From 06ca3797ac89c7c16a80ae8276bd23ef5b6f6a6f Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Tue, 15 Nov 2011 08:20:59 -0800 Subject: doc: update for ISO/IEC 80000-13 * doc/coreutils.texi (Block size): IEC 60027-2 has been superseded by ISO/IEC 80000-13, so prefer the newer standard but also mention the old. The new standard specifies Zi and Yi, so they are no longer GNU extensions. Fix stale URL to BIPM. 2011-11-14 Paul Eggert id: handle (uid_t) -1 more portably * src/id.c (GETID_MAY_FAIL): Remove. (main): Check for negative return values, not for -1. The old code was incorrect if uid_t was narrower than int, regardless of whether we were on a GNU or a POSIX platform. The new code is simpler and doesn't need GETID_MAY_FAIL. (print_full_info): Remove unnecessary cast to -1. --- src/id.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) (limited to 'src/id.c') diff --git a/src/id.c b/src/id.c index 047e40b88..b3ee437fd 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 +201,36 @@ main (int argc, char **argv) } else { + /* On GNU/Hurd hosts, getuid etc. can fail and return -1. + However, on GNU/Linux hosts, uid_t is an unsigned value and + getuid etc. can return the positive value (uid_t) -1. To + handle both cases correctly, consider getuid etc. to fail if + it returns a negative value (a value that is impossible on + GNU/Linux hosts). + + GNU/Linux sysadmins should not give users the UID (uid_t) -1 + even though uid_t is unsigned, as system calls like chown would + not have the desired behavior with such a UID, and other + coreutils applications therefore do not support such a UID. + However, 'id' makes a special attempt to handle this UID, to + help people diagnose the problem. */ + euid = geteuid (); - if (GETID_MAY_FAIL && euid == -1 && !use_real + if (euid < 0 && !use_real && !just_group && !just_group_list && !just_context) error (EXIT_FAILURE, errno, _("cannot get effective UID")); ruid = getuid (); - if (GETID_MAY_FAIL && ruid == -1 && use_real + if (ruid < 0 && use_real && !just_group && !just_group_list && !just_context) error (EXIT_FAILURE, errno, _("cannot get real UID")); egid = getegid (); - if (GETID_MAY_FAIL && egid == -1 && !use_real && !just_user) + if (egid < 0 && !use_real && !just_user) error (EXIT_FAILURE, errno, _("cannot get effective GID")); rgid = getgid (); - if (GETID_MAY_FAIL && rgid == -1 && use_real && !just_user) + if (rgid < 0 && use_real && !just_user) error (EXIT_FAILURE, errno, _("cannot get real GID")); } @@ -316,7 +323,7 @@ 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 v1.2.3-54-g00ecf