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/**
* @name Null metadata in print function
* @description Print functions need to check that the metadata isn't null before calling methods on it.
* @kind problem
* @problem.severity warning
* @id cpp/null-metadata-in-print
*/
import cpp
import semmle.code.cpp.controlflow.Guards
import semmle.code.cpp.controlflow.Nullness
import semmle.code.cpp.rangeanalysis.RangeAnalysisUtils
// Find all the print functions by looking for TagInfo initializers
// like this one:
// https://github.com/Exiv2/exiv2/blob/6b186a4cd276ac11b3ea69951c2112f4c4814b9a/src/canonmn_int.cpp#L660-L679
class PrintFunction extends Function {
PrintFunction() {
exists(Initializer i, Field f |
i.getExpr().(ArrayAggregateLiteral).getAChild().(ClassAggregateLiteral).getAFieldExpr(f) =
this.getAnAccess() and
f.getName() = "printFct_"
)
}
}
from PrintFunction f, Parameter p, Call call, Expr qualifier
where
p = f.getParameter(2) and
qualifier = p.getAnAccess() and
call.getQualifier() = qualifier and
// Don't complain if the access is protected by a null check.
not exists(GuardCondition nonNullCheck, BasicBlock block, boolean branch |
validCheckExpr(nonNullCheck, p) and
nonNullCheck.controls(block, branch) and
block.contains(call)
)
select qualifier, "Print functions need to check that the metadata isn't null."