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Diffstat (limited to '')
| -rw-r--r-- | lib/module.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/lib/module.c b/lib/module.c new file mode 100644 index 0000000..68abc84 --- /dev/null +++ b/lib/module.c @@ -0,0 +1,170 @@ +/* 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)); +} |