[clang] Fixed issue #128882: don't warn if 1st argument to 'getcwd' is NULL (PR #135720)

[Balazs Benics via cfe-commits]

https://github.com/steakhal updated https://github.com/llvm/llvm-project/pull/135720

>From cfd32680ac4a534b4060d8cc3549edfe45e721bf Mon Sep 17 00:00:00 2001
From: Sean McBride <sean at rogue-research.com>
Date: Mon, 14 Apr 2025 20:58:24 -0400
Subject: [PATCH 1/2] Fixed issue #128882: don't warn if 1st argument to
 'getcwd' is NULL

---
 .../lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp | 1 -
 clang/test/Analysis/errno-stdlibraryfunctions.c                | 3 ---
 2 files changed, 4 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index 9c0b79ab58618..34bab80307a04 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -2663,7 +2663,6 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
             .Case({ArgumentCondition(1, WithinRange, Range(1, SizeMax)),
                    IsNull(Ret)},
                   ErrnoNEZeroIrrelevant, GenericFailureMsg)
-            .ArgConstraint(NotNull(ArgNo(0)))
             .ArgConstraint(
                 BufferSize(/*Buffer*/ ArgNo(0), /*BufSize*/ ArgNo(1)))
             .ArgConstraint(
diff --git a/clang/test/Analysis/errno-stdlibraryfunctions.c b/clang/test/Analysis/errno-stdlibraryfunctions.c
index 657aa37a42670..0bc82b595eed8 100644
--- a/clang/test/Analysis/errno-stdlibraryfunctions.c
+++ b/clang/test/Analysis/errno-stdlibraryfunctions.c
@@ -105,9 +105,6 @@ 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'}}

>From 039952f6517c6e732fb5ce578291a35668c46c7b Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs at gmail.com>
Date: Tue, 20 May 2025 12:05:00 +0200
Subject: [PATCH 2/2] Add NotNull constaints to arg 0 for the summary Cases

---
 .../Checkers/StdLibraryFunctionsChecker.cpp            |  9 ++++++---
 clang/test/Analysis/errno-stdlibraryfunctions.c        | 10 ++++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index 54583ce54a45e..8ee616f5ed37e 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/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(
diff --git a/clang/test/Analysis/errno-stdlibraryfunctions.c b/clang/test/Analysis/errno-stdlibraryfunctions.c
index 0bc82b595eed8..84809751e1eee 100644
--- a/clang/test/Analysis/errno-stdlibraryfunctions.c
+++ b/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}}