lib/util: Import logging helpers from xdp-tools

Include logging.{h,c} from xdp-tools so utilities can use them for setting
libxdp and libbpf logging.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

lib/Makefile

@@ -5,7 +5,7 @@ LIB_DIR = .
 LIB_INSTALL := $(LIB_DIR)/install
 include defines.mk
 
-SUBDIRS=
+SUBDIRS=util
 
 all: $(OBJECT_LIBBPF) $(OBJECT_LIBXDP)
 	@set -e; \

lib/util/Makefile

@@ -0,0 +1,18 @@
+include util.mk
+
+LIB_DIR ?= ..
+
+include $(LIB_DIR)/defines.mk
+
+all: $(UTIL_OBJS)
+
+# Create expansions for dependencies
+UTIL_H := ${UTIL_OBJS:.o=.h}
+
+CFLAGS+= -I$(LIB_DIR)/install/include
+
+$(UTIL_OBJS): %.o: %.c $(UTIL_H) $(LIBMK)
+	$(QUIET_CC)$(CC) $(CFLAGS) -Wall -I../../headers -c -o $@ $<
+
+clean:
+	$(Q)rm -f $(UTIL_OBJS)

lib/util/logging.c

@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <stdio.h>
+#include <stdarg.h>
+
+#include <bpf/libbpf.h>
+#include <xdp/libxdp.h>
+
+#define __unused __attribute__((unused))
+#include "logging.h"
+
+static enum logging_print_level log_level = LOG_INFO;
+
+static int print_func(enum logging_print_level level, const char *format,
+		      va_list args)
+{
+	if (level > log_level)
+		return 0;
+
+	return vfprintf(stderr, format, args);
+}
+
+static int libbpf_print_func(enum libbpf_print_level level, const char *format,
+			     va_list args)
+{
+	return print_func(level + 1, format, args);
+}
+
+static int libbpf_silent_func(__unused enum libbpf_print_level level,
+			      __unused const char *format,
+			      __unused va_list args)
+{
+	return 0;
+}
+
+static int libxdp_print_func(enum libxdp_print_level level, const char *format,
+			     va_list args)
+{
+	return print_func(level + 1, format, args);
+}
+
+static int libxdp_silent_func(__unused enum libxdp_print_level level,
+			      __unused const char *format,
+			      __unused va_list args)
+{
+	return 0;
+}
+
+#define __printf(a, b) __attribute__((format(printf, a, b)))
+
+__printf(2, 3) void logging_print(enum logging_print_level level,
+				  const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	print_func(level, format, args);
+	va_end(args);
+}
+
+void init_lib_logging(void)
+{
+	libbpf_set_print(libbpf_print_func);
+	libxdp_set_print(libxdp_print_func);
+}
+
+void silence_libbpf_logging(void)
+{
+	if (log_level < LOG_VERBOSE)
+		libbpf_set_print(libbpf_silent_func);
+}
+
+void silence_libxdp_logging(void)
+{
+	if (log_level < LOG_VERBOSE)
+		libxdp_set_print(libxdp_silent_func);
+}
+
+enum logging_print_level set_log_level(enum logging_print_level level)
+{
+	enum logging_print_level old_level = log_level;
+
+	log_level = level;
+	return old_level;
+}
+
+enum logging_print_level increase_log_level(void)
+{
+	if (log_level < LOG_VERBOSE)
+		log_level++;
+	return log_level;
+}

lib/util/logging.h

@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __LOGGING_H
+#define __LOGGING_H
+
+/* This matches the libbpf logging levels, but with an additional VERBOSE level;
+ * we demote all libbpf messages by one level so debug messages only show up on
+ * VERBOSE.
+ */
+enum logging_print_level {
+	LOG_WARN,
+	LOG_INFO,
+	LOG_DEBUG,
+	LOG_VERBOSE,
+};
+
+extern void logging_print(enum logging_print_level level, const char *format,
+			  ...) __attribute__((format(printf, 2, 3)));
+
+#define __pr(level, fmt, ...)                             \
+	do {                                              \
+		logging_print(level, fmt, ##__VA_ARGS__); \
+	} while (0)
+
+#define pr_warn(fmt, ...) __pr(LOG_WARN, fmt, ##__VA_ARGS__)
+#define pr_info(fmt, ...) __pr(LOG_INFO, fmt, ##__VA_ARGS__)
+#define pr_debug(fmt, ...) __pr(LOG_DEBUG, fmt, ##__VA_ARGS__)
+
+void init_lib_logging(void);
+void silence_libbpf_logging(void);
+void silence_libxdp_logging(void);
+enum logging_print_level set_log_level(enum logging_print_level level);
+enum logging_print_level increase_log_level();
+
+#endif

lib/util/util.mk

@@ -1,2 +1,2 @@
 # list of objects in this directory
-UTIL_OBJS := json_writer.o
+UTIL_OBJS := json_writer.o logging.o