[PATCH 09/14] tools lib bpf: Add bpf_object__pin()

From: Arnaldo Carvalho de Melo
Date: Wed Feb 01 2017 - 07:28:03 EST


From: Joe Stringer <joe@xxxxxxx>

Add a new API to pin a BPF object to the filesystem. The user can
specify the path within a BPF filesystem to pin the object.
Programs will be pinned under a subdirectory named the same as the
program, with each instance appearing as a numbered file under that
directory, and maps will be pinned under the path using the name of
the map as the file basename.

For example, with the directory '/sys/fs/bpf/foo' and a BPF object which
contains two instances of a program named 'bar', and a map named 'baz':

/sys/fs/bpf/foo/bar/0
/sys/fs/bpf/foo/bar/1
/sys/fs/bpf/foo/baz

Signed-off-by: Joe Stringer <joe@xxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20170126212001.14103-4-joe@xxxxxxx
[ Check snprintf >= for truncation, as snprintf(bf, size, ...) == size also means truncation ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 1 +
2 files changed, 54 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 6a8c8beeb291..ac6eb863b2a4 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1379,6 +1379,59 @@ int bpf_map__pin(struct bpf_map *map, const char *path)
return 0;
}

+int bpf_object__pin(struct bpf_object *obj, const char *path)
+{
+ struct bpf_program *prog;
+ struct bpf_map *map;
+ int err;
+
+ if (!obj)
+ return -ENOENT;
+
+ if (!obj->loaded) {
+ pr_warning("object not yet loaded; load it first\n");
+ return -ENOENT;
+ }
+
+ err = make_dir(path);
+ if (err)
+ return err;
+
+ bpf_map__for_each(map, obj) {
+ char buf[PATH_MAX];
+ int len;
+
+ len = snprintf(buf, PATH_MAX, "%s/%s", path,
+ bpf_map__name(map));
+ if (len < 0)
+ return -EINVAL;
+ else if (len >= PATH_MAX)
+ return -ENAMETOOLONG;
+
+ err = bpf_map__pin(map, buf);
+ if (err)
+ return err;
+ }
+
+ bpf_object__for_each_program(prog, obj) {
+ char buf[PATH_MAX];
+ int len;
+
+ len = snprintf(buf, PATH_MAX, "%s/%s", path,
+ prog->section_name);
+ if (len < 0)
+ return -EINVAL;
+ else if (len >= PATH_MAX)
+ return -ENAMETOOLONG;
+
+ err = bpf_program__pin(prog, buf);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
void bpf_object__close(struct bpf_object *obj)
{
size_t i;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 2addf9d5b13c..b30394f9947a 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -65,6 +65,7 @@ struct bpf_object *bpf_object__open(const char *path);
struct bpf_object *bpf_object__open_buffer(void *obj_buf,
size_t obj_buf_sz,
const char *name);
+int bpf_object__pin(struct bpf_object *object, const char *path);
void bpf_object__close(struct bpf_object *object);

/* Load/unload object into/from kernel */
--
2.9.3