extcap: Read stderr on extcap error without an infinite loop

Check if data is available on stderr before doing a blocking read() to
avoid an infinite read loop when having less data than STDERR_BUFFER_SIZE.

Append data instead of overwrite when doing multiple read() to fetch
available data.

This is a regression from g6a949ed155.

Bug: 15205
Change-Id: I84b232aeafb6123f77f3f5d48bbe89326fe7eb0f
Reviewed-on: https://code.wireshark.org/review/30209
Petri-Dish: Stig Bjørlykke <stig@bjorlykke.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Roland Knall <rknall@gmail.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/extcap.c b/extcap.c
index 1744655685..bcbc9a8c9a 100644
--- a/extcap.c
+++ b/extcap.c
@@ -1131,7 +1131,7 @@ void extcap_if_cleanup(capture_options *capture_opts, gchar **errormsg)
         pipedata = (ws_pipe_t *) interface_opts->extcap_pipedata;
         if (pipedata)
         {
-            if (pipedata->stderr_fd > 0 && ws_pipe_data_available(pipedata->stderr_fd))
+            if (pipedata->stderr_fd > 0)
             {
                 buffer = (gchar *)g_malloc0(STDERR_BUFFER_SIZE + 1);
                 ws_read_string_from_pipe(ws_get_pipe_handle(pipedata->stderr_fd), buffer, STDERR_BUFFER_SIZE + 1);