libc: Adapt libc to getprocid() + add getppid()

Now, we have one single system call to fetch all sorts of identifiers:
PID, PPID, UID, GID; EUID, EGID, and more...

apps/src/init.c

@@ -64,7 +64,7 @@ int main()
 
     printf("Welcome to Luna!\n");
 
-    printf("Running as PID %ld\n\n", getpid());
+    printf("Running as PID %ld, PPID %ld\n\n", getpid(), getppid());
 
     sleep(1);
 
@@ -163,7 +163,7 @@ int main()
     if (child == 0)
     {
         msleep(500);
-        printf("I am the child, who is my parent?\n");
+        printf("I am the child (PID %ld), my parent is PID %ld!!\n", getpid(), getppid());
         execv("/bin/sym", NULL);
         perror("execv");
         return 1;

kernel/include/sys/Syscall.h

@@ -7,7 +7,7 @@
 #define SYS_sleep 2
 #define SYS_write 3
 #define SYS_paint 4
-#define SYS_getpid 5
+#define SYS_getprocid 5
 #define SYS_mmap 6
 #define SYS_munmap 7
 #define SYS_open 8
@@ -33,7 +33,7 @@ void sys_yield(Context* context);
 void sys_sleep(Context* context, uint64_t ms);
 void sys_write(Context* context, int fd, size_t size, const char* addr);
 void sys_paint(Context* context, uint64_t x, uint64_t y, uint64_t w, uint64_t h, uint64_t col);
-void sys_getpid(Context* context);
+void sys_getprocid(Context* context, int field);
 void sys_mmap(Context* context, void* address, size_t size, int prot);
 void sys_munmap(Context* context, void* address, size_t size);
 void sys_open(Context* context, const char* filename, int flags);

kernel/src/sys/Syscall.cpp

@@ -16,7 +16,7 @@ void Syscall::entry(Context* context)
     case SYS_sleep: sys_sleep(context, context->rdi); break;
     case SYS_write: sys_write(context, (int)context->rdi, context->rsi, (const char*)context->rdx); break;
     case SYS_paint: sys_paint(context, context->rdi, context->rsi, context->rdx, context->r10, context->r8); break;
-    case SYS_getpid: sys_getpid(context); break;
+    case SYS_getprocid: sys_getprocid(context, (int)context->rdi); break;
     case SYS_mmap: sys_mmap(context, (void*)context->rdi, context->rsi, (int)context->rdx); break;
     case SYS_munmap: sys_munmap(context, (void*)context->rdi, context->rsi); break;
     case SYS_open: sys_open(context, (const char*)context->rdi, (int)context->rsi); break;

kernel/src/sys/id.cpp

@@ -0,0 +1,24 @@
+#include "errno.h"
+#include "thread/Scheduler.h"
+
+#define ID_PID 0
+#define ID_PPID 1
+
+void sys_getprocid(Context* context, int field)
+{
+    if (field == ID_PID)
+    {
+        context->rax = Scheduler::current_task()->id;
+        return;
+    }
+    else if (field == ID_PPID)
+    {
+        context->rax = Scheduler::current_task()->ppid;
+        return;
+    }
+    else
+    {
+        context->rax = -EINVAL;
+        return;
+    }
+}

kernel/src/sys/sched.cpp

@@ -18,9 +18,4 @@ void sys_sleep(Context* context, uint64_t ms)
     task->task_sleep = ms;
     task->state = task->Sleeping;
     Scheduler::task_yield(context);
-}
-
-void sys_getpid(Context* context)
-{
-    context->rax = Scheduler::current_task()->id;
 }

libs/libc/include/bits/getprocid.h

@@ -0,0 +1,7 @@
+#ifndef _BITS_GETPROCID_H
+#define _BITS_GETPROCID_H
+
+#define ID_PID 0
+#define ID_PPID 1
+
+#endif

libs/libc/include/luna.h

@@ -1,6 +1,7 @@
 #ifndef _LUNA_H
 #define _LUNA_H
 
+#include <bits/getprocid.h>
 #include <bits/macros.h>
 #include <sys/types.h>
 
@@ -9,6 +10,9 @@ extern "C"
 {
 #endif
 
+    /* Returns a numeric identifier associated with the current process, depending on field. */
+    long getprocid(int field);
+
     /* Sleeps for ms milliseconds. */
     unsigned int msleep(unsigned int ms);
 

libs/libc/include/luna/syscall.h

@@ -6,7 +6,7 @@
 #define SYS_sleep 2
 #define SYS_write 3
 #define SYS_paint 4
-#define SYS_getpid 5
+#define SYS_getprocid 5
 #define SYS_mmap 6
 #define SYS_munmap 7
 #define SYS_open 8

libs/libc/include/unistd.h

@@ -27,9 +27,12 @@ extern "C"
      * the parent. */
     pid_t fork(void);
 
-    /* Returns the current process's process ID. */
+    /* Returns the current process' process ID. */
     pid_t getpid(void);
 
+    /* Returns the current process' parent's process ID. */
+    pid_t getppid(void);
+
     /* Terminates the program with the status code status. */
     __lc_noreturn void _exit(int status);
 

libs/libc/src/luna.cpp

@@ -7,6 +7,11 @@
 
 extern "C"
 {
+    long getprocid(int field)
+    {
+        return syscall(SYS_getprocid, field);
+    }
+
     unsigned int msleep(unsigned int ms)
     {
         return (unsigned int)syscall(SYS_sleep, ms);

libs/libc/src/unistd.cpp

@@ -27,7 +27,12 @@ extern "C"
 
     pid_t getpid(void)
     {
-        return syscall(SYS_getpid);
+        return getprocid(ID_PID);
+    }
+
+    pid_t getppid(void)
+    {
+        return getprocid(ID_PPID);
     }
 
     long syscall(long number, ...)
@@ -40,9 +45,9 @@ extern "C"
         {
         case SYS_clock:
         case SYS_yield:
-        case SYS_fork:
-        case SYS_getpid: result = __luna_syscall0(number); break;
+        case SYS_fork: result = __luna_syscall0(number); break;
         case SYS_exit:
+        case SYS_getprocid:
         case SYS_close:
         case SYS_exec:
         case SYS_mkdir: