merge revision(s) 66242: [Backport #15387]

	io.c (io_write_nonblock): add RB_GC_GUARD, io_fflush may switch threads

	Since io_fflush may block on mutex or rb_io_wait_readable and
	switch threads, we need to ensure the `str' VALUE returned by
	`rb_obj_as_string` is visible to GC.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@66965 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 0 deletions

diff --git a/io.c b/io.c
index 4440418d96..be5c0d2b27 100644
--- a/io.c
+++ b/io.c
@@ -2712,6 +2712,7 @@ io_write_nonblock(VALUE io, VALUE str, VALUE ex)
 
     rb_io_set_nonblock(fptr);
     n = write(fptr->fd, RSTRING_PTR(str), RSTRING_LEN(str));
+    RB_GC_GUARD(str);
 
     if (n == -1) {
 	int e = errno;