2021-03-09 20:04 UTC-0800 ~ Andrii Nakryiko <andrii@xxxxxxxxxx>
> Add `bpftool gen bpfo <output-file> <input_file>...` command to statically
> link multiple BPF object files into a single output BPF object file.
>
> Similarly to existing '*.o' convention, bpftool is establishing a '*.bpfo'
> convention for statically-linked BPF object files. Both .o and .bpfo suffixes
> will be stripped out during BPF skeleton generation to infer BPF object name.
>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> ---
> tools/bpf/bpftool/gen.c | 46 ++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
> index 4033c46d83e7..8b1ed6c0a62f 100644
> --- a/tools/bpf/bpftool/gen.c
> +++ b/tools/bpf/bpftool/gen.c
> +static int do_bpfo(int argc, char **argv)
> +{
> + struct bpf_linker *linker;
> + const char *output_file, *file;
> + int err;
> +
> + if (!REQ_ARGS(2)) {
> + usage();
> + return -1;
> + }
> +
> + output_file = GET_ARG();
> +
> + linker = bpf_linker__new(output_file, NULL);
> + if (!linker) {
> + p_err("failed to create BPF linker instance");
> + return -1;
> + }
> +
> + while (argc) {
> + file = GET_ARG();
> +
> + err = bpf_linker__add_file(linker, file);
> + if (err) {
> + p_err("failed to link '%s': %d", file, err);
I think you mentioned before that your preference was for having just
the error code instead of using strerror(), but I think it would be more
user-friendly for the majority of users who don't know the error codes
if we had something more verbose? How about having both strerror()
output and the error code?
> + goto err_out;
> + }
> + }
> +
> + err = bpf_linker__finalize(linker);
> + if (err) {
> + p_err("failed to finalize ELF file: %d", err);
> + goto err_out;
> + }
> +
> + return 0;
> +err_out:
> + bpf_linker__free(linker);
> + return -1;
Should you call bpf_linker__free() even on success? I see that
bpf_linker__finalize() frees some of the resources, but it seems that
bpf_linker__free() does a more thorough job?
> +}
> +
> static int do_help(int argc, char **argv)
> {
> if (json_output) {
> @@ -611,6 +654,7 @@ static int do_help(int argc, char **argv)
>
> static const struct cmd cmds[] = {
> { "skeleton", do_skeleton },
> + { "bpfo", do_bpfo },
> { "help", do_help },
> { 0 }
> };
>
Please update the usage help message, man page, and bash completion,
thanks. Especially because what "bpftool gen bpfo" does is not intuitive
(but I don't have a better name suggestion at the moment).
Great work!
Quentin
