Hide the usage of `rb_io_t` where possible. (#7880)

This retries the compatible parts of the previously reverted PR so we can continue to update related code without breaking backwards compatibility.

1 files changed, 34 insertions, 1 deletions

diff --git a/include/ruby/io.h b/include/ruby/io.h
index 8be83a215c..9b05c7b164 100644
--- a/include/ruby/io.h
+++ b/include/ruby/io.h
@@ -331,7 +331,16 @@ typedef struct rb_io_enc_t rb_io_enc_t;
  * Setting this one and #FMODE_BINMODE at the same time is a contradiction.
  */
 #define FMODE_TEXTMODE              0x00001000
-/* #define FMODE_PREP               0x00010000 */
+/**
+ * This flag means that an IO object is wrapping an "external" file descriptor,
+ * which is owned by something outside the Ruby interpreter (usually a C extension).
+ * Ruby will not close this file when the IO object is garbage collected.
+ * If this flag is set, then IO#autoclose? is false, and vice-versa.
+ *
+ * This flag was previously called FMODE_PREP internally.
+ */
+#define FMODE_EXTERNAL              0x00010000
+
 /* #define FMODE_SIGNAL_ON_EPIPE    0x00020000 */
 
 /**
@@ -346,6 +355,18 @@ typedef struct rb_io_enc_t rb_io_enc_t;
 /** @} */
 
 /**
+ * Allocate a new IO object, with the given file descriptor.
+ */
+VALUE rb_io_open_descriptor(VALUE klass, int descriptor, int mode, VALUE path, VALUE timeout, struct rb_io_enc_t *encoding);
+
+/**
+ * Returns whether or not the underlying IO is closed.
+ *
+ * @return Whether the underlying IO is closed.
+ */
+VALUE rb_io_closed_p(VALUE io);
+
+/**
  * Queries the underlying IO pointer.
  *
  * @param[in]   obj              An IO object.
@@ -704,6 +725,12 @@ VALUE rb_io_set_write_io(VALUE io, VALUE w);
 void rb_io_set_nonblock(rb_io_t *fptr);
 
 /**
+ * Returns the path for the given IO.
+ *
+ */
+VALUE rb_io_path(VALUE io);
+
+/**
  * Returns an integer representing the numeric file descriptor for
  * <em>io</em>.
  *
@@ -713,6 +740,12 @@ void rb_io_set_nonblock(rb_io_t *fptr);
 int rb_io_descriptor(VALUE io);
 
 /**
+ * Get the mode of the IO.
+ *
+ */
+int rb_io_mode(VALUE io);
+
+/**
  * This function  breaks down the  option hash that `IO#initialize`  takes into
  * components.   This is  an implementation  detail of  rb_io_extract_modeenc()
  * today.  People prefer that API instead.