1 files changed, 128 insertions, 0 deletions
diff --git a/lib/getugroups.c b/lib/getugroups.c
new file mode 100644
index 0000000..0145165
--- /dev/null
+++ b/lib/getugroups.c
@@ -0,0 +1,128 @@
+/* getugroups.c -- return a list of the groups a user is in
+
+   Copyright (C) 1990-1991, 1998-2000, 2003-2023 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file 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 Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by David MacKenzie. */
+
+#include <config.h>
+
+#include "getugroups.h"
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h> /* grp.h on alpha OSF1 V2.0 uses "FILE *". */
+#include <string.h>
+#include <unistd.h>
+
+#if !HAVE_GRP_H || defined __ANDROID__
+
+/* Mingw lacks all things related to group management.  The best we
+   can do is fail with ENOSYS.
+
+   Bionic declares e.g. getgrent() in <grp.h> but it isn't actually
+   defined in the library.  */
+
+int
+getugroups (_GL_UNUSED int maxcount,
+            _GL_UNUSED gid_t *grouplist,
+            _GL_UNUSED char const *username,
+            _GL_UNUSED gid_t gid)
+{
+  errno = ENOSYS;
+  return -1;
+}
+
+#else /* HAVE_GRP_H */
+# include <grp.h>
+
+# define STREQ(a, b) (strcmp (a, b) == 0)
+
+/* Like 'getgroups', but for user USERNAME instead of for the current
+   process.  Store at most MAXCOUNT group IDs in the GROUPLIST array.
+   If GID is not -1, store it first (if possible).  GID should be the
+   group ID (pw_gid) obtained from getpwuid, in case USERNAME is not
+   listed in /etc/groups.  Upon failure, set errno and return -1.
+   Otherwise, return the number of IDs we've written into GROUPLIST.  */
+
+int
+getugroups (int maxcount, gid_t *grouplist, char const *username,
+            gid_t gid)
+{
+  int count = 0;
+
+  if (gid != (gid_t) -1)
+    {
+      if (maxcount != 0)
+        grouplist[count] = gid;
+      ++count;
+    }
+
+  setgrent ();
+  while (1)
+    {
+      char **cp;
+      struct group *grp;
+
+      errno = 0;
+      grp = getgrent ();
+      if (grp == NULL)
+        break;
+
+      for (cp = grp->gr_mem; *cp; ++cp)
+        {
+          int n;
+
+          if ( ! STREQ (username, *cp))
+            continue;
+
+          /* See if this group number is already on the list.  */
+          for (n = 0; n < count; ++n)
+            if (grouplist && grouplist[n] == grp->gr_gid)
+              break;
+
+          /* If it's a new group number, then try to add it to the list.  */
+          if (n == count)
+            {
+              if (maxcount != 0)
+                {
+                  if (count >= maxcount)
+                    goto done;
+                  grouplist[count] = grp->gr_gid;
+                }
+              if (count == INT_MAX)
+                {
+                  errno = EOVERFLOW;
+                  goto done;
+                }
+              count++;
+            }
+        }
+    }
+
+  if (errno != 0)
+    count = -1;
+
+ done:
+  {
+    int saved_errno = errno;
+    endgrent ();
+    errno = saved_errno;
+  }
+
+  return count;
+}
+
+#endif /* HAVE_GRP_H */