shell: Use job_write_cb for closing stdin

Commit @45525853d352 removed usage of the `job_write_cb` for closing stdin due
to a memory error, but that doesn't work anymore because `job_close_in` closes
stdin immediately, possibly trimming input data before it is fully written.

Since most memory issues with jobs have been fixed, re-add the `job_write_cb`
call to ensure stdin is only closed when it should. Also add tests for scenarios
where using the callback makes a difference.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index 7449ac637c..1b279f18f5 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -244,6 +244,9 @@ static int shell(const char *cmd,
       job_stop(job);
       return -1;
     }
+    // close the input stream after everything is written
+    job_write_cb(job, shell_write_cb);
+  } else {
     // close the input stream, let the process know that no more input is
     // coming
     job_close_in(job);
@@ -447,3 +450,9 @@ static void write_output(char *output, size_t remaining)
     curbuf->b_no_eol_lnum = 0;
   }
 }
+
+static void shell_write_cb(WStream *wstream, void *data, int status)
+{
+  Job *job = data;
+  job_close_in(job);
+}