On 11/8/19 10:07 AM, Eric Blake wrote:
On 11/8/19 8:40 AM, Philippe Mathieu-Daudé wrote:
Since not all trace backends support dynamic field width in
format (dtrace via stap does not), forbid them.
Add a check to refuse field width in new formats:
+++ b/scripts/tracetool/__init__.py
@@ -206,6 +206,7 @@ class Event(object):
"\s*"
"(?:(?:(?P<fmt_trans>\".+),)?\s*(?P<fmt>\".+))?"
"\s*")
+ _DFWRE = re.compile(".*(%0?\*).*")
The use of leading and trailing .* is pointless if the RE itself is used
unanchored and where you only care if the () matched.
Following up on this (based on an IRC conversation):
re.match _is_ anchored by default, while re.search is unanchored
This doesn't catch all valid uses of * in a printf format. Better might
be something like:
_DFWRE = re.compile("%[\d\.\- +#']*\*")
which matches only if there is a %, any number of characters that can
form a printf flag, as well as a numeric field width but dynamic precision.
+ if Event._DFWRE.match(fmt):
Or put differently, if you want to drop the .* from the compiled regex,
then you need to use .search(fmt) here rather than .match(fmt).
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
