[clang] [clang][analyzer] Improve modeling of 'popen' and 'pclose' in StdLibraryFunctionsChecker (PR #78895)

[Ben Shi via cfe-commits]

================
@@ -2211,6 +2221,15 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
                   ErrnoNEZeroIrrelevant, GenericFailureMsg)
             .ArgConstraint(NotNull(ArgNo(0))));
 
+    // int pclose(FILE *stream);
+    addToFunctionSummaryMap(
+        "pclose", Signature(ArgTypes{FilePtrTy}, RetType{IntTy}),
+        Summary(NoEvalCall)
+            .Case({ReturnValueCondition(WithinRange, {{0, IntMax}})},
+                  ErrnoMustNotBeChecked, GenericSuccessMsg)
+            .Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant, GenericFailureMsg)
+            .ArgConstraint(NotNull(ArgNo(0))));
+
----------------
benshi001 wrote:

@balazske What is your opinion?

I think we can keep current form:
1. Negative but non -1 return values are not mentioned in the POSIX document.
2. Negative return values are not supported on real world linux&MacOS.

There may be negative but non -1 return values on other platforms, however we currently choose a conservative way as current form.

https://github.com/llvm/llvm-project/pull/78895