From 47e511a1d0ee8c82d6e9014fb6a74ab6dfd89d3d Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Tue, 15 Nov 2011 09:30:49 -0800 Subject: 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. --- src/id.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) (limited to 'src') diff --git a/src/id.c b/src/id.c index 047e40b88..9fa93f83e 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 && !just_group && !just_group_list && !just_context) error (EXIT_FAILURE, errno, _("cannot get effective UID")); + errno = 0; ruid = getuid (); - if (GETID_MAY_FAIL && ruid == -1 && use_real + if (ruid == NO_UID && errno && use_real && !just_group && !just_group_list && !just_context) error (EXIT_FAILURE, errno, _("cannot get real UID")); + errno = 0; egid = getegid (); - if (GETID_MAY_FAIL && egid == -1 && !use_real && !just_user) + if (egid == NO_GID && errno && !use_real && !just_user) error (EXIT_FAILURE, errno, _("cannot get effective GID")); + errno = 0; rgid = getgid (); - if (GETID_MAY_FAIL && rgid == -1 && use_real && !just_user) + if (rgid == NO_GID && errno && use_real && !just_user) error (EXIT_FAILURE, errno, _("cannot get real GID")); } @@ -316,7 +319,7 @@ print_full_info (const char *username) gid_t *groups; int i; - int n_groups = xgetgroups (username, (pwd ? pwd->pw_gid : (gid_t) -1), + int n_groups = xgetgroups (username, (pwd ? pwd->pw_gid : -1), &groups); if (n_groups < 0) { -- cgit v1.2.3-70-g09d2