https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67956
Bug ID: 67956
Summary: gcc's printf attribute accepts %m as a format
character
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: christos at zoulas dot com
Target Milestone: ---
Created attachment 36503
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36503&action=edit
patch
According to TOG
(http://pubs.opengroup.org/onlinepubs/009695399/functions/fprintf.html), %m is
not a legal formatting character for printf(3) like functions. Some
implementations (glibc) accept this formatting character as an extension and
expand it to the error string via strerror(3) that errno currently points to.
Most other c library implementations do not expand %m.
Attached is a patch that makes printf warn when %m is present and adds a
"syslog" attribute that accepts %m. I recognize that this is an incompatible
change, and I welcome suggestions how to do this in a less intrusive way.
I tried to mininize the size of the patch; there are better ways to do this,
but require more refactoring.
