1 files changed, 87 insertions, 0 deletions
diff --git a/src/lib/iostream-proxy.h b/src/lib/iostream-proxy.h
new file mode 100644
index 0000000..5e8850f
--- /dev/null
+++ b/src/lib/iostream-proxy.h
@@ -0,0 +1,87 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file
+ */
+#ifndef IOSTREAM_PROXY_H
+#define IOSTREAM_PROXY_H 1
+
+/**
+
+iostream-proxy
+=============
+
+This construct will proxy data between two pairs of
+istream and ostream. Data is proxied from left to right
+and right to left using iostream-pump.
+
+The proxy requires you to provide completion callback. The
+completion callback is called with success parameter to
+indicate whether it ended with error.
+
+The istreams and ostreams are reffed on creation and unreffed
+on unref.
+
+**/
+
+struct istream;
+struct ostream;
+struct iostream_proxy;
+
+enum iostream_proxy_side {
+	/* Input is coming from left side's istream and is proxied to
+	   right side's ostream. */
+	IOSTREAM_PROXY_SIDE_LEFT,
+	/* Input is coming from right side's istream and is proxied to
+	   left side's ostream. */
+	IOSTREAM_PROXY_SIDE_RIGHT
+};
+
+enum iostream_proxy_status {
+	/* proxy succeeded - EOF received from istream and all output was
+	   written successfully to ostream. */
+	IOSTREAM_PROXY_STATUS_INPUT_EOF,
+	/* proxy failed - istream returned an error */
+	IOSTREAM_PROXY_STATUS_INPUT_ERROR,
+	/* proxy failed - other side's ostream returned an error */
+	IOSTREAM_PROXY_STATUS_OTHER_SIDE_OUTPUT_ERROR,
+};
+
+/* The callback maybe be called once or twice. Usually the first call should
+   destroy the proxy, but it's possible for it to just wait for the other
+   direction of the proxy to finish as well and call the callback.
+
+   Note that the sides mean which side is the reader side. If the failure is in
+   ostream, it's the other side's ostream that failed. So for example if
+   side=left, the write failed to the right side's ostream.
+
+   The callback is called when the proxy succeeds or fails due to
+   iostreams. (It's not called if proxy is destroyed.) */
+typedef void iostream_proxy_callback_t(enum iostream_proxy_side side,
+				       enum iostream_proxy_status status,
+				       void *context);
+
+struct iostream_proxy *
+iostream_proxy_create(struct istream *left_input, struct ostream *left_output,
+		      struct istream *right_input, struct ostream *right_output);
+
+struct istream *iostream_proxy_get_istream(struct iostream_proxy *proxy, enum iostream_proxy_side);
+struct ostream *iostream_proxy_get_ostream(struct iostream_proxy *proxy, enum iostream_proxy_side);
+
+void iostream_proxy_start(struct iostream_proxy *proxy);
+void iostream_proxy_stop(struct iostream_proxy *proxy);
+
+/* See iostream_pump_is_waiting_output() */
+bool iostream_proxy_is_waiting_output(struct iostream_proxy *proxy,
+				      enum iostream_proxy_side side);
+
+void iostream_proxy_set_completion_callback(struct iostream_proxy *proxy,
+				       iostream_proxy_callback_t *callback, void *context);
+#define iostream_proxy_set_completion_callback(proxy, callback, context) \
+	iostream_proxy_set_completion_callback(proxy, (iostream_proxy_callback_t *)callback, \
+		TRUE ? context : \
+		CALLBACK_TYPECHECK(callback, void (*)(enum iostream_proxy_side side, enum iostream_proxy_status, typeof(context))))
+
+void iostream_proxy_ref(struct iostream_proxy *proxy);
+void iostream_proxy_unref(struct iostream_proxy **proxy_r);
+
+void iostream_proxy_switch_ioloop(struct iostream_proxy *proxy);
+
+#endif