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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "SprintfLiteralChecker.h"
#include "CustomMatchers.h"
void SprintfLiteralChecker::registerMatchers(MatchFinder *AstMatcher) {
AstMatcher->addMatcher(
callExpr(
isSnprintfLikeFunc(),
allOf(hasArgument(
0, ignoringParenImpCasts(declRefExpr().bind("buffer"))),
anyOf(hasArgument(1, sizeOfExpr(has(ignoringParenImpCasts(
declRefExpr().bind("size"))))),
hasArgument(1, integerLiteral().bind("immediate")),
hasArgument(1, declRefExpr(to(varDecl(
hasType(isConstQualified()),
hasInitializer(integerLiteral().bind(
"constant")))))))))
.bind("funcCall"),
this);
}
void SprintfLiteralChecker::check(const MatchFinder::MatchResult &Result) {
if (!Result.Context->getLangOpts().CPlusPlus) {
// SprintfLiteral is not usable in C, so there is no point in issuing these
// warnings.
return;
}
const char *Error =
"Use %1 instead of %0 when writing into a character array.";
const char *Note =
"This will prevent passing in the wrong size to %0 accidentally.";
const CallExpr *D = Result.Nodes.getNodeAs<CallExpr>("funcCall");
StringRef Name = D->getDirectCallee()->getName();
const char *Replacement;
if (Name == "snprintf") {
Replacement = "SprintfLiteral";
} else {
assert(Name == "vsnprintf");
Replacement = "VsprintfLiteral";
}
const DeclRefExpr *Buffer = Result.Nodes.getNodeAs<DeclRefExpr>("buffer");
const DeclRefExpr *Size = Result.Nodes.getNodeAs<DeclRefExpr>("size");
if (Size) {
// Match calls like snprintf(x, sizeof(x), ...).
if (Buffer->getFoundDecl() != Size->getFoundDecl()) {
return;
}
diag(D->getBeginLoc(), Error, DiagnosticIDs::Error) << Name << Replacement;
diag(D->getBeginLoc(), Note, DiagnosticIDs::Note) << Name;
return;
}
const QualType QType = Buffer->getType();
const ConstantArrayType *Type =
dyn_cast<ConstantArrayType>(QType.getTypePtrOrNull());
if (Type) {
// Match calls like snprintf(x, 100, ...), where x is int[100];
const IntegerLiteral *Literal =
Result.Nodes.getNodeAs<IntegerLiteral>("immediate");
if (!Literal) {
// Match calls like: const int y = 100; snprintf(x, y, ...);
Literal = Result.Nodes.getNodeAs<IntegerLiteral>("constant");
}
// We're going to assume here that the bitwidth of both of these values fits
// within 64 bits. and zero-extend both values to 64-bits before comparing
// them.
uint64_t Size = Type->getSize().getZExtValue();
uint64_t Lit = Literal->getValue().getZExtValue();
if (Size <= Lit) {
diag(D->getBeginLoc(), Error, DiagnosticIDs::Error)
<< Name << Replacement;
diag(D->getBeginLoc(), Note, DiagnosticIDs::Note) << Name;
}
}
}