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author | Jim Meyering <jim@meyering.net> | 1996-10-22 03:19:35 +0000 |
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committer | Jim Meyering <jim@meyering.net> | 1996-10-22 03:19:35 +0000 |
commit | e028e025df2b931d0035475ab5044b1631c55c12 (patch) | |
tree | 1d233283a7b61c2ac9daed60b35879e55e274064 | |
parent | 8978c64869b2fd317c025586027da43f46c1369e (diff) | |
download | coreutils-e028e025df2b931d0035475ab5044b1631c55c12.tar.xz |
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-rw-r--r-- | lib/group_member.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/lib/group_member.c b/lib/group_member.c new file mode 100644 index 000000000..9a079e293 --- /dev/null +++ b/lib/group_member.c @@ -0,0 +1,151 @@ +/* group-member.c -- determine whether group id is in calling user's group list + Copyright (C) 1994 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 2, 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, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include <stdio.h> +#include <sys/types.h> + +#ifdef STDC_HEADERS +# include <stdlib.h> +#endif + +#ifdef HAVE_UNISTD_H +# include <unistd.h> +#endif + +#include "group-member.h" + +char *xmalloc (); +char *xrealloc (); + +struct group_info + { + int n_groups; + GETGROUPS_T *group; + }; + +#ifdef HAVE_GETGROUPS + +static void +free_group_info (g) + struct group_info *g; +{ + free (g->group); + free (g); +} + +static struct group_info * +get_group_info () +{ + int n_groups; + int n_group_slots; + struct group_info *gi; + GETGROUPS_T *group; + + /* getgroups () returns the number of elements that it was able to + place into the array. We simply continue to call getgroups () + until the number of elements placed into the array is smaller than + the physical size of the array. */ + + group = NULL; + n_groups = 0; + n_group_slots = 0; + while (n_groups == n_group_slots) + { + n_group_slots += 64; + group = (GETGROUPS_T *) xrealloc (group, + n_group_slots * sizeof (GETGROUPS_T)); + n_groups = getgroups (n_group_slots, group); + } + + /* In case of error, the user loses. */ + if (n_groups < 0) + { + free (group); + return NULL; + } + + gi = (struct group_info *) xmalloc (sizeof (*gi)); + gi->n_groups = n_groups; + gi->group = group; + + return gi; +} + +#endif /* not HAVE_GETGROUPS */ + +/* Return non-zero if GID is one that we have in our groups list. + If there is no getgroups function, return non-zero if GID matches + either of the current or effective group IDs. */ + +int +group_member (gid) + gid_t gid; +{ +#ifndef HAVE_GETGROUPS + return ((gid == getgid ()) || (gid == getegid ())); +#else + int i; + int found; + struct group_info *gi; + + gi = get_group_info (); + if (gi == NULL) + return 0; + + /* Search through the list looking for GID. */ + found = 0; + for (i = 0; i < gi->n_groups; i++) + { + if (gid == gi->group[i]) + { + found = 1; + break; + } + } + + free_group_info (gi); + + return found; +#endif /* HAVE_GETGROUPS */ +} + +#ifdef TEST + +char *program_name; + +int +main (int argc, char** argv) +{ + int i; + + program_name = argv[0]; + + for (i=1; i<argc; i++) + { + gid_t gid; + + gid = atoi (argv[i]); + printf ("%d: %s\n", gid, group_member (gid) ? "yes" : "no"); + } + exit (0); +} + +#endif /* TEST */ |