Chore: cleaned up the exit code to cleanly interface with libc

We use weak linking to ensure we clean up at exit time correctly. If
libc is linked, then we call our cleanup function by registering an
atexit callback with the library. If libc is not linked, we have a weak
symbol that results in a noop. Similarly, if we call rt·exit while
linked with libc, this immediately calls libc's exit (which will call
our cleanup as we registered it). If we are not linked to libc, exit()
is given as a weak link to a noop function.

1 files changed, 1 insertions, 0 deletions

diff --git a/include/u.h b/include/u.h
index d415d82..fe251ac 100644
--- a/include/u.h
+++ b/include/u.h
@@ -112,6 +112,7 @@ typedef __builtin_va_list va_list;
 #define noreturn _Noreturn

 #define hidden __attribute__((__visibility__("hidden")))

 #define weakalias(old, new) extern __typeof(old) new __attribute__((weak, alias(#old)))

+#define weaklink __attribute__((weak))

 

 /* offsets */

 #define offsetof(t, d) __builtin_offsetof(t, d)