126 lines
3.6 KiB
C
126 lines
3.6 KiB
C
/* provide consistent interface to getgroups for systems that don't allow N==0
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Copyright (C) 1996, 1999, 2003, 2006-2024 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file 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 Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://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 (_GL_UNUSED int n, _GL_UNUSED GETGROUPS_T *groups)
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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 OS X 10.6 and later, use the usual getgroups, not the one
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supplied when _DARWIN_C_SOURCE is defined. _DARWIN_C_SOURCE is
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normally defined, since it means "conform to POSIX, but add
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non-POSIX extensions even if that violates the POSIX namespace
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rules", which is what we normally want. But with getgroups there
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is an inconsistency, and _DARWIN_C_SOURCE means "change getgroups()
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so that it no longer works right". The BUGS section of compat(5)
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says that the behavior is dubious if you compile different sections
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of a program with different _DARWIN_C_SOURCE settings, so fix only
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the offending symbol. */
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# ifdef __APPLE__
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int posix_getgroups (int, gid_t []) __asm ("_getgroups");
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# define getgroups posix_getgroups
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# endif
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/* On at least NeXTstep 3.2, getgroups (0, NULL) always fails.
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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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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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free (gbuf);
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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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free (gbuf);
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return n_groups;
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}
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#endif /* HAVE_GETGROUPS */
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