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//===--- MisleadingBidirectional.cpp - clang-tidy -------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "MisleadingBidirectional.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Lex/Preprocessor.h"
#include "llvm/Support/ConvertUTF.h"
#include <optional>
using namespace clang;
using namespace clang::tidy::misc;
static bool containsMisleadingBidi(StringRef Buffer,
bool HonorLineBreaks = true) {
const char *CurPtr = Buffer.begin();
enum BidiChar {
PS = 0x2029,
RLO = 0x202E,
RLE = 0x202B,
LRO = 0x202D,
LRE = 0x202A,
PDF = 0x202C,
RLI = 0x2067,
LRI = 0x2066,
FSI = 0x2068,
PDI = 0x2069
};
SmallVector<BidiChar> BidiContexts;
// Scan each character while maintaining a stack of opened bidi context.
// RLO/RLE/LRO/LRE all are closed by PDF while RLI LRI and FSI are closed by
// PDI. New lines reset the context count. Extra PDF / PDI are ignored.
//
// Warn if we end up with an unclosed context.
while (CurPtr < Buffer.end()) {
unsigned char C = *CurPtr;
if (isASCII(C)) {
++CurPtr;
bool IsParagrapSep =
(C == 0xA || C == 0xD || (0x1C <= C && C <= 0x1E) || C == 0x85);
bool IsSegmentSep = (C == 0x9 || C == 0xB || C == 0x1F);
if (IsParagrapSep || IsSegmentSep)
BidiContexts.clear();
continue;
}
llvm::UTF32 CodePoint;
llvm::ConversionResult Result = llvm::convertUTF8Sequence(
(const llvm::UTF8 **)&CurPtr, (const llvm::UTF8 *)Buffer.end(),
&CodePoint, llvm::strictConversion);
// If conversion fails, utf-8 is designed so that we can just try next char.
if (Result != llvm::conversionOK) {
++CurPtr;
continue;
}
// Open a PDF context.
if (CodePoint == RLO || CodePoint == RLE || CodePoint == LRO ||
CodePoint == LRE)
BidiContexts.push_back(PDF);
// Close PDF Context.
else if (CodePoint == PDF) {
if (!BidiContexts.empty() && BidiContexts.back() == PDF)
BidiContexts.pop_back();
}
// Open a PDI Context.
else if (CodePoint == RLI || CodePoint == LRI || CodePoint == FSI)
BidiContexts.push_back(PDI);
// Close a PDI Context.
else if (CodePoint == PDI) {
auto R = llvm::find(llvm::reverse(BidiContexts), PDI);
if (R != BidiContexts.rend())
BidiContexts.resize(BidiContexts.rend() - R - 1);
}
// Line break or equivalent
else if (CodePoint == PS)
BidiContexts.clear();
}
return !BidiContexts.empty();
}
class MisleadingBidirectionalCheck::MisleadingBidirectionalHandler
: public CommentHandler {
public:
MisleadingBidirectionalHandler(MisleadingBidirectionalCheck &Check)
: Check(Check) {}
bool HandleComment(Preprocessor &PP, SourceRange Range) override {
// FIXME: check that we are in a /* */ comment
StringRef Text =
Lexer::getSourceText(CharSourceRange::getCharRange(Range),
PP.getSourceManager(), PP.getLangOpts());
if (containsMisleadingBidi(Text, true))
Check.diag(
Range.getBegin(),
"comment contains misleading bidirectional Unicode characters");
return false;
}
private:
MisleadingBidirectionalCheck &Check;
};
MisleadingBidirectionalCheck::MisleadingBidirectionalCheck(
StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
Handler(std::make_unique<MisleadingBidirectionalHandler>(*this)) {}
MisleadingBidirectionalCheck::~MisleadingBidirectionalCheck() = default;
void MisleadingBidirectionalCheck::registerPPCallbacks(
const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
PP->addCommentHandler(Handler.get());
}
void MisleadingBidirectionalCheck::check(
const ast_matchers::MatchFinder::MatchResult &Result) {
if (const auto *SL = Result.Nodes.getNodeAs<StringLiteral>("strlit")) {
StringRef Literal = SL->getBytes();
if (containsMisleadingBidi(Literal, false))
diag(SL->getBeginLoc(), "string literal contains misleading "
"bidirectional Unicode characters");
}
}
void MisleadingBidirectionalCheck::registerMatchers(
ast_matchers::MatchFinder *Finder) {
Finder->addMatcher(ast_matchers::stringLiteral().bind("strlit"), this);
}
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