text: Paul Eggert wrote: > On 11/15/11 05:07, Ludovic Courtès wrote: > >> On GNU/Hurd, no error would ever be raised (since uid_t is unsigned), > > Ouch. Thanks, now I understand Roland's suggestion. > How about this patch instead? > > id: handle (uid_t) -1 more portably > * src/id.c (GETID_MAY_FAIL): Remove. > (main): Check for nonzero errno, rather than having a compile-time > GETID_MAY_FAIL guess. Suggested by Roland McGrath in > <>. > Also, the old code was incorrect if uid_t was narrower than int. > (print_full_info): Remove unnecessary cast to -1. > diff --git a/src/id.c b/src/id.c > index 047e40b..9fa93f8 100644 > --- a/src/id.c > +++ b/src/id.c > @@ -38,13 +38,6 @@ > proper_name ("Arnold Robbins"), \ > proper_name ("David MacKenzie") > > -/* Whether the functions getuid, geteuid, getgid and getegid may fail. */ > -#ifdef __GNU__ > -# define GETID_MAY_FAIL 1 > -#else > -# define GETID_MAY_FAIL 0 > -#endif > - > /* If nonzero, output only the SELinux context. -Z */ > static int just_context = 0; > > @@ -208,22 +201,32 @@ main (int argc, char **argv) > } > else > { > + /* POSIX says getuid etc. cannot fail, but they can fail under > + GNU/Hurd and a few other systems. Test for failure by > + checking errno. */ > + uid_t NO_UID = -1; > + gid_t NO_GID = -1; > + > + errno = 0; > euid = geteuid (); > - if (GETID_MAY_FAIL && euid == -1 && !use_real > + if (euid == NO_UID && errno && !use_real I like that. Thanks!