Plugin register mechanism

callbacks.c

@@ -19,7 +19,7 @@ cb_destroy(GtkWidget* widget, gpointer data)
   document_close();
 
   /* free registered plugins */
-  zathura_document_plugin_free();
+  zathura_document_plugins_free();
 
   return TRUE;
 }

config.mk

@@ -12,7 +12,7 @@ GTK_INC = $(shell pkg-config --cflags gtk+-2.0 poppler-glib ddjvuapi)
 GTK_LIB = $(shell pkg-config --libs gtk+-2.0 gthread-2.0 poppler-glib ddjvuapi)
 
 INCS = -I. -I/usr/include ${GTK_INC}
-LIBS = -lc ${GTK_LIB} -lpthread -lm -lgirara
+LIBS = -lc ${GTK_LIB} -lpthread -lm -lgirara -ldl
 
 # flags
 CFLAGS += -std=c99 -pedantic -Wall -Wno-format-zero-length $(INCS)

document.c

@@ -8,6 +8,9 @@
 #include <stdio.h>
 #include <string.h>
 #include <limits.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <dlfcn.h>
 
 #include "document.h"
 #include "utils.h"
@@ -17,6 +20,76 @@
 
 zathura_document_plugin_t* zathura_document_plugins = NULL;
 
+void
+zathura_document_plugins_load(void)
+{
+  /* read all files in the plugin directory */
+  DIR* dir = opendir(PLUGIN_DIR);
+  if (dir == NULL) {
+    fprintf(stderr, "error: could not open plugin directory: %s\n", PLUGIN_DIR);
+    return;
+  }
+
+  struct dirent* entry;
+  while ((entry = readdir(dir)) != NULL) {
+    /* check if entry is a file */
+    if (entry->d_type == 0x8) {
+      /* get full path */
+      char* path = string_concat(PLUGIN_DIR, "/", entry->d_name, NULL);
+
+      if (path == NULL) {
+        continue;
+      }
+
+      /* load plugin */
+      void* handle = dlopen(path, RTLD_NOW);
+      free(path);
+
+      if (handle == NULL) {
+        fprintf(stderr, "error: could not load plugin (%s)\n", dlerror());
+        continue;
+      }
+
+      /* resolve symbol */
+      zathura_plugin_register_service_t register_plugin;
+      *(void**)(&register_plugin) = dlsym(handle, PLUGIN_REGISTER_FUNCTION);
+
+      if (register_plugin == NULL) {
+        fprintf(stderr, "error: could not find '%s' function in the plugin\n", PLUGIN_REGISTER_FUNCTION);
+        dlclose(handle);
+        continue;
+      }
+
+      bool r = register_plugin();
+
+      if (r == false) {
+        fprintf(stderr, "error: could not register plugin\n");
+      }
+
+      dlclose(handle);
+    }
+  }
+
+  if (closedir(dir) == -1) {
+    fprintf(stderr, "error: could not close plugin directory: %s\n", PLUGIN_DIR);
+  }
+
+}
+
+void
+zathura_document_plugins_free(void)
+{
+  /* free registered plugins */
+  zathura_document_plugin_t* plugin = zathura_document_plugins;
+  while (plugin) {
+    zathura_document_plugin_t* tmp = plugin->next;
+    free(plugin);
+    plugin = tmp;
+  }
+
+  zathura_document_plugins = NULL;
+}
+
 bool
 zathura_document_register_plugin(char* file_extension, zathura_document_open_t open_function)
 {
@@ -61,20 +134,6 @@ zathura_document_register_plugin(char* file_extension, zathura_document_open_t o
   return true;
 }
 
-void
-zathura_document_plugin_free(void)
-{
-  /* free registered plugins */
-  zathura_document_plugin_t* plugin = zathura_document_plugins;
-  while (plugin) {
-    zathura_document_plugin_t* tmp = plugin->next;
-    free(plugin);
-    plugin = tmp;
-  }
-
-  zathura_document_plugins = NULL;
-}
-
 zathura_document_t*
 zathura_document_open(const char* path, const char* password)
 {

document.h

@@ -8,6 +8,9 @@
 
 #include <girara-datastructures.h>
 
+#define PLUGIN_DIR "/usr/lib/zathura"
+#define PLUGIN_REGISTER_FUNCTION "plugin_register"
+
 typedef struct zathura_list_s zathura_list_t;
 typedef struct zathura_document_s zathura_document_t;
 
@@ -20,6 +23,8 @@ typedef struct zathura_document_plugin_s
   struct zathura_document_plugin_s *next;
 } zathura_document_plugin_t;
 
+typedef bool (*zathura_plugin_register_service_t)(void);
+
 struct zathura_list_s
 {
   void* data;
@@ -114,8 +119,9 @@ struct zathura_document_s
   zathura_page_t** pages;
 };
 
+void zathura_document_plugins_load(void);
+void zathura_document_plugins_free(void);
 bool zathura_document_plugin_register(char* file_extension, zathura_document_open_t open_function);
-void zathura_document_plugin_free(void);
 
 zathura_document_t* zathura_document_open(const char* path, const char* password);
 bool zathura_document_free(zathura_document_t* document);

utils.c

 /* See LICENSE file for license and copyright information */
 
 #include <stdlib.h>
+#include <stdarg.h>
 #include <string.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -175,3 +176,60 @@ document_index_build(GtkTreeModel* model, GtkTreeIter* parent, girara_tree_node_
     printf("%s\n", index_element->title);
   } while ((it = girara_list_iterator_next(it)));
 }
+
+char* string_concat(const char* string1, ...)
+{
+  if(!string1) {
+    return NULL;
+  }
+
+  va_list args;
+  char* s;
+  int l = strlen(string1) + 1;
+
+  /* calculate length */
+  va_start(args, string1);
+
+  s = va_arg(args, char*);
+
+  while(s) {
+    l += strlen(s);
+    s = va_arg(args, char*);
+  }
+
+  va_end(args);
+
+  /* prepare */
+  char* c = malloc(sizeof(char) * l);
+  char* p = c;
+
+  /* copy */
+  char* d = p;
+  char* x = (char*) string1;
+
+  do {
+    *d++ = *x;
+  } while (*x++ != '\0');
+
+  p = d - 1;
+
+  va_start(args, string1);
+
+  s = va_arg(args, char*);
+
+  while(s) {
+    d = p;
+    x = s;
+
+    do {
+      *d++ = *x;
+    } while (*x++ != '\0');
+
+    p = d - 1;
+    s = va_arg(args, char*);
+  }
+
+  va_end(args);
+
+  return c;
+}

utils.h

@@ -51,4 +51,14 @@ GtkWidget* page_blank(unsigned int width, unsigned int height);
  */
 void document_index_build(GtkTreeModel* model, GtkTreeIter* parent, girara_tree_node_t* tree);
 
+/**
+ * This function is used to concatenate multiple strings. Argument list has to
+ * be ended with NULL. Returned string has to be freed with free().
+ *
+ * @param string1 First string
+ * @param ... Additional strings
+ * @return Concatenated string or NULL if an error occured
+ */
+char* string_concat(const char* string1, ...);
+
 #endif // UTILS_H

zathura.c

@@ -64,6 +64,9 @@ init_zathura()
   /* girara events */
   Zathura.UI.session->events.buffer_changed = buffer_changed;
 
+  /* load plugins */
+  zathura_document_plugins_load();
+
   /* configuration */
   config_load_default();