[freestanding] prefer strncpy with known length (#80005)

Author: ktoso

stdlib/public/Concurrency/TaskStatus.cpp

@@ -793,9 +793,11 @@ void AsyncTask::pushInitialTaskName(const char* _taskName) {
       this, sizeof(class TaskNameStatusRecord));
 
   // TODO: Copy the string maybe into the same allocation at an offset or retain the swift string?
+  auto taskNameLen = strlen(_taskName);
   char* taskNameCopy = reinterpret_cast<char*>(
-      _swift_task_alloc_specific(this, strlen(_taskName) + 1/*null terminator*/));
-  (void) strcpy(/*dst=*/taskNameCopy, /*src=*/_taskName);
+      _swift_task_alloc_specific(this, taskNameLen + 1/*null terminator*/));
+  (void) strncpy(/*dst=*/taskNameCopy, /*src=*/_taskName, taskNameLen);
+  taskNameCopy[taskNameLen] = '\0'; // make sure we null-terminate
 
   auto record =
       ::new (allocation) TaskNameStatusRecord(taskNameCopy);

test/embedded/dependencies-concurrency-custom-executor.swift

@@ -26,7 +26,7 @@
 // DEP: _putchar
 // DEP: _puts
 // DEP: _strlen
-// DEP: _strcpy
+// DEP: _strncpy
 // DEP: _vprintf
 // DEP: _vsnprintf
 

test/embedded/dependencies-concurrency-custom-executor2.swift

@@ -25,7 +25,7 @@
 // DEP: _putchar
 // DEP: _puts
 // DEP: _strlen
-// DEP: _strcpy
+// DEP: _strncpy
 // DEP: _vprintf
 // DEP: _vsnprintf
 

test/embedded/dependencies-concurrency.swift

@@ -26,7 +26,7 @@
 // DEP: _putchar
 // DEP: _puts
 // DEP: _strlen
-// DEP: _strcpy
+// DEP: _strncpy
 // DEP: _vprintf
 // DEP: _vsnprintf
 

test/embedded/dependencies-concurrency2.swift

@@ -23,7 +23,7 @@
 // DEP: _putchar
 // DEP: _puts
 // DEP: _strlen
-// DEP: _strcpy
+// DEP: _strncpy
 // DEP: _swift_task_asyncMainDrainQueueImpl
 // DEP: _swift_task_enqueueGlobalImpl
 // DEP: _swift_task_getMainExecutorImpl