Refactor libinterfork and add support for clone() interception

[ust.git] / libust / tracectl.c

diff --git a/libust/tracectl.c b/libust/tracectl.c
index f9312b4340238e79e3e2dd6abf51d82bd962cca1..5e59ca7bc0e8f5cf3ffee07cd6b25e06b3a98a3b 100644 (file)
--- a/libust/tracectl.c
+++ b/libust/tracectl.c
@@ -30,6 +30,7 @@
 #include <urcu-bp.h>
 
 #include <ust/marker.h>
+#include <ust/tracectl.h>
 #include "tracer.h"
 #include "usterr.h"
 #include "ustcomm.h"
@@ -1122,9 +1123,13 @@ void ust_potential_exec(void)
  * the new process, anytime a process whose memory is not shared with
  * the parent is created. If this function is not called, the events
  * of the new process will not be collected.
+ *
+ * Signals should be disabled before the fork and reenabled only after
+ * this call in order to guarantee tracing is not started before ust_fork()
+ * sanitizes the new process.
  */
 
-void ust_fork(void)
+static void ust_fork(void)
 {
        struct blocked_consumer *bc;
        struct blocked_consumer *deletable_bc = NULL;
@@ -1160,3 +1165,55 @@ void ust_fork(void)
        inform_consumer_daemon("auto");
 }
 
+void ust_before_fork(ust_fork_info_t *fork_info)
+{
+        /* Disable signals. This is to avoid that the child
+         * intervenes before it is properly setup for tracing. It is
+         * safer to disable all signals, because then we know we are not
+         * breaking anything by restoring the original mask.
+         */
+       sigset_t all_sigs;
+       int result;
+
+        /* FIXME:
+                - only do this if tracing is active
+        */
+
+        /* Disable signals */
+        sigfillset(&all_sigs);
+        result = sigprocmask(SIG_BLOCK, &all_sigs, &fork_info->orig_sigs);
+        if(result == -1) {
+                PERROR("sigprocmask");
+                return;
+        }
+}
+
+/* Don't call this function directly in a traced program */
+static void ust_after_fork_common(ust_fork_info_t *fork_info)
+{
+       int result;
+       sigset_t orig_sigs;
+
+        /* Restore signals */
+        result = sigprocmask(SIG_SETMASK, &fork_info->orig_sigs, NULL);
+        if(result == -1) {
+                PERROR("sigprocmask");
+                return;
+        }
+}
+
+void ust_after_fork_parent(ust_fork_info_t *fork_info)
+{
+       /* Reenable signals */
+       ust_after_fork_common(fork_info);
+}
+
+void ust_after_fork_child(ust_fork_info_t *fork_info)
+{
+       /* First sanitize the child */
+       ust_fork();
+
+       /* Then reenable interrupts */
+       ust_after_fork_common(fork_info);
+}
+