[PATCH bpf-next v2 02/13] bpfilter: Add logging facility

[Dmitrii Banshchikov <me@ubique.spb.ru>]

There are three logging levels for messages: FATAL, NOTICE and DEBUG.
When a message is logged with FATAL level it results in bpfilter
usermode helper termination.

Introduce struct context to avoid use of global objects and store there
the logging parameters: log level and log sink.

Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
---
 net/bpfilter/context.h | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 net/bpfilter/context.h

diff --git a/net/bpfilter/context.h b/net/bpfilter/context.h
new file mode 100644
index 000000000000..6503eda27809
--- /dev/null
+++ b/net/bpfilter/context.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021 Telegram FZ-LLC
+ */
+
+#ifndef NET_BPFILTER_CONTEXT_H
+#define NET_BPFILTER_CONTEXT_H
+
+#include <sys/syslog.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+struct context {
+	FILE *log_file;
+};
+
+#define BFLOG_IMPL(ctx, level, fmt, ...)                                                           \
+	do {                                                                                       \
+		if ((ctx)->log_file)                                                               \
+			fprintf((ctx)->log_file, "<%d>bpfilter: " fmt, (level), ##__VA_ARGS__);    \
+		if ((level) == LOG_EMERG)                                                          \
+			exit(EXIT_FAILURE);                                                        \
+	} while (0)
+
+#define BFLOG_EMERG(ctx, fmt, ...)                                                                 \
+	BFLOG_IMPL(ctx, LOG_KERN | LOG_EMERG, "fatal error: " fmt, ##__VA_ARGS__)
+
+#define BFLOG_NOTICE(ctx, fmt, ...) BFLOG_IMPL(ctx, LOG_KERN | LOG_NOTICE, fmt, ##__VA_ARGS__)
+
+#if 0
+#define BFLOG_DEBUG(ctx, fmt, ...) BFLOG_IMPL(ctx, LOG_KERN | LOG_DEBUG, fmt, ##__VA_ARGS__)
+#else
+#define BFLOG_DEBUG(ctx, fmt, ...)
+#endif
+
+#endif // NET_BPFILTER_CONTEXT_H
-- 
2.25.1