trace-cmd: Add utility to add options to plugins

Added trace_util_add_option() and trace_util_read_plugin_options();

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 186 insertions, 0 deletions

diff --git a/trace-cmd.h b/trace-cmd.h
index 9063c8c..b8137b5 100644
--- a/trace-cmd.h
+++ b/trace-cmd.h
@@ -207,12 +207,15 @@ void tracecmd_stop_recording(struct tracecmd_recorder *recorder);
 void tracecmd_stat_cpu(struct trace_seq *s, int cpu);
 
 /* --- Plugin handling --- */
+void trace_util_add_option(const char *name, const char *val);
 void trace_util_load_plugins(struct pevent *pevent, const char *suffix,
                              void (*load_plugin)(struct pevent *pevent,
                                                  const char *path,
                                                  const char *name,
                                                  void *data),
                              void *data);
+struct plugin_option *trace_util_read_plugin_options(void);
+void trace_util_free_options(struct plugin_option *options);
 
 /* --- Hack! --- */
 int tracecmd_blk_hack(struct tracecmd_input *handle);
diff --git a/trace-util.c b/trace-util.c
index 970e6bc..04cb087 100644
--- a/trace-util.c
+++ b/trace-util.c
@@ -40,6 +40,14 @@
 int tracecmd_disable_sys_plugins;
 int tracecmd_disable_plugins;
 
+
+static struct trace_plugin_options {
+        struct trace_plugin_options     *next;
+        char                            *plugin;
+        char                            *option;
+        char                            *value;
+} *trace_plugin_options;
+
 #define _STR(x) #x
 #define STR(x) _STR(x)
 
@@ -53,6 +61,35 @@ struct plugin_list {
         void                    *handle;
 };
 
+void trace_util_add_option(const char *name, const char *val)
+{
+        struct trace_plugin_options *option;
+        char *p;
+
+        option = malloc_or_die(sizeof(*option));
+        memset(option, 0, sizeof(*option));
+        option->next = trace_plugin_options;
+        trace_plugin_options = option;
+
+        option->option = strdup(name);
+        if (!option->option)
+                die("malloc");
+
+        if ((p = strstr(option->option, ":"))) {
+                option->plugin = option->option;
+                *p = '\0';
+                option->option = strdup(p + 1);
+                if (!option->option)
+                        die("malloc");
+        }
+
+        if (val) {
+                option->value = strdup(val);
+                if (!option->value)
+                        die("malloc");
+        }
+}
+
 void parse_cmdlines(struct pevent *pevent,
                     char *file, int size __unused)
 {
@@ -131,12 +168,63 @@ void parse_ftrace_printk(struct pevent *pevent,
         }
 }
 
+static void update_option(const char *file, struct plugin_option *option)
+{
+        struct trace_plugin_options *op;
+        char *plugin;
+
+        if (option->plugin_alias) {
+                plugin = strdup(option->plugin_alias);
+                if (!plugin)
+                        die("malloc");
+        } else {
+                char *p;
+                plugin = strdup(file);
+                if (!plugin)
+                        die("malloc");
+                p = strstr(plugin, ".");
+                if (p)
+                        *p = '\0';
+        }
+
+        /* first look for named options */
+        for (op = trace_plugin_options; op; op = op->next) {
+                if (!op->plugin)
+                        continue;
+                if (strcmp(op->plugin, plugin) != 0)
+                        continue;
+                if (strcmp(op->option, option->name) != 0)
+                        continue;
+
+                option->value = op->value;
+                option->set = 1;
+                goto out;
+        }
+
+        /* first look for unnamed options */
+        for (op = trace_plugin_options; op; op = op->next) {
+                if (op->plugin)
+                        continue;
+                if (strcmp(op->option, option->name) != 0)
+                        continue;
+
+                option->value = op->value;
+                option->set = 1;
+                break;
+        }
+
+ out:
+        free(plugin);
+}
+
 static void load_plugin(struct pevent *pevent, const char *path,
                         const char *file, void *data)
 {
         struct plugin_list **plugin_list = data;
         pevent_plugin_load_func func;
         struct plugin_list *list;
+        struct plugin_option *options;
+        const char *alias;
         char *plugin;
         void *handle;
 
@@ -153,6 +241,18 @@ static void load_plugin(struct pevent *pevent, const char *path,
                 goto out_free;
         }
 
+        alias = dlsym(handle, PEVENT_PLUGIN_ALIAS_NAME);
+        if (!alias)
+                alias = file;
+
+        options = dlsym(handle, PEVENT_PLUGIN_OPTIONS_NAME);
+        if (options) {
+                while (options->name) {
+                        update_option(alias, options);
+                        options++;
+                }
+        }
+
         func = dlsym(handle, PEVENT_PLUGIN_LOADER_NAME);
         if (!func) {
                 warning("cound not find func '%s' in plugin '%s'\n%s\n",
@@ -805,6 +905,89 @@ void trace_util_load_plugins(struct pevent *pevent, const char *suffix,
         free(path);
 }
 
+struct plugin_option_read {
+        struct plugin_option    *options;
+};
+
+static void read_options(struct pevent *pevent, const char *path,
+                         const char *file, void *data)
+{
+        struct plugin_option_read *option = data;
+        struct plugin_option *options;
+        struct plugin_option *op;
+        const char *alias;
+        int unload = 0;
+        char *plugin;
+        void *handle;
+
+        plugin = malloc_or_die(strlen(path) + strlen(file) + 2);
+
+        strcpy(plugin, path);
+        strcat(plugin, "/");
+        strcat(plugin, file);
+
+        handle = dlopen(plugin, RTLD_NOW | RTLD_GLOBAL);
+        if (!handle) {
+                warning("cound not load plugin '%s'\n%s\n",
+                        plugin, dlerror());
+                goto out_free;
+        }
+
+        alias = dlsym(handle, PEVENT_PLUGIN_ALIAS_NAME);
+        if (!alias)
+                alias = file;
+
+        options = dlsym(handle, PEVENT_PLUGIN_OPTIONS_NAME);
+        if (!options) {
+                unload = 1;
+                goto out_unload;
+        }
+
+        while (options->name) {
+                op = malloc_or_die(sizeof(*op));
+                *op = *options;
+                op->next = option->options;
+                option->options = op;
+                op->file = strdup(alias);
+                op->handle = handle;
+                options++;
+        }
+
+ out_unload:
+        if (unload)
+                dlclose(handle);
+ out_free:
+        free(plugin);
+}
+
+struct plugin_option *trace_util_read_plugin_options(void)
+{
+        struct plugin_option_read option = {
+                .options = NULL,
+        };
+
+        trace_util_load_plugins(NULL, ".so", read_options, &option);
+
+        return option.options;
+}
+
+void trace_util_free_options(struct plugin_option *options)
+{
+        struct plugin_option *op;
+        void *last_handle = NULL;
+
+        while (options) {
+                op = options;
+                options = op->next;
+                if (op->handle && op->handle != last_handle) {
+                        last_handle = op->handle;
+                        dlclose(op->handle);
+                }
+                free(op->file);
+                free(op);
+        }
+}
+
 struct plugin_list *tracecmd_load_plugins(struct pevent *pevent)
 {
         struct plugin_list *list = NULL;