* string.c: add internal API rb_str_locktmp_ensure().

* io.c (io_fread): use rb_str_locktmp_ensure().
  [ruby-core:56121] [Bug #8669]

* test/ruby/test_io.rb: add a test for above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42212 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,12 @@
+Sun Jul 28 17:38:32 2013  Masaki Matsushita  <glass.saga@gmail.com>
+
+	* string.c: add internal API rb_str_locktmp_ensure().
+
+	* io.c (io_fread): use rb_str_locktmp_ensure().
+	  [ruby-core:56121] [Bug #8669]
+
+	* test/ruby/test_io.rb: add a test for above.
+
 Sun Jul 28 13:04:39 2013  Masaki Matsushita  <glass.saga@gmail.com>
 
 	* io.c (interpret_seek_whence): support SEEK_DATA and SEEK_HOLE.

internal.h

@@ -419,6 +419,7 @@ VALUE rb_id_quote_unprintable(ID);
 #define QUOTE(str) rb_str_quote_unprintable(str)
 #define QUOTE_ID(id) rb_id_quote_unprintable(id)
 void rb_str_fill_terminator(VALUE str, const int termlen);
+VALUE rb_str_locktmp_ensure(VALUE str, VALUE (*func)(VALUE), VALUE arg);
 
 /* struct.c */
 VALUE rb_struct_init_copy(VALUE copy, VALUE s);

io.c

@@ -2061,15 +2061,32 @@ io_bufread(char *ptr, long len, rb_io_t *fptr)
 
 static void io_setstrbuf(VALUE *str, long len);
 
+struct bufread_arg {
+    char *str_ptr;
+    long len;
+    rb_io_t *fptr;
+};
+
+static VALUE
+bufread_call(VALUE arg)
+{
+    struct bufread_arg *p = (struct bufread_arg *)arg;
+    p->len = io_bufread(p->str_ptr, p->len, p->fptr);
+    return Qundef;
+}
+
 static long
 io_fread(VALUE str, long offset, long size, rb_io_t *fptr)
 {
     long len;
+    struct bufread_arg arg;
 
     io_setstrbuf(&str, offset + size);
-    rb_str_locktmp(str);
-    len = io_bufread(RSTRING_PTR(str) + offset, size, fptr);
-    rb_str_unlocktmp(str);
+    arg.str_ptr = RSTRING_PTR(str) + offset;
+    arg.len = size;
+    arg.fptr = fptr;
+    rb_str_locktmp_ensure(str, bufread_call, (VALUE)&arg);
+    len = arg.len;
     if (len < 0) rb_sys_fail_path(fptr->pathv);
     return len;
 }

string.c

@@ -1871,6 +1871,13 @@ rb_str_unlocktmp(VALUE str)
     return str;
 }
 
+VALUE
+rb_str_locktmp_ensure(VALUE str, VALUE (*func)(VALUE), VALUE arg)
+{
+    rb_str_locktmp(str);
+    return rb_ensure(func, arg, rb_str_unlocktmp, str);
+}
+
 void
 rb_str_set_len(VALUE str, long len)
 {

test/ruby/test_io.rb

@@ -2801,4 +2801,18 @@ End
       end
     }
   end if /mswin|mingw/ =~ RUBY_PLATFORM
+
+  def test_read_unlocktmp_ensure
+    bug8669 = '[ruby-core:56121] [Bug #8669]'
+
+    str = ""
+    r, = IO.pipe
+    t = Thread.new { r.read(nil, str) }
+    sleep 0.1 until t.stop?
+    t.raise
+    sleep 0.1 while t.alive?
+    assert_nothing_raised(RuntimeError, bug8669) { str.clear }
+  ensure
+    t.kill
+  end
 end