add: SIGPIPE handling in ReZygiskd

This commit adds "SIGPIPE" signal handling in ReZygiskd. Some processes might die while ReZygiskd is still processing the response, and it will fail to write to the reader, now dead, resulting in a "SIGPIPE". Without proper handling, the process (ReZygiskd) would die, and this commit properly handled it to gracefully log it instead of dying.

zygiskd/src/companion.c

@@ -121,11 +121,7 @@ void companion_entry(int fd) {
     ASSURE_SIZE_WRITE("ZygiskdCompanion", "module_entry", ret, sizeof(uint8_t));
   }
 
-  struct sigaction sa;
-  memset(&sa, 0, sizeof(sa));
-
-  sigemptyset(&sa.sa_mask);
-  sa.sa_handler = SIG_IGN;
+  struct sigaction sa = { .sa_handler = SIG_IGN };
   sigaction(SIGPIPE, &sa, NULL);
 
   while (1) {

zygiskd/src/zygiskd.c

@@ -357,6 +357,9 @@ void zygiskd_start(char *restrict argv[]) {
     return;
   }
 
+  struct sigaction sa = { .sa_handler = SIG_IGN };
+  sigaction(SIGPIPE, &sa, NULL);
+
   bool first_process = true;
   while (1) {
     int client_fd = accept(socket_fd, NULL, NULL);