From d20c77c618556ab4c1e5f555551feb4be1442095 Mon Sep 17 00:00:00 2001
From: "Justin C. Miller" <justin@devjustinian.com>
Date: Sat, 12 Feb 2022 13:55:07 -0800
Subject: [PATCH] [libc] Call global ctors in user code

This change adds a new __init_libc function which calls all the global
ctors in .init_array, and is called from _start.
---
 src/libraries/libc/arch/amd64/crt/crt0.s   |  2 ++
 src/libraries/libc/arch/amd64/crt/init.cpp | 27 ++++++++++++++++++++++
 src/user/srv.init/start.s                  |  2 ++
 3 files changed, 31 insertions(+)
 create mode 100644 src/libraries/libc/arch/amd64/crt/init.cpp

diff --git a/src/libraries/libc/arch/amd64/crt/crt0.s b/src/libraries/libc/arch/amd64/crt/crt0.s
index 280a28a..6353370 100644
--- a/src/libraries/libc/arch/amd64/crt/crt0.s
+++ b/src/libraries/libc/arch/amd64/crt/crt0.s
@@ -1,12 +1,14 @@
 extern main
 extern exit
 extern __init_libj6
+extern __init_libc
 
 global _start:function (_start.end - _start)
 _start:
 	mov rbp, rsp
 	mov rdi, rsp
 	call __init_libj6
+	call __init_libc
 
 	pop rdi
 	mov rsi, rsp
diff --git a/src/libraries/libc/arch/amd64/crt/init.cpp b/src/libraries/libc/arch/amd64/crt/init.cpp
new file mode 100644
index 0000000..b183c01
--- /dev/null
+++ b/src/libraries/libc/arch/amd64/crt/init.cpp
@@ -0,0 +1,27 @@
+#include <stddef.h>
+
+using cb = void (*)(void);
+extern cb __init_array_start[0];
+extern cb __init_array_end;
+
+namespace {
+
+void
+run_global_ctors()
+{
+    size_t i = 0;
+    while (true) {
+        const cb &fp = __init_array_start[i++];
+        if (&fp == &__init_array_end)
+            return;
+        fp();
+    }
+}
+
+} // namespace
+
+extern "C"
+void __init_libc()
+{
+    run_global_ctors();
+}
diff --git a/src/user/srv.init/start.s b/src/user/srv.init/start.s
index 8244410..33229dd 100644
--- a/src/user/srv.init/start.s
+++ b/src/user/srv.init/start.s
@@ -1,6 +1,7 @@
 extern main
 extern exit
 extern __init_libj6
+extern __init_libc
 extern _arg_modules_phys
 
 section .bss
@@ -28,6 +29,7 @@ _start:
  	mov rbp, rsp
 	mov rdi, rsp
 	call __init_libj6
+	call __init_libc
 
 	pop rdi
 	mov rsi, rsp