plugins: only dlopen() each plugin once. dlcose() in destructor

CMakeLists.txt

@@ -30,6 +30,7 @@ add_executable(f00bar
   main.c
   module.c module.h
   particle.c particle.h
+  plugin.c plugin.h
   tag.c tag.h
   xcb.c xcb.h
   yml.c yml.h

config-verify.c

@@ -3,15 +3,10 @@
 #include <string.h>
 #include <assert.h>
 
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <dirent.h>
-#include <fcntl.h>
-#include <dlfcn.h>
-
 #define LOG_MODULE "config:verify"
 #define LOG_ENABLE_DBG 0
 #include "log.h"
+#include "plugin.h"
 #include "tllist.h"
 
 const char *
@@ -434,40 +429,13 @@ verify_module(keychain_t *chain, const struct yml_node *node)
         return false;
     }
 
-    char path[1024];
+    const struct module_info *info = plugin_load_module(mod_name);
-    snprintf(path, sizeof(path), "./modules/lib%s.so", mod_name);
+    if (info == NULL) {
-
+        LOG_ERR(
-    void *lib = dlopen(path, RTLD_LOCAL | RTLD_NOW | RTLD_NOLOAD);
+            "%s: invalid module name: %s", conf_err_prefix(chain, node), mod_name);
-
-    if (lib == NULL)
-        lib = dlopen(path, RTLD_LOCAL | RTLD_NOW);
-
-    if (lib == NULL) {
-        const char *dl_error = dlerror();
-        if (dl_error != NULL)
-            LOG_ERR("%s: dlopen: %s", mod_name, dlerror());
-        else
-            LOG_ERR("%s: invalid module name: %s",
-                    conf_err_prefix(chain, module), mod_name);
-
         return false;
     }
 
-    char sym[1024];
-    snprintf(sym, sizeof(sym), "module_%s", mod_name);
-
-    dlerror(); /* Clear previous error */
-    const struct module_info *info = dlsym(lib, sym);
-
-    const char *dlsym_error = dlerror();
-    if (dlsym_error != NULL) {
-        LOG_ERR("%s: dlsym: %s", mod_name, dlsym_error);
-        dlclose(lib);
-        return false;
-    }
-
-    assert(info != NULL);
-
     if (!conf_verify_dict(chain_push(chain, mod_name), values,
                           info->attrs, info->attr_count))
         return false;
@@ -512,45 +480,6 @@ verify_bar_location(keychain_t *chain, const struct yml_node *node)
     return conf_verify_enum(chain, node, (const char *[]){"top", "bottom"}, 2);
 }
 
-#if defined(LOG_ENABLE_DBG) && LOG_ENABLE_DBG
-static void
-find_modules(void)
-{
-    int cwd = open(".", O_RDONLY);
-    assert(cwd != -1);
-
-    int modules = openat(cwd, "modules", O_RDONLY);
-    assert(modules != -1);
-
-    DIR *dir = fdopendir(modules);
-    assert(dir != NULL);
-
-    for (struct dirent *e = readdir(dir); e != NULL; e = readdir(dir)) {
-        const size_t len = strlen(e->d_name);
-
-        if (len <= 6) {
-            /* Need at least "libX.so" */
-            continue;
-        }
-
-        if (strncmp(e->d_name, "lib", 3) != 0)
-            continue;
-
-        if (strcmp(&e->d_name[len - 3], ".so") != 0)
-            continue;
-
-        char *name = malloc(len - 6 + 1);
-        memcpy(name, &e->d_name[3], len - 6);
-        name[len - 6] = '\0';
-
-        LOG_DBG("%s", name);
-        free(name);
-    }
-
-    closedir(dir);
-}
-#endif
-
 bool
 conf_verify_bar(const struct yml_node *bar)
 {
@@ -559,10 +488,6 @@ conf_verify_bar(const struct yml_node *bar)
         return false;
     }
 
-#if defined(LOG_ENABLE_DBG) && LOG_ENABLE_DBG
-    find_modules();
-#endif
-
     keychain_t chain = tll_init();
     chain_push(&chain, "bar");
 

config.c

@@ -5,10 +5,6 @@
 #include <string.h>
 #include <assert.h>
 
-
-#include <dlfcn.h>
-
-
 #include "color.h"
 
 #include "decoration.h"
@@ -26,6 +22,7 @@
 
 #include "module.h"
 #include "config-verify.h"
+#include "plugin.h"
 
 static uint8_t
 hex_nibble(char hex)
@@ -444,18 +441,7 @@ conf_to_bar(const struct yml_node *bar)
                 struct yml_dict_iter m = yml_dict_iter(it.node);
                 const char *mod_name = yml_value_as_string(m.key);
 
-                char path[1024];
+                const struct module_info *info = plugin_load_module(mod_name);
-                snprintf(path, sizeof(path), "./modules/lib%s.so", mod_name);
-
-                void *lib = dlopen(path, RTLD_LOCAL | RTLD_NOW | RTLD_NOLOAD);
-                assert(lib != NULL);
-
-                char sym[1024];
-                snprintf(sym, sizeof(sym), "module_%s", mod_name);
-
-                const struct module_info *info = dlsym(lib, sym);
-                assert(info != NULL);
-
                 mods[idx] = info->from_conf(m.value, font);
             }
 

plugin.c

@@ -0,0 +1,82 @@
+#include "plugin.h"
+
+#include <string.h>
+#include <dlfcn.h>
+
+#define LOG_MODULE "plugin"
+#define LOG_ENABLE_DBG 0
+#include "log.h"
+#include "config.h"
+#include "tllist.h"
+
+struct plugin {
+    char *name;
+    void *lib;
+};
+
+static tll(struct plugin) libs = tll_init();
+
+static void __attribute__((destructor))
+fini(void)
+{
+    tll_foreach(libs, plug) {
+        dlerror();
+        dlclose(plug->item.lib);
+
+        const char *dl_error = dlerror();
+        if (dl_error != NULL)
+            LOG_ERR("%s: dlclose(): %s", plug->item.name, dl_error);
+
+        free(plug->item.name);
+    }
+
+    tll_free(libs);
+}
+
+const struct module_info *
+plugin_load_module(const char *name)
+{
+    char path[128];
+    snprintf(path, sizeof(path), "./modules/lib%s.so", name);
+
+    void *lib = NULL;
+
+    /* Have we already loaded it? */
+    tll_foreach(libs, plug) {
+        if (strcmp(plug->item.name, name) == 0) {
+            lib = plug->item.lib;
+            LOG_DBG("%s already loaded: %p", name, lib);
+            break;
+        }
+    }
+
+    if (lib == NULL) {
+        /* Not loaded - do it now */
+        lib = dlopen(path, RTLD_LOCAL | RTLD_NOW);
+        LOG_DBG("%s: dlopened to %p", name, lib);
+
+        if (lib == NULL) {
+            LOG_ERR("%s: dlopen: %s", name, dlerror());
+            return NULL;
+        }
+
+        tll_push_back(libs, ((struct plugin){strdup(name), lib}));
+    }
+
+    /* TODO: use same name in all modules */
+    char sym[128];
+    snprintf(sym, sizeof(sym), "module_%s", name);
+
+    /* TODO: cache symbol */
+    dlerror(); /* Clear previous error */
+    const struct module_info *info = dlsym(lib, sym);
+
+    const char *dlsym_error = dlerror();
+    if (dlsym_error != NULL) {
+        LOG_ERR("%s: dlsym: %s", name, dlsym_error);
+        return NULL;
+    }
+
+    assert(info != NULL);
+    return info;
+}

plugin.h

@@ -0,0 +1,5 @@
+#pragma once
+
+#include "module.h"
+
+const struct module_info *plugin_load_module(const char *name);