[ruby/stringio] StringIO#pread: handle 0 length like IO#pread

(https://github.com/ruby/stringio/pull/67)

Fix: https://github.com/ruby/stringio/issues/66

If length is 0, IO#pread don't even try to read the IO, it simply return
the buffer untouched if there is one or a new empty buffer otherwise.

It also doesn't validate the offset when length is 0.

cc @jdelStrother @kou

https://github.com/ruby/stringio/commit/37e9279337

Co-authored-by: Jean Boussier <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/ext/stringio/stringio.c b/ext/stringio/stringio.c
index 1feb9231db..d5753a97a0 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));
     }