util: minor tweaks to disable_core_dumps()

First, let's rename it to disable_coredumps(), as in the rest of our
codebase we spell it "coredump" rather than "core_dump", so let's stick
to that.

However, also log about failures to turn off core dumpling on LOG_DEBUG,
because debug logging is always a good idea.

src/basic/util.c

@@ -618,7 +618,13 @@ int str_verscmp(const char *s1, const char *s2) {
 }
 
 /* Turn off core dumps but only if we're running outside of a container. */
-void disable_core_dumps(void) {
-        if (detect_container() <= 0)
-                (void) write_string_file("/proc/sys/kernel/core_pattern", "|/bin/false", 0);
+void disable_coredumps(void) {
+        int r;
+
+        if (detect_container() > 0)
+                return;
+
+        r = write_string_file("/proc/sys/kernel/core_pattern", "|/bin/false", 0);
+        if (r < 0)
+                log_debug_errno(r, "Failed to turn off coredumps, ignoring: %m");
 }

src/basic/util.h

@@ -192,4 +192,4 @@ int version(void);
 
 int str_verscmp(const char *s1, const char *s2);
 
-void disable_core_dumps(void);
+void disable_coredumps(void);

src/core/main.c

@@ -1604,7 +1604,7 @@ static void initialize_coredump(bool skip_setup) {
         /* But at the same time, turn off the core_pattern logic by default, so that no coredumps are stored
          * until the systemd-coredump tool is enabled via sysctl. */
         if (!skip_setup)
-                disable_core_dumps();
+                disable_coredumps();
 }
 
 static void do_reexecute(

src/core/shutdown.c

@@ -323,8 +323,7 @@ int main(int argc, char *argv[]) {
         if (!in_container)
                 sync_with_progress();
 
-        /* Prevent coredumps */
-        disable_core_dumps();
+        disable_coredumps();
 
         log_info("Sending SIGTERM to remaining processes...");
         broadcast_signal(SIGTERM, true, true);

src/coredump/coredump.c

@@ -1126,7 +1126,7 @@ static int gather_pid_metadata(
                 /* If this is PID 1 disable coredump collection, we'll unlikely be able to process it later on. */
                 if (is_pid1_crash((const char**) context)) {
                         log_notice("Due to PID 1 having crashed coredump collection will now be turned off.");
-                        disable_core_dumps();
+                        disable_coredumps();
                 }
 
                 set_iovec_field(iovec, n_iovec, "COREDUMP_UNIT=", context[CONTEXT_UNIT]);