ladybird/Kernel/Syscalls/setpgid.cpp
AnotherTest 688e54eac7 Kernel: Distinguish between new and old process groups with equal pgids
This does not add any behaviour change to the processes, but it ties a
TTY to an active process group via TIOCSPGRP, and returns the TTY to the
kernel when all processes in the process group die.
Also makes the TTY keep a link to the original controlling process' parent (for
SIGCHLD) instead of the process itself.
2020-08-19 21:21:34 +02:00

142 lines
4.9 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <Kernel/Process.h>
#include <Kernel/TTY/TTY.h>
namespace Kernel {
pid_t Process::sys$getsid(pid_t pid)
{
REQUIRE_PROMISE(proc);
if (pid == 0)
return m_sid.value();
ScopedSpinLock lock(g_processes_lock);
auto process = Process::from_pid(pid);
if (!process)
return -ESRCH;
if (m_sid != process->m_sid)
return -EPERM;
return process->m_sid.value();
}
pid_t Process::sys$setsid()
{
REQUIRE_PROMISE(proc);
InterruptDisabler disabler;
bool found_process_with_same_pgid_as_my_pid = false;
Process::for_each_in_pgrp(pid().value(), [&](auto&) {
found_process_with_same_pgid_as_my_pid = true;
return IterationDecision::Break;
});
if (found_process_with_same_pgid_as_my_pid)
return -EPERM;
// Create a new Session and a new ProcessGroup.
m_sid = m_pid.value();
m_pg = ProcessGroup::create(ProcessGroupID(m_pid.value()));
m_tty = nullptr;
return m_sid.value();
}
pid_t Process::sys$getpgid(pid_t pid)
{
REQUIRE_PROMISE(proc);
if (pid == 0)
return pgid().value();
ScopedSpinLock lock(g_processes_lock); // FIXME: Use a ProcessHandle
auto process = Process::from_pid(pid);
if (!process)
return -ESRCH;
return process->pgid().value();
}
pid_t Process::sys$getpgrp()
{
REQUIRE_PROMISE(stdio);
return pgid().value();
}
SessionID Process::get_sid_from_pgid(ProcessGroupID pgid)
{
// FIXME: This xor sys$setsid() uses the wrong locking mechanism.
ScopedSpinLock lock(g_processes_lock);
SessionID sid { -1 };
Process::for_each_in_pgrp(pgid, [&](auto& process) {
sid = process.sid();
return IterationDecision::Break;
});
return sid;
}
int Process::sys$setpgid(pid_t specified_pid, pid_t specified_pgid)
{
REQUIRE_PROMISE(proc);
ScopedSpinLock lock(g_processes_lock); // FIXME: Use a ProcessHandle
ProcessID pid = specified_pid ? ProcessID(specified_pid) : m_pid;
if (specified_pgid < 0) {
// The value of the pgid argument is less than 0, or is not a value supported by the implementation.
return -EINVAL;
}
auto process = Process::from_pid(pid);
if (!process)
return -ESRCH;
if (process != this && process->ppid() != m_pid) {
// The value of the pid argument does not match the process ID
// of the calling process or of a child process of the calling process.
return -ESRCH;
}
if (process->is_session_leader()) {
// The process indicated by the pid argument is a session leader.
return -EPERM;
}
if (process->ppid() == m_pid && process->sid() != sid()) {
// The value of the pid argument matches the process ID of a child
// process of the calling process and the child process is not in
// the same session as the calling process.
return -EPERM;
}
ProcessGroupID new_pgid = specified_pgid ? ProcessGroupID(specified_pgid) : process->m_pid.value();
SessionID current_sid = sid();
SessionID new_sid = get_sid_from_pgid(new_pgid);
if (new_sid != -1 && current_sid != new_sid) {
// Can't move a process between sessions.
return -EPERM;
}
if (new_sid == -1 && new_pgid != process->m_pid.value()) {
// The value of the pgid argument is valid, but is not
// the calling pid, and is not an existing process group.
return -EPERM;
}
// FIXME: There are more EPERM conditions to check for here..
process->m_pg = ProcessGroup::find_or_create(new_pgid);
return 0;
}
}