await() 1: wait for child to die, without message passing

The length is a int, because the syscall will have a signed output. A
negative return value will mean an error (such as when it gets called
by a childless process).

1 files changed, 6 insertions, 0 deletions

diff --git a/src/kernel/syscalls.h b/src/kernel/syscalls.h
index d3ad2a8..a986a33 100644
--- a/src/kernel/syscalls.h
+++ b/src/kernel/syscalls.h
@@ -5,6 +5,7 @@
 enum {
 	// idc about stable syscall numbers just yet
 	_SYSCALL_EXIT,
+	_SYSCALL_AWAIT,
 	_SYSCALL_FORK,
 
 	_SYSCALL_DEBUGLOG
@@ -15,6 +16,11 @@ enum {
  */
 _Noreturn void _syscall_exit(const char *msg, size_t len);
 
+/** Waits for a child to exit, putting its exit message into *buf.
+ * @return the length of the message
+ */
+int _syscall_await(char *buf, int *len);
+
 /** Creates a copy of the current process, and executes it.
  * All user memory pages get copied too.
  * @return 0 in the child, a meaningless positive value in the parent.