liblttng-ust-fork: override daemon() call

[lttng-ust.git] / liblttng-ust-fork / ustfork.c

diff --git a/liblttng-ust-fork/ustfork.c b/liblttng-ust-fork/ustfork.c
index 5e6acba16e87fb9893ee7c9fe3b756afae12dd38..af7a6afa32283ed915c3664e3f510cd7062a9e2b 100644 (file)
--- a/liblttng-ust-fork/ustfork.c
+++ b/liblttng-ust-fork/ustfork.c
@@ -33,7 +33,7 @@ struct user_desc;
 pid_t fork(void)
 {
        static pid_t (*plibc_func)(void) = NULL;
-       ust_fork_info_t fork_info;
+       sigset_t sigset;
        pid_t retval;
 
        if (plibc_func == NULL) {
@@ -44,14 +44,42 @@ pid_t fork(void)
                }
        }
 
-       ust_before_fork(&fork_info);
+       ust_before_fork(&sigset);
        /* Do the real fork */
        retval = plibc_func();
        if (retval == 0) {
                /* child */
-               ust_after_fork_child(&fork_info);
+               ust_after_fork_child(&sigset);
        } else {
-               ust_after_fork_parent(&fork_info);
+               ust_after_fork_parent(&sigset);
+       }
+       return retval;
+}
+
+int daemon(int nochdir, int noclose)
+{
+       static int (*plibc_func)(int nochdir, int noclose) = NULL;
+       sigset_t sigset;
+       int retval;
+
+       if (plibc_func == NULL) {
+               plibc_func = dlsym(RTLD_NEXT, "daemon");
+               if (plibc_func == NULL) {
+                       fprintf(stderr, "libustfork: unable to find \"daemon\" symbol\n");
+                       errno = ENOSYS;
+                       return -1;
+               }
+       }
+
+       ust_before_fork(&sigset);
+       /* Do the real daemon call */
+       retval = plibc_func(nochdir, noclose);
+       if (retval == 0) {
+               /* child, parent called _exit() directly */
+               ust_after_fork_child(&sigset);
+       } else {
+               /* on error in the parent */
+               ust_after_fork_parent(&sigset);
        }
        return retval;
 }
@@ -59,7 +87,7 @@ pid_t fork(void)
 struct ustfork_clone_info {
        int (*fn)(void *);
        void *arg;
-       ust_fork_info_t fork_info;
+       sigset_t sigset;
 };
 
 static int clone_fn(void *arg)
@@ -67,7 +95,7 @@ static int clone_fn(void *arg)
        struct ustfork_clone_info *info = (struct ustfork_clone_info *) arg;
 
        /* clone is now done and we are in child */
-       ust_after_fork_child(&info->fork_info);
+       ust_after_fork_child(&info->sigset);
        return info->fn(info->arg);
 }
 
@@ -107,13 +135,13 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
                                tls, ctid);
        } else {
                /* Creating a real process, we need to intervene. */
-               struct ustfork_clone_info info = { fn: fn, arg: arg };
+               struct ustfork_clone_info info = { fn = fn, arg = arg };
 
-               ust_before_fork(&info.fork_info);
+               ust_before_fork(&info.sigset);
                retval = plibc_func(clone_fn, child_stack, flags, &info,
                                ptid, tls, ctid);
                /* The child doesn't get here. */
-               ust_after_fork_parent(&info.fork_info);
+               ust_after_fork_parent(&info.sigset);
        }
        return retval;
 }