init: fix a bug where on reload order of entries might be wrong
authorDenis Vlasenko <vda.linux@googlemail.com>
Sat, 31 Jan 2009 18:55:54 +0000 (18:55 -0000)
committerDenis Vlasenko <vda.linux@googlemail.com>
Sat, 31 Jan 2009 18:55:54 +0000 (18:55 -0000)
function                                             old     new   delta
run_shutdown_and_kill_processes                        -      97     +97
pause_and_low_level_reboot                             -      48     +48
run_actions                                           81     107     +26
restart_handler                                       56      81     +25
new_init_action                                      137     150     +13
run                                                  576     579      +3
open_stdio_to_tty                                    110      98     -12
check_delayed_sigs                                   195     170     -25
waitfor                                              354     318     -36
low_level_reboot                                      53       -     -53
kill_all_processes                                   115       -    -115
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 4/3 up/down: 212/-241)          Total: -29 bytes

init/init.c

index ed01e71..7ba8b67 100644 (file)
@@ -95,18 +95,15 @@ enum {
 #endif
 };
 
-static void halt_reboot_pwoff(int sig) NORETURN;
-
 /* Print a message to the specified device.
  * "where" may be bitwise-or'd from L_LOG | L_CONSOLE
  * NB: careful, we can be called after vfork!
  */
-#define messageD(...) do { if (DEBUG_INIT) message(__VA_ARGS__); } while (0)
+#define dbg_message(...) do { if (DEBUG_INIT) message(__VA_ARGS__); } while (0)
 static void message(int where, const char *fmt, ...)
        __attribute__ ((format(printf, 2, 3)));
 static void message(int where, const char *fmt, ...)
 {
-       static int log_fd = -1;
        va_list arguments;
        unsigned l;
        char msg[128];
@@ -116,20 +113,23 @@ static void message(int where, const char *fmt, ...)
        l = 1 + vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments);
        if (l > sizeof(msg) - 1)
                l = sizeof(msg) - 1;
-       msg[l] = '\0';
        va_end(arguments);
 
-       if (ENABLE_FEATURE_INIT_SYSLOG) {
-               if (where & L_LOG) {
-                       /* Log the message to syslogd */
-                       openlog("init", 0, LOG_DAEMON);
-                       /* don't print "\r" */
-                       syslog(LOG_INFO, "%s", msg + 1);
-                       closelog();
-               }
-               msg[l++] = '\n';
-               msg[l] = '\0';
-       } else {
+#if ENABLE_FEATURE_INIT_SYSLOG
+       msg[l] = '\0';
+       if (where & L_LOG) {
+               /* Log the message to syslogd */
+               openlog("init", 0, LOG_DAEMON);
+               /* don't print "\r" */
+               syslog(LOG_INFO, "%s", msg + 1);
+               closelog();
+       }
+       msg[l++] = '\n';
+       msg[l] = '\0';
+#else
+       {
+               static int log_fd = -1;
+
                msg[l++] = '\n';
                msg[l] = '\0';
                /* Take full control of the log tty, and never close it.
@@ -153,6 +153,7 @@ static void message(int where, const char *fmt, ...)
                                return; /* don't print dup messages */
                }
        }
+#endif
 
        if (where & L_CONSOLE) {
                /* Send console messages to console so people will see them. */
@@ -199,7 +200,7 @@ static void console_init(void)
                        dup2(fd, STDOUT_FILENO);
                        xmove_fd(fd, STDERR_FILENO);
                }
-               messageD(L_LOG, "console='%s'", s);
+               dbg_message(L_LOG, "console='%s'", s);
        } else {
                /* Make sure fd 0,1,2 are not closed
                 * (so that they won't be used by future opens) */
@@ -261,7 +262,7 @@ static void set_sane_term(void)
 
 /* Open the new terminal device.
  * NB: careful, we can be called after vfork! */
-static void open_stdio_to_tty(const char* tty_name, int exit_on_failure)
+static int open_stdio_to_tty(const char* tty_name)
 {
        /* empty tty_name means "use init's tty", else... */
        if (tty_name[0]) {
@@ -273,19 +274,13 @@ static void open_stdio_to_tty(const char* tty_name, int exit_on_failure)
                if (fd) {
                        message(L_LOG | L_CONSOLE, "can't open %s: %s",
                                tty_name, strerror(errno));
-                       if (exit_on_failure)
-                               _exit(EXIT_FAILURE);
-                       if (DEBUG_INIT)
-                               _exit(2);
-                       /* NB: we don't reach this if we were called after vfork.
-                        * Thus halt_reboot_pwoff() itself needs not be vfork-safe.
-                        */
-                       halt_reboot_pwoff(SIGUSR1); /* halt the system */
+                       return 0; /* failure */
                }
                dup2(STDIN_FILENO, STDOUT_FILENO);
                dup2(STDIN_FILENO, STDERR_FILENO);
        }
        set_sane_term();
+       return 1; /* success */
 }
 
 /* Wrapper around exec:
@@ -369,7 +364,8 @@ static pid_t run(const struct init_action *a)
        setsid();
 
        /* Open the new terminal device */
-       open_stdio_to_tty(a->terminal, 1 /* - exit if open fails */);
+       if (!open_stdio_to_tty(a->terminal))
+               _exit(EXIT_FAILURE);
 
        /* NB: on NOMMU we can't wait for input in child, so
         * "askfirst" will work the same as "respawn". */
@@ -388,7 +384,7 @@ static pid_t run(const struct init_action *a)
                 * be allowed to start a shell or whatever an init script
                 * specifies.
                 */
-               messageD(L_LOG, "waiting for enter to start '%s'"
+               dbg_message(L_LOG, "waiting for enter to start '%s'"
                                        "(pid %d, tty '%s')\n",
                                a->command, getpid(), a->terminal);
                full_write(STDOUT_FILENO, press_enter, sizeof(press_enter) - 1);
@@ -422,21 +418,6 @@ static pid_t run(const struct init_action *a)
        _exit(-1);
 }
 
-static void delete_init_action(struct init_action *action)
-{
-       struct init_action *a, **nextp;
-
-       nextp = &init_action_list;
-       while ((a = *nextp) != NULL) {
-               if (a == action) {
-                       *nextp = a->next;
-                       free(a);
-                       break;
-               }
-               nextp = &a->next;
-       }
-}
-
 static struct init_action *mark_terminated(int pid)
 {
        struct init_action *a;
@@ -497,36 +478,44 @@ static void new_init_action(uint8_t action_type, const char *command, const char
 {
        struct init_action *a, **nextp;
 
-//BUG
-//old:
-//::shutdown:umount -a -r
-//::shutdown:swapoff -a
-//new: swapped:
-//::shutdown:swapoff -a
-//::shutdown:umount -a -r
-//on SIGHUP, new one will be loaded, but order will be wrong.
+       /* Scenario:
+        * old inittab:
+        * ::shutdown:umount -a -r
+        * ::shutdown:swapoff -a
+        * new inittab:
+        * ::shutdown:swapoff -a
+        * ::shutdown:umount -a -r
+        * On reload, we must ensure entries end up in correct order.
+        * To achieve that, if we find a matching entry, we move it
+        * to the end.
+        */
        nextp = &init_action_list;
        while ((a = *nextp) != NULL) {
                /* Don't enter action if it's already in the list,
-                * just overwrite existing one's type.
                 * This prevents losing running RESPAWNs.
                 */
                if ((strcmp(a->command, command) == 0)
                 && (strcmp(a->terminal, cons) == 0)
                ) {
-                       a->action_type = action_type;
-                       return;
+                       /* Remove from list */
+                       *nextp = a->next;
+                       /* Find the end of the list */
+                       while (*nextp != NULL)
+                               nextp = &(*nextp)->next;
+                       a->next = NULL;
+                       break;
                }
                nextp = &a->next;
        }
 
+       if (!a)
+               a = xzalloc(sizeof(*a));
        /* Append to the end of the list */
-       a = xzalloc(sizeof(*a));
        *nextp = a;
        a->action_type = action_type;
        safe_strncpy(a->command, command, sizeof(a->command));
        safe_strncpy(a->terminal, cons, sizeof(a->terminal));
-       messageD(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n",
+       dbg_message(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n",
                a->command, a->action_type, a->terminal);
 }
 
@@ -603,8 +592,8 @@ static void parse_inittab(void)
 #endif
 }
 
-static void low_level_reboot(unsigned magic) NORETURN;
-static void low_level_reboot(unsigned magic)
+static void pause_and_low_level_reboot(unsigned magic) NORETURN;
+static void pause_and_low_level_reboot(unsigned magic)
 {
        pid_t pid;
 
@@ -619,12 +608,11 @@ static void low_level_reboot(unsigned magic)
                reboot(magic);
                _exit(EXIT_SUCCESS);
        }
-       waitfor(pid);
        while (1)
                sleep(1);
 }
 
-static void kill_all_processes(void)
+static void run_shutdown_and_kill_processes(void)
 {
        /* Run everything to be run at "shutdown".  This is done _prior_
         * to killing everything, in case people wish to use scripts to
@@ -633,19 +621,16 @@ static void kill_all_processes(void)
 
        message(L_CONSOLE | L_LOG, "The system is going down NOW!");
 
-       /* Allow Ctrl-Alt-Del to reboot system. */
-       reboot(RB_ENABLE_CAD); /* misnomer */
-
        /* Send signals to every process _except_ pid 1 */
-       message(L_CONSOLE | L_LOG, "Sending SIG%s to all processes", "TERM");
        kill(-1, SIGTERM);
+       message(L_CONSOLE | L_LOG, "Sent SIG%s to all processes", "TERM");
        sync();
        sleep(1);
 
-       message(L_CONSOLE, "Sending SIG%s to all processes", "KILL");
        kill(-1, SIGKILL);
+       message(L_CONSOLE, "Sent SIG%s to all processes", "KILL");
        sync();
-       sleep(1);
+       /*sleep(1); - callers take care about making a pause */
 }
 
 /* Signal handling by init:
@@ -684,12 +669,13 @@ static void kill_all_processes(void)
  * and only one will be remebered and acted upon.
  */
 
+static void halt_reboot_pwoff(int sig) NORETURN;
 static void halt_reboot_pwoff(int sig)
 {
        const char *m;
        unsigned rb;
 
-       kill_all_processes();
+       run_shutdown_and_kill_processes();
 
        m = "halt";
        rb = RB_HALT_SYSTEM;
@@ -701,7 +687,7 @@ static void halt_reboot_pwoff(int sig)
                rb = RB_POWER_OFF;
        }
        message(L_CONSOLE, "Requesting system %s", m);
-       low_level_reboot(rb);
+       pause_and_low_level_reboot(rb);
        /* not reached */
 }
 
@@ -752,11 +738,21 @@ static void restart_handler(int sig UNUSED_PARAM)
                 * Thus don't need to worry about preserving errno
                 * and such.
                 */
-               kill_all_processes();
-               open_stdio_to_tty(a->terminal, 0 /* - halt if open fails */);
-               messageD(L_CONSOLE, "Trying to re-exec %s", a->command);
-               init_exec(a->command);
-               low_level_reboot(RB_HALT_SYSTEM);
+               run_shutdown_and_kill_processes();
+
+               /* Allow Ctrl-Alt-Del to reboot the system.
+                * This is how kernel sets it up for init, we follow suit.
+                */
+               reboot(RB_ENABLE_CAD); /* misnomer */
+
+               if (open_stdio_to_tty(a->terminal)) {
+                       dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command);
+                       while (wait(NULL) > 0)
+                               continue;
+                       init_exec(a->command);
+               }
+               /* Open or exec failed */
+               pause_and_low_level_reboot(RB_HALT_SYSTEM);
                /* not reached */
        }
 }
@@ -764,40 +760,50 @@ static void restart_handler(int sig UNUSED_PARAM)
 #if ENABLE_FEATURE_USE_INITTAB
 static void reload_inittab(void)
 {
-       struct init_action *a, *tmp;
+       struct init_action *a, **nextp;
 
        message(L_LOG, "reloading /etc/inittab");
 
        /* Disable old entries */
-       for (a = init_action_list; a; a = a->next) {
+       for (a = init_action_list; a; a = a->next)
                a->action_type = ONCE;
-       }
 
+       /* Append new entries, or modify existing entries
+        * (set a->action_type) if cmd and device name
+        * match new ones. End result: only entries with
+        * a->action_type == ONCE are stale.
+        */
        parse_inittab();
 
        if (ENABLE_FEATURE_KILL_REMOVED) {
+               /* Kill stale entries */
                /* Be nice and send SIGTERM first */
                for (a = init_action_list; a; a = a->next)
-                       if (a->pid != 0)
+                       if (a->action_type == ONCE && a->pid != 0)
                                kill(a->pid, SIGTERM);
                if (CONFIG_FEATURE_KILL_DELAY) {
                        /* NB: parent will wait in NOMMU case */
                        if ((BB_MMU ? fork() : vfork()) == 0) { /* child */
                                sleep(CONFIG_FEATURE_KILL_DELAY);
                                for (a = init_action_list; a; a = a->next)
-                                       if (a->pid != 0)
+                                       if (a->action_type == ONCE && a->pid != 0)
                                                kill(a->pid, SIGKILL);
                                _exit(EXIT_SUCCESS);
                        }
                }
        }
 
-       /* Remove old and unused entries */
-       for (a = init_action_list; a; a = tmp) {
-               tmp = a->next;
-               if (a->action_type & (ONCE | SYSINIT | WAIT))
-                       delete_init_action(a);
+       /* Remove stale (ONCE) and not useful (SYSINIT,WAIT) entries */
+       nextp = &init_action_list;
+       while ((a = *nextp) != NULL) {
+               if (a->action_type & (ONCE | SYSINIT | WAIT)) {
+                       *nextp = a->next;
+                       free(a);
+               } else {
+                       nextp = &a->next;
+               }
        }
+
        /* Not needed: */
        /* run_actions(RESPAWN | ASKFIRST); */
        /* - we return to main loop, which does this automagically */