diff --git a/ext/stringio/stringio.c b/ext/stringio/stringio.c index 1feb9231..d5753a97 100644 --- a/ext/stringio/stringio.c +++ b/ext/stringio/stringio.c @@ -1602,6 +1602,13 @@ strio_pread(int argc, VALUE *argv, VALUE self) rb_raise(rb_eArgError, "negative string size (or size too big): %" PRIsVALUE, rb_len); } + if (len == 0) { + if (NIL_P(rb_buf)) { + return rb_str_new("", 0); + } + return rb_buf; + } + if (offset < 0) { rb_syserr_fail_str(EINVAL, rb_sprintf("pread: Invalid offset argument: %" PRIsVALUE, rb_offset)); } diff --git a/test/stringio/test_stringio.rb b/test/stringio/test_stringio.rb index d2d96c57..cb828412 100644 --- a/test/stringio/test_stringio.rb +++ b/test/stringio/test_stringio.rb @@ -750,6 +750,13 @@ def test_pread assert_raise(EOFError) { f.pread(1, 5) } assert_raise(ArgumentError) { f.pread(-1, 0) } assert_raise(Errno::EINVAL) { f.pread(3, -1) } + + assert_equal "".b, StringIO.new("").pread(0, 0) + assert_equal "".b, StringIO.new("").pread(0, -10) + + buf = "stale".b + assert_equal "stale".b, StringIO.new("").pread(0, 0, buf) + assert_equal "stale".b, buf end def test_size