1 files changed, 122 insertions, 0 deletions
diff --git a/src/group-list.c b/src/group-list.c
new file mode 100644
index 0000000..05f5720
--- /dev/null
+++ b/src/group-list.c
@@ -0,0 +1,122 @@
+/* group-list.c --Print a list of group IDs or names.
+   Copyright (C) 1989-2022 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 3 of the License, 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, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Arnold Robbins.
+   Major rewrite by David MacKenzie, djm@gnu.ai.mit.edu.
+   Extracted from id.c by James Youngman. */
+
+#include <config.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include "system.h"
+#include "error.h"
+#include "mgetgroups.h"
+#include "quote.h"
+#include "group-list.h"
+
+
+/* Print all of the distinct groups the user is in. */
+extern bool
+print_group_list (char const *username,
+                  uid_t ruid, gid_t rgid, gid_t egid,
+                  bool use_names, char delim)
+{
+  bool ok = true;
+  struct passwd *pwd = NULL;
+
+  if (username)
+    {
+      pwd = getpwuid (ruid);
+      if (pwd == NULL)
+        ok = false;
+    }
+
+  if (!print_group (rgid, use_names))
+    ok = false;
+
+  if (egid != rgid)
+    {
+      putchar (delim);
+      if (!print_group (egid, use_names))
+        ok = false;
+    }
+
+  {
+    gid_t *groups;
+
+    int n_groups = xgetgroups (username, (pwd ? pwd->pw_gid : egid), &groups);
+    if (n_groups < 0)
+      {
+        if (username)
+          {
+            error (0, errno, _("failed to get groups for user %s"),
+                   quote (username));
+          }
+        else
+          {
+            error (0, errno, _("failed to get groups for the current process"));
+          }
+        return false;
+      }
+
+    for (int i = 0; i < n_groups; i++)
+      if (groups[i] != rgid && groups[i] != egid)
+        {
+          putchar (delim);
+          if (!print_group (groups[i], use_names))
+            ok = false;
+        }
+    free (groups);
+  }
+  return ok;
+}
+
+/* Convert a gid_t to string.  Do not use this function directly.
+   Instead, use it via the gidtostr macro.
+   Beware that it returns a pointer to static storage.  */
+static char *
+gidtostr_ptr (gid_t const *gid)
+{
+  static char buf[INT_BUFSIZE_BOUND (uintmax_t)];
+  return umaxtostr (*gid, buf);
+}
+#define gidtostr(g) gidtostr_ptr (&(g))
+
+/* Print the name or value of group ID GID. */
+extern bool
+print_group (gid_t gid, bool use_name)
+{
+  struct group *grp = NULL;
+  bool ok = true;
+
+  if (use_name)
+    {
+      grp = getgrgid (gid);
+      if (grp == NULL)
+        {
+          error (0, 0, _("cannot find name for group ID %lu"),
+                 (unsigned long int) gid);
+          ok = false;
+        }
+    }
+
+  char *s = grp ? grp->gr_name : gidtostr (gid);
+  fputs (s, stdout);
+  return ok;
+}