liblttng-ust-fork: override daemon() call

Fixes #252

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/liblttng-ust-fork/ustfork.c b/liblttng-ust-fork/ustfork.c
index 9ed087c2eff59bc1b6dd53f37e9d6f5ce9b7e555..af7a6afa32283ed915c3664e3f510cd7062a9e2b 100644 (file)
--- a/liblttng-ust-fork/ustfork.c
+++ b/liblttng-ust-fork/ustfork.c
@@ -56,6 +56,34 @@ pid_t fork(void)
        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;
+}
+
 struct ustfork_clone_info {
        int (*fn)(void *);
        void *arg;