[Darwin][ASan][Test] Create a unoptimized wrapper function in unsanitized dylib for reliable suppression in test.

compiler-rt/test/asan/TestCases/Darwin/suppressions-sandbox.cpp

@@ -1,5 +1,9 @@
+// Compile the intermediate function to a dylib without -fsanitize to avoid
+// suppressing symbols in sanitized code.
+// RUN: %clangxx -O0 -DSHARED_LIB %s -dynamiclib -o %t.dylib -framework Foundation
+
 // Check that without suppressions, we catch the issue.
-// RUN: %clangxx_asan -O0 %s -o %t -framework Foundation
+// RUN: %clangxx_asan -O0 %s -o %t -framework Foundation %t.dylib
 // RUN: not %run %t 2>&1 | FileCheck --check-prefix=CHECK-CRASH %s
 
 // Check that suppressing a function name works within a no-fork sandbox
@@ -13,17 +17,37 @@
 
 #include <CoreFoundation/CoreFoundation.h>
 
+#if defined(SHARED_LIB)
+
+extern "C" {
+// Disable optimizations to ensure that this function appears on the stack trace so our
+// configured suppressions `interceptor_via_fun:createCFString` can take effect.
+__attribute__((disable_tail_calls)) CFStringRef
+createCFString(const unsigned char *bytes, CFIndex length) {
+  return CFStringCreateWithBytes(kCFAllocatorDefault, bytes, length,
+                                 kCFStringEncodingUTF8, FALSE);
+}
+}
+
+#else
+
+extern "C" {
+CFStringRef createCFString(const unsigned char *bytes, CFIndex length);
+}
+
 int main() {
   char *a = (char *)malloc(6);
   strcpy(a, "hello");
-  CFStringRef str =
-      CFStringCreateWithBytes(kCFAllocatorDefault, (unsigned char *)a, 10,
-                              kCFStringEncodingUTF8, FALSE);  // BOOM
+  // Intentional out-of-bounds access that will be caught unless an ASan suppression is provided.
+  CFStringRef str = createCFString((unsigned char *)a, 10); // BOOM
+  // If this is printed to stderr then the ASan suppression has worked.
   fprintf(stderr, "Ignored.\n");
   free(a);
   CFRelease(str);
 }
 
+#endif
+
 // CHECK-CRASH: AddressSanitizer: heap-buffer-overflow
 // CHECK-CRASH-NOT: Ignored.
 // CHECK-IGNORE-NOT: AddressSanitizer: heap-buffer-overflow