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id: fix infinite loop on some systems

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Steven Parkes reported that `id -G $USER` went into an infinite loop
on Darwin systems for users in more than 10 groups:
http://bugs.gentoo.org/show_bug.cgi?id=264007
* gl/lib/mgetgroups.c (mgetgroups): Work around buggy getgrouplist
implementations that don't update the required size correctly,
by doubling the result buffer and retrying. Also return the
parameter updated by getgrouplist rather than its return value,
as the documentation doesn't actually state the number of groups
stored is returned by getgrouplist.
* tests/misc/id-groups: Add test to exercise this logic
* tests/Makefile.am: Reference new test
* NEWS: Mention the fix
* THANKS: Update
This commit is contained in:
Pádraig Brady 2009-04-08 10:43:15 +01:00
parent 148ddb3232
commit bf87a2c8ea
5 changed files with 47 additions and 1 deletions
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8
NEWS
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@ -14,6 +14,14 @@ GNU coreutils NEWS -*- outline -*-
default should proceed at the speed of the disk. Previously /dev/urandom
was used if available, which is relatively slow on GNU/Linux systems.
** Portability
`id -G $USER` now works correctly even on Darwin and NetBSD. Previously it
would either truncate the group list to 10, or go into an infinite loop,
due to their non-standard getgroups implementations.
[truncation introduced in coreutils-6.11]
[infinite loop introduced in coreutils-7.1]
* Noteworthy changes in release 7.2 (2009-03-31) [stable]
** New features

1
THANKS
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@ -525,6 +525,7 @@ Steve McIntyre steve@einval.com
Steve Ward planet36@gmail.com
Steven G. Johnson stevenj@alum.mit.edu
Steven Mocking ufo@quicknet.nl
Steven Parkes smparkes@smparkes.net
Steven Schveighoffer schveiguy@yahoo.com
Steven P Watson steven@magelico.net
Stuart Kemp skemp@peter.bmc.com

10
gl/lib/mgetgroups.c
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@ -81,10 +81,16 @@ mgetgroups (char const *username, gid_t gid, GETGROUPS_T **groups)
while (1)
{
GETGROUPS_T *h;
int last_n_groups = max_n_groups;
/* getgrouplist updates max_n_groups to num required. */
ng = getgrouplist (username, gid, g, &max_n_groups);
/* Some systems (like Darwin) have a bug where they
never increase max_n_groups. */
if (ng < 0 && last_n_groups == max_n_groups)
max_n_groups *= 2;
if ((h = realloc_groupbuf (g, max_n_groups)) == NULL)
{
int saved_errno = errno;
@ -97,7 +103,9 @@ mgetgroups (char const *username, gid_t gid, GETGROUPS_T **groups)
if (0 <= ng)
{
*groups = g;
return ng;
/* On success some systems just return 0 from getgrouplist,
so return max_n_groups rather than ng. */
return max_n_groups;
}
}
}

1
tests/Makefile.am
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@ -171,6 +171,7 @@ TESTS = \
misc/head-c \
misc/head-pos \
misc/id-context \
misc/id-groups \
misc/md5sum \
misc/md5sum-newline \
misc/mknod \

28
tests/misc/id-groups Executable file
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@ -0,0 +1,28 @@
#!/bin/sh
# Ensure that "id" outputs groups for a user
# Copyright (C) 2009 Free Software Foundation, Inc.
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
if test "$VERBOSE" = yes; then
set -x
id --version
fi
. $srcdir/test-lib.sh
fail=0
id -G $(id -nu) || fail=1
Exit $fail