From 391832de43d1f780e4ee31ab977292fad48a9b17 Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Fri, 10 Mar 2017 15:31:16 -0800
Subject: [PATCH] Strip chroot path from $LOADED_FEATURES when calling
 Dir.chroot

Currently, Dir.chroot doesn't modify $LOADED_FEATURES, leading
to a situation where Kernel#require will attempt to load the same
file twice, or a different file not at all because it thinks it
is already loaded.

With this example code:

  require 'fileutils'
  File.write('baz.rb', 'A = 1')
  require './baz'
  pwd = Dir.pwd
  Dir.chroot(pwd)
  require './baz'
  FileUtils.mkdir_p(pwd)
  File.write(File.join(pwd, 'baz.rb'), '$a = 2')
  require "#{pwd}/baz"
  warn "$a => #{$a.inspect}" unless $a == 2

Previous output on stderr:

/baz.rb:1: warning: already initialized constant A
/home/billg/baz.rb:1: warning: previous definition of A was here
$a => nil

With this patch, no output on stderr.
---
 dir.c  | 27 +++++++++++++++++++++++++++
 load.c |  2 +-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/dir.c b/dir.c
index 365f059b0f..8e6cdc0a0e 100644
--- a/dir.c
+++ b/dir.c
@@ -1119,10 +1119,37 @@ check_dirname(VALUE dir)
 static VALUE
 dir_s_chroot(VALUE dir, VALUE path)
 {
+    VALUE features = rb_gv_get("$LOADED_FEATURES");
+    VALUE chroot_to;
+
     path = check_dirname(path);
+    chroot_to = rb_file_s_expand_path(1, &path);
     if (chroot(RSTRING_PTR(path)) == -1)
 	rb_sys_fail_path(path);
 
+    if (rb_type(features) == RUBY_T_ARRAY &&
+        rb_type(chroot_to) == RUBY_T_STRING) {
+	long i, features_len, chroot_len, feature_min_len;
+	VALUE feature;
+	char * chroot_str = RSTRING_PTR(chroot_to);
+
+	features_len = RARRAY_LEN(features);
+	chroot_len = RSTRING_LEN(chroot_to);
+	feature_min_len = chroot_len + 1;
+
+	for (i=0; i < features_len; i++) {
+	    feature = RARRAY_AREF(features, i);
+	    if ((rb_type(feature) == RUBY_T_STRING) &&
+		RSTRING_LEN(feature) > feature_min_len &&
+	        strncmp(chroot_str, RSTRING_PTR(feature), chroot_len) == 0) {
+		feature = rb_str_substr(feature, chroot_len,
+		                        RSTRING_LEN(feature));
+		RARRAY_ASET(features, i, feature);
+		features_index_add(feature, INT2FIX(i));
+	    }
+	}
+    }
+
     return INT2FIX(0);
 }
 #else
diff --git a/load.c b/load.c
index 284ebf2e48..701f039d3e 100644
--- a/load.c
+++ b/load.c
@@ -220,7 +220,7 @@ features_index_add_single(VALUE short_feature, VALUE offset)
    or ends in '/'.  This maintains the invariant that `rb_feature_p()`
    relies on for its fast lookup.
 */
-static void
+void
 features_index_add(VALUE feature, VALUE offset)
 {
     VALUE short_feature;
-- 
2.11.0