perf config: Validate config variable arguments before trying use them

You can show the values for several config items as below:

    # perf config report.queue-size call-graph.record-mode

but it is necessary to more precisely check arguments, before passing
them to show_spec_config().  This validation function would be also used
when parsing config key-value pairs arguments in the near future.

Committer notes:

Testing it:

  $ perf config bla.
  The config variable does not contain a variable name: bla.
  $ perf config .bla
  The config variable does not contain a section name: .bla
  $ perf config bla.bla
  $

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Nambong Ha <over3025@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Wookje Kwon <aweee0@gmail.com>
Link: http://lkml.kernel.org/r/1478241862-31230-4-git-send-email-treeze.taeung@gmail.com
[ Fix some spelling errors ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-config.c b/tools/perf/builtin-config.c
index df3fa1c..88a43fe 100644 (file)
--- a/tools/perf/builtin-config.c
+++ b/tools/perf/builtin-config.c
@@ -82,6 +82,27 @@ static int show_config(struct perf_config_set *set)
        return 0;
 }
 
+static int parse_config_arg(char *arg, char **var)
+{
+       const char *last_dot = strchr(arg, '.');
+
+       /*
+        * Since "var" actually contains the section name and the real
+        * config variable name separated by a dot, we have to know where the dot is.
+        */
+       if (last_dot == NULL || last_dot == arg) {
+               pr_err("The config variable does not contain a section name: %s\n", arg);
+               return -1;
+       }
+       if (!last_dot[1]) {
+               pr_err("The config variable does not contain a variable name: %s\n", arg);
+               return -1;
+       }
+
+       *var = arg;
+       return 0;
+}
+
 int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
 {
        int i, ret = 0;
@@ -130,10 +151,26 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
                }
                break;
        default:
-               if (argc)
-                       for (i = 0; argv[i]; i++)
-                               ret = show_spec_config(set, argv[i]);
-               else
+               if (argc) {
+                       for (i = 0; argv[i]; i++) {
+                               char *var, *arg = strdup(argv[i]);
+
+                               if (!arg) {
+                                       pr_err("%s: strdup failed\n", __func__);
+                                       ret = -1;
+                                       break;
+                               }
+
+                               if (parse_config_arg(arg, &var) < 0) {
+                                       free(arg);
+                                       ret = -1;
+                                       break;
+                               }
+
+                               ret = show_spec_config(set, var);
+                               free(arg);
+                       }
+               } else
                        usage_with_options(config_usage, config_options);
        }