libbpf: temorary WA for invalid BTF info generated by Zig

close #3

Signed-off-by: Tw <weii.tan>

.github/workflows/main.yaml

@@ -14,6 +14,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: goto-bus-stop/setup-zig@v2
       - run: sudo apt-get install -y libelf-dev libz-dev
+      - run: uname -a
       - run: zig build test
       - run: sudo ./zig-out/bin/test
   lint:

build.zig

@@ -62,6 +62,7 @@ fn create_libbpf(b: *Builder, target: std.zig.CrossTarget, optimize: std.builtin
     const libbpfFlags = [_][]const u8{
         "-D_LARGEFILE64_SOURCE",
         "-D_FILE_OFFSET_BITS=64",
+        "-DZIG_BTF_WA",
     };
     libbpf.addCSourceFiles(&libbpfSources, &libbpfFlags);
     libbpf.addIncludePath("external/libbpf/include");

external/libbpf/src/libbpf.c

@@ -2780,6 +2780,20 @@ static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
 				m->offset = 0;
 			}
 		}
+
+#ifdef ZIG_BTF_WA
+		// https://github.com/tw4452852/zbpf/issues/3
+		else if (btf_is_ptr(t)) {
+			t->name_off = 0;
+		} else if (btf_is_fwd(t) || btf_is_struct(t)) {
+			char *name = (char *)btf__name_by_offset(btf, t->name_off);
+			while (*name) {
+				if (*name == '.')
+					*name = '_';
+				name++;
+			}
+		}
+#endif
 	}
 
 	return 0;
@@ -3121,7 +3135,11 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
 	}
 
 	sanitize = btf_needs_sanitization(obj);
+#ifdef ZIG_BTF_WA
+	if (true) {
+#else
 	if (sanitize) {
+#endif
 		const void *raw_data;
 		__u32 sz;
 

samples/ringbuf.zig

@@ -8,7 +8,7 @@ var my_pid = bpf.Map.ArrayMap("my_pid", u32, 1, 0).init();
 
 var n: u32 = 0;
 
-export fn test_ringbuf(_: *opaque {}) linksection("kprobe/do_nanosleep") c_int {
+export fn test_ringbuf() linksection("kprobe/do_nanosleep") c_int {
     const pid = my_pid.lookup(0) orelse return 1;
 
     const cur_pid = @truncate(u32, helpers.get_current_pid_tgid());