Kernel: Move syscall implementations out of Process.cpp

This is something I've been meaning to do for a long time, and here we
finally go. This patch moves all sys$foo functions out of Process.cpp
and into files in Kernel/Syscalls/.

It's not exactly one syscall per file (although it could be, but I got
a bit tired of the repetitive work here..)

This makes hacking on individual syscalls a lot less painful since you
don't have to rebuild nearly as much code every time. I'm also hopeful
that this makes it easier to understand individual syscalls. :^)

1 files changed, 159 insertions, 0 deletions

diff --git a/Kernel/Syscalls/kill.cpp b/Kernel/Syscalls/kill.cpp
new file mode 100644
index 0000000000..dd651bc90a
--- /dev/null
+++ b/Kernel/Syscalls/kill.cpp
@@ -0,0 +1,159 @@
+/*
+ * 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>
+
+namespace Kernel {
+
+KResult Process::do_kill(Process& process, int signal)
+{
+    // FIXME: Allow sending SIGCONT to everyone in the process group.
+    // FIXME: Should setuid processes have some special treatment here?
+    if (!is_superuser() && m_euid != process.m_uid && m_uid != process.m_uid)
+        return KResult(-EPERM);
+    if (process.is_ring0() && signal == SIGKILL) {
+        klog() << "attempted to send SIGKILL to ring 0 process " << process.name().characters() << "(" << process.pid() << ")";
+        return KResult(-EPERM);
+    }
+    if (signal != 0)
+        return process.send_signal(signal, this);
+    return KSuccess;
+}
+
+KResult Process::do_killpg(pid_t pgrp, int signal)
+{
+    InterruptDisabler disabler;
+
+    ASSERT(pgrp >= 0);
+
+    // Send the signal to all processes in the given group.
+    if (pgrp == 0) {
+        // Send the signal to our own pgrp.
+        pgrp = pgid();
+    }
+
+    bool group_was_empty = true;
+    bool any_succeeded = false;
+    KResult error = KSuccess;
+
+    Process::for_each_in_pgrp(pgrp, [&](auto& process) {
+        group_was_empty = false;
+
+        KResult res = do_kill(process, signal);
+        if (res.is_success())
+            any_succeeded = true;
+        else
+            error = res;
+
+        return IterationDecision::Continue;
+    });
+
+    if (group_was_empty)
+        return KResult(-ESRCH);
+    if (any_succeeded)
+        return KSuccess;
+    return error;
+}
+
+KResult Process::do_killall(int signal)
+{
+    InterruptDisabler disabler;
+
+    bool any_succeeded = false;
+    KResult error = KSuccess;
+
+    // Send the signal to all processes we have access to for.
+    ScopedSpinLock lock(g_processes_lock);
+    for (auto& process : *g_processes) {
+        KResult res = KSuccess;
+        if (process.pid() == m_pid)
+            res = do_killself(signal);
+        else
+            res = do_kill(process, signal);
+
+        if (res.is_success())
+            any_succeeded = true;
+        else
+            error = res;
+    }
+
+    if (any_succeeded)
+        return KSuccess;
+    return error;
+}
+
+KResult Process::do_killself(int signal)
+{
+    if (signal == 0)
+        return KSuccess;
+
+    auto current_thread = Thread::current();
+    if (!current_thread->should_ignore_signal(signal)) {
+        current_thread->send_signal(signal, this);
+        (void)current_thread->block<Thread::SemiPermanentBlocker>(Thread::SemiPermanentBlocker::Reason::Signal);
+    }
+
+    return KSuccess;
+}
+
+int Process::sys$kill(pid_t pid, int signal)
+{
+    if (pid == m_pid)
+        REQUIRE_PROMISE(stdio);
+    else
+        REQUIRE_PROMISE(proc);
+
+    if (signal < 0 || signal >= 32)
+        return -EINVAL;
+    if (pid < -1) {
+        if (pid == NumericLimits<i32>::min())
+            return -EINVAL;
+        return do_killpg(-pid, signal);
+    }
+    if (pid == -1)
+        return do_killall(signal);
+    if (pid == m_pid) {
+        return do_killself(signal);
+    }
+    ScopedSpinLock lock(g_processes_lock);
+    auto* peer = Process::from_pid(pid);
+    if (!peer)
+        return -ESRCH;
+    return do_kill(*peer, signal);
+}
+
+int Process::sys$killpg(int pgrp, int signum)
+{
+    REQUIRE_PROMISE(proc);
+    if (signum < 1 || signum >= 32)
+        return -EINVAL;
+    if (pgrp < 0)
+        return -EINVAL;
+
+    return do_killpg(pgrp, signum);
+}
+
+}