vmsplice: avoid referencing invalid stack address for strings

Newer GCC more aggressively optimizes stack allocations away,
so we need to avoid passing out-of-scope addresses to vmsplice.
Not that vmsplice is useful in Ruby...

1 files changed, 3 insertions, 4 deletions

diff --git a/ext/io_splice/io_splice_ext.c b/ext/io_splice/io_splice_ext.c
index 32de838..876d07d 100644
--- a/ext/io_splice/io_splice_ext.c
+++ b/ext/io_splice/io_splice_ext.c
@@ -492,19 +492,18 @@ static VALUE my_vmsplice(int argc, VALUE * argv, VALUE self)
         ssize_t rv = 0;
         ssize_t left;
         struct vmsplice_args a;
+        struct iovec iov;
+
         VALUE io, data, flags;
 
         rb_scan_args(argc, argv, "21", &io, &data, &flags);
 
         switch (TYPE(data)) {
-        case T_STRING: {
-                struct iovec iov;
-
+        case T_STRING:
                 iov.iov_base = RSTRING_PTR(data);
                 iov.iov_len = (size_t)(left = (ssize_t)RSTRING_LEN(data));
                 a.iov = &iov;
                 a.nr_segs = 1;
-                }
                 break;
         case T_ARRAY:
                 ARY2IOVEC(a.iov, a.nr_segs, left, data);