType::kMod:
    return "%";

  case BinopType::kConcat:
    return "..";

  case BinopType::kLess:
    return "<";
  case BinopType::kLessEqual:
    return "<=";
  case BinopType::kGreater:
    return ">";
  case BinopType::kGreaterEqual:
    return ">=";
  case BinopType::kEqual:
    return "==";
  case BinopType::kNotEqual:
    return "~=";
  case BinopType::kAnd:
    return "and";
  case BinopType::kOr:
    return "or";

#if LUA_VERSION_NUM >= 503
  case BinopType::kBAnd:
    return "&";
  case BinopType::kBOr:
    return "|";
  case BinopType::kBXor:
    return "~";
  case BinopType::kBShl:
    return "<<";
  case BinopType::kBShr:
    return ">>";
#endif
  default:
    /* Works in most cases. */
    return "==";
  }
}

PROTO_TOSTRING(UnaryOperator, op)
{
  using UnaryopType = UnaryOperator::UnaryOneofCase;
  switch (op.unary_oneof_case()) {
  case UnaryopType::kNegate:
    return "-";
  case UnaryopType::kNot:
    return "not ";
  case UnaryopType::kLength:
    return "#";
#if LUA_VERSION_NUM >= 503
  case UnaryopType::kBNot:
    return "~";
#endif
  default:
    /* Works in most cases. */
    return "not ";
  }
}

/**
 * Identifier (Name).
 */
PROTO_TOSTRING(Name, name)
{
  std::string ident = ConvertToStringDefault(name.name(), true);
  /* Prevent using reserved keywords as identifiers. */
  if (KReservedLuaKeywords.find(ident) != KReservedLuaKeywords.end()) {
    ident += "_1";
  }
  /* Identifier has default name, add an index. */
  if (!ident.compare(kDefaultIdent)) {
    ident += std::to_string(name.num() % kMaxIdentifiers);
  }
  return ident;
}

} /* namespace */

std::string
MainBlockToString(const Block &block)
{
  GetCounterIdProvider().clean();

  std::string block_str = BlockToString(block);
  std::string retval = preamble_lua;

  for (size_t i = 0; i < GetCounterIdProvider().count(); ++i) {
    retval += GetCounterName(i);
    retval += " = 0\n";
  }
  retval += block_str;

  return retval;
}

} /* namespace luajit_fuzzer */

Coverage Report

Created: 2025-08-25 07:03