Fix pcl-bga: make psync_status.status accesses atomic (#346)

psync_status.status is written in pstatus_set() (pstatus.c:263) after
releasing status_internal_mutex, while status_change() (pclsync_lib.cpp:435)
reads it concurrently from the callback thread without any lock. TSan
reports the race between T9 (write in pstatus_set) and the status callback
thread (read in status_change).

Replace all reads and writes of psync_status.status with
__atomic_load_n/__atomic_store_n (__ATOMIC_RELAXED) across pstatus.c,
pqevent.c, and pclsync_lib.cpp. In status_change_thread, capture the
atomic value once into cur_status before the condition to avoid multiple
inconsistent loads. In status_change(), capture cur_status at entry and
use it throughout, also propagating it to the copied status_ struct.

Closes #334

Co-authored-by: Levi Neely <lkn@darkstar.example.net>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

pclsync/pqevent.c

@@ -265,6 +265,7 @@ static void status_change_thread(void *ptr) {
       pthread_cond_wait(&statuscond, &statusmutex);
     }
     statuschanges = 0;
+    uint32_t cur_status = __atomic_load_n(&psync_status.status, __ATOMIC_RELAXED);
     if (((status_old.filestodownload > 0) &&
          (psync_status.filestodownload == 0)) ||
         ((psync_status.filestodownload > 0) &&
@@ -273,14 +274,16 @@ static void status_change_thread(void *ptr) {
         ((psync_status.filestoupload > 0) && (status_old.filestoupload == 0)) ||
         ((psync_status.localisfull != status_old.localisfull)) ||
         ((psync_status.remoteisfull != status_old.remoteisfull)) ||
-        ((psync_status.status != status_old.status) &&
+        ((cur_status != status_old.status) &&
-         ((psync_status.status == PSTATUS_STOPPED) ||
+         ((cur_status == PSTATUS_STOPPED) ||
-          (psync_status.status == PSTATUS_PAUSED) ||
+          (cur_status == PSTATUS_PAUSED) ||
-          (psync_status.status == PSTATUS_OFFLINE) ||
+          (cur_status == PSTATUS_OFFLINE) ||
           (status_old.status == PSTATUS_STOPPED) ||
           (status_old.status == PSTATUS_PAUSED) ||
-          (status_old.status == PSTATUS_OFFLINE))))
+          (status_old.status == PSTATUS_OFFLINE)))) {
-    status_old = psync_status;
+      status_old = psync_status;
+      status_old.status = cur_status;
+    }
     pthread_mutex_unlock(&statusmutex);
     if (!psync_do_run)
       break;

pclsync/pstatus.c

@@ -164,7 +164,7 @@ void pstatus_init() {
   }
   pstatus_download_recalc();
   pstatus_upload_recalc();
-  psync_status.status = calc_status();
+  __atomic_store_n(&psync_status.status, calc_status(), __ATOMIC_RELAXED);
 }
 
 void pstatus_download_recalc() {
@@ -184,7 +184,7 @@ void pstatus_download_recalc() {
   if (!psync_status.filestodownload) {
     psync_status.downloadspeed = 0;
   }
-  psync_status.status = calc_status();
+  __atomic_store_n(&psync_status.status, calc_status(), __ATOMIC_RELAXED);
 }
 
 void pstatus_upload_recalc() {
@@ -230,7 +230,7 @@ void pstatus_upload_recalc() {
   psync_status.bytestoupload = bytestou;
   if (!filestou)
     psync_status.uploadspeed = 0;
-  psync_status.status = calc_status();
+  __atomic_store_n(&psync_status.status, calc_status(), __ATOMIC_RELAXED);
 }
 
 void pstatus_download_recalc_async() {
@@ -259,8 +259,8 @@ void pstatus_set(uint32_t statusid, uint32_t status) {
       (statuses[PSTATUS_TYPE_DISKFULL] == PSTATUS_DISKFULL_FULL);
   pthread_mutex_unlock(&status_internal_mutex);
   status = calc_status();
-  if (psync_status.status != status) {
+  if (__atomic_load_n(&psync_status.status, __ATOMIC_RELAXED) != status) {
-    psync_status.status = status;
+    __atomic_store_n(&psync_status.status, status, __ATOMIC_RELAXED);
     pstatus_send_status_update();
   }
 }
@@ -354,6 +354,6 @@ void pstatus_upload_set_speed(uint32_t speed) {
 }
 
 void pstatus_send_update() {
-  psync_status.status = calc_status();
+  __atomic_store_n(&psync_status.status, calc_status(), __ATOMIC_RELAXED);
   pstatus_send_status_update();
 }

pclsync_lib.cpp

@@ -431,10 +431,12 @@ static void status_change(pstatus_t *status) {
   char *err;
   err = (char *)malloc(1024);
 
+  uint32_t cur_status = __atomic_load_n(&status->status, __ATOMIC_RELAXED);
   std::cout << "Down: " << status->downloadstr << "| Up: " << status->uploadstr
-            << ", status is " << status2string(status->status) << std::endl;
+            << ", status is " << status2string(cur_status) << std::endl;
   *clib::pclsync_lib::get_lib().status_ = *status;
-  if (status->status == PSTATUS_LOGIN_REQUIRED) {
+  clib::pclsync_lib::get_lib().status_->status = cur_status;
+  if (cur_status == PSTATUS_LOGIN_REQUIRED) {
     if (clib::pclsync_lib::get_lib().get_password().empty()) {
       clib::pclsync_lib::get_lib().read_password();
     }
@@ -444,20 +446,20 @@ static void status_change(pstatus_t *status) {
                         (int)clib::pclsync_lib::get_lib().save_pass_);
     clib::pclsync_lib::get_lib().wipe_password();
     std::cout << "logging in" << std::endl;
-  } else if (status->status == PSTATUS_TFA_REQUIRED) {
+  } else if (cur_status == PSTATUS_TFA_REQUIRED) {
     if (clib::pclsync_lib::get_lib().get_tfa_code().empty()) {
       clib::pclsync_lib::get_lib().read_tfa_code();
     }
     psync_tfa_set_code(clib::pclsync_lib::get_lib().get_tfa_code().c_str(),
                        1 /* trusted */, 0);
     clib::pclsync_lib::get_lib().wipe_tfa_code();
-  } else if (status->status == PSTATUS_BAD_TFA_CODE) {
+  } else if (cur_status == PSTATUS_BAD_TFA_CODE) {
     clib::pclsync_lib::get_lib().wipe_tfa_code();
     clib::pclsync_lib::get_lib().read_tfa_code(false /* auto_sms */);
     psync_tfa_set_code(clib::pclsync_lib::get_lib().get_tfa_code().c_str(),
                        1 /* trusted */, 0);
     clib::pclsync_lib::get_lib().wipe_tfa_code();
-  } else if (status->status == PSTATUS_BAD_LOGIN_DATA) {
+  } else if (cur_status == PSTATUS_BAD_LOGIN_DATA) {
     if (!clib::pclsync_lib::get_lib().newuser_) {
       clib::pclsync_lib::get_lib().read_password();
       psync_set_user_pass(clib::pclsync_lib::get_lib().get_username().c_str(),
@@ -478,9 +480,9 @@ static void status_change(pstatus_t *status) {
       }
     }
   }
-  if (status->status == PSTATUS_READY || status->status == PSTATUS_UPLOADING ||
+  if (cur_status == PSTATUS_READY || cur_status == PSTATUS_UPLOADING ||
-      status->status == PSTATUS_DOWNLOADING ||
+      cur_status == PSTATUS_DOWNLOADING ||
-      status->status == PSTATUS_DOWNLOADINGANDUPLOADING) {
+      cur_status == PSTATUS_DOWNLOADINGANDUPLOADING) {
     if (!cryptocheck) {
       cryptocheck = 1;
       if (clib::pclsync_lib::get_lib().setup_crypto_) {
@@ -491,7 +493,7 @@ static void status_change(pstatus_t *status) {
   }
   if (clib::pclsync_lib::get_lib().status_callback_) {
     clib::pclsync_lib::get_lib().status_callback_(
-        (int)status->status, status2string(status->status));
+        (int)cur_status, status2string(cur_status));
   }
 
   if (err) {