src/module.c

   1 #if !defined(__FreeBSD__) && !defined(_GNU_SOURCE)
   2 #define _GNU_SOURCE
   3 #endif
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <unistd.h>
   9 #include <errno.h>
  10 #include <dlfcn.h>
  11
  12 #include <sys/types.h>
  13
  14 #include "list.h"
  15 #include "util.h"
  16
  17 #include "plugin.h"
  18
  19 #include "module.h"
  20
  21 #define VLOCK_MODULE_DIR PREFIX "/lib/vlock/modules"
  22
  23 typedef bool (*vlock_hook_fn)(void **);
  24 typedef vlock_hook_fn (*hook_dlsym_t)(void *, const char *);
  25
  26 struct module_context
  27 {
  28   void *dl_handle;
  29   vlock_hook_fn hooks[nr_hooks];
  30 };
  31
  32 static void close_module(struct plugin *m);
  33
  34 struct plugin *open_module(const char *name, char **error)
  35 {
  36   char *path;
  37   struct plugin *m = __allocate_plugin(name);
  38   struct module_context *context = ensure_malloc(sizeof (struct module_context));
  39
  40   if (asprintf(&path, "%s/%s.so", VLOCK_MODULE_DIR, name) < 0) {
  41     *error = strdup("filename too long");
  42     goto path_error;
  43   }
  44
  45   if (access(path, R_OK) < 0) {
  46     (void) asprintf(error, "%s: %s", path, strerror(errno));
  47     goto file_error;
  48   }
  49
  50   context->dl_handle = dlopen(path, RTLD_NOW | RTLD_LOCAL);
  51
  52   if (context->dl_handle == NULL) {
  53     *error = strdup(dlerror());
  54     goto file_error;
  55   }
  56
  57   free(path);
  58
  59   for (size_t i = 0; i < nr_hooks; i++)
  60     *(void **) (&context->hooks[i]) = dlsym(context->dl_handle, hooks[i].name);
  61
  62
  63   for (size_t i = 0; i < nr_dependencies; i++) {
  64     const char *(*dependency)[] = dlsym(context->dl_handle, dependency_names[i]);
  65
  66     for (size_t j = 0; dependency != NULL && (*dependency)[j] != NULL; j++)
  67       list_append(m->dependencies[i], strdup((*dependency)[j]));
  68   }
  69
  70   m->context = context;
  71   m->close = close_module;
  72
  73   return m;
  74
  75 file_error:
  76   free(path);
  77
  78 path_error:
  79   free(context);
  80   __destroy_plugin(m);
  81   return NULL;
  82 }
  83
  84 static void close_module(struct plugin *m)
  85 {
  86   struct module_context *context = m->context;
  87   dlclose(context->dl_handle);
  88 }