1 files changed, 65 insertions, 0 deletions
diff --git a/libc/src/exit.c b/libc/src/exit.c
new file mode 100644
index 0000000..fc2446f
--- /dev/null
+++ b/libc/src/exit.c
@@ -0,0 +1,65 @@
+#include <stddef.h>
+#include <stdlib.h>
+
+extern void (*__preinit_array_start []) (void) __attribute__((weak));
+extern void (*__preinit_array_end []) (void) __attribute__((weak));
+extern void (*__init_array_start []) (void) __attribute__((weak));
+extern void (*__init_array_end []) (void) __attribute__((weak));
+extern void (*__fini_array_start []) (void) __attribute__((weak));
+extern void (*__fini_array_end []) (void) __attribute__((weak));
+
+void _init();
+void _fini();
+void _exit(int return_code) __attribute__((noreturn));
+
+
+void __libc_init_array() {
+    size_t count, i;
+    
+    count = __preinit_array_end - __preinit_array_start;
+    for (i = 0; i < count; i++)
+        __preinit_array_start[i]();
+    
+    _init();
+
+    count = __init_array_end - __init_array_start;
+    for (i = 0; i < count; i++)
+        __init_array_start[i]();
+}
+
+void __libc_fini_array() {
+    size_t count, i;
+    
+    count = __preinit_array_end - __preinit_array_start;
+    for (i = count - 1; i >= 0; i--)
+        __fini_array_start[i]();
+    
+    _fini();
+}
+
+#define MAX_ATEXIT 32
+
+static volatile uint8_t atexit_count = 0;
+static volatile atexit_func_t atexit_funcs[MAX_ATEXIT];
+
+int atexit(atexit_func_t func) {
+    uint8_t pos = __sync_fetch_and_add(&atexit_count, 1);
+    
+    if (pos >= MAX_ATEXIT) {
+        atexit_count = 32;
+        return -1;
+    }
+    
+    atexit_funcs[pos] = func;
+    return 0;
+}
+
+void exit(int return_code) {
+    uint8_t i;
+    
+    for (i = 0; i < atexit_count; i++) {
+        atexit_funcs[i]();
+    }
+    
+    _exit(return_code);
+}