[PATCH 1/2] signal: add helper to get siginfo without removing from the queue

[Andrey Vagin]

Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 include/linux/sched.h |  2 ++
 kernel/signal.c       | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 206bb08..a907854 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2222,6 +2222,8 @@ extern void __flush_signals(struct task_struct *);
 extern void ignore_signals(struct task_struct *);
 extern void flush_signal_handlers(struct task_struct *, int force_default);
 extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);
+extern int peek_signal(struct task_struct *tsk, sigset_t *mask,
+				siginfo_t *info, int offset, bool group);
 
 static inline int dequeue_signal_lock(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
 {
diff --git a/kernel/signal.c b/kernel/signal.c
index ac5f5e7..aa71213 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -536,6 +536,34 @@ unblock_all_signals(void)
 	spin_unlock_irqrestore(&current->sighand->siglock, flags);
 }
 
+int peek_signal(struct task_struct *tsk, sigset_t *mask,
+			siginfo_t *info, int offset, bool group)
+{
+	struct sigpending *pending;
+	struct sigqueue *q;
+	int i = 0, ret = 0;
+
+	if (group)
+		pending = &tsk->signal->shared_pending;
+	else
+		pending = &tsk->pending;
+
+	list_for_each_entry(q, &pending->list, list) {
+		if (sigismember(mask, q->info.si_signo))
+			continue;
+
+		if (i == offset) {
+			copy_siginfo(info, &q->info);
+			ret = info->si_signo;
+			break;
+		}
+
+		i++;
+	}
+
+	return ret;
+}
+
 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
 {
 	struct sigqueue *q, *first = NULL;
-- 
1.7.11.7


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