Re: [PATCH v3 4/6] trace-cmd record / report: Record BTF file if function arguments are recorded

On Mon,  2 Feb 2026 17:36:59 -0500
Steven Rostedt <[email protected]> wrote:

> +#define BTF_FILE "/sys/kernel/btf/vmlinux"
> +
> +int tracecmd_append_btf_file(struct tracecmd_output *handle)
> +{
> +	tsize_t offset, size, check_size;
> +	struct tracecmd_option *option;
> +	struct iovec *vect;
> +	struct stat st;
> +	int ret;
> +
> +	if (!HAS_SECTIONS(handle))
> +		return -1;
> +
> +	ret = stat(BTF_FILE, &st);
> +	if (ret < 0)
> +		return -1;
> +
> +	offset = write_compress_section_header(handle, TRACECMD_OPTION_BTF_FILE, NULL, true);
> +	if (offset == (off_t)-1)
> +		return -1;
> +
> +	tcmd_out_compression_start(handle);
> +
> +	check_size = copy_file(handle, BTF_FILE);
> +	if (st.st_size != check_size) {
> +		errno = EINVAL;
> +		tracecmd_warning("error in size of file '%s'", BTF_FILE);
> +		return -1;
> +	}
> +
> +	if (tcmd_out_compression_end(handle))
> +		return -1;
> +
> +	if (tcmd_out_update_section_header(handle, offset))
> +		return -1;
> +
> +	return 0;

Bah, the below was from some old versions. I keep forgetting to remove it.

Will be sending a v4 shortly.

-- Steve


> +
> +	/*
> +	 * BTF file
> +	 *  - data offset in the file
> +	 *  - data size
> +	 */
> +
> +	vect = calloc(2, sizeof(struct iovec));
> +	if (!vect)
> +		return -1;
> +	vect[0].iov_base = &offset;
> +	vect[0].iov_len = 8;
> +	vect[1].iov_base = &size;
> +	vect[1].iov_len = 8;
> +
> +	option = tracecmd_add_option_v(handle, TRACECMD_OPTION_BTF_FILE, vect, 2);
> +	free(vect);
> +
> +	if (!option)
> +		return -1;
> +
> +	if (do_lseek(handle, 0, SEEK_END) == (off_t)-1)
> +		return -1;
> +
> +	return 0;
> +}
> +