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/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
* SPDX-License-Identifier: GPL-3.0-or-later
*/
#include <stdlib.h>
#include <dlfcn.h>
#include <contrib/cleanup.h>
#include "kresconfig.h"
#include "lib/defines.h"
#include "lib/utils.h"
#include "lib/module.h"
/* List of embedded modules. These aren't (un)loaded. */
int iterate_init(struct kr_module *self);
int validate_init(struct kr_module *self);
int cache_init(struct kr_module *self);
kr_module_init_cb kr_module_get_embedded(const char *name)
{
if (strcmp(name, "iterate") == 0)
return iterate_init;
if (strcmp(name, "validate") == 0)
return validate_init;
if (strcmp(name, "cache") == 0)
return cache_init;
return NULL;
}
/** 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)
{
if (kr_fails_assert(module && name && path))
return kr_error(EINVAL);
/* 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);
}
/** Load C module symbols. */
static int load_sym_c(struct kr_module *module, uint32_t api_required)
{
module->init = kr_module_get_embedded(module->name);
if (module->init) {
return kr_ok();
}
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic" /* casts after load_symbol() */
/* Check if it's embedded first */
/* 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);
#undef ML
if (load_symbol(module->lib, m_prefix, "layer")
|| load_symbol(module->lib, m_prefix, "props")) {
/* In case someone re-compiled against new kresd
* but haven't actually changed the symbols. */
kr_log_error(SYSTEM, "module %s requires upgrade. Please refer to "
"https://knot-resolver.readthedocs.io/en/stable/upgrading.html",
module->name);
return kr_error(ENOTSUP);
}
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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