129 lines
3.2 KiB
C
129 lines
3.2 KiB
C
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/* getugroups.c -- return a list of the groups a user is in
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Copyright (C) 1990-1991, 1998-2000, 2003-2020 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 <https://www.gnu.org/licenses/>. */
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/* Written by David MacKenzie. */
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#include <config.h>
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#include "getugroups.h"
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#include <errno.h>
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#include <limits.h>
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#include <stdio.h> /* grp.h on alpha OSF1 V2.0 uses "FILE *". */
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#include <string.h>
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#include <unistd.h>
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#if !HAVE_GRP_H || defined __ANDROID__
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/* Mingw lacks all things related to group management. The best we
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can do is fail with ENOSYS.
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Bionic declares e.g. getgrent() in <grp.h> but it isn't actually
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defined in the library. */
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int
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getugroups (int maxcount _GL_UNUSED,
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gid_t *grouplist _GL_UNUSED,
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char const *username _GL_UNUSED,
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gid_t gid _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_GRP_H */
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# include <grp.h>
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# define STREQ(a, b) (strcmp (a, b) == 0)
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/* Like 'getgroups', but for user USERNAME instead of for the current
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process. Store at most MAXCOUNT group IDs in the GROUPLIST array.
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If GID is not -1, store it first (if possible). GID should be the
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group ID (pw_gid) obtained from getpwuid, in case USERNAME is not
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listed in /etc/groups. Upon failure, set errno and return -1.
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Otherwise, return the number of IDs we've written into GROUPLIST. */
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int
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getugroups (int maxcount, gid_t *grouplist, char const *username,
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gid_t gid)
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{
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int count = 0;
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if (gid != (gid_t) -1)
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{
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if (maxcount != 0)
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grouplist[count] = gid;
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++count;
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}
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setgrent ();
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while (1)
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{
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char **cp;
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struct group *grp;
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errno = 0;
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grp = getgrent ();
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if (grp == NULL)
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break;
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for (cp = grp->gr_mem; *cp; ++cp)
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{
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int n;
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if ( ! STREQ (username, *cp))
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continue;
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/* See if this group number is already on the list. */
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for (n = 0; n < count; ++n)
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if (grouplist && grouplist[n] == grp->gr_gid)
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break;
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/* If it's a new group number, then try to add it to the list. */
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if (n == count)
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{
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if (maxcount != 0)
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{
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if (count >= maxcount)
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goto done;
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grouplist[count] = grp->gr_gid;
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}
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if (count == INT_MAX)
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{
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errno = EOVERFLOW;
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goto done;
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}
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count++;
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}
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}
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}
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if (errno != 0)
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count = -1;
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done:
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{
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int saved_errno = errno;
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endgrent ();
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errno = saved_errno;
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}
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return count;
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}
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#endif /* HAVE_GRP_H */
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