Adding upstream version 5.6.0.upstream/5.6.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 148 insertions, 0 deletions

diff --git a/lib/module.c b/lib/module.c
new file mode 100644
index 0000000..83ae773
--- /dev/null
+++ b/lib/module.c
@@ -0,0 +1,148 @@
+/*  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));
+}