From e3e661e7e5ad8e572cefcd79dca74c96f7e97a79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Fri, 24 Feb 2017 15:30:45 +0100
Subject: [PATCH] [USER] Exit and wait syscalls

---
 init/init.c               | 26 +++++++++++++++++--------
 kernel/include/syscall.h  |  2 ++
 kernel/syscall/sys_proc.c | 41 ++++++++++++++++++++++++++++++++++++++-
 kernel/syscall/syscall.c  |  2 ++
 libc/syscall_num.h        |  2 ++
 libc/thread.c             | 12 ++++++++++++
 6 files changed, 76 insertions(+), 9 deletions(-)

diff --git a/init/init.c b/init/init.c
index 425ecc7..79833ec 100644
--- a/init/init.c
+++ b/init/init.c
@@ -1,22 +1,32 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <sys/wait.h>
 int main(int argc, char **argv)
 {
   (void) argc;
   (void) argv;
 
-  int num = 5;
-
-  if(fork())
+  if(!fork())
   {
-    num = 10;
-    printf("I am the parent! - %d\n", num);
-  } else {
-    num = 3;
-    printf("I am the child! - %d\n", num);
+    if(!fork())
+      return 200;
+    return 100;
   }
 
+  for(int j=0; j <= 10; j++)
+  {
+    if(!fork())
+      return j;
+  }
+  while(1)
+  {
+    int retval;
+    int pid = wait(&retval);
+    printf("Pid: %d exited with %d\n", pid, retval);
+  }
+
+
   for(;;);
   return 0;
 }
diff --git a/kernel/include/syscall.h b/kernel/include/syscall.h
index 3eb2368..8ef4f02 100644
--- a/kernel/include/syscall.h
+++ b/kernel/include/syscall.h
@@ -43,3 +43,5 @@ typedef long (*syscall_handler_t)(long num, long, long, long, long, long, long);
 SYSCALL_DECL(write);
 SYSCALL_DECL(brk);
 SYSCALL_DECL(fork);
+SYSCALL_DECL(exit);
+SYSCALL_DECL(wait);
diff --git a/kernel/syscall/sys_proc.c b/kernel/syscall/sys_proc.c
index adae757..7499d67 100644
--- a/kernel/syscall/sys_proc.c
+++ b/kernel/syscall/sys_proc.c
@@ -3,6 +3,9 @@
 #include <thread.h>
 #include <scheduler.h>
 #include <string.h>
+#include <mem.h>
+#include <debug.h>
+#include <list.h>
 
 SYSCALL_DEF(fork)
 {
@@ -23,5 +26,41 @@ SYSCALL_DEF(fork)
 
   // Return new pid
   return new->pid;
-
+}
+
+__attribute__((noreturn)) SYSCALL_DEF(exit)
+{
+  SYSCALL_INIT(int, status);
+
+  process_t *proc = get_current_process();
+
+  process_exit(proc, status);
+
+  schedule();
+  debug_error("PANIC - This line should be unreachable (%s:%d)\n", __FILE__, __LINE__);
+  for(;;);
+}
+
+SYSCALL_DEF(wait)
+{
+  SYSCALL_INIT(int *, status);
+
+  process_t *proc = get_current_process();
+  int pid = 0;
+  while(!pid)
+  {
+    LIST_FOREACH(proc->children, process_t, p, siblings)
+    {
+      if(p->state == PROC_STATE_ZOMBIE)
+      {
+        pid = p->pid;
+        *status = p->status;
+        // Destroy the process
+        process_free(p);
+        break;
+      }
+    }
+    schedule();
+  }
+  return pid;
 }
diff --git a/kernel/syscall/syscall.c b/kernel/syscall/syscall.c
index 9de60da..b9b03ed 100644
--- a/kernel/syscall/syscall.c
+++ b/kernel/syscall/syscall.c
@@ -59,6 +59,8 @@ void syscall_init()
     SYSCALL_REGISTER(write, SYS_WRITE);
     SYSCALL_REGISTER(brk, SYS_BRK);
     SYSCALL_REGISTER(fork, SYS_FORK);
+    SYSCALL_REGISTER(exit, SYS_EXIT);
+    SYSCALL_REGISTER(wait, SYS_WAIT);
   }
 
 }
diff --git a/libc/syscall_num.h b/libc/syscall_num.h
index 01da47e..0ab8f51 100644
--- a/libc/syscall_num.h
+++ b/libc/syscall_num.h
@@ -3,4 +3,6 @@
 #define SYS_WRITE 0x001
 #define SYS_BRK   0x002
 #define SYS_FORK  0x003
+#define SYS_EXIT  0x004
+#define SYS_WAIT  0x005
 #define SYS_DEBUG 0x3FF
diff --git a/libc/thread.c b/libc/thread.c
index 7397af7..1e77f5d 100644
--- a/libc/thread.c
+++ b/libc/thread.c
@@ -42,3 +42,15 @@ SYSCALL_DEF(gettid)
   SYSCALL_INIT();
   return 0;
 }
+
+SYSCALL_DEF(exit_group)
+{
+  SYSCALL_INIT(int, result);
+  return kernel_syscall(SYS_EXIT, result);
+}
+
+SYSCALL_DEF(wait4)
+{
+  SYSCALL_INIT(int, pid, int *, result, int, options, void *, rusage);
+  return kernel_syscall(SYS_WAIT, result);
+}