tools lib bpf: Add bpf_object__pin()

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@ovn.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20170126212001.14103-4-joe@ovn.org
[ Check snprintf >= for truncation, as snprintf(bf, size, ...) == size also means truncation ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 53 insertions, 0 deletions

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;