path: root/lib/Analysis/PrintfFormatString.cpp

//= PrintfFormatStrings.cpp - Analysis of printf format strings --*- C++ -*-==//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Handling of format string in printf and friends.  The structure of format
// strings for fprintf() are described in C99 7.19.6.1.
//
//===----------------------------------------------------------------------===//

#include "clang/Analysis/Analyses/PrintfFormatString.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Type.h"
#include "llvm/Support/raw_ostream.h"

using clang::analyze_printf::ArgTypeResult;
using clang::analyze_printf::FormatSpecifier;
using clang::analyze_printf::FormatStringHandler;
using clang::analyze_printf::OptionalAmount;
using clang::analyze_printf::PositionContext;
using clang::analyze_printf::ConversionSpecifier;
using clang::analyze_printf::LengthModifier;

using namespace clang;

namespace {
class FormatSpecifierResult {
  FormatSpecifier FS;
  const char *Start;
  bool Stop;
public:
  FormatSpecifierResult(bool stop = false)
    : Start(0), Stop(stop) {}
  FormatSpecifierResult(const char *start,
                        const FormatSpecifier &fs)
    : FS(fs), Start(start), Stop(false) {}

  const char *getStart() const { return Start; }
  bool shouldStop() const { return Stop; }
  bool hasValue() const { return Start != 0; }
  const FormatSpecifier &getValue() const {
    assert(hasValue());
    return FS;
  }
  const FormatSpecifier &getValue() { return FS; }
};
} // end anonymous namespace

template <typename T>
class UpdateOnReturn {
  T &ValueToUpdate;
  const T &ValueToCopy;
public:
  UpdateOnReturn(T &valueToUpdate, const T &valueToCopy)
    : ValueToUpdate(valueToUpdate), ValueToCopy(valueToCopy) {}

  ~UpdateOnReturn() {
    ValueToUpdate = ValueToCopy;
  }
};

//===----------------------------------------------------------------------===//
// Methods for parsing format strings.
//===----------------------------------------------------------------------===//

static OptionalAmount ParseAmount(const char *&Beg, const char *E) {
  const char *I = Beg;
  UpdateOnReturn <const char*> UpdateBeg(Beg, I);

  unsigned accumulator = 0;
  bool hasDigits = false;

  for ( ; I != E; ++I) {
    char c = *I;
    if (c >= '0' && c <= '9') {
      hasDigits = true;
      accumulator = (accumulator * 10) + (c - '0');
      continue;
    }

    if (hasDigits)
      return OptionalAmount(OptionalAmount::Constant, accumulator, Beg, I - Beg,
          false);

    break;
  }

  return OptionalAmount();
}

static OptionalAmount ParseNonPositionAmount(const char *&Beg, const char *E,
                                             unsigned &argIndex) {
  if (*Beg == '*') {
    ++Beg;
    return OptionalAmount(OptionalAmount::Arg, argIndex++, Beg, 0, false);
  }

  return ParseAmount(Beg, E);
}

static OptionalAmount ParsePositionAmount(FormatStringHandler &H,
                                          const char *Start,
                                          const char *&Beg, const char *E,
                                          PositionContext p) {
  if (*Beg == '*') {
    const char *I = Beg + 1;
    const OptionalAmount &Amt = ParseAmount(I, E);

    if (Amt.getHowSpecified() == OptionalAmount::NotSpecified) {
      H.HandleInvalidPosition(Beg, I - Beg, p);
      return OptionalAmount(false);
    }

    if (I== E) {
      // No more characters left?
      H.HandleIncompleteFormatSpecifier(Start, E - Start);
      <