wstream/shell: Fix memory errors caused by os_system

The os_system function uses a write callback to close the input stream when the
write completes, but this causes a memory error because the callback is invoked
right before the stream is freed by the caller.

This fixes the problem by removing the callback set by os_system. Instead, it
calls job_close_in immediately after writing(the stream will only close after
the write completes). The 'pending' parameter was also removed from the
'write_cb' as it should be hidden by the wstream module.

While the `wstream_set_write_cb` and `job_write_cb` are no longer used, they
will remain in the codebase for future use.

1 files changed, 2 insertions, 3 deletions

diff --git a/src/nvim/os/wstream.c b/src/nvim/os/wstream.c
index 00a53d1628..eb7de02a2f 100644
--- a/src/nvim/os/wstream.c
+++ b/src/nvim/os/wstream.c
@@ -208,15 +208,14 @@ static void write_cb(uv_write_t *req, int status)
 
   release_wbuffer(data->buffer);
 
-  data->wstream->pending_reqs--;
-
   if (data->wstream->cb) {
     data->wstream->cb(data->wstream,
                       data->wstream->data,
-                      data->wstream->pending_reqs,
                       status);
   }
 
+  data->wstream->pending_reqs--;
+
   if (data->wstream->freed && data->wstream->pending_reqs == 0) {
     // Last pending write, free the wstream;
     free(data->wstream);