More checks for localtime() and gmtime() returning NULL.

And some comments in the case where we're converting the result of
time() - if your machine's idea of time predates January 1, 1970,
00:00:00 UTC, it'll crash on Windows, but that's not a case where a
*file* can cause the problem due either to a bad file time stamp or bad
time stamps in the file.

Change-Id: I837a438e4b875dd8c4f3ec2137df7a16ee4e9498
Reviewed-on: https://code.wireshark.org/review/18369
Reviewed-by: Guy Harris <guy@alum.mit.edu>

1 files changed, 6 insertions, 0 deletions

diff --git a/ringbuffer.c b/ringbuffer.c
index 7f0f67d5e7..099e8c4783 100644
--- a/ringbuffer.c
+++ b/ringbuffer.c
@@ -102,6 +102,12 @@ static int ringbuf_open_file(rb_file *rfile, int *err)
   current_time = time(NULL);
 
   g_snprintf(filenum, sizeof(filenum), "%05u", (rb_data.curr_file_num + 1) % RINGBUFFER_MAX_NUM_FILES);
+  /*
+   * XXX - We trust Windows not to return a time before the Epoch, so
+   * localtime() doesn't return a null pointer.  localtime() can probably
+   * handle pre-Epoch times on most UN*X systems, and we trust them not
+   * to return a time before the Epoch in any case.
+   */
   strftime(timestr, sizeof(timestr), "%Y%m%d%H%M%S", localtime(&current_time));
   rfile->name = g_strconcat(rb_data.fprefix, "_", filenum, "_", timestr,
                             rb_data.fsuffix, NULL);