Initial project import

tools/v/vlib/dl/loader/loader.v

@@ -0,0 +1,150 @@
+@[has_globals]
+module loader
+
+import dl
+import os
+
+const dl_no_path_issue_msg = 'no paths to dynamic library'
+const dl_open_issue_msg = 'could not open dynamic library'
+const dl_sym_issue_msg = 'could not get optional symbol from dynamic library'
+const dl_close_issue_msg = 'could not close dynamic library'
+const dl_register_issue_msg = 'could not register dynamic library loader'
+
+pub const dl_no_path_issue_code = 1
+pub const dl_open_issue_code = 1
+pub const dl_sym_issue_code = 2
+pub const dl_close_issue_code = 3
+pub const dl_register_issue_code = 4
+
+pub const dl_no_path_issue_err = error_with_code(dl_no_path_issue_msg, dl_no_path_issue_code)
+pub const dl_open_issue_err = error_with_code(dl_open_issue_msg, dl_open_issue_code)
+pub const dl_sym_issue_err = error_with_code(dl_sym_issue_msg, dl_sym_issue_code)
+pub const dl_close_issue_err = error_with_code(dl_close_issue_msg, dl_close_issue_code)
+pub const dl_register_issue_err = error_with_code(dl_register_issue_msg, dl_register_issue_code)
+
+__global (
+	registered_dl_loaders map[string]&DynamicLibLoader
+)
+
+fn register_dl_loader(dl_loader &DynamicLibLoader) ! {
+	if dl_loader.key in registered_dl_loaders {
+		return dl_register_issue_err
+	}
+	registered_dl_loaders[dl_loader.key] = dl_loader
+}
+
+// registered_dl_loader_keys returns the keys of registered DynamicLibLoader.
+pub fn registered_dl_loader_keys() []string {
+	return registered_dl_loaders.keys()
+}
+
+// DynamicLibLoader is a wrapper around dlopen, dlsym and dlclose.
+@[heap]
+pub struct DynamicLibLoader {
+pub:
+	key   string
+	flags int = dl.rtld_lazy
+	paths []string
+mut:
+	handle  voidptr
+	sym_map map[string]voidptr
+}
+
+// DynamicLibLoaderConfig is a configuration for DynamicLibLoader.
+@[params]
+pub struct DynamicLibLoaderConfig {
+pub:
+	// flags is the flags for dlopen.
+	flags int = dl.rtld_lazy
+	// key is the key to register the DynamicLibLoader.
+	key string
+	// env_path is the environment variable name that contains the path to the dynamic library.
+	env_path string
+	// paths is the list of paths to the dynamic library.
+	paths []string
+}
+
+// new_dynamic_lib_loader returns a new DynamicLibLoader.
+fn new_dynamic_lib_loader(conf DynamicLibLoaderConfig) !&DynamicLibLoader {
+	mut paths := []string{}
+
+	if conf.env_path != '' {
+		if env_path := os.getenv_opt(conf.env_path) {
+			paths << env_path.split(os.path_delimiter)
+		}
+	}
+
+	paths << conf.paths
+
+	if paths.len == 0 {
+		return dl_no_path_issue_err
+	}
+
+	mut dl_loader := &DynamicLibLoader{
+		key:   conf.key
+		flags: conf.flags
+		paths: paths
+	}
+
+	register_dl_loader(dl_loader)!
+	return dl_loader
+}
+
+// get_or_create_dynamic_lib_loader returns a DynamicLibLoader.
+// If the DynamicLibLoader is not registered, it creates a new DynamicLibLoader.
+pub fn get_or_create_dynamic_lib_loader(conf DynamicLibLoaderConfig) !&DynamicLibLoader {
+	if dl_loader := registered_dl_loaders[conf.key] {
+		return dl_loader
+	}
+	return new_dynamic_lib_loader(conf)
+}
+
+// load loads the dynamic library.
+pub fn (mut dl_loader DynamicLibLoader) open() !voidptr {
+	if !isnil(dl_loader.handle) {
+		return dl_loader.handle
+	}
+
+	for path in dl_loader.paths {
+		if handle := dl.open_opt(path, dl_loader.flags) {
+			dl_loader.handle = handle
+			return handle
+		}
+	}
+
+	return dl_open_issue_err
+}
+
+// close closes the dynamic library.
+pub fn (mut dl_loader DynamicLibLoader) close() ! {
+	if !isnil(dl_loader.handle) {
+		if dl.close(dl_loader.handle) {
+			dl_loader.handle = unsafe { nil }
+			return
+		}
+	}
+
+	return dl_close_issue_err
+}
+
+// get_sym gets a symbol from the dynamic library.
+pub fn (mut dl_loader DynamicLibLoader) get_sym(name string) !voidptr {
+	if sym := dl_loader.sym_map[name] {
+		return sym
+	}
+
+	handle := dl_loader.open()!
+	if sym := dl.sym_opt(handle, name) {
+		dl_loader.sym_map[name] = sym
+		return sym
+	}
+
+	dl_loader.close()!
+	return dl_sym_issue_err
+}
+
+// unregister unregisters the DynamicLibLoader.
+pub fn (mut dl_loader DynamicLibLoader) unregister() {
+	dl_loader.close() or {}
+	registered_dl_loaders.delete(dl_loader.key)
+}