4 files changed, 69 insertions, 6 deletions
diff --git a/sys/rt/atexit.c b/sys/rt/atexit.c
new file mode 100644
index 0000000..208cc6e
--- /dev/null
+++ b/sys/rt/atexit.c
@@ -0,0 +1,49 @@
+#include <u.h>
+#include <rt.h>
+
+#define COUNT 32
+
+static struct cleaner
+{
+    struct cleaner *next;
+    void (*clean[COUNT])(void *);
+    void *arg[COUNT];
+} arena, *head;
+static int slot;
+
+void weaklink exit(int code){};
+
+void
+rt·clean(void)
+{
+    void (*clean)(void *), *arg;
+    /*LOCK*/
+    for(; head; head=head->next, slot=COUNT) {
+        while(slot-- > 0){
+            arg   = head->arg[slot];
+            clean = head->clean[slot];
+            /* UNLOCK */
+            clean(arg);
+            /* LOCK */
+        }
+    }
+}
+
+int
+rt·atexit(void (*clean)(void *), void *arg)
+{
+    /* LOCK */
+    if(!head)
+        head = &arena;
+
+    /* we need malloc... */
+    if(slot==COUNT)
+        return -1;
+
+    head->arg[slot]   = arg;
+    head->clean[slot] = clean;
+    slot++;
+
+    /* UNLOCK */
+    return 0;
+}
diff --git a/sys/rt/boot.c b/sys/rt/boot.c
index 320a596..8c6616d 100644
--- a/sys/rt/boot.c
+++ b/sys/rt/boot.c
@@ -3,7 +3,10 @@
 #include <elf.h>
 
 /* tell linker to go find */
+int atexit(void (*)(void));
 int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv);
+
+void rt·clean(void);
 void rt·guardstack(void);
 
 #define NAUX 38
@@ -30,6 +33,7 @@ rt·boot(int (*main)(), int argc, char **argv, void (*init)(), void (*fini)(), v
 	rt·init(env, argv[0]);
 
 	/* ring libc, anyone home? */
+    atexit(rt·clean);
 	__libc_start_main(main, argc, argv);
 
 	/* no? ok we continue on if there is no libc linked */
diff --git a/sys/rt/dummy.c b/sys/rt/dummy.c
index f123d16..0cef224 100644
--- a/sys/rt/dummy.c
+++ b/sys/rt/dummy.c
@@ -4,3 +4,6 @@
 /* provide a dummy implementation if libc is not linked */
 static int noop(int (*main)(), int argc, char **argv) { return 0; }
 weakalias(noop, __libc_start_main);
+
+static int noop2(void (*func)(void)) { return 0; }
+weakalias(noop, atexit);
diff --git a/sys/rt/exit.c b/sys/rt/exit.c
index e6027b7..386a1bf 100644
--- a/sys/rt/exit.c
+++ b/sys/rt/exit.c
@@ -2,10 +2,13 @@
 #include <rt.h>
 #include <syscall.h>
 
-/* XXX:
- * if we are here, we are in charge, call exit syscalls
- * think of better way to encapsulate these syscalls?
- */
+/* tell linker to go find */
+void noreturn exit(int code);
+
+/* if did not call rt·atexit, then don't pull it in */
+static void noop(void){}
+weakalias(noop, rt·clean);
+
 static noreturn void
 rt·shutdown(int code)
 {
@@ -14,14 +17,18 @@ rt·shutdown(int code)
     if(rt·context.exit)
         rt·context.exit();
 
+    /* XXX: better way to encapsulate these calls? */
 	_syscall1(·ExitGroup, code);
     for(;;)
 		_syscall1(·Exit, code);
 }
-weakalias(rt·shutdown, exit);
 
 noreturn void
 rt·exit(int code)
 {
-	rt·shutdown(code);
+    /* ring libc, anyone home? */
+	exit(code);
+    /* if we are here, we are in charge, shut it down */
+    rt·clean();
+    rt·shutdown(code);
 }