libbpf: Fix handling of optional field_name in btf_dump__emit_type_decl

Internal functions, used by btf_dump__emit_type_decl(), assume field_name is
never going to be NULL. Ensure it's always the case.

Fixes: 9f81654eebe8 ("libbpf: Expose BTF-to-C type declaration emitting API")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200303180800.3303471-1-andriin@fb.com

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index bd09ed1..dc451e4 100644 (file)
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -1030,7 +1030,7 @@ int btf_dump__emit_type_decl(struct btf_dump *d, __u32 id,
        if (!OPTS_VALID(opts, btf_dump_emit_type_decl_opts))
                return -EINVAL;
 
-       fname = OPTS_GET(opts, field_name, NULL);
+       fname = OPTS_GET(opts, field_name, "");
        lvl = OPTS_GET(opts, indent_level, 0);
        btf_dump_emit_type_decl(d, id, fname, lvl);
        return 0;