Add NotNull constaints to arg 0 for the summary Cases

Author: steakhal

clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp

@@ -2651,13 +2651,16 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
     addToFunctionSummaryMap(
         "getcwd", Signature(ArgTypes{CharPtrTy, SizeTy}, RetType{CharPtrTy}),
         Summary(NoEvalCall)
-            .Case({ArgumentCondition(1, WithinRange, Range(1, SizeMax)),
+            .Case({NotNull(ArgNo(0)),
+                   ArgumentCondition(1, WithinRange, Range(1, SizeMax)),
                    ReturnValueCondition(BO_EQ, ArgNo(0))},
                   ErrnoMustNotBeChecked, GenericSuccessMsg)
-            .Case({ArgumentCondition(1, WithinRange, SingleValue(0)),
+            .Case({NotNull(ArgNo(0)),
+                   ArgumentCondition(1, WithinRange, SingleValue(0)),
                    IsNull(Ret)},
                   ErrnoNEZeroIrrelevant, "Assuming that argument 'size' is 0")
-            .Case({ArgumentCondition(1, WithinRange, Range(1, SizeMax)),
+            .Case({NotNull(ArgNo(0)),
+                   ArgumentCondition(1, WithinRange, Range(1, SizeMax)),
                    IsNull(Ret)},
                   ErrnoNEZeroIrrelevant, GenericFailureMsg)
             .ArgConstraint(

clang/test/Analysis/errno-stdlibraryfunctions.c

@@ -8,6 +8,7 @@
 
 #include "Inputs/errno_var.h"
 #include "Inputs/std-c-library-functions-POSIX.h"
+#include "Inputs/system-header-simulator-for-malloc.h"
 
 #define NULL ((void *) 0)
 
@@ -105,12 +106,21 @@ void errno_getcwd(char *Buf, size_t Sz) {
     clang_analyzer_eval(errno != 0);   // expected-warning{{TRUE}}
     clang_analyzer_eval(Path == NULL); // expected-warning{{TRUE}}
     if (errno) {}                      // no warning
+  } else if (Path == NULL) {
+    clang_analyzer_eval(errno != 0);   // expected-warning{{TRUE}}
+    if (errno) {}                      // no warning
   } else {
     clang_analyzer_eval(Path == Buf);  // expected-warning{{TRUE}}
     if (errno) {}                      // expected-warning{{An undefined value may be read from 'errno'}}
   }
 }
 
+void gh_128882_getcwd(void) {
+  // We expect no warnings here.
+  char* currentPath = getcwd(NULL, 0);
+  free(currentPath);
+}
+
 void errno_execv(char *Path, char * Argv[]) {
   int Ret = execv(Path, Argv);
   clang_analyzer_eval(Ret == -1);  // expected-warning{{TRUE}}