kernel: spawn: Add support for SPAWN_WAIT flag

Add SPAWN_WAIT flag that causes spawn() to wait until the child process
completes.

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 33 insertions, 1 deletions

diff --git a/sys/include/sys/spawn.h b/sys/include/sys/spawn.h
index 3828d5c..9d823db 100644
--- a/sys/include/sys/spawn.h
+++ b/sys/include/sys/spawn.h
@@ -31,6 +31,9 @@
 #define _SYS_SPAWN_H_
 
 #include <sys/types.h>
+#include <sys/param.h>
+
+#define SPAWN_WAIT BIT(0)
 
 #if !defined(_KERNEL)
 pid_t spawn(const char *pathname, int flags);
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index a421e52..b6cbc4e 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -111,6 +111,7 @@ int
 exit1(struct proc *td, int flags)
 {
     struct proc *curtd, *procp;
+    struct proc *parent;
     struct cpu_info *ci;
     pid_t target_pid, curpid;
 
@@ -120,6 +121,7 @@ exit1(struct proc *td, int flags)
 
     curpid = curtd->pid;
     td->flags |= PROC_EXITING;
+    parent = td->parent;
 
     /* If we have any children, kill them too */
     if (td->nleaves > 0) {
@@ -149,6 +151,13 @@ exit1(struct proc *td, int flags)
      */
     if (target_pid == curpid) {
         ci->curtd = NULL;
+        if (parent->pid == 0)
+            sched_enter();
+        if (td->data == NULL)
+            sched_enter();
+
+        sched_enqueue_td(parent);
+        parent->flags &= ~PROC_SLEEP;
         sched_enter();
     }
 
@@ -163,6 +172,7 @@ sys_exit(struct syscall_args *scargs)
 {
     struct proc *td = this_td();
 
+    td->data = scargs->tf;
     td->exit_status = scargs->arg0;
     exit1(td, 0);
     __builtin_unreachable();
diff --git a/sys/kern/kern_spawn.c b/sys/kern/kern_spawn.c
index 3360443..d72eeae 100644
--- a/sys/kern/kern_spawn.c
+++ b/sys/kern/kern_spawn.c
@@ -111,6 +111,7 @@ spawn(struct proc *cur, void(*func)(void), void *p, int flags, struct proc **new
     struct proc *newproc;
     struct mmap_lgdr *mlgdr;
     int error;
+    pid_t pid;
 
     newproc = dynalloc(sizeof(*newproc));
     if (newproc == NULL) {
@@ -161,7 +162,25 @@ spawn(struct proc *cur, void(*func)(void), void *p, int flags, struct proc **new
     newproc->pid = ++nthreads;
     signals_init(newproc);
     sched_enqueue_td(newproc);
-    return newproc->pid;
+    pid = newproc->pid;
+
+    if (ISSET(flags, SPAWN_WAIT)) {
+        newproc->flags |= PROC_WAITED;
+        cur->flags |= PROC_SLEEP;
+
+        while (ISSET(cur->flags, PROC_SLEEP)) {
+            sched_yield();
+        }
+
+        if (!ISSET(newproc->flags, PROC_ZOMB)) {
+            pr_error("spawn: fatal: %d not zombie\n");
+            panic("possibly memory corruption\n");
+        }
+
+        proc_reap(newproc);
+    }
+
+    return pid;
 }
 
 /*