The previous attempt at using a pipe to guarantee astcanary shutdown did not work.
authorTilghman Lesher <tilghman@meg.abyt.es>
Fri, 15 Jan 2010 21:40:14 +0000 (21:40 +0000)
committerTilghman Lesher <tilghman@meg.abyt.es>
Fri, 15 Jan 2010 21:40:14 +0000 (21:40 +0000)
We're revisiting the previous patch, albeit with a method that overcomes the
prior criticism that it was not POSIX-compliant.
(closes issue #16602)
 Reported by: frawd
 Patches:
       20100114__issue16602.diff.txt uploaded by tilghman (license 14)
 Tested by: frawd

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@240499 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/asterisk.c
utils/astcanary.c

index 39940eb..427ddf6 100644 (file)
@@ -276,7 +276,6 @@ static int restartnow;
 static pthread_t consolethread = AST_PTHREADT_NULL;
 static int canary_pid = 0;
 static char canary_filename[128];
-static int canary_pipe = -1;
 
 static char randompool[256];
 
@@ -3495,15 +3494,6 @@ int main(int argc, char *argv[])
 
        /* Spawning of astcanary must happen AFTER the call to daemon(3) */
        if (isroot && ast_opt_high_priority) {
-               int cpipe[2];
-
-               /* PIPE signal ensures that astcanary dies when Asterisk dies */
-               if (pipe(cpipe)) {
-                       fprintf(stderr, "Unable to open pipe for canary process: %s\n", strerror(errno));
-                       exit(1);
-               }
-               canary_pipe = cpipe[0];
-
                snprintf(canary_filename, sizeof(canary_filename), "%s/alt.asterisk.canary.tweet.tweet.tweet", ast_config_AST_RUN_DIR);
 
                /* Don't let the canary child kill Asterisk, if it dies immediately */
@@ -3511,18 +3501,17 @@ int main(int argc, char *argv[])
 
                canary_pid = fork();
                if (canary_pid == 0) {
-                       char canary_binary[128], *lastslash;
+                       char canary_binary[128], *lastslash, ppid[12];
 
                        /* Reset signal handler */
                        signal(SIGCHLD, SIG_DFL);
                        signal(SIGPIPE, SIG_DFL);
 
-                       dup2(cpipe[1], 0);
-                       close(cpipe[1]);
                        ast_close_fds_above_n(0);
                        ast_set_priority(0);
+                       snprintf(ppid, sizeof(ppid), "%d", (int) getpid());
 
-                       execlp("astcanary", "astcanary", canary_filename, (char *)NULL);
+                       execlp("astcanary", "astcanary", canary_filename, ppid, (char *)NULL);
 
                        /* If not found, try the same path as used to execute asterisk */
                        ast_copy_string(canary_binary, argv[0], sizeof(canary_binary));
@@ -3535,12 +3524,11 @@ int main(int argc, char *argv[])
                        _exit(1);
                } else if (canary_pid > 0) {
                        pthread_t dont_care;
-                       close(cpipe[1]);
                        ast_pthread_create_detached(&dont_care, NULL, canary_thread, NULL);
                }
 
                /* Kill the canary when we exit */
-               atexit(canary_exit);
+               ast_register_atexit(canary_exit);
        }
 
        if (ast_event_init()) {
index aa13c56..bcf2abb 100644 (file)
@@ -87,9 +87,25 @@ static const char explanation[] =
 int main(int argc, char *argv[])
 {
        int fd;
+       pid_t parent;
+
+       if (argc < 3) {
+               fprintf(stderr, "Usage: %s <monitor-filename> <ppid>\n", argv[0]);
+               exit(1);
+       }
+
        /* Run at normal priority */
        setpriority(PRIO_PROCESS, 0, 0);
-       for (;;) {
+
+       /*!\note
+        * See http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap03.html#tag_03_265
+        * for a justification of this approach.  The PPID after the creator dies in Linux and
+        * most other Unix-like systems will be 1, but this is not strictly the case.  The POSIX
+        * specification allows it to be an implementation-defined system process.  However, it
+        * most certainly will not be the original parent PID, which makes the following code
+        * POSIX-compliant.
+        */
+       for (parent = atoi(argv[2]); parent == getppid() ;) {
                /* Update the modification times (checked from Asterisk) */
                if (utime(argv[1], NULL)) {
                        /* Recreate the file if it doesn't exist */
@@ -108,7 +124,7 @@ int main(int argc, char *argv[])
                sleep(5);
        }
 
-       /* Never reached */
+       /* Exit when the parent dies */
        return 0;
 }