perf annotate: Introduce strerror for handling symbol__disassemble() errors

We were just using pr_error() which makes it difficult for non stdio UIs
to provide errors using its widgets, as they need to somehow catch what
was passed to pr_error().

Fix it by introducing a __strerror() interface like the ones used
elsewhere, for instance target__strerror().

This is just the initial step, more work will be done, but first some
error handling bugs noticed while working on this need to be dealt with.

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-top.c

···
 	if (err == 0) {
 out_assign:
 		top->sym_filter_entry = he;
+	} else {
+		char msg[BUFSIZ];
+		symbol__strerror_disassemble(sym, map, err, msg, sizeof(msg));
+		pr_err("Couldn't annotate %s: %s\n", sym->name, msg);
 	}
 
 	pthread_mutex_unlock(&notes->lock);

tools/perf/ui/browsers/annotate.c

···
 			.use_navkeypressed = true,
 		},
 	};
-	int ret = -1;
+	int ret = -1, err;
 	int nr_pcnt = 1;
 	size_t sizeof_bdl = sizeof(struct browser_disasm_line);
 
···
 		  (nr_pcnt - 1);
 	}
 
-	if (symbol__disassemble(sym, map, sizeof_bdl) < 0) {
-		ui__error("%s", ui_helpline__last_msg);
+	err = symbol__disassemble(sym, map, sizeof_bdl);
+	if (err) {
+		char msg[BUFSIZ];
+		symbol__strerror_disassemble(sym, map, err, msg, sizeof(msg));
+		ui__error("Couldn't annotate %s:\n%s", sym->name, msg);
 		goto out_free_offsets;
 	}
 

tools/perf/ui/gtk/annotate.c

···
 	GtkWidget *notebook;
 	GtkWidget *scrolled_window;
 	GtkWidget *tab_label;
+	int err;
 
 	if (map->dso->annotate_warned)
 		return -1;
 
-	if (symbol__disassemble(sym, map, 0) < 0) {
-		ui__error("%s", ui_helpline__current);
+	err = symbol__disassemble(sym, map, 0);
+	if (err) {
+		char msg[BUFSIZ];
+		symbol__strerror_disassemble(sym, map, err, msg, sizeof(msg));
+		ui__error("Couldn't annotate %s: %s\n", sym->name, msg);
 		return -1;
 	}
 

tools/perf/util/annotate.c

···
 	}
 }
 
+int symbol__strerror_disassemble(struct symbol *sym __maybe_unused, struct map *map,
+			      int errnum, char *buf, size_t buflen)
+{
+	struct dso *dso = map->dso;
+
+	BUG_ON(buflen == 0);
+
+	if (errnum >= 0) {
+		str_error_r(errnum, buf, buflen);
+		return 0;
+	}
+
+	switch (errnum) {
+	case SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX: {
+		char bf[SBUILD_ID_SIZE + 15] = " with build id ";
+		char *build_id_msg = NULL;
+
+		if (dso->has_build_id) {
+			build_id__sprintf(dso->build_id,
+					  sizeof(dso->build_id), bf + 15);
+			build_id_msg = bf;
+		}
+		scnprintf(buf, buflen,
+			  "No vmlinux file%s\nwas found in the path.\n\n"
+			  "Note that annotation using /proc/kcore requires CAP_SYS_RAWIO capability.\n\n"
+			  "Please use:\n\n"
+			  "  perf buildid-cache -vu vmlinux\n\n"
+			  "or:\n\n"
+			  "  --vmlinux vmlinux\n", build_id_msg ?: "");
+	}
+		break;
+	default:
+		scnprintf(buf, buflen, "Internal error: Invalid %d error code\n", errnum);
+		break;
+	}
+
+	return 0;
+}
+
 int symbol__disassemble(struct symbol *sym, struct map *map, size_t privsize)
 {
 	struct dso *dso = map->dso;
···
 		symbol__join_symfs(symfs_filename, filename);
 
 	if (filename == NULL) {
-		if (dso->has_build_id) {
-			pr_err("Can't annotate %s: not enough memory\n",
-			       sym->name);
-			return -ENOMEM;
-		}
+		if (dso->has_build_id)
+			return ENOMEM;
 		goto fallback;
 	} else if (dso__is_kcore(dso)) {
 		goto fallback;
···
 
 	if (dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
 	    !dso__is_kcore(dso)) {
-		char bf[SBUILD_ID_SIZE + 15] = " with build id ";
-		char *build_id_msg = NULL;
-
-		if (dso->annotate_warned)
-			goto out_free_filename;
-
-		if (dso->has_build_id) {
-			build_id__sprintf(dso->build_id,
-					  sizeof(dso->build_id), bf + 15);
-			build_id_msg = bf;
-		}
-		err = -ENOENT;
-		dso->annotate_warned = 1;
-		pr_err("Can't annotate %s:\n\n"
-		       "No vmlinux file%s\nwas found in the path.\n\n"
-		       "Note that annotation using /proc/kcore requires CAP_SYS_RAWIO capability.\n\n"
-		       "Please use:\n\n"
-		       "  perf buildid-cache -vu vmlinux\n\n"
-		       "or:\n\n"
-		       "  --vmlinux vmlinux\n",
-		       sym->name, build_id_msg ?: "");
+		err = SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX;
 		goto out_free_filename;
 	}
 

tools/perf/util/annotate.h

···
 
 int symbol__disassemble(struct symbol *sym, struct map *map, size_t privsize);
 
+enum symbol_disassemble_errno {
+	SYMBOL_ANNOTATE_ERRNO__SUCCESS		= 0,
+
+	/*
+	 * Choose an arbitrary negative big number not to clash with standard
+	 * errno since SUS requires the errno has distinct positive values.
+	 * See 'Issue 6' in the link below.
+	 *
+	 * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html
+	 */
+	__SYMBOL_ANNOTATE_ERRNO__START		= -10000,
+
+	SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX	= __SYMBOL_ANNOTATE_ERRNO__START,
+
+	__SYMBOL_ANNOTATE_ERRNO__END,
+};
+
+int symbol__strerror_disassemble(struct symbol *sym, struct map *map,
+				 int errnum, char *buf, size_t buflen);
+
 int symbol__annotate_init(struct map *map, struct symbol *sym);
 int symbol__annotate_printf(struct symbol *sym, struct map *map,
 			    struct perf_evsel *evsel, bool full_paths,