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Re: bug#10021: [PATCH id] Add error-checking on GNU
From: |
Paul Eggert |
Subject: |
Re: bug#10021: [PATCH id] Add error-checking on GNU |
Date: |
Tue, 15 Nov 2011 08:59:51 -0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:7.0) Gecko/20110927 Thunderbird/7.0 |
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
<http://debbugs.gnu.org/cgi/bugreport.cgi?bug=10021#47>.
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
&& !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)
{
- Re: bug#10021: [PATCH id] Add error-checking on GNU, (continued)
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Paul Eggert, 2011/11/14
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Roland McGrath, 2011/11/14
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Eric Blake, 2011/11/14
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Ludovic Courtès, 2011/11/14
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Paul Eggert, 2011/11/14
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Ludovic Courtès, 2011/11/15
- Re: bug#10021: [PATCH id] Add error-checking on GNU,
Paul Eggert <=
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Eric Blake, 2011/11/15
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Eric Blake, 2011/11/16
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Jim Meyering, 2011/11/15
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Paul Eggert, 2011/11/15
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Paul Eggert, 2011/11/16
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Paul Eggert, 2011/11/20
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Jim Meyering, 2011/11/13
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Ludovic Courtès, 2011/11/13
- Re: bug#10021: [PATCH id] Add error-checking on GNU, Jim Meyering, 2011/11/14