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/* Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <dlfcn.h>
#include <pthread.h>
#include <contrib/cleanup.h>
#include "lib/defines.h"
#include "lib/utils.h"
#include "lib/module.h"
/* List of embedded modules */
const kr_layer_api_t *iterate_layer(struct kr_module *module);
const kr_layer_api_t *validate_layer(struct kr_module *module);
const kr_layer_api_t *cache_layer(struct kr_module *module);
static const struct kr_module embedded_modules[] = {
{ "iterate", NULL, NULL, NULL, iterate_layer, NULL, NULL, NULL },
{ "validate", NULL, NULL, NULL, validate_layer, NULL, NULL, NULL },
{ "cache", NULL, NULL, NULL, cache_layer, NULL, NULL, NULL },
};
/** Library extension. */
#if defined(__APPLE__)
#define LIBEXT ".dylib"
#elif _WIN32
#define LIBEXT ".dll"
#else
#define LIBEXT ".so"
#endif
/** Load prefixed symbol. */
static void *load_symbol(void *lib, const char *prefix, const char *name)
{
auto_free char *symbol = kr_strcatdup(2, prefix, name);
return dlsym(lib, symbol);
}
static int load_library(struct kr_module *module, const char *name, const char *path)
{
assert(module && name && path);
/* Absolute or relative path (then only library search path is used). */
auto_free char *lib_path = kr_strcatdup(4, path, "/", name, LIBEXT);
if (lib_path == NULL) {
return kr_error(ENOMEM);
}
/* Workaround for buggy _fini/__attribute__((destructor)) and dlclose(),
* this keeps the library mapped until the program finishes though. */
module->lib = dlopen(lib_path, RTLD_NOW | RTLD_NODELETE);
if (module->lib) {
return kr_ok();
}
return kr_error(ENOENT);
}
const struct kr_module * kr_module_embedded(const char *name)
{
for (unsigned i = 0; i < sizeof(embedded_modules)/sizeof(embedded_modules[0]); ++i) {
if (strcmp(name, embedded_modules[i].name) == 0)
return embedded_modules + i;
}
return NULL;
}
/** Load C module symbols. */
static int load_sym_c(struct kr_module *module, uint32_t api_required)
{
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic" /* casts after load_symbol() */
/* Check if it's embedded first */
const struct kr_module *embedded = kr_module_embedded(module->name);
if (embedded) {
module->init = embedded->init;
module->deinit = embedded->deinit;
module->config = embedded->config;
module->layer = embedded->layer;
module->props = embedded->props;
return kr_ok();
}
/* Load dynamic library module */
auto_free char *m_prefix = kr_strcatdup(2, module->name, "_");
/* Check ABI version, return error on mismatch. */
module_api_cb *api = load_symbol(module->lib, m_prefix, "api");
if (api == NULL) {
return kr_error(ENOENT);
}
if (api() != api_required) {
return kr_error(ENOTSUP);
}
/* Load ABI by symbol names. */
#define ML(symname) module->symname = \
load_symbol(module->lib, m_prefix, #symname)
ML(init);
ML(deinit);
ML(config);
ML(layer);
ML(props);
#undef ML
return kr_ok();
#pragma GCC diagnostic pop
}
int kr_module_load(struct kr_module *module, const char *name, const char *path)
{
if (module == NULL || name == NULL) {
return kr_error(EINVAL);
}
/* Initialize, keep userdata */
void *data = module->data;
memset(module, 0, sizeof(struct kr_module));
module->data = data;
module->name = strdup(name);
if (module->name == NULL) {
return kr_error(ENOMEM);
}
/* Search for module library. */
if (!path || load_library(module, name, path) != 0) {
module->lib = RTLD_DEFAULT;
}
/* Try to load module ABI. */
int ret = load_sym_c(module, KR_MODULE_API);
if (ret == 0 && module->init) {
ret = module->init(module);
}
if (ret != 0) {
kr_module_unload(module);
}
return ret;
}
void kr_module_unload(struct kr_module *module)
{
if (module == NULL) {
return;
}
if (module->deinit) {
module->deinit(module);
}
if (module->lib && module->lib != RTLD_DEFAULT) {
dlclose(module->lib);
}
free(module->name);
memset(module, 0, sizeof(struct kr_module));
}
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