[StaticAnalyzer] Relax the pre-condition of 'setsockopt' (#130683)

For the unix function
`int setsockopt(int, int, int, const void *, socklen_t);`, the last two
parameters represent a buffer and a size.

In case the size is zero, buffer can be null. Previously, the hard-coded
pre-condition requires the buffer to never be null, which can cause
false positives.

(rdar://146678142)

1 files changed, 3 insertions, 2 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index 356d63e..fef19b4 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -1797,7 +1797,8 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
   auto IsNull = [&](ArgNo ArgN) {
     return std::make_shared<NotNullConstraint>(ArgN, false);
   };
-  auto NotNullBuffer = [&](ArgNo ArgN, ArgNo SizeArg1N, ArgNo SizeArg2N) {
+  auto NotNullBuffer = [&](ArgNo ArgN, ArgNo SizeArg1N,
+                           std::optional<ArgNo> SizeArg2N = std::nullopt) {
     return std::make_shared<NotNullBufferConstraint>(ArgN, SizeArg1N,
                                                      SizeArg2N);
   };
@@ -3365,7 +3366,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
         Summary(NoEvalCall)
             .Case(ReturnsZero, ErrnoMustNotBeChecked, GenericSuccessMsg)
             .Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant, GenericFailureMsg)
-            .ArgConstraint(NotNull(ArgNo(3)))
+            .ArgConstraint(NotNullBuffer(ArgNo(3), ArgNo(4)))
             .ArgConstraint(
                 BufferSize(/*Buffer=*/ArgNo(3), /*BufSize=*/ArgNo(4)))
             .ArgConstraint(