file: Only change the file descriptors on a Save with Copy

If we do a save with copy, so that we just copied the binary
file, everything in the wtap structure should be the same except
for the filename and the file descriptors, so just change that
instead of closing wtap and reopening it.

The current behavior of calling wtap_open_offline does not work
for files that have blocks (SHBs, IDBs, NRBs, DSBs, ISBs, etc.) in
the middle of the file instead of at the beginning, but we shouldn't
have to waste time rescanning the entire file either.

In the case where a specific file format reader was manually selected,
this will keep the same file format as selected instead of switching to
the auto-detection when opening the copy, just as SAVE_WITH_MOVE already
does and presumably what the user wants.

Update wtap_fdreopen to change the wtap struct's pathname if
wtap_fdreopen is called with a different filename than currently.

Fix #17472

1 files changed, 4 insertions, 0 deletions

diff --git a/wiretap/file_access.c b/wiretap/file_access.c
index 9724c8ef9e..7b7e3f8b66 100644
--- a/wiretap/file_access.c
+++ b/wiretap/file_access.c
@@ -1237,6 +1237,10 @@ wtap_fdreopen(wtap *wth, const char *filename, int *err)
 		*err = errno;
 		return FALSE;
 	}
+	if (strcmp(filename, wth->pathname) != 0) {
+		g_free(wth->pathname);
+		wth->pathname = g_strdup(filename);
+	}
 	return TRUE;
 }