Move signal handling to libuv event loop

This removes all signal handling code from os_unix.c to os/signal.c. Now signal
handling is done like this:

- Watchers for signals are registered with libuv default event loop
- `event_poll` continuously calls `poll_uv_loop` to produce events until it
  receives user input, SIGINT or a timeout
- Any signals received in `poll_uv_loop` will push events to a queue that is
  drained and processed by `event_poll`

Signals aren't handled directly in the libuv callback to avoid recursion in the
event loop(which isn't supported by libuv).

The same principle will apply to other events in the future: Push to a queue
from a libuv callback and drain it from `event_poll`

1 files changed, 6 insertions, 4 deletions

diff --git a/src/os/input.c b/src/os/input.c
index 1e2d331fc0..14a7088024 100644
--- a/src/os/input.c
+++ b/src/os/input.c
@@ -1,3 +1,4 @@
+#include <string.h>
 #include <stdint.h>
 #include <stdbool.h>
 
@@ -58,7 +59,7 @@ void input_init()
   }
 }
 
-// Check if there's a pending input event
+// Check if there's pending input
 bool input_ready()
 {
   return rbuffer.rpos < rbuffer.wpos || eof;
@@ -126,11 +127,11 @@ int os_inchar(char_u *buf, int maxlen, int32_t ms, int tb_change_cnt)
   InbufPollResult result;
 
   if (ms >= 0) {
-    if ((result = inbuf_poll(ms)) != kInputAvail) {
+    if ((result = inbuf_poll(ms)) == kInputNone) {
       return 0;
     }
   } else {
-    if ((result = inbuf_poll(p_ut)) != kInputAvail) {
+    if ((result = inbuf_poll(p_ut)) == kInputNone) {
       if (trigger_cursorhold() && maxlen >= 3
           && !typebuf_changed(tb_change_cnt)) {
         buf[0] = K_SPECIAL;
@@ -177,9 +178,10 @@ static InbufPollResult inbuf_poll(int32_t ms)
     return kInputAvail;
 
   if (event_poll(ms)) {
-    if (rbuffer.rpos == rbuffer.wpos && eof) {
+    if (!got_int && rbuffer.rpos == rbuffer.wpos && eof) {
       return kInputEof;
     }
+
     return kInputAvail;
   }