Re: [RFC][PATCH bpf-next] libbpf: add bpf_object__open_{file,mem} w/ sized opts
From: Jesper Dangaard Brouer <hidden>
Date: 2019-10-01 16:48:27
Also in:
bpf
On Mon, 30 Sep 2019 09:42:39 -0700 Andrii Nakryiko [off-list ref] wrote:
quoted hunk ↗ jump to hunk
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 2e83a34f8c79..1cf2cf8d80f3 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h@@ -47,6 +47,12 @@ do { \ #define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__) #define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__) +#define OPTS_VALID(opts) (!(opts) || (opts)->sz >= sizeof((opts)->sz))
Do be aware that C sizeof() will include the padding the compiler does. Thus, when extending a struct (e.g. in a newer version) the size (sizeof) might not actually increase (if compiler padding room exist).
+#define OPTS_HAS(opts, field) \ + ((opts) && opts->sz >= offsetofend(typeof(*(opts)), field)) +#define OPTS_GET(opts, field, fallback_value) \ + (OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
I do think, that these two "accessor" defines address the padding issue I described above. p.s. I appreciate that you are working on this, and generally like the idea. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer