From 1506331872d713eea24e775c8be34fe83233fb27 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Thu, 18 May 2023 21:48:47 +0200
Subject: [PATCH] kernel+libc: Add the pstat() system call

Luna-specific, but I like it.
---
 kernel/CMakeLists.txt          |  1 +
 kernel/src/sys/pstat.cpp       | 41 ++++++++++++++++++++++++++++++++++
 libc/CMakeLists.txt            |  1 +
 libc/include/bits/pstat.h      | 34 ++++++++++++++++++++++++++++
 libc/include/sys/pstat.h       | 23 +++++++++++++++++++
 libc/src/sys/pstat.cpp         | 26 +++++++++++++++++++++
 libluna/include/luna/Syscall.h |  2 +-
 7 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 kernel/src/sys/pstat.cpp
 create mode 100644 libc/include/bits/pstat.h
 create mode 100644 libc/include/sys/pstat.h
 create mode 100644 libc/src/sys/pstat.cpp

diff --git a/kernel/CMakeLists.txt b/kernel/CMakeLists.txt
index ff1e593c..e7f79232 100644
--- a/kernel/CMakeLists.txt
+++ b/kernel/CMakeLists.txt
@@ -31,6 +31,7 @@ set(SOURCES
     src/sys/file.cpp
     src/sys/id.cpp
     src/sys/mkdir.cpp
+    src/sys/pstat.cpp
     src/sys/waitpid.cpp
     src/sys/getdents.cpp
     src/sys/stat.cpp
diff --git a/kernel/src/sys/pstat.cpp b/kernel/src/sys/pstat.cpp
new file mode 100644
index 00000000..5e9fd584
--- /dev/null
+++ b/kernel/src/sys/pstat.cpp
@@ -0,0 +1,41 @@
+#include "memory/MemoryManager.h"
+#include "sys/Syscall.h"
+#include "thread/Scheduler.h"
+#include <bits/pstat.h>
+
+static void set_timespec(struct timespec& ts, u64 ticks)
+{
+    ts.tv_sec = ticks / 1000;
+    ts.tv_nsec = (ticks % 1000) * 1000 * 1000;
+}
+
+Result<u64> sys_pstat(Registers*, SyscallArgs args)
+{
+    pid_t pid = (pid_t)args[0];
+    struct process* ps = (struct process*)args[1];
+
+    // If pid == -1, return the PID of the last spawned thread.
+    if (pid == -1) return g_threads.expect_last()->id;
+
+    auto* thread = TRY(Result<Thread*>::from_option(Scheduler::find_by_pid(pid), ESRCH));
+
+    struct process proc;
+    proc.ps_pid = (pid_t)thread->id;
+    proc.ps_ppid = thread->parent ? (pid_t)thread->parent->id : 0;
+    proc.ps_uid = thread->auth.uid;
+    proc.ps_gid = thread->auth.gid;
+    proc.ps_euid = thread->auth.euid;
+    proc.ps_egid = thread->auth.egid;
+    proc.ps_state = (int)thread->state;
+    proc.ps_flags = thread->is_kernel ? PS_FLAG_KRNL : 0;
+    set_timespec(proc.ps_time, thread->ticks);
+    set_timespec(proc.ps_ktime, thread->ticks_in_kernel);
+    set_timespec(proc.ps_utime, thread->ticks_in_user);
+    strlcpy(proc.ps_name, thread->name.chars(), sizeof(proc.ps_name));
+    strlcpy(proc.ps_cwd, thread->current_directory_path.is_empty() ? "/" : thread->current_directory_path.chars(),
+            sizeof(proc.ps_cwd));
+
+    if (!MemoryManager::copy_to_user_typed(ps, &proc)) return err(EFAULT);
+
+    return (u64)pid;
+}
diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
index e781678e..1123601d 100644
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -25,6 +25,7 @@ set(SOURCES
     src/sys/ioctl.cpp
     src/sys/utsname.cpp
     src/sys/mount.cpp
+    src/sys/pstat.cpp
 )
 
 if(${LUNA_ARCH} STREQUAL "x86_64")
diff --git a/libc/include/bits/pstat.h b/libc/include/bits/pstat.h
new file mode 100644
index 00000000..043b3136
--- /dev/null
+++ b/libc/include/bits/pstat.h
@@ -0,0 +1,34 @@
+/* bits/pstat.h: The process structure and flags for the pstat() system call. */
+
+#ifndef _BITS_PSTAT_H
+#define _BITS_PSTAT_H
+
+#include <bits/timespec.h>
+#include <sys/types.h>
+
+#define PS_IDLE 1
+#define PS_RUNNABLE 2
+#define PS_SLEEPING 3
+#define PS_WAITING 4
+#define PS_ENDED 5
+
+#define PS_FLAG_KRNL 1
+
+struct process
+{
+    pid_t ps_pid;
+    pid_t ps_ppid;
+    uid_t ps_uid;
+    uid_t ps_euid;
+    gid_t ps_gid;
+    gid_t ps_egid;
+    int ps_state;
+    int ps_flags;
+    struct timespec ps_time;
+    struct timespec ps_ktime;
+    struct timespec ps_utime;
+    char ps_name[129];
+    char ps_cwd[256];
+};
+
+#endif
diff --git a/libc/include/sys/pstat.h b/libc/include/sys/pstat.h
new file mode 100644
index 00000000..6d278b28
--- /dev/null
+++ b/libc/include/sys/pstat.h
@@ -0,0 +1,23 @@
+/* sys/pstat.h: The pstat() system call. */
+
+#ifndef _SYS_PSTAT_H
+#define _SYS_PSTAT_H
+
+#include <bits/pstat.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /* Retrieve information about a process. */
+    pid_t pstat(pid_t pid, struct process* ps);
+
+    /* Get a string representing a process' state. */
+    const char* ps_state_name(int state);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/libc/src/sys/pstat.cpp b/libc/src/sys/pstat.cpp
new file mode 100644
index 00000000..9aa97fae
--- /dev/null
+++ b/libc/src/sys/pstat.cpp
@@ -0,0 +1,26 @@
+#include <bits/errno-return.h>
+#include <sys/pstat.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+extern "C"
+{
+    pid_t pstat(pid_t pid, struct process* ps)
+    {
+        long rc = syscall(SYS_pstat, pid, ps);
+        __errno_return(rc, pid_t);
+    }
+
+    const char* ps_state_name(int state)
+    {
+        switch (state)
+        {
+        case PS_IDLE: return "Idle";
+        case PS_RUNNABLE: return "Running";
+        case PS_SLEEPING: return "Sleeping";
+        case PS_WAITING: return "Waiting";
+        case PS_ENDED: return "Zombie";
+        default: return "???";
+        }
+    }
+}
diff --git a/libluna/include/luna/Syscall.h b/libluna/include/luna/Syscall.h
index 763ed8e5..a219df64 100644
--- a/libluna/include/luna/Syscall.h
+++ b/libluna/include/luna/Syscall.h
@@ -5,7 +5,7 @@
         _e(lseek) _e(mkdir) _e(execve) _e(fork) _e(waitpid) _e(getppid) _e(fcntl) _e(getdents) _e(getuid) _e(geteuid)  \
             _e(getgid) _e(getegid) _e(setuid) _e(setgid) _e(seteuid) _e(setegid) _e(fchmodat) _e(fchownat) _e(ioctl)   \
                 _e(fstatat) _e(chdir) _e(getcwd) _e(unlinkat) _e(uname) _e(sethostname) _e(dup2) _e(pipe) _e(mount)    \
-                    _e(umount)
+                    _e(umount) _e(pstat)
 
 enum Syscalls
 {