[PATCH v2] tools/bpftool: Fix error handing in do_skeleton()

[YueHaibing]

Fix pass 0 to PTR_ERR, also dump more err info using
libbpf_strerror.

Fixes: 5dc7a8b21144 ("bpftool, selftests/bpf: Embed object file inside skeleton")
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
Reviewed-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
---
v2: use libbpf_strerror
---
 tools/bpf/bpftool/gen.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index b59d26e89367..8a4c2b3b0cd6 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -302,8 +302,11 @@ static int do_skeleton(int argc, char **argv)
 	opts.object_name = obj_name;
 	obj = bpf_object__open_mem(obj_data, file_sz, &opts);
 	if (IS_ERR(obj)) {
+		char err_buf[256];
+
+		libbpf_strerror(PTR_ERR(obj), err_buf, sizeof(err_buf));
+		p_err("failed to open BPF object file: %s", err_buf);
 		obj = NULL;
-		p_err("failed to open BPF object file: %ld", PTR_ERR(obj));
 		goto out;
 	}
 
-- 
2.17.1