Migrate psync_set_signal to psignal module

- Added psignal_set_custom_handler() to psignal.h and psignal.c
- Replaced psync_set_signal() calls in pfs.c with psignal_set_custom_handler()
- Centralizes all signal handling in psignal module

pclsync/pfs.c

@@ -3601,20 +3601,7 @@ static void psync_usr2_handler(int sig) {
   pdbg_reopen_log();
 }
 
-static void psync_set_signal(int sig, void (*handler)(int)) {
-  struct sigaction sa;
-
-  if (pdbg_unlikely(sigaction(sig, NULL, &sa)))
-    return;
-
-  if (sa.sa_handler == SIG_DFL) {
-    memset(&sa, 0, sizeof(struct sigaction));
-    sigemptyset(&(sa.sa_mask));
-    sa.sa_handler = handler;
-    sa.sa_flags = 0;
-    sigaction(sig, &sa, NULL);
-  }
-}
+#include "psignal.h"
 
 static void pfs_init_once() {
 #if pfs_need_per_folder_refresh_const()
@@ -3630,7 +3617,7 @@ static void pfs_init_once() {
   ppagecache_init();
   atexit(pfs_do_stop);
   pfs_debug_register_signal_handlers();
-  psync_set_signal(SIGUSR2, psync_usr2_handler);
+  psignal_set_custom_handler(SIGUSR2, psync_usr2_handler);
   pfs_stat_add_files();
   pfs_task_add_banned_folders();
 }

pclsync/psignal.c

@@ -18,8 +18,23 @@ static void sighup_handler(int sig) {
   sighup_flag = 1;
 }
 
-void psignal_register(int signum) {
+void psignal_set_custom_handler(int sig, void (*handler)(int)) {
   struct sigaction sa;
+
+  if (sigaction(sig, NULL, &sa) != 0)
+    return;
+
+  if (sa.sa_handler == SIG_DFL) {
+    sa.sa_handler = handler;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = 0;
+    if (sigaction(sig, &sa, NULL) != 0) {
+      return;
+    }
+  }
+}
+
+void psignal_register(int signum) {
   void (*handler)(int) = NULL;
   
   if (signum == SIGINT) {
@@ -32,12 +47,7 @@ void psignal_register(int signum) {
     return;
   }
   
-  sa.sa_handler = handler;
-  sigemptyset(&sa.sa_mask);
-  sa.sa_flags = 0;
-  if (sigaction(signum, &sa, NULL) != 0) {
-    return;
-  }
+  psignal_set_custom_handler(signum, handler);
 }
 
 int psignal_check_pending(void) {

pclsync/psignal.h

@@ -9,6 +9,7 @@ extern "C" {
 
 void psignal_register(int signum);
 int psignal_check_pending(void);
+void psignal_set_custom_handler(int sig, void (*handler)(int));
 
 #ifdef __cplusplus
 }