Kernel+LibC+UE: Implement sleep() via sys$clock_nanosleep()

This doesn't need to be its own syscall either. :^)

DevTools/UserspaceEmulator/Emulator.cpp

@@ -256,8 +256,6 @@ u32 Emulator::virt_syscall(u32 function, u32 arg1, u32 arg2, u32 arg3)
         return virt$setpgid(arg1, arg2);
     case SC_execve:
         return virt$execve(arg1);
-    case SC_sleep:
-        return virt$sleep(arg1);
     case SC_sigaction:
         return virt$sigaction(arg1, arg2, arg3);
     case SC_sigreturn:
@@ -1055,11 +1053,6 @@ int Emulator::virt$sigaction(int signum, FlatPtr act, FlatPtr oldact)
     return 0;
 }
 
-int Emulator::virt$sleep(unsigned seconds)
-{
-    return syscall(SC_sleep, seconds);
-}
-
 int Emulator::virt$sigreturn()
 {
     u32 stack_ptr = m_cpu.esp().value();

DevTools/UserspaceEmulator/Emulator.h

@@ -135,7 +135,6 @@ private:
     int virt$connect(int sockfd, FlatPtr address, socklen_t address_size);
     void virt$exit(int);
     ssize_t virt$getrandom(FlatPtr buffer, size_t buffer_size, unsigned int flags);
-    int virt$sleep(unsigned);
     int virt$chdir(FlatPtr, size_t);
     int virt$dup2(int, int);
     int virt$getpgrp();

Kernel/API/Syscall.h

@@ -48,7 +48,6 @@ typedef u32 socklen_t;
 namespace Kernel {
 
 #define ENUMERATE_SYSCALLS(S) \
-    S(sleep)                  \
     S(yield)                  \
     S(open)                   \
     S(close)                  \

Kernel/CMakeLists.txt

@@ -144,7 +144,6 @@ set(KERNEL_SOURCES
     Syscalls/shbuf.cpp
     Syscalls/shutdown.cpp
     Syscalls/sigaction.cpp
-    Syscalls/sleep.cpp
     Syscalls/socket.cpp
     Syscalls/stat.cpp
     Syscalls/sync.cpp

Kernel/Syscalls/sleep.cpp

@@ -1,45 +0,0 @@
-/*
- * 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/Time/TimeManagement.h>
-
-namespace Kernel {
-
-int Process::sys$sleep(unsigned seconds)
-{
-    REQUIRE_PROMISE(stdio);
-    if (!seconds)
-        return 0;
-    u64 wakeup_time = Thread::current()->sleep(seconds * TimeManagement::the().ticks_per_second());
-    if (wakeup_time > g_uptime) {
-        u32 ticks_left_until_original_wakeup_time = wakeup_time - g_uptime;
-        return ticks_left_until_original_wakeup_time / TimeManagement::the().ticks_per_second();
-    }
-    return 0;
-}
-
-}

Libraries/LibC/unistd.cpp

@@ -332,7 +332,10 @@ char* getwd(char* buf)
 
 int sleep(unsigned seconds)
 {
-    return syscall(SC_sleep, seconds);
+    struct timespec ts = { seconds, 0 };
+    if (clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, &ts) < 0)
+        return ts.tv_sec;
+    return 0;
 }
 
 int usleep(useconds_t usec)