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construct/ircd/mods.cc

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C++

/*
* ircd-ratbox: A slightly useful ircd.
* modules.c: A module loader.
*
* Copyright (C) 1990 Jarkko Oikarinen and University of Oulu, Co Center
* Copyright (C) 1996-2002 Hybrid Development Team
* Copyright (C) 2002-2005 ircd-ratbox development team
* Copyright (C) 2016 Charybdis Development Team
* Copyright (C) 2016 Jason Volk <jason@zemos.net>
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*/
#include <cxxabi.h>
#include <boost/filesystem.hpp>
#include <boost/dll.hpp>
namespace filesystem = boost::filesystem;
namespace load_mode = boost::dll::load_mode;
#include <ircd/mapi.h> // Module's internal API
namespace ircd {
namespace mods {
struct mod
:std::enable_shared_from_this<mod>
{
static std::stack<mod *> loading; // State of current dlopen() recursion.
static std::map<std::string, mod *> loaded;
filesystem::path path;
load_mode::type mode;
std::deque<mod *> children;
boost::dll::shared_library handle;
mapi::header *header;
// Metadata
auto &operator[](const std::string &s) const { return header->meta.operator[](s); }
auto &operator[](const std::string &s) { return header->meta.operator[](s); }
auto name() const { return handle.location().filename().string(); }
auto location() const { return handle.location().string(); }
auto &version() const { return header->version; }
auto &description() const { return (*this)["description"]; }
bool has(const std::string &name) const;
template<class T> const T &get(const std::string &name) const;
template<class T> T &get(const std::string &name);
template<class T = uint8_t> const T *ptr(const std::string &name) const;
template<class T = uint8_t> T *ptr(const std::string &name);
bool unload();
mod(const filesystem::path &,
const load_mode::type & = load_mode::rtld_local | load_mode::rtld_now);
~mod() noexcept;
};
static const auto suffix
{
boost::dll::shared_library::suffix()
};
filesystem::path prefix_if_relative(const filesystem::path &path);
filesystem::path postfixed(const filesystem::path &path);
filesystem::path unpostfixed(const filesystem::path &path);
std::string postfixed(const std::string &name);
std::string unpostfixed(const std::string &name);
template<class R, class F> R info(const filesystem::path &, F&& closure);
std::vector<std::string> sections(const filesystem::path &path);
std::vector<std::string> symbols(const filesystem::path &path);
std::vector<std::string> symbols(const filesystem::path &path, const std::string &section);
// Get the full path of a [valid] available module by name
filesystem::path fullpath(const std::string &name);
// Checks if loadable module containing a mapi header (does not verify the magic)
bool is_module(const filesystem::path &);
bool is_module(const filesystem::path &, std::string &why);
bool is_module(const filesystem::path &, std::nothrow_t);
bool is_module(const std::string &fullpath, std::string &why);
bool is_module(const std::string &fullpath, std::nothrow_t);
bool is_module(const std::string &fullpath);
struct log::log log
{
"modules", 'M'
};
} // namespace mods
} // namespace ircd
///////////////////////////////////////////////////////////////////////////////
//
// module
//
ircd::mods::module::module(const std::string &name)
try
:std::shared_ptr<mod>{[&name]
{
const auto path(fullpath(name));
const auto filename(postfixed(name));
// Search for loaded module and increment the reference counter for this handle if loaded.
auto it(mod::loaded.find(filename));
if(it != end(mod::loaded))
{
auto &mod(*it->second);
return shared_from(mod);
}
static const load_mode::type flags
{
load_mode::rtld_local |
load_mode::rtld_now
};
log.debug("Attempting to load '%s' @ `%s'", filename, path.string());
return std::make_shared<mod>(path, flags);
}()}
{
}
catch(const std::exception &e)
{
log.error("Failed to load '%s': %s", name, e.what());
throw;
}
ircd::mods::module::~module()
noexcept
{
}
std::string
ircd::mods::module::path()
const
{
if(unlikely(!*this))
return std::string{};
auto &mod(**this);
return mod.location();
}
std::string
ircd::mods::module::name()
const
{
if(unlikely(!*this))
return std::string{};
auto &mod(**this);
return mod.name();
}
template<> uint8_t *
ircd::mods::module::ptr<uint8_t>(const std::string &name)
{
auto &mod(**this);
return mod.ptr<uint8_t>(name);
}
template<>
const uint8_t *
ircd::mods::module::ptr<const uint8_t>(const std::string &name)
const
{
const auto &mod(**this);
return mod.ptr<const uint8_t>(name);
}
bool
ircd::mods::module::has(const std::string &name)
const
{
if(unlikely(!*this))
return false;
const auto &mod(**this);
return mod.has(name);
}
///////////////////////////////////////////////////////////////////////////////
//
// sym_ptr
//
ircd::mods::sym_ptr::sym_ptr(const std::string &modname,
const std::string &symname)
:std::weak_ptr<mod>
{
module(modname)
}
,ptr{[this, &modname, &symname]
{
const life_guard<mods::mod> mod(*this);
if(unlikely(!mod->has(symname)))
throw undefined_symbol("Could not find symbol '%s' in module '%s'", symname, mod->name());
return mod->ptr(symname);
}()}
{
}
ircd::mods::sym_ptr::~sym_ptr()
noexcept
{
}
///////////////////////////////////////////////////////////////////////////////
//
// misc
//
namespace ircd {
namespace mods {
} // namespace mods
} // namespace ircd
bool
ircd::mods::loaded(const std::string &name)
{
return mod::loaded.count(postfixed(name));
}
bool
ircd::mods::available(const std::string &name)
{
using filesystem::path;
std::vector<std::string> why;
return !search(name, why).empty();
}
std::string
ircd::mods::search(const std::string &name)
{
std::vector<std::string> why;
return search(name, why);
}
std::vector<std::string>
ircd::mods::find_symbol(const std::string &symbol)
{
std::vector<std::string> ret;
const auto av(available());
std::copy_if(begin(av), end(av), std::back_inserter(ret), [&symbol]
(const auto &name)
{
return has_symbol(name, symbol);
});
return ret;
}
bool
ircd::mods::has_symbol(const std::string &name,
const std::string &symbol)
{
const auto fullpath(search(name));
if(fullpath.empty())
return false;
const auto syms(symbols(fullpath));
return std::find(begin(syms), end(syms), symbol) != end(syms);
}
filesystem::path
ircd::mods::fullpath(const std::string &name)
{
std::vector<std::string> why;
const filesystem::path path(search(name, why));
if(path.empty())
{
for(const auto &str : why)
log.error("candidate for module '%s' failed: %s", name, str);
throw error("No valid module by name `%s'", name);
}
return path;
}
std::string
ircd::mods::search(const std::string &name,
std::vector<std::string> &why)
{
using filesystem::path;
const path path(postfixed(name));
if(!path.is_relative())
{
why.resize(why.size() + 1);
return is_module(path, why.back())? name : std::string{};
}
else for(const auto &dir : paths)
{
why.resize(why.size() + 1);
if(is_module(dir/path, why.back()))
return (dir/path).string();
}
return {};
}
std::forward_list<std::string>
ircd::mods::available()
{
using filesystem::path;
using filesystem::directory_iterator;
std::forward_list<std::string> ret;
for(const auto &dir : paths) try
{
for(directory_iterator it(dir); it != directory_iterator(); ++it)
if(is_module(it->path(), std::nothrow))
ret.emplace_front(relative(it->path(), dir).string());
}
catch(const filesystem::filesystem_error &e)
{
log.warning("Module path [%s]: %s", dir, e.what());
continue;
}
return ret;
}
bool
ircd::mods::is_module(const std::string &fullpath)
{
return is_module(filesystem::path(fullpath));
}
bool
ircd::mods::is_module(const std::string &fullpath,
std::nothrow_t)
{
return is_module(filesystem::path(fullpath), std::nothrow);
}
bool
ircd::mods::is_module(const std::string &fullpath,
std::string &why)
{
return is_module(filesystem::path(fullpath), why);
}
bool
ircd::mods::is_module(const filesystem::path &path,
std::nothrow_t)
try
{
return is_module(path);
}
catch(const std::exception &e)
{
return false;
}
bool
ircd::mods::is_module(const filesystem::path &path,
std::string &why)
try
{
return is_module(path);
}
catch(const std::exception &e)
{
why = e.what();
return false;
}
bool
ircd::mods::is_module(const filesystem::path &path)
{
if(!exists(path))
throw filesystem_error("`%s' does not exist", path.string());
if(!is_regular_file(path))
throw filesystem_error("`%s' is not a file", path.string());
const auto syms(symbols(path));
const auto &header_name(mapi::header_symbol_name);
const auto it(std::find(begin(syms), end(syms), header_name));
if(it == end(syms))
throw error("`%s': has no MAPI header (%s)", path.string(), header_name);
return true;
}
std::vector<std::string>
ircd::mods::sections(const std::string &fullpath)
{
return sections(filesystem::path(fullpath));
}
std::vector<std::string>
ircd::mods::symbols(const std::string &fullpath)
{
return symbols(filesystem::path(fullpath));
}
std::vector<std::string>
ircd::mods::symbols(const std::string &fullpath,
const std::string &section)
{
return symbols(filesystem::path(fullpath), section);
}
std::vector<std::string>
ircd::mods::sections(const filesystem::path &path)
{
return info<std::vector<std::string>>(path, []
(boost::dll::library_info &info)
{
return info.sections();
});
}
std::vector<std::string>
ircd::mods::symbols(const filesystem::path &path)
{
return info<std::vector<std::string>>(path, []
(boost::dll::library_info &info)
{
return info.symbols();
});
}
std::vector<std::string>
ircd::mods::symbols(const filesystem::path &path,
const std::string &section)
{
return info<std::vector<std::string>>(path, [&section]
(boost::dll::library_info &info)
{
return info.symbols(section);
});
}
template<class R,
class F>
R
ircd::mods::info(const filesystem::path &path,
F&& closure)
{
if(!exists(path))
throw filesystem_error("`%s' does not exist", path.string());
if(!is_regular_file(path))
throw filesystem_error("`%s' is not a file", path.string());
boost::dll::library_info info(path);
return closure(info);
}
///////////////////////////////////////////////////////////////////////////////
//
// paths
//
namespace ircd {
namespace mods {
const filesystem::path modroot
{
ircd::fs::get(ircd::fs::MODULES)
};
struct paths paths;
} // namespace mods
} // namespace ircd
ircd::mods::paths::paths()
:std::vector<std::string>
{{
modroot.string()
}}
{
}
bool
ircd::mods::paths::add(const std::string &dir)
{
using filesystem::path;
const path path(prefix_if_relative(dir));
if(!exists(path))
throw filesystem_error("path `%s' (%s) does not exist", dir, path.string());
if(!is_directory(path))
throw filesystem_error("path `%s' (%s) is not a directory", dir, path.string());
if(added(dir))
return false;
emplace(begin(), dir);
return true;
}
bool
ircd::mods::paths::add(const std::string &dir,
std::nothrow_t)
try
{
return add(dir);
}
catch(const std::exception &e)
{
log.error("Failed to add path: %s", e.what());
return false;
}
bool
ircd::mods::paths::del(const std::string &dir)
{
std::remove(begin(), end(), prefix_if_relative(dir).string());
return true;
}
bool
ircd::mods::paths::added(const std::string &dir)
const
{
return std::find(begin(), end(), dir) != end();
}
std::string
ircd::mods::unpostfixed(const std::string &name)
{
return unpostfixed(filesystem::path(name)).string();
}
std::string
ircd::mods::postfixed(const std::string &name)
{
return postfixed(filesystem::path(name)).string();
}
filesystem::path
ircd::mods::unpostfixed(const filesystem::path &path)
{
if(extension(path) != suffix)
return path;
return filesystem::path(path).replace_extension();
}
filesystem::path
ircd::mods::postfixed(const filesystem::path &path)
{
if(extension(path) == suffix)
return path;
filesystem::path ret(path);
return ret += suffix;
}
filesystem::path
ircd::mods::prefix_if_relative(const filesystem::path &path)
{
return path.is_relative()? (modroot / path) : path;
}
std::string
ircd::mods::demangle(const std::string &symbol)
{
size_t len;
int status;
const custom_ptr<char> buf
{
abi::__cxa_demangle(symbol.c_str(), nullptr, &len, &status),
std::free
};
switch(status)
{
case 0: break;
case -1: throw error("Demangle failed -1: memory allocation failure");
case -2: throw error("Demangle failed -2: mangled name is not valid");
case -3: throw error("Demangle failed -3: invalid argument");
default: throw error("Demangle failed %d: unknown error", status);
}
return { buf.get(), len };
}
///////////////////////////////////////////////////////////////////////////////
//
// mod (internal)
//
namespace ircd {
namespace mods {
std::stack<mod *> mod::loading;
std::map<std::string, mod *> mod::loaded;
} // namespace mods
} // namespace ircd
ircd::mods::mod::mod(const filesystem::path &path,
const load_mode::type &mode)
try
:path{path}
,mode{mode}
,handle{[this, &path, &mode]
{
const auto theirs
{
std::get_terminate()
};
const auto ours([]
{
log.critical("std::terminate() called during the static construction of a module.");
if(std::current_exception()) try
{
std::rethrow_exception(std::current_exception());
}
catch(const std::exception &e)
{
log.error("%s", e.what());
}
});
const scope reset{[this, &theirs]
{
assert(loading.top() == this);
loading.pop();
std::set_terminate(theirs);
}};
loading.push(this);
std::set_terminate(ours);
return boost::dll::shared_library{path, mode};
}()}
,header
{
&handle.get<mapi::header>(mapi::header_symbol_name)
}
{
log.debug("Loaded static segment of '%s' @ `%s'", name(), path.string());
if(unlikely(!header))
throw error("Unexpected null header");
if(header->magic != mapi::MAGIC)
throw error("Bad magic [%04x] need: [%04x]", header->magic, mapi::MAGIC);
// Set some basic metadata
auto &meta(header->meta);
meta["name"] = name();
meta["location"] = location();
if(!loading.empty())
{
const auto &m(mod::loading.top());
m->children.emplace_back(this);
log.debug("Module '%s' recursively loaded by '%s'",
name(),
m->path.filename().string());
}
// If init throws an exception from here the loading process will back out.
if(header->init)
header->init();
log.info("Loaded module %s v%u \"%s\" (depth: %zu)",
name(),
header->version,
description().size()? description() : "<no description>"s,
loading.size());
// Without init exception, the module is now considered loaded.
loaded.emplace(name(), this);
}
catch(const boost::system::system_error &e)
{
switch(e.code().value())
{
case boost::system::errc::bad_file_descriptor:
{
const string_view what(e.what());
const auto pos(what.find("undefined symbol: "));
if(pos == std::string_view::npos)
break;
const string_view msg(what.substr(pos));
const std::string mangled(between(msg, ": ", ")"));
const std::string demangled(demangle(mangled));
throw error("undefined symbol: '%s' (%s)",
demangled,
mangled);
}
default:
break;
}
throw error("%s", e.what());
}
// Allows module to communicate static destruction is taking place when mapi::header
// destructs. If dlclose() returns without this being set, dlclose() lied about really
// unloading the module. That is considered a "stuck" module.
bool ircd::mapi::static_destruction;
ircd::mods::mod::~mod()
noexcept try
{
unload();
}
catch(const std::exception &e)
{
log::critical("Module @%p unload: %s", (const void *)this, e.what());
if(!ircd::debugmode)
return;
}
bool
ircd::mods::mod::unload()
{
if(!handle.is_loaded())
return false;
const auto name(this->name());
log.debug("Attempting unload module '%s' @ `%s'", name, location());
const size_t erased(loaded.erase(name));
assert(erased == 1);
if(header->fini)
header->fini();
// Save the children! dlclose() does not like to be called recursively during static
// destruction of a module. The mod ctor recorded all of the modules loaded while this
// module was loading so we can reverse the record and unload them here.
// Note: If the user loaded more modules from inside their module they will have to dtor them
// before 'static destruction' does. They can also do that by adding them to this vector.
std::for_each(rbegin(this->children), rend(this->children), []
(mod *const &ptr)
{
if(shared_from(*ptr).use_count() <= 2)
ptr->unload();
});
log.debug("Attempting static unload for '%s' @ `%s'", name, location());
mapi::static_destruction = false;
handle.unload();
assert(!handle.is_loaded());
if(!mapi::static_destruction)
{
log.error("Module \"%s\" is stuck and failing to unload.", name);
log.warning("Module \"%s\" may result in undefined behavior if not fixed.", name);
} else {
log.info("Unloaded '%s'", name);
}
return true;
}
template<class T>
T *
ircd::mods::mod::ptr(const std::string &name)
{
return &handle.get<T>(name);
}
template<class T>
const T *
ircd::mods::mod::ptr(const std::string &name)
const
{
return &handle.get<T>(name);
}
template<class T>
T &
ircd::mods::mod::get(const std::string &name)
{
handle.get<T>(name);
}
template<class T>
const T &
ircd::mods::mod::get(const std::string &name)
const
{
handle.get<T>(name);
}
bool
ircd::mods::mod::has(const std::string &name)
const
{
return handle.has(name);
}