shylie/llvm-project
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
llvm-project/clang/lib/AST/ScanfFormatString.cpp
Matheus Izvekov 7c51f02eff
[clang] Implement ElaboratedType sugaring for types written bare 
Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.

The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.

An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.

---

Troubleshooting list to deal with any breakage seen with this patch:

1) The most likely effect one would see by this patch is a change in how
   a type is printed. The type printer will, by design and default,
   print types as written. There are customization options there, but
   not that many, and they mainly apply to how to print a type that we
   somehow failed to track how it was written. This patch fixes a
   problem where we failed to distinguish between a type
   that was written without any elaborated-type qualifiers,
   such as a 'struct'/'class' tags and name spacifiers such as 'std::',
   and one that has been stripped of any 'metadata' that identifies such,
   the so called canonical types.
   Example:
   ```
   namespace foo {
     struct A {};
     A a;
   };
   ```
   If one were to print the type of `foo::a`, prior to this patch, this
   would result in `foo::A`. This is how the type printer would have,
   by default, printed the canonical type of A as well.
   As soon as you add any name qualifiers to A, the type printer would
   suddenly start accurately printing the type as written. This patch
   will make it print it accurately even when written without
   qualifiers, so we will just print `A` for the initial example, as
   the user did not really write that `foo::` namespace qualifier.

2) This patch could expose a bug in some AST matcher. Matching types
   is harder to get right when there is sugar involved. For example,
   if you want to match a type against being a pointer to some type A,
   then you have to account for getting a type that is sugar for a
   pointer to A, or being a pointer to sugar to A, or both! Usually
   you would get the second part wrong, and this would work for a
   very simple test where you don't use any name qualifiers, but
   you would discover is broken when you do. The usual fix is to
   either use the matcher which strips sugar, which is annoying
   to use as for example if you match an N level pointer, you have
   to put N+1 such matchers in there, beginning to end and between
   all those levels. But in a lot of cases, if the property you want
   to match is present in the canonical type, it's easier and faster
   to just match on that... This goes with what is said in 1), if
   you want to match against the name of a type, and you want
   the name string to be something stable, perhaps matching on
   the name of the canonical type is the better choice.

3) This patch could exposed a bug in how you get the source range of some
   TypeLoc. For some reason, a lot of code is using getLocalSourceRange(),
   which only looks at the given TypeLoc node. This patch introduces a new,
   and more common TypeLoc node which contains no source locations on itself.
   This is not an inovation here, and some other, more rare TypeLoc nodes could
   also have this property, but if you use getLocalSourceRange on them, it's not
   going to return any valid locations, because it doesn't have any. The right fix
   here is to always use getSourceRange() or getBeginLoc/getEndLoc which will dive
   into the inner TypeLoc to get the source range if it doesn't find it on the
   top level one. You can use getLocalSourceRange if you are really into
   micro-optimizations and you have some outside knowledge that the TypeLocs you are
   dealing with will always include some source location.

4) Exposed a bug somewhere in the use of the normal clang type class API, where you
   have some type, you want to see if that type is some particular kind, you try a
   `dyn_cast` such as `dyn_cast<TypedefType>` and that fails because now you have an
   ElaboratedType which has a TypeDefType inside of it, which is what you wanted to match.
   Again, like 2), this would usually have been tested poorly with some simple tests with
   no qualifications, and would have been broken had there been any other kind of type sugar,
   be it an ElaboratedType or a TemplateSpecializationType or a SubstTemplateParmType.
   The usual fix here is to use `getAs` instead of `dyn_cast`, which will look deeper
   into the type. Or use `getAsAdjusted` when dealing with TypeLocs.
   For some reason the API is inconsistent there and on TypeLocs getAs behaves like a dyn_cast.

5) It could be a bug in this patch perhaps.

Let me know if you need any help!

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Differential Revision: https://reviews.llvm.org/D112374
2022-07-15 04:16:55 +02:00

568 lines
19 KiB
C++
Raw Blame History

//= ScanfFormatString.cpp - Analysis of printf format strings --*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Handling of format string in scanf and friends. The structure of format
// strings for fscanf() are described in C99 7.19.6.2.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/FormatString.h"
#include "FormatStringParsing.h"
#include "clang/Basic/TargetInfo.h"
using clang::analyze_format_string::ArgType;
using clang::analyze_format_string::FormatStringHandler;
using clang::analyze_format_string::LengthModifier;
using clang::analyze_format_string::OptionalAmount;
using clang::analyze_format_string::ConversionSpecifier;
using clang::analyze_scanf::ScanfConversionSpecifier;
using clang::analyze_scanf::ScanfSpecifier;
using clang::UpdateOnReturn;
using namespace clang;
typedef clang::analyze_format_string::SpecifierResult<ScanfSpecifier>
ScanfSpecifierResult;
static bool ParseScanList(FormatStringHandler &H,
ScanfConversionSpecifier &CS,
const char *&Beg, const char *E) {
const char *I = Beg;
const char *start = I - 1;
UpdateOnReturn <const char*> UpdateBeg(Beg, I);
// No more characters?
if (I == E) {
H.HandleIncompleteScanList(start, I);
return true;
}
// Special case: ']' is the first character.
if (*I == ']') {
if (++I == E) {
H.HandleIncompleteScanList(start, I - 1);
return true;
}
}
// Special case: "^]" are the first characters.
if (I + 1 != E && I[0] == '^' && I[1] == ']') {
I += 2;
if (I == E) {
H.HandleIncompleteScanList(start, I - 1);
return true;
}
}
// Look for a ']' character which denotes the end of the scan list.
while (*I != ']') {
if (++I == E) {
H.HandleIncompleteScanList(start, I - 1);
return true;
}
}
CS.setEndScanList(I);
return false;
}
// FIXME: Much of this is copy-paste from ParsePrintfSpecifier.
// We can possibly refactor.
static ScanfSpecifierResult ParseScanfSpecifier(FormatStringHandler &H,
const char *&Beg,
const char *E,
unsigned &argIndex,
const LangOptions &LO,
const TargetInfo &Target) {
using namespace clang::analyze_format_string;
using namespace clang::analyze_scanf;
const char *I = Beg;
const char *Start = nullptr;
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.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
ScanfSpecifier FS;
if (ParseArgPosition(H, FS, Start, I, E))
return true;
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
// Look for '*' flag if it is present.
if (*I == '*') {
FS.setSuppressAssignment(I);
if (++I == E) {
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
}
// Look for the field width (if any). Unlike printf, this is either
// a fixed integer or isn't present.
const OptionalAmount &Amt = clang::analyze_format_string::ParseAmount(I, E);
if (Amt.getHowSpecified() != OptionalAmount::NotSpecified) {
assert(Amt.getHowSpecified() == OptionalAmount::Constant);
FS.setFieldWidth(Amt);
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
}
// Look for the length modifier.
if (ParseLengthModifier(FS, I, E, LO, /*IsScanf=*/true) && I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
// Detect spurious null characters, which are likely errors.
if (*I == '\0') {
H.HandleNullChar(I);
return true;
}
// Finally, look for the conversion specifier.
const char *conversionPosition = I++;
ScanfConversionSpecifier::Kind k = ScanfConversionSpecifier::InvalidSpecifier;
switch (*conversionPosition) {
default:
break;
case '%': k = ConversionSpecifier::PercentArg; break;
case 'A': k = ConversionSpecifier::AArg; break;
case 'E': k = ConversionSpecifier::EArg; break;
case 'F': k = ConversionSpecifier::FArg; break;
case 'G': k = ConversionSpecifier::GArg; break;
case 'X': k = ConversionSpecifier::XArg; break;
case 'a': k = ConversionSpecifier::aArg; break;
case 'd': k = ConversionSpecifier::dArg; break;
case 'e': k = ConversionSpecifier::eArg; break;
case 'f': k = ConversionSpecifier::fArg; break;
case 'g': k = ConversionSpecifier::gArg; break;
case 'i': k = ConversionSpecifier::iArg; break;
case 'n': k = ConversionSpecifier::nArg; break;
case 'c': k = ConversionSpecifier::cArg; break;
case 'C': k = ConversionSpecifier::CArg; break;
case 'S': k = ConversionSpecifier::SArg; break;
case '[': k = ConversionSpecifier::ScanListArg; break;
case 'u': k = ConversionSpecifier::uArg; break;
case 'x': k = ConversionSpecifier::xArg; break;
case 'o': k = ConversionSpecifier::oArg; break;
case 's': k = ConversionSpecifier::sArg; break;
case 'p': k = ConversionSpecifier::pArg; break;
// Apple extensions
// Apple-specific
case 'D':
if (Target.getTriple().isOSDarwin())
k = ConversionSpecifier::DArg;
break;
case 'O':
if (Target.getTriple().isOSDarwin())
k = ConversionSpecifier::OArg;
break;
case 'U':
if (Target.getTriple().isOSDarwin())
k = ConversionSpecifier::UArg;
break;
}
ScanfConversionSpecifier CS(conversionPosition, k);
if (k == ScanfConversionSpecifier::ScanListArg) {
if (ParseScanList(H, CS, I, E))
return true;
}
FS.setConversionSpecifier(CS);
if (CS.consumesDataArgument() && !FS.getSuppressAssignment()
&& !FS.usesPositionalArg())
FS.setArgIndex(argIndex++);
// FIXME: '%' and '*' doesn't make sense. Issue a warning.
// FIXME: 'ConsumedSoFar' and '*' doesn't make sense.
if (k == ScanfConversionSpecifier::InvalidSpecifier) {
unsigned Len = I - Beg;
if (ParseUTF8InvalidSpecifier(Beg, E, Len)) {
CS.setEndScanList(Beg + Len);
FS.setConversionSpecifier(CS);
}
// Assume the conversion takes one argument.
return !H.HandleInvalidScanfConversionSpecifier(FS, Beg, Len);
}
return ScanfSpecifierResult(Start, FS);
}
ArgType ScanfSpecifier::getArgType(ASTContext &Ctx) const {
const ScanfConversionSpecifier &CS = getConversionSpecifier();
if (!CS.consumesDataArgument())
return ArgType::Invalid();
switch(CS.getKind()) {
// Signed int.
case ConversionSpecifier::dArg:
case ConversionSpecifier::DArg:
case ConversionSpecifier::iArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(Ctx.IntTy);
case LengthModifier::AsChar:
return ArgType::PtrTo(ArgType::AnyCharTy);
case LengthModifier::AsShort:
return ArgType::PtrTo(Ctx.ShortTy);
case LengthModifier::AsLong:
return ArgType::PtrTo(Ctx.LongTy);
case LengthModifier::AsLongLong:
case LengthModifier::AsQuad:
return ArgType::PtrTo(Ctx.LongLongTy);
case LengthModifier::AsInt64:
return ArgType::PtrTo(ArgType(Ctx.LongLongTy, "__int64"));
case LengthModifier::AsIntMax:
return ArgType::PtrTo(ArgType(Ctx.getIntMaxType(), "intmax_t"));
case LengthModifier::AsSizeT:
return ArgType::PtrTo(ArgType(Ctx.getSignedSizeType(), "ssize_t"));
case LengthModifier::AsPtrDiff:
return ArgType::PtrTo(ArgType(Ctx.getPointerDiffType(), "ptrdiff_t"));
case LengthModifier::AsLongDouble:
// GNU extension.
return ArgType::PtrTo(Ctx.LongLongTy);
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
case LengthModifier::AsInt32:
case LengthModifier::AsInt3264:
case LengthModifier::AsWide:
case LengthModifier::AsShortLong:
return ArgType::Invalid();
}
llvm_unreachable("Unsupported LengthModifier Type");
// Unsigned int.
case ConversionSpecifier::oArg:
case ConversionSpecifier::OArg:
case ConversionSpecifier::uArg:
case ConversionSpecifier::UArg:
case ConversionSpecifier::xArg:
case ConversionSpecifier::XArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(Ctx.UnsignedIntTy);
case LengthModifier::AsChar:
return ArgType::PtrTo(Ctx.UnsignedCharTy);
case LengthModifier::AsShort:
return ArgType::PtrTo(Ctx.UnsignedShortTy);
case LengthModifier::AsLong:
return ArgType::PtrTo(Ctx.UnsignedLongTy);
case LengthModifier::AsLongLong:
case LengthModifier::AsQuad:
return ArgType::PtrTo(Ctx.UnsignedLongLongTy);
case LengthModifier::AsInt64:
return ArgType::PtrTo(ArgType(Ctx.UnsignedLongLongTy, "unsigned __int64"));
case LengthModifier::AsIntMax:
return ArgType::PtrTo(ArgType(Ctx.getUIntMaxType(), "uintmax_t"));
case LengthModifier::AsSizeT:
return ArgType::PtrTo(ArgType(Ctx.getSizeType(), "size_t"));
case LengthModifier::AsPtrDiff:
return ArgType::PtrTo(
ArgType(Ctx.getUnsignedPointerDiffType(), "unsigned ptrdiff_t"));
case LengthModifier::AsLongDouble:
// GNU extension.
return ArgType::PtrTo(Ctx.UnsignedLongLongTy);
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
case LengthModifier::AsInt32:
case LengthModifier::AsInt3264:
case LengthModifier::AsWide:
case LengthModifier::AsShortLong:
return ArgType::Invalid();
}
llvm_unreachable("Unsupported LengthModifier Type");
// Float.
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(Ctx.FloatTy);
case LengthModifier::AsLong:
return ArgType::PtrTo(Ctx.DoubleTy);
case LengthModifier::AsLongDouble:
return ArgType::PtrTo(Ctx.LongDoubleTy);
default:
return ArgType::Invalid();
}
// Char, string and scanlist.
case ConversionSpecifier::cArg:
case ConversionSpecifier::sArg:
case ConversionSpecifier::ScanListArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(ArgType::AnyCharTy);
case LengthModifier::AsLong:
case LengthModifier::AsWide:
return ArgType::PtrTo(ArgType(Ctx.getWideCharType(), "wchar_t"));
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
return ArgType::PtrTo(ArgType::CStrTy);
case LengthModifier::AsShort:
if (Ctx.getTargetInfo().getTriple().isOSMSVCRT())
return ArgType::PtrTo(ArgType::AnyCharTy);
LLVM_FALLTHROUGH;
default:
return ArgType::Invalid();
}
case ConversionSpecifier::CArg:
case ConversionSpecifier::SArg:
// FIXME: Mac OS X specific?
switch (LM.getKind()) {
case LengthModifier::None:
case LengthModifier::AsWide:
return ArgType::PtrTo(ArgType(Ctx.getWideCharType(), "wchar_t"));
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
return ArgType::PtrTo(ArgType(ArgType::WCStrTy, "wchar_t *"));
case LengthModifier::AsShort:
if (Ctx.getTargetInfo().getTriple().isOSMSVCRT())
return ArgType::PtrTo(ArgType::AnyCharTy);
LLVM_FALLTHROUGH;
default:
return ArgType::Invalid();
}
// Pointer.
case ConversionSpecifier::pArg:
return ArgType::PtrTo(ArgType::CPointerTy);
// Write-back.
case ConversionSpecifier::nArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(Ctx.IntTy);
case LengthModifier::AsChar:
return ArgType::PtrTo(Ctx.SignedCharTy);
case LengthModifier::AsShort:
return ArgType::PtrTo(Ctx.ShortTy);
case LengthModifier::AsLong:
return ArgType::PtrTo(Ctx.LongTy);
case LengthModifier::AsLongLong:
case LengthModifier::AsQuad:
return ArgType::PtrTo(Ctx.LongLongTy);
case LengthModifier::AsInt64:
return ArgType::PtrTo(ArgType(Ctx.LongLongTy, "__int64"));
case LengthModifier::AsIntMax:
return ArgType::PtrTo(ArgType(Ctx.getIntMaxType(), "intmax_t"));
case LengthModifier::AsSizeT:
return ArgType::PtrTo(ArgType(Ctx.getSignedSizeType(), "ssize_t"));
case LengthModifier::AsPtrDiff:
return ArgType::PtrTo(ArgType(Ctx.getPointerDiffType(), "ptrdiff_t"));
case LengthModifier::AsLongDouble:
return ArgType(); // FIXME: Is this a known extension?
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
case LengthModifier::AsInt32:
case LengthModifier::AsInt3264:
case LengthModifier::AsWide:
case LengthModifier::AsShortLong:
return ArgType::Invalid();
}
default:
break;
}
return ArgType();
}
bool ScanfSpecifier::fixType(QualType QT, QualType RawQT,
const LangOptions &LangOpt,
ASTContext &Ctx) {
// %n is different from other conversion specifiers; don't try to fix it.
if (CS.getKind() == ConversionSpecifier::nArg)
return false;
if (!QT->isPointerType())
return false;
QualType PT = QT->getPointeeType();
// If it's an enum, get its underlying type.
if (const EnumType *ETy = PT->getAs<EnumType>()) {
// Don't try to fix incomplete enums.
if (!ETy->getDecl()->isComplete())
return false;
PT = ETy->getDecl()->getIntegerType();
}
const BuiltinType *BT = PT->getAs<BuiltinType>();
if (!BT)
return false;
// Pointer to a character.
if (PT->isAnyCharacterType()) {
CS.setKind(ConversionSpecifier::sArg);
if (PT->isWideCharType())
LM.setKind(LengthModifier::AsWideChar);
else
LM.setKind(LengthModifier::None);
// If we know the target array length, we can use it as a field width.
if (const ConstantArrayType *CAT = Ctx.getAsConstantArrayType(RawQT)) {
if (CAT->getSizeModifier() == ArrayType::Normal)
FieldWidth = OptionalAmount(OptionalAmount::Constant,
CAT->getSize().getZExtValue() - 1,
"", 0, false);
}
return true;
}
// Figure out the length modifier.
switch (BT->getKind()) {
// no modifier
case BuiltinType::UInt:
case BuiltinType::Int:
case BuiltinType::Float:
LM.setKind(LengthModifier::None);
break;
// hh
case BuiltinType::Char_U:
case BuiltinType::UChar:
case BuiltinType::Char_S:
case BuiltinType::SChar:
LM.setKind(LengthModifier::AsChar);
break;
// h
case BuiltinType::Short:
case BuiltinType::UShort:
LM.setKind(LengthModifier::AsShort);
break;
// l
case BuiltinType::Long:
case BuiltinType::ULong:
case BuiltinType::Double:
LM.setKind(LengthModifier::AsLong);
break;
// ll
case BuiltinType::LongLong:
case BuiltinType::ULongLong:
LM.setKind(LengthModifier::AsLongLong);
break;
// L
case BuiltinType::LongDouble:
LM.setKind(LengthModifier::AsLongDouble);
break;
// Don't know.
default:
return false;
}
// Handle size_t, ptrdiff_t, etc. that have dedicated length modifiers in C99.
if (LangOpt.C99 || LangOpt.CPlusPlus11)
namedTypeToLengthModifier(PT, LM);
// If fixing the length modifier was enough, we are done.
if (hasValidLengthModifier(Ctx.getTargetInfo(), LangOpt)) {
const analyze_scanf::ArgType &AT = getArgType(Ctx);
if (AT.isValid() && AT.matchesType(Ctx, QT))
return true;
}
// Figure out the conversion specifier.
if (PT->isRealFloatingType())
CS.setKind(ConversionSpecifier::fArg);
else if (PT->isSignedIntegerType())
CS.setKind(ConversionSpecifier::dArg);
else if (PT->isUnsignedIntegerType())
CS.setKind(ConversionSpecifier::uArg);
else
llvm_unreachable("Unexpected type");
return true;
}
void ScanfSpecifier::toString(raw_ostream &os) const {
os << "%";
if (usesPositionalArg())
os << getPositionalArgIndex() << "$";
if (SuppressAssignment)
os << "*";
FieldWidth.toString(os);
os << LM.toString();
os << CS.toString();
}
bool clang::analyze_format_string::ParseScanfString(FormatStringHandler &H,
const char *I,
const char *E,
const LangOptions &LO,
const TargetInfo &Target) {
unsigned argIndex = 0;
// Keep looking for a format specifier until we have exhausted the string.
while (I != E) {
const ScanfSpecifierResult &FSR = ParseScanfSpecifier(H, I, E, argIndex,
LO, Target);
// 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.HandleScanfSpecifier(FSR.getValue(), FSR.getStart(),
I - FSR.getStart())) {
return true;
}
}
assert(I == E && "Format string not exhausted");
return false;
}
Reference in New Issue View Git Blame Copy Permalink