From 5e86b005c0f2ef30df2f9906c7e2f3abefe286a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=8D=9C=E9=83=A8=E6=98=8C=E5=B9=B3?=
 <shyouhei@ruby-lang.org>
Date: Fri, 23 Aug 2019 12:14:06 +0900
Subject: [PATCH] uid_t and gid_t are narrower than VALUE.

Often uid / gid are 16 bit or 32 bit integers, while VALUE are 32
to 64 bits.  They tend to differ in size.  Because rb_ensure expects
its callbacks to take VALUE arguments, narrowing must be done by
hand, otherwise data corruption can happen depending on machine ABI.
---
 process.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/process.c b/process.c
index db3f38de1b..8cd42db802 100644
--- a/process.c
+++ b/process.c
@@ -7133,8 +7133,9 @@ p_uid_have_saved_id(void)
 
 #if defined(HAVE_SETRESUID) || defined(HAVE_SETEUID) || defined(_POSIX_SAVED_IDS)
 static VALUE
-p_uid_sw_ensure(rb_uid_t id)
+p_uid_sw_ensure(VALUE i)
 {
+    rb_uid_t id = (rb_uid_t/* narrowing */)i;
     under_uid_switch = 0;
     id = rb_seteuid_core(id);
     return UIDT2NUM(id);
@@ -7246,8 +7247,9 @@ p_gid_have_saved_id(void)
 
 #if defined(HAVE_SETRESGID) || defined(HAVE_SETEGID) || defined(_POSIX_SAVED_IDS)
 static VALUE
-p_gid_sw_ensure(rb_gid_t id)
+p_gid_sw_ensure(VALUE i)
 {
+    rb_gid_t id = (rb_gid_t/* narrowing */)i;
     under_gid_switch = 0;
     id = rb_setegid_core(id);
     return GIDT2NUM(id);