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//= 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"
using clang::analyze_printf::FormatSpecifier;
using clang::analyze_printf::OptionalAmount;
using clang::analyze_printf::ArgTypeResult;
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;
}
};
static OptionalAmount ParseAmount(const char *&Beg, const char *E) {
const char *I = Beg;
UpdateOnReturn <const char*> UpdateBeg(Beg, I);
bool foundDigits = false;
unsigned accumulator = 0;
for ( ; I != E; ++I) {
char c = *I;
if (c >= '0' && c <= '9') {
foundDigits = true;
accumulator += (accumulator * 10) + (c - '0');
continue;
}
if (foundDigits)
return OptionalAmount(accumulator, Beg);
if (c == '*') {
++I;
return OptionalAmount(OptionalAmount::Arg, Beg);
}
break;
}
return OptionalAmount();
}
static FormatSpecifierResult ParseFormatSpecifier(FormatStringHandler &H,
const char *&Beg, const char *E) {
using namespace clang::analyze_printf;
const char *I = Beg;
const char *Start = 0;
UpdateOnReturn <const char*> UpdateBeg(Beg, I);
// Look for a '%' character that indicates the start of a format specifier.
for ( ; I != E ; ++I) {
char c = *I;
if (c == '\0') {
// Detect spurious null characters, which are likely errors.
H.HandleNullChar(I);
return true;
}
if (c == '%') {
Start = I++; // Record the start of the format specifier.
break;
}
}
// No format specifier found?
if (!Start)
return false;
if (I == E) {
// No more characters left?
H.HandleIncompleteFormatSpecifier(Start, E - Start);
return true;
}
FormatSpecifier FS;
// Look for flags (if any).
bool hasMore = true;
for ( ; I != E; ++I) {
switch (*I) {
default: hasMore = false; break;
case '-': FS.setIsLeftJustified(); break;
case '+': FS.setHasPlusPrefix(); break;
case ' ': FS.setHasSpacePrefix(); break;
case '#': FS.setHasAlternativeForm(); break;
case '0': FS.setHasLeadingZeros(); break;
}
if (!hasMore)
break;
}
if (I == E) {
// No more characters left?
H.HandleIncompleteFormatSpecifier(Start, E - Start);
return true;
}
// Look for the field width (if any).
FS.setFieldWidth(ParseAmount(I, E));
if (I == E) {
// No more characters left?
H.HandleIncompleteFormatSpecifier(Start, E - Start);
return true;
}
// Look for the precision (if any).
if (*I == '.') {
++I;
if (I == E) {
H.HandleIncompleteFormatSpecifier(Start, E - Start);
return true;
}
FS.setPrecision(ParseAmount(I, E));
if (I == E) {
// No more characters left?
H.HandleIncompleteFormatSpecifier(Start, E - Start);
return true;
}
}
// Look for the length modifier.
LengthModifier lm = None;
switch (*I) {
default:
break;
case 'h':
++I;
lm = (I != E && *I == 'h') ? ++I, AsChar : AsShort;
break;
case 'l':
++I;
lm = (I != E && *I == 'l') ? ++I, AsLongLong : AsLong;
break;
case 'j': lm = AsIntMax; ++I; break;
case 'z': lm = AsSizeT; ++I; break;
case 't': lm = AsPtrDiff; ++I; break;
case 'L': lm = AsLongDouble; ++I; break;
case 'q': lm = AsLongLong; ++I; break;
}
FS.setLengthModifier(lm);
if (I == E) {
// No more characters left?
H.HandleIncompleteFormatSpecifier(Start, E - Start);
return true;
}
if (*I == '\0') {
// Detect spurious null characters, which are likely errors.
H.HandleNullChar(I);
return true;
}
// Finally, look for the conversion specifier.
const char *conversionPosition = I++;
ConversionSpecifier::Kind k = ConversionSpecifier::InvalidSpecifier;
switch (*conversionPosition) {
default:
break;
// C99: 7.19.6.1 (section 8).
case 'd': k = ConversionSpecifier::dArg; break;
case 'i': k = ConversionSpecifier::iArg; break;
case 'o': k = ConversionSpecifier::oArg; break;
case 'u': k = ConversionSpecifier::uArg; break;
case 'x': k = ConversionSpecifier::xArg; break;
case 'X': k = ConversionSpecifier::XArg; break;
case 'f': k = ConversionSpecifier::fArg; break;
case 'F': k = ConversionSpecifier::FArg; break;
case 'e': k = ConversionSpecifier::eArg; break;
case 'E': k = ConversionSpecifier::EArg; break;
case 'g': k = ConversionSpecifier::gArg; break;
case 'G': k = ConversionSpecifier::GArg; break;
case 'a': k = ConversionSpecifier::aArg; break;
case 'A': k = ConversionSpecifier::AArg; break;
case 'c': k = ConversionSpecifier::IntAsCharArg; break;
case 's': k = ConversionSpecifier::CStrArg; break;
case 'p': k = ConversionSpecifier::VoidPtrArg; break;
case 'n': k = ConversionSpecifier::OutIntPtrArg; break;
case '%': k = ConversionSpecifier::PercentArg; break;
// Objective-C.
case '@': k = ConversionSpecifier::ObjCObjArg; break;
// Glibc specific.
case 'm': k = ConversionSpecifier::PrintErrno; break;
}
FS.setConversionSpecifier(ConversionSpecifier(conversionPosition, k));
if (k == ConversionSpecifier::InvalidSpecifier) {
H.HandleInvalidConversionSpecifier(FS, Beg, I - Beg);
return false; // Keep processing format specifiers.
}
return FormatSpecifierResult(Start, FS);
}
bool clang::ParseFormatString(FormatStringHandler &H,
const char *I, const char *E) {
// Keep looking for a format specifier until we have exhausted the string.
while (I != E) {
const FormatSpecifierResult &FSR = ParseFormatSpecifier(H, I, E);
// Did a fail-stop error of any kind occur when parsing the specifier?
// If so, don't do any more processing.
if (FSR.shouldStop())
return true;;
// Did we exhaust the string or encounter an error that
// we can recover from?
if (!FSR.hasValue())
continue;
// We have a format specifier. Pass it to the callback.
if (!H.HandleFormatSpecifier(FSR.getValue(), FSR.getStart(),
I - FSR.getStart()))
return true;
}
assert(I == E && "Format string not exhausted");
return false;
}
FormatStringHandler::~FormatStringHandler() {}
//===----------------------------------------------------------------------===//
// Methods on FormatSpecifier.
//===----------------------------------------------------------------------===//
ArgTypeResult FormatSpecifier::getArgType(ASTContext &Ctx) const {
if (!CS.consumesDataArgument())
return ArgTypeResult::Invalid();
if (CS.isIntArg())
switch (LM) {
case AsLongDouble:
return ArgTypeResult::Invalid();
case None: return Ctx.IntTy;
case AsChar: return Ctx.SignedCharTy;
case AsShort: return Ctx.ShortTy;
case AsLong: return Ctx.LongTy;
case AsLongLong: return Ctx.LongLongTy;
case AsIntMax:
// FIXME: Return unknown for now.
return ArgTypeResult();
case AsSizeT: return Ctx.getSizeType();
case AsPtrDiff: return Ctx.getPointerDiffType();
}
if (CS.isUIntArg())
switch (LM) {
case AsLongDouble:
return ArgTypeResult::Invalid();
case None: return Ctx.UnsignedIntTy;
case AsChar: return Ctx.UnsignedCharTy;
case AsShort: return Ctx.UnsignedShortTy;
case AsLong: return Ctx.UnsignedLongTy;
case AsLongLong: return Ctx.UnsignedLongLongTy;
case AsIntMax:
// FIXME: Return unknown for now.
return ArgTypeResult();
case AsSizeT:
// FIXME: How to get the corresponding unsigned
// version of size_t?
return ArgTypeResult();
case AsPtrDiff:
// FIXME: How to get the corresponding unsigned
// version of ptrdiff_t?
return ArgTypeResult();
}
if (CS.isDoubleArg()) {
if (LM == AsLongDouble)
return Ctx.LongDoubleTy;
return Ctx.DoubleTy;
}
// FIXME: Handle other cases.
return ArgTypeResult();
}