[ruby/stringio] Check if closed in loop

[Bug #17675] https://bugs.ruby-lang.org/issues/17675

https://github.com/ruby/stringio/commit/1ed61d0cbc

ext/stringio/stringio.c

@@ -1,3 +1,4 @@
+/* -*- mode: c; indent-tabs-mode: t -*- */
 /**********************************************************************
 
   stringio.c -
@@ -599,6 +600,14 @@ strio_closed_write(VALUE self)
     return Qtrue;
 }
 
+static struct StringIO *
+strio_to_read(VALUE self)
+{
+    struct StringIO *ptr = readable(self);
+    if (ptr->pos < RSTRING_LEN(ptr->string)) return ptr;
+    return NULL;
+}
+
 /*
  * call-seq:
  *   strio.eof     -> true or false
@@ -610,8 +619,7 @@ strio_closed_write(VALUE self)
 static VALUE
 strio_eof(VALUE self)
 {
-    struct StringIO *ptr = readable(self);
-    if (ptr->pos < RSTRING_LEN(ptr->string)) return Qfalse;
+    if (strio_to_read(self)) return Qfalse;
     return Qtrue;
 }
 
@@ -821,11 +829,11 @@ strio_get_sync(VALUE self)
 static VALUE
 strio_each_byte(VALUE self)
 {
-    struct StringIO *ptr = readable(self);
+    struct StringIO *ptr;
 
     RETURN_ENUMERATOR(self, 0, 0);
 
-    while (ptr->pos < RSTRING_LEN(ptr->string)) {
+    while ((ptr = strio_to_read(self)) != NULL) {
 	char c = RSTRING_PTR(ptr->string)[ptr->pos++];
 	rb_yield(CHR2FIX(c));
     }
@@ -1064,11 +1072,7 @@ strio_each_codepoint(VALUE self)
 
     ptr = readable(self);
     enc = get_enc(ptr);
-    for (;;) {
-	if (ptr->pos >= RSTRING_LEN(ptr->string)) {
-	    return self;
-	}
-
+    while ((ptr = strio_to_read(self)) != NULL) {
 	c = rb_enc_codepoint_len(RSTRING_PTR(ptr->string)+ptr->pos,
 				 RSTRING_END(ptr->string), &n, enc);
 	ptr->pos += n;

test/stringio/test_stringio.rb

@@ -446,6 +446,15 @@ class TestStringIO < Test::Unit::TestCase
     f.close unless f.closed?
   end
 
+  def test_each_byte_closed
+    f = StringIO.new("1234")
+    assert_equal("1".ord, f.each_byte {|c| f.close; break c })
+    f = StringIO.new("1234")
+    assert_raise(IOError) do
+      f.each_byte { f.close }
+    end
+  end
+
   def test_getbyte
     f = StringIO.new("1234")
     assert_equal("1".ord, f.getbyte)
@@ -520,11 +529,29 @@ class TestStringIO < Test::Unit::TestCase
     assert_equal(%w(1 2 3 4), f.each_char.to_a)
   end
 
+  def test_each_char_closed
+    f = StringIO.new("1234")
+    assert_equal("1", f.each_char {|c| f.close; break c })
+    f = StringIO.new("1234")
+    assert_raise(IOError) do
+      f.each_char { f.close }
+    end
+  end
+
   def test_each_codepoint
     f = StringIO.new("1234")
     assert_equal([49, 50, 51, 52], f.each_codepoint.to_a)
   end
 
+  def test_each_codepoint_closed
+    f = StringIO.new("1234")
+    assert_equal("1".ord, f.each_codepoint {|c| f.close; break c })
+    f = StringIO.new("1234")
+    assert_raise(IOError) do
+      f.each_codepoint { f.close }
+    end
+  end
+
   def test_each_codepoint_enumerator
     io = StringIO.new('你好построить')