1 files changed, 75 insertions, 0 deletions
diff --git a/user/init.c b/user/init.c
new file mode 100644
index 0000000..18e70a2
--- /dev/null
+++ b/user/init.c
@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <unistd.h>
+
+#define MAX_ARGS 4
+
+struct proc {
+	pid_t pid;
+	const char *filename;
+	const char *args[MAX_ARGS];
+};
+
+static struct proc spawn_table[] = {
+	// apple
+	{ 0, "bin/apple", { NULL } },
+	// end,
+	{ 0, NULL, { NULL } },
+};
+
+static int spawn(const char *filename, const char **args)
+{
+	int ret;
+
+	// fork init
+	if ((ret = fork()) != 0)
+		return ret;
+
+	// call exec
+	if ((ret = exec(filename, args)))
+		exit(ret);
+
+	// should not happen!
+	exit(1);
+}
+
+int main(void)
+{
+	struct proc *proc;
+
+	// spawn our processes
+	for (proc = spawn_table; proc->filename != NULL; proc++) {
+		int pid;
+		pid = spawn(proc->filename, proc->args);
+		if (pid < 0)
+			fprintf(stderr, "init: cannot exec '%s': %d\n", proc->filename,
+					pid);
+		proc->pid = pid;
+	}
+
+	// clean up dead on restart ours
+	while (1) {
+		int pid, status;
+
+		pid = waitpid(0, &status);
+		if (pid < 0)
+			continue;
+
+		printf("init: pid %d exited with %d\n", pid, status);
+
+		// figure out if this is one of ours
+		for (proc = spawn_table; proc->filename != NULL; proc++) {
+			if (proc->pid == pid) {
+				proc->pid = 0;
+				pid = spawn(proc->filename, proc->args);
+				if (pid < 0)
+					fprintf(stderr, "init: cannot exec '%s': %d\n",
+							proc->filename, pid);
+				proc->pid = pid;
+				break;
+			}
+		}
+	}
+
+	// very very bad!
+	return 1;
+}