From be2cc9f93077ad024aa2aee31dd9ad5fa5873ecc Mon Sep 17 00:00:00 2001
From: Aditya Kumar <appujee@google.com>
Date: Thu, 5 Sep 2024 14:03:59 -0700
Subject: [PATCH] Fix type of android_thread_func typedef

Found the error with latest clang: https://android-build.corp.google.com/artifact/pending/P80448506/art-host-x86_64/latest/view/logs%2Fbuild_error.log

```
out/soong/.intermediates/system/core/libutils/libutils/linux_glibc_x86_64_static/obj/system/core/libutils/Threads.o system/core/libutils/Threads.cpp
system/core/libutils/Threads.cpp:149:21: error: cast from 'android_thread_func_t' (aka 'int (*)(void *)') to 'android_pthread_entry' (aka 'void *(*)(void *)') converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]
  149 |                     (android_pthread_entry)entryFunction, userData);
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
```

Change-Id: Ie2423a568483c975a36a1fa0b06a3f93a27be5aa
---
 libutils/Threads.cpp | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/libutils/Threads.cpp b/libutils/Threads.cpp
index 0b96ab0bb..d8d75acf4 100644
--- a/libutils/Threads.cpp
+++ b/libutils/Threads.cpp
@@ -60,7 +60,7 @@ using namespace android;
  * We create it "detached", so it cleans up after itself.
  */
 
-typedef void* (*android_pthread_entry)(void*);
+typedef int (*android_pthread_entry)(void*);
 
 #if defined(__ANDROID__)
 struct thread_data_t {
@@ -88,6 +88,20 @@ struct thread_data_t {
 };
 #endif
 
+// Adapted from bionic's implmenetation of trampoline to make C11 thrd_create
+// work with pthread_create.
+struct libutil_thread_data {
+  android_pthread_entry _Nonnull entry_func;
+  void* _Nullable entry_func_arg;
+};
+
+static void* _Nonnull libutil_thread_trampoline(void* _Nonnull arg) {
+  libutil_thread_data *data_ptr = static_cast<libutil_thread_data*>(arg);
+  int result = data_ptr->entry_func(data_ptr->entry_func_arg);
+  delete data_ptr;
+  return reinterpret_cast<void*>(static_cast<uintptr_t>(result));
+}
+
 void androidSetThreadName(const char* name) {
 #if defined(__linux__)
     // Mac OS doesn't have this, and we build libutil for the host too
@@ -145,8 +159,13 @@ int androidCreateRawThreadEtc(android_thread_func_t entryFunction,
 
     errno = 0;
     pthread_t thread;
+
+    libutil_thread_data* pthread_arg = new libutil_thread_data;
+    pthread_arg->entry_func = entryFunction;
+    pthread_arg->entry_func_arg = userData;
+
     int result = pthread_create(&thread, &attr,
-                    (android_pthread_entry)entryFunction, userData);
+                    libutil_thread_trampoline, pthread_arg);
     pthread_attr_destroy(&attr);
     if (result != 0) {
         ALOGE("androidCreateRawThreadEtc failed (entry=%p, res=%d, %s)\n"