init: reduce the window when init can lose reboot/poweroff signals

function                                             old     new   delta
init_main                                            695     712     +17

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/init/init.c b/init/init.c
index 5304e5c2c068bed271df2d20f80b055d9d218b0c..6f3374eaca658aedb41c0f0b861451e35e181084 100644 (file)
--- a/init/init.c
+++ b/init/init.c
@@ -1064,6 +1064,12 @@ int init_main(int argc UNUSED_PARAM, char **argv)
 #endif
 
        if (!DEBUG_INIT) {
+               /* Some users send poweroff signals to init VERY early.
+                * To handle this, mask signals early,
+                * and unmask them only after signal handlers are installed.
+                */
+               sigprocmask_allsigs(SIG_BLOCK);
+
                /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
                if (getpid() != 1
                 && (!ENABLE_LINUXRC || applet_name[0] != 'l') /* not linuxrc? */
@@ -1106,29 +1112,6 @@ int init_main(int argc UNUSED_PARAM, char **argv)
        message(L_CONSOLE | L_LOG, "init started: %s", bb_banner);
 #endif
 
-#if 0
-/* It's 2013, does anyone really still depend on this? */
-/* If you do, consider adding swapon to sysinit actions then! */
-/* struct sysinfo is linux-specific */
-# ifdef __linux__
-       /* Make sure there is enough memory to do something useful. */
-       /*if (ENABLE_SWAPONOFF) - WRONG: we may have non-bbox swapon*/ {
-               struct sysinfo info;
-
-               if (sysinfo(&info) == 0
-                && (info.mem_unit ? info.mem_unit : 1) * (long long)info.totalram < 1024*1024
-               ) {
-                       message(L_CONSOLE, "Low memory, forcing swapon");
-                       /* swapon -a requires /proc typically */
-                       new_init_action(SYSINIT, "mount -t proc proc /proc", "");
-                       /* Try to turn on swap */
-                       new_init_action(SYSINIT, "swapon -a", "");
-                       run_actions(SYSINIT);   /* wait and removing */
-               }
-       }
-# endif
-#endif
-
        /* Check if we are supposed to be in single user mode */
        if (argv[1]
         && (strcmp(argv[1], "single") == 0 || strcmp(argv[1], "-s") == 0 || LONE_CHAR(argv[1], '1'))
@@ -1204,6 +1187,8 @@ int init_main(int argc UNUSED_PARAM, char **argv)
                        + (1 << SIGHUP)  /* reread /etc/inittab */
 #endif
                        , record_signo);
+
+               sigprocmask_allsigs(SIG_UNBLOCK);
        }
 
        /* Now run everything that needs to be run */