[PATCH 05/07][RFC] RACF audit plugin - queue interface

[Klaus Heinrich Kiwi <klausk@br.ibm.com>]

This patch implements a queue for already-encoded BER elements for the
racf plugin.
This is entirely based on audit dispatcher code by Steve Grubb.

Signed-off-by: Klaus Heinrich Kiwi <klausk@br.ibm.com>

diff -purN audit-1.6.2/audisp/plugins/racf/racf-queue.h audit-1.6.2_racf/audisp/plugins/racf/racf-queue.h
--- audit-1.6.2/audisp/plugins/racf/racf-queue.h	1969-12-31 21:00:00.000000000 -0300
+++ audit-1.6.2_racf/audisp/plugins/racf/racf-queue.h	2007-09-28 09:18:08.000000000 -0300
@@ -0,0 +1,38 @@
+/***************************************************************************
+ *   Copyright (C) 2007 International Business Machines  Corp.             *
+ *   All Rights Reserved.                                                  *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ *                                                                         *
+ * Authors:                                                                *
+ *   Klaus Heinrich Kiwi <klausk@br.ibm.com>                               *
+ *   based on code by Steve Grubb <sgrubb@redhat.com>                      *
+ ***************************************************************************/
+
+#ifndef _RACF_QUEUE_H
+#define _RACF_QUEUE_H
+
+#include <lber.h>
+
+int init_queue(unsigned int size);
+void enqueue(BerElement *);
+BerElement *dequeue(void);
+void nudge_queue(void);
+void increase_queue_depth(unsigned int size);
+void destroy_queue(void);
+
+#endif       /* _RACF_QUEUE_H */
+
diff -purN audit-1.6.2/audisp/plugins/racf/racf-queue.c audit-1.6.2_racf/audisp/plugins/racf/racf-queue.c
--- audit-1.6.2/audisp/plugins/racf/racf-queue.c	1969-12-31 21:00:00.000000000 -0300
+++ audit-1.6.2_racf/audisp/plugins/racf/racf-queue.c	2007-09-28 09:18:08.000000000 -0300
@@ -0,0 +1,144 @@
+/***************************************************************************
+ *   Copyright (C) 2007 International Business Machines  Corp.             *
+ *   All Rights Reserved.                                                  *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ *                                                                         *
+ * Authors:                                                                *
+ *   Klaus Heinrich Kiwi <klausk@br.ibm.com>                               *
+ *   based on code by Steve Grubb <sgrubb@redhat.com>                      *
+ ***************************************************************************/
+
+#include "racf-queue.h"
+
+#include <stdlib.h>
+#include <pthread.h>
+#include <syslog.h>
+#include "racf-log.h"
+
+static volatile BerElement **q;
+static pthread_mutex_t queue_lock;
+static pthread_cond_t queue_nonempty;
+static unsigned int q_next, q_last, q_depth;
+
+
+int init_queue(unsigned int size)
+{
+    unsigned int i;
+
+    q_next = 0;
+    q_last = 0;
+    q_depth = size;
+    q = malloc(q_depth * sizeof(BerElement *));
+    if (q == NULL)
+        return -1;
+
+    for (i=0; i<q_depth; i++) 
+        q[i] = NULL;
+
+    /* Setup IPC mechanisms */
+    pthread_mutex_init(&queue_lock, NULL);
+    pthread_cond_init(&queue_nonempty, NULL);
+
+    return 0;
+}
+
+void enqueue(BerElement *ber)
+{
+    unsigned int n, retry_cnt = 0;
+
+retry:
+    /* We allow 3 retries and then its over */
+    if (retry_cnt > 3) {
+        log_err("queue is full - dropping event");
+        return;
+    }
+    pthread_mutex_lock(&queue_lock);
+
+    /* OK, have lock add event */
+    n = q_next%q_depth;
+    if (q[n] == NULL) {
+        q[n] = ber;
+        q_next = (n+1) % q_depth;
+        pthread_cond_signal(&queue_nonempty);
+        pthread_mutex_unlock(&queue_lock);
+    } else {
+        pthread_mutex_unlock(&queue_lock);
+        pthread_yield(); /* Let dequeue thread run to clear queue */
+        retry_cnt++;
+        goto retry;
+    }
+}
+
+BerElement *dequeue(void)
+{
+    BerElement *ber;
+    unsigned int n;
+
+    /* Wait until its got something in it */
+    pthread_mutex_lock(&queue_lock);
+    n = q_last%q_depth;
+    if (q[n] == NULL) {
+        pthread_cond_wait(&queue_nonempty, &queue_lock);
+        n = q_last%q_depth;
+    }
+
+    /* OK, grab the next event */
+    if (q[n] != NULL) {
+        ber = (BerElement *) q[n];
+        q[n] = NULL;
+        q_last = (n+1) % q_depth;
+    } else
+        ber = NULL;
+
+    pthread_mutex_unlock(&queue_lock);
+
+    /* Process the event */
+    return ber;
+}
+
+void nudge_queue(void)
+{
+    pthread_cond_signal(&queue_nonempty);
+}
+
+void increase_queue_depth(unsigned int size)
+{
+    pthread_mutex_lock(&queue_lock);
+    if (size > q_depth) {
+        unsigned int i;
+        void *tmp_q;
+
+        tmp_q = realloc(q, size * sizeof(BerElement *));
+        q = tmp_q;
+        for (i=q_depth; i<size; i++)
+            q[i] = NULL;
+        q_depth = size;
+    }
+    pthread_mutex_unlock(&queue_lock);
+}
+
+void destroy_queue(void)
+{
+    unsigned int i;
+
+    for (i=0; i<q_depth; i++) {
+        ber_free(q[i], 1);
+    }
+
+    free(q);
+}
+