[Clang][Sema] Add fortify warnings for stpcpy

[Sharjeel-Khan]

As mentioned in #142230, I am adding fortify warnings for functions missing in Clang and I am starting with stpcpy.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Sharjeel Khan (Sharjeel-Khan)

Changes

Android has local fortify warnings for functions not seen in LLVM. My plan is to upstream them all and I am starting with stpcpy.

---

Full diff: https://github.com/llvm/llvm-project/pull/141646.diff

2 Files Affected:

• (modified) clang/lib/Sema/SemaChecking.cpp (+3)
• (modified) clang/test/Sema/warn-fortify-source.c (+8)

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 930e9083365a1..025592beff5b0 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1257,6 +1257,8 @@ void Sema::checkFortifiedBuiltinMemoryFunction(FunctionDecl *FD,
   switch (BuiltinID) {
   default:
     return;
+  case Builtin::BI__builtin_stpcpy:
+  case Builtin::BIstpcpy:
   case Builtin::BI__builtin_strcpy:
   case Builtin::BIstrcpy: {
     DiagID = diag::warn_fortify_strlen_overflow;
@@ -1265,6 +1267,7 @@ void Sema::checkFortifiedBuiltinMemoryFunction(FunctionDecl *FD,
     break;
   }
 
+  case Builtin::BI__builtin___stpcpy_chk:
   case Builtin::BI__builtin___strcpy_chk: {
     DiagID = diag::warn_fortify_strlen_overflow;
     SourceSize = ComputeStrLenArgument(1);
diff --git a/clang/test/Sema/warn-fortify-source.c b/clang/test/Sema/warn-fortify-source.c
index a12460b963cd0..f48ea0907c657 100644
--- a/clang/test/Sema/warn-fortify-source.c
+++ b/clang/test/Sema/warn-fortify-source.c
@@ -71,6 +71,14 @@ void call_strcpy_nowarn(void) {
   __builtin_strcpy(dst, src);
 }
 
+void call_stpcpy(void) {
+  const char *const src = "abcd";
+  char dst1[5];
+  char dst2[4];
+  __builtin_stpcpy(dst1, src);
+  __builtin_stpcpy(dst2, src); // expected-warning {{'stpcpy' will always overflow; destination buffer has size 4, but the source string has length 5 (including NUL byte)}}
+}
+
 void call_memmove(void) {
   char s1[10], s2[20];
   __builtin_memmove(s2, s1, 20);

[gburgessiv]

Thanks for working on this!