ladybird/Userland/Libraries/LibCore/SessionManagement.cpp
Andreas Kling 5dcc58d54a Kernel+LibCore: Make %sid path parsing not take ages
Before this patch, Core::SessionManagement::parse_path_with_sid() would
figure out the root session ID by sifting through /sys/kernel/processes.

That file can take quite a while to generate (sometimes up to 40ms on my
machine, which is a problem on its own!) and with no caching, many of
our programs were effectively doing this multiple times on startup when
unveiling something in /tmp/session/%sid/

While we should find ways to make generating /sys/kernel/processes fast
again, this patch addresses the specific problem by introducing a new
syscall: sys$get_root_session_id(). This extracts the root session ID
by looking directly at the process table and takes <1ms instead of 40ms.

This cuts WebContent process startup time by ~100ms on my machine. :^)
2023-01-10 19:32:31 +01:00

55 lines
1.5 KiB
C++

/*
* Copyright (c) 2022, Peter Elliott <pelliott@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibCore/Directory.h>
#include <LibCore/SessionManagement.h>
#include <LibCore/System.h>
#ifdef AK_OS_SERENITY
# include <LibSystem/syscall.h>
#endif
namespace Core::SessionManagement {
ErrorOr<pid_t> root_session_id([[maybe_unused]] Optional<pid_t> force_sid)
{
#ifdef AK_OS_SERENITY
int rc = syscall(SC_get_root_session_id, force_sid.value_or(-1));
if (rc < 0) {
return Error::from_syscall("get_root_session_id"sv, rc);
}
return static_cast<pid_t>(rc);
#else
return 0;
#endif
}
ErrorOr<void> logout(Optional<pid_t> force_sid)
{
pid_t sid = TRY(root_session_id(force_sid));
TRY(System::kill(-sid, SIGTERM));
return {};
}
ErrorOr<DeprecatedString> parse_path_with_sid(StringView general_path, Optional<pid_t> force_sid)
{
if (general_path.contains("%sid"sv)) {
pid_t sid = TRY(root_session_id(force_sid));
return general_path.replace("%sid"sv, DeprecatedString::number(sid), ReplaceMode::All);
}
return DeprecatedString(general_path);
}
ErrorOr<void> create_session_temporary_directory_if_needed(uid_t uid, gid_t gid, Optional<pid_t> force_sid)
{
pid_t sid = TRY(root_session_id(force_sid));
auto const temporary_directory = DeprecatedString::formatted("/tmp/session/{}", sid);
auto directory = TRY(Core::Directory::create(temporary_directory, Core::Directory::CreateDirectories::Yes));
TRY(directory.chown(uid, gid));
return {};
}
}