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117 lines
2.9 KiB
C
117 lines
2.9 KiB
C
/* provide consistent interface to getgroups for systems that don't allow N==0
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Copyright (C) 1996, 1999, 2003, 2006-2013 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* written by Jim Meyering */
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#include <config.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <stdint.h>
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#if !HAVE_GETGROUPS
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/* Provide a stub that fails with ENOSYS, since there is no group
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information available on mingw. */
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int
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getgroups (int n _GL_UNUSED, GETGROUPS_T *groups _GL_UNUSED)
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{
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errno = ENOSYS;
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return -1;
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}
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#else /* HAVE_GETGROUPS */
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# undef getgroups
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# ifndef GETGROUPS_ZERO_BUG
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# define GETGROUPS_ZERO_BUG 0
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# endif
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/* On at least Ultrix 4.3 and NextStep 3.2, getgroups (0, NULL) always
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fails. On other systems, it returns the number of supplemental
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groups for the process. This function handles that special case
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and lets the system-provided function handle all others. However,
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it can fail with ENOMEM if memory is tight. It is unspecified
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whether the effective group id is included in the list. */
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int
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rpl_getgroups (int n, gid_t *group)
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{
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int n_groups;
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GETGROUPS_T *gbuf;
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int saved_errno;
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if (n < 0)
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{
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errno = EINVAL;
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return -1;
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}
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if (n != 0 || !GETGROUPS_ZERO_BUG)
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{
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int result;
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if (sizeof *group == sizeof *gbuf)
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return getgroups (n, (GETGROUPS_T *) group);
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if (SIZE_MAX / sizeof *gbuf <= n)
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{
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errno = ENOMEM;
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return -1;
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}
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gbuf = malloc (n * sizeof *gbuf);
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if (!gbuf)
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return -1;
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result = getgroups (n, gbuf);
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if (0 <= result)
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{
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n = result;
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while (n--)
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group[n] = gbuf[n];
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}
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saved_errno = errno;
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free (gbuf);
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errno == saved_errno;
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return result;
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}
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n = 20;
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while (1)
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{
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/* No need to worry about address arithmetic overflow here,
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since the ancient systems that we're running on have low
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limits on the number of secondary groups. */
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gbuf = malloc (n * sizeof *gbuf);
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if (!gbuf)
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return -1;
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n_groups = getgroups (n, gbuf);
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if (n_groups == -1 ? errno != EINVAL : n_groups < n)
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break;
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free (gbuf);
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n *= 2;
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}
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saved_errno = errno;
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free (gbuf);
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errno = saved_errno;
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return n_groups;
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}
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#endif /* HAVE_GETGROUPS */
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