Author: dab Date: Thu Jun 28 17:01:04 2018 New Revision: 335765 URL: https://svnweb.freebsd.org/changeset/base/335765
Log: Remove potential identifier conflict in the EV_SET macro. PR43905 pointed out a problem with the EV_SET macro if the passed struct kevent pointer were specified with an expression with side effects (e.g., "kevp++"). This was fixed in rS110241, but by using a local block that defined an internal variable (named "kevp") to get the pointer value once. This worked, but could cause issues if an existing variable named "kevp" is in scope. To avoid that issue, jilles@ pointed out that "C99 compound literals and designated initializers allow doing this cleanly using a macro". This change incorporates that suggestion, essentially verbatim from jilles@ comment on PR43905, except retaining the old definition for pre-C99 or non-STDC (e.g., C++) compilers. PR: 43905 Submitted by: Jilles Tjoelker (jilles@) Reported by: Lamont Granquist <lam...@scriptkiddie.org> Reviewed by: jmg (no comments), jilles MFC after: 1 week Sponsored by: Dell EMC Differential Revision: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=43905 Modified: head/sys/sys/event.h Modified: head/sys/sys/event.h ============================================================================== --- head/sys/sys/event.h Thu Jun 28 15:30:51 2018 (r335764) +++ head/sys/sys/event.h Thu Jun 28 17:01:04 2018 (r335765) @@ -49,7 +49,26 @@ #define EVFILT_EMPTY (-13) /* empty send socket buf */ #define EVFILT_SYSCOUNT 13 +#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L #define EV_SET(kevp_, a, b, c, d, e, f) do { \ + *(kevp_) = (struct kevent){ \ + .ident = (a), \ + .filter = (b), \ + .flags = (c), \ + .fflags = (d), \ + .data = (e), \ + .udata = (f), \ + .ext[0] = 0, \ + .ext[1] = 0, \ + .ext[2] = 0, \ + .ext[3] = 0, \ + }; \ +} while(0) +#else /* Pre-C99 or not STDC (e.g., C++) */ +/* The definition of the local variable kevp could possibly conflict + * with a user-defined value passed in parameters a-f. + */ +#define EV_SET(kevp_, a, b, c, d, e, f) do { \ struct kevent *kevp = (kevp_); \ (kevp)->ident = (a); \ (kevp)->filter = (b); \ @@ -62,6 +81,7 @@ (kevp)->ext[2] = 0; \ (kevp)->ext[3] = 0; \ } while(0) +#endif struct kevent { __uintptr_t ident; /* identifier for this event */ _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
