From 903581b7eb05a566373eb784eeb958b9cd792493 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Thu, 28 Nov 2019 19:20:25 +0100
Subject: [PATCH] async: first synchronous write may succeed partially

When trying to write (to e.g. the slave, or to a clipboard receiver),
we first try to send the data synchronously, and only if that fails do
we switch to asynchronous mode.

However, the first synchronous may (in fact, is likely to) succeed
partially.
---
 selection.c | 10 ++++++----
 terminal.c  |  5 +++--
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/selection.c b/selection.c
index 8ed0b6da..2839636a 100644
--- a/selection.c
+++ b/selection.c
@@ -384,13 +384,14 @@ send(void *data, struct wl_data_source *wl_data_source, const char *mime_type,
         return;
     }
 
-    switch (async_write(fd, selection, len, &(size_t){0})) {
+    size_t async_idx = 0;
+    switch (async_write(fd, selection, len, &async_idx)) {
     case ASYNC_WRITE_REMAIN: {
         struct clipboard_send *ctx = malloc(sizeof(*ctx));
         *ctx = (struct clipboard_send) {
             .data = strdup(selection),
             .len = len,
-            .idx = 0,
+            .idx = async_idx,
         };
 
         if (fdm_add(wayl->fdm, fd, EPOLLOUT, &fdm_send, ctx))
@@ -475,13 +476,14 @@ primary_send(void *data,
         return;
     }
 
-    switch (async_write(fd, selection, len, &(size_t){0})) {
+    size_t async_idx = 0;
+    switch (async_write(fd, selection, len, &async_idx)) {
     case ASYNC_WRITE_REMAIN: {
         struct clipboard_send *ctx = malloc(sizeof(*ctx));
         *ctx = (struct clipboard_send) {
             .data = strdup(selection),
             .len = len,
-            .idx = 0,
+            .idx = async_idx,
         };
 
         if (fdm_add(wayl->fdm, fd, EPOLLOUT, &fdm_send, ctx))
diff --git a/terminal.c b/terminal.c
index 887e90c1..0cfbdb2e 100644
--- a/terminal.c
+++ b/terminal.c
@@ -32,6 +32,7 @@
 bool
 term_to_slave(struct terminal *term, const void *_data, size_t len)
 {
+    size_t async_idx = 0;
     if (tll_length(term->ptmx_buffer) > 0) {
         /* With a non-empty queue, EPOLLOUT has already been enabled */
         goto enqueue_data;
@@ -42,7 +43,7 @@ term_to_slave(struct terminal *term, const void *_data, size_t len)
      * switch to asynchronous.
      */
 
-    switch (async_write(term->ptmx, _data, len, &(size_t){0})) {
+    switch (async_write(term->ptmx, _data, len, &async_idx)) {
     case ASYNC_WRITE_REMAIN:
         /* Switch to asynchronous mode; let FDM write the remaining data */
         if (!fdm_event_add(term->fdm, term->ptmx, EPOLLOUT))
@@ -73,7 +74,7 @@ enqueue_data:
         struct ptmx_buffer queued = {
             .data = copy,
             .len = len,
-            .idx = 0,
+            .idx = async_idx,
         };
         tll_push_back(term->ptmx_buffer, queued);
     }