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Message-Id: <20181121172944.146320-1-sdf@google.com>
Date: Wed, 21 Nov 2018 09:29:44 -0800
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net
Cc: yhs@...com, Stanislav Fomichev <sdf@...gle.com>
Subject: [PATCH bpf-next v3] libbpf: make sure bpf headers are c++ include-able
Wrap headers in extern "C", to turn off C++ mangling.
This simplifies including libbpf in c++ and linking against it.
v2 changes:
* do the same for btf.h
v3 changes:
* test_libbpf.cpp to test for possible future c++ breakages
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
tools/lib/bpf/Makefile | 15 ++++++++++++---
tools/lib/bpf/bpf.h | 9 +++++++++
tools/lib/bpf/btf.h | 8 ++++++++
tools/lib/bpf/libbpf.h | 9 +++++++++
tools/lib/bpf/test_libbpf.cpp | 18 ++++++++++++++++++
5 files changed, 56 insertions(+), 3 deletions(-)
create mode 100644 tools/lib/bpf/test_libbpf.cpp
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 425b480bda75..1b4a683a00fc 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -66,7 +66,7 @@ ifndef VERBOSE
endif
FEATURE_USER = .libbpf
-FEATURE_TESTS = libelf libelf-mmap bpf reallocarray
+FEATURE_TESTS = libelf libelf-mmap bpf reallocarray cxx
FEATURE_DISPLAY = libelf bpf
INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi
@@ -148,6 +148,12 @@ LIB_FILE := $(addprefix $(OUTPUT),$(LIB_FILE))
CMD_TARGETS = $(LIB_FILE)
+CXX_TEST_TARGET = $(OUTPUT)test_libbpf
+
+ifeq ($(feature-cxx), 1)
+ CMD_TARGETS += $(CXX_TEST_TARGET)
+endif
+
TARGETS = $(CMD_TARGETS)
all: fixdep all_cmd
@@ -175,6 +181,9 @@ $(OUTPUT)libbpf.so: $(BPF_IN)
$(OUTPUT)libbpf.a: $(BPF_IN)
$(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^
+$(OUTPUT)test_libbpf: test_libbpf.cpp $(OUTPUT)libbpf.a
+ $(QUIET_LINK)$(CXX) $^ -lelf -o $@
+
define do_install
if [ ! -d '$(DESTDIR_SQ)$2' ]; then \
$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$2'; \
@@ -201,8 +210,8 @@ install: install_lib
$(Q)$(MAKE) -C $(srctree)/tools/build/feature/ clean >/dev/null
clean:
- $(call QUIET_CLEAN, libbpf) $(RM) *.o *~ $(TARGETS) *.a *.so .*.d .*.cmd \
- $(RM) LIBBPF-CFLAGS
+ $(call QUIET_CLEAN, libbpf) $(RM) $(TARGETS) $(CXX_TEST_TARGET) \
+ *.o *~ *.a *.so .*.d .*.cmd LIBBPF-CFLAGS
$(call QUIET_CLEAN, core-gen) $(RM) $(OUTPUT)FEATURE-DUMP.libbpf
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 26a51538213c..9ea3aec82d8a 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -27,6 +27,10 @@
#include <stdbool.h>
#include <stddef.h>
+#ifdef __cplusplus
+extern "C" {
+#endif
+
#ifndef LIBBPF_API
#define LIBBPF_API __attribute__((visibility("default")))
#endif
@@ -128,4 +132,9 @@ LIBBPF_API int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf,
LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
__u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
__u64 *probe_offset, __u64 *probe_addr);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
#endif /* __LIBBPF_BPF_H */
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index b77e7080f7e7..5f3d7de850fc 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -6,6 +6,10 @@
#include <linux/types.h>
+#ifdef __cplusplus
+extern "C" {
+#endif
+
#ifndef LIBBPF_API
#define LIBBPF_API __attribute__((visibility("default")))
#endif
@@ -29,4 +33,8 @@ LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
LIBBPF_API int btf__fd(const struct btf *btf);
LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
#endif /* __LIBBPF_BTF_H */
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index b1686a787102..74e57e041705 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -16,6 +16,10 @@
#include <sys/types.h> // for size_t
#include <linux/bpf.h>
+#ifdef __cplusplus
+extern "C" {
+#endif
+
#ifndef LIBBPF_API
#define LIBBPF_API __attribute__((visibility("default")))
#endif
@@ -335,4 +339,9 @@ int libbpf_nl_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
libbpf_dump_nlmsg_t dump_qdisc_nlmsg, void *cookie);
int libbpf_nl_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
libbpf_dump_nlmsg_t dump_filter_nlmsg, void *cookie);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
#endif /* __LIBBPF_LIBBPF_H */
diff --git a/tools/lib/bpf/test_libbpf.cpp b/tools/lib/bpf/test_libbpf.cpp
new file mode 100644
index 000000000000..abf3fc25c9fa
--- /dev/null
+++ b/tools/lib/bpf/test_libbpf.cpp
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#include "libbpf.h"
+#include "bpf.h"
+#include "btf.h"
+
+/* do nothing, just make sure we can link successfully */
+
+int main(int argc, char *argv[])
+{
+ /* libbpf.h */
+ libbpf_set_print(NULL, NULL, NULL);
+
+ /* bpf.h */
+ bpf_prog_get_fd_by_id(0);
+
+ /* btf.h */
+ btf__new(NULL, 0, NULL);
+}
--
2.19.1.1215.g8438c0b245-goog
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