patch 8.0.0312: failure when a channel receives a split json message

Problem:    When a json message arrives in pieces, the start is dropped and
            the decoding fails.
Solution:   Do not drop the start when it is still needed. (Kay Zheng)  Add a
            test.  Reset the timeout when something is received.

src/channel.c

@@ -1840,39 +1840,42 @@ channel_save(channel_T *channel, ch_part_T part, char_u *buf, int len,
     return OK;
 }
 
+/*
+ * Try to fill the buffer of "reader".
+ * Returns FALSE when nothing was added.
+ */
     static int
 channel_fill(js_read_T *reader)
 {
     channel_T	*channel = (channel_T *)reader->js_cookie;
     ch_part_T	part = reader->js_cookie_arg;
     char_u	*next = channel_get(channel, part);
-    int		unused;
-    int		len;
+    int		keeplen;
+    int		addlen;
     char_u	*p;
 
     if (next == NULL)
 	return FALSE;
 
-    unused = reader->js_end - reader->js_buf - reader->js_used;
-    if (unused > 0)
+    keeplen = reader->js_end - reader->js_buf;
+    if (keeplen > 0)
     {
 	/* Prepend unused text. */
-	len = (int)STRLEN(next);
-	p = alloc(unused + len + 1);
+	addlen = (int)STRLEN(next);
+	p = alloc(keeplen + addlen + 1);
 	if (p == NULL)
 	{
 	    vim_free(next);
 	    return FALSE;
 	}
-	mch_memmove(p, reader->js_buf + reader->js_used, unused);
-	mch_memmove(p + unused, next, len + 1);
+	mch_memmove(p, reader->js_buf, keeplen);
+	mch_memmove(p + keeplen, next, addlen + 1);
 	vim_free(next);
 	next = p;
     }
 
     vim_free(reader->js_buf);
     reader->js_buf = next;
-    reader->js_used = 0;
     return TRUE;
 }
 
@@ -1952,16 +1955,20 @@ channel_parse_json(channel_T *channel, ch_part_T part)
     }
 
     if (status == OK)
-	chanpart->ch_waiting = FALSE;
+	chanpart->ch_wait_len = 0;
     else if (status == MAYBE)
     {
-	if (!chanpart->ch_waiting)
+	size_t buflen = STRLEN(reader.js_buf);
+
+	if (chanpart->ch_wait_len < buflen)
 	{
-	    /* First time encountering incomplete message, set a deadline of
-	     * 100 msec. */
-	    ch_log(channel, "Incomplete message - wait for more");
+	    /* First time encountering incomplete message or after receiving
+	     * more (but still incomplete): set a deadline of 100 msec. */
+	    ch_logn(channel,
+		    "Incomplete message (%d bytes) - wait 100 msec for more",
+		    buflen);
 	    reader.js_used = 0;
-	    chanpart->ch_waiting = TRUE;
+	    chanpart->ch_wait_len = buflen;
 #ifdef WIN32
 	    chanpart->ch_deadline = GetTickCount() + 100L;
 #else
@@ -1992,7 +1999,8 @@ channel_parse_json(channel_T *channel, ch_part_T part)
 	    if (timeout)
 	    {
 		status = FAIL;
-		chanpart->ch_waiting = FALSE;
+		chanpart->ch_wait_len = 0;
+		ch_log(channel, "timed out");
 	    }
 	    else
 	    {
@@ -2006,7 +2014,7 @@ channel_parse_json(channel_T *channel, ch_part_T part)
     {
 	ch_error(channel, "Decoding failed - discarding input");
 	ret = FALSE;
-	chanpart->ch_waiting = FALSE;
+	chanpart->ch_wait_len = 0;
     }
     else if (reader.js_buf[reader.js_used] != NUL)
     {
@@ -3369,7 +3377,7 @@ channel_read_json_block(
 	    /* Wait for up to the timeout.  If there was an incomplete message
 	     * use the deadline for that. */
 	    timeout = timeout_arg;
-	    if (chanpart->ch_waiting)
+	    if (chanpart->ch_wait_len > 0)
 	    {
 #ifdef WIN32
 		timeout = chanpart->ch_deadline - GetTickCount() + 1;
@@ -3389,7 +3397,7 @@ channel_read_json_block(
 		{
 		    /* Something went wrong, channel_parse_json() didn't
 		     * discard message.  Cancel waiting. */
-		    chanpart->ch_waiting = FALSE;
+		    chanpart->ch_wait_len = 0;
 		    timeout = timeout_arg;
 		}
 		else if (timeout > timeout_arg)

src/structs.h

@@ -1563,9 +1563,11 @@ typedef struct {
     jsonq_T	ch_json_head;	/* header for circular json read queue */
     int		ch_block_id;	/* ID that channel_read_json_block() is
 				   waiting for */
-    /* When ch_waiting is TRUE use ch_deadline to wait for incomplete message
-     * to be complete. */
-    int		ch_waiting;
+    /* When ch_wait_len is non-zero use ch_deadline to wait for incomplete
+     * message to be complete. The value is the length of the incomplete
+     * message when the deadline was set.  If it gets longer (something was
+     * received) the deadline is reset. */
+    size_t	ch_wait_len;
 #ifdef WIN32
     DWORD	ch_deadline;
 #else

src/testdir/test_channel.vim

@@ -1141,7 +1141,11 @@ func Test_out_cb()
 
   let dict = {'thisis': 'dict: '}
   func dict.outHandler(chan, msg) dict
-    let g:Ch_outmsg = self.thisis . a:msg
+    if type(a:msg) == v:t_string
+      let g:Ch_outmsg = self.thisis . a:msg
+    else
+      let g:Ch_outobj = a:msg
+    endif
   endfunc
   func dict.errHandler(chan, msg) dict
     let g:Ch_errmsg = self.thisis . a:msg
@@ -1161,6 +1165,12 @@ func Test_out_cb()
     call assert_equal("dict: hello", g:Ch_outmsg)
     call WaitFor('g:Ch_errmsg != ""')
     call assert_equal("dict: there", g:Ch_errmsg)
+
+    " Receive a json object split in pieces
+    unlet! g:Ch_outobj
+    call ch_sendraw(job, "echosplit [0, {\"one\": 1,| \"tw|o\": 2, \"three\": 3|}]\n")
+    call WaitFor('exists("g:Ch_outobj")')
+    call assert_equal({'one': 1, 'two': 2, 'three': 3}, g:Ch_outobj)
   finally
     call job_stop(job)
   endtry

src/testdir/test_channel_pipe.py

@@ -29,6 +29,11 @@
         if typed.startswith("echo "):
             print(typed[5:-1])
             sys.stdout.flush()
+        if typed.startswith("echosplit "):
+            for part in typed[10:-1].split('|'):
+                sys.stdout.write(part)
+                sys.stdout.flush()
+                time.sleep(0.05)
         if typed.startswith("double "):
             print(typed[7:-1] + "\nAND " + typed[7:-1])
             sys.stdout.flush()

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    312,
 /**/
     311,
 /**/