Adding upstream version 9.4.upstream/9.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 197 insertions, 0 deletions

diff --git a/lib/mgetgroups.c b/lib/mgetgroups.c
new file mode 100644
index 0000000..fdf9d59
--- /dev/null
+++ b/lib/mgetgroups.c
@@ -0,0 +1,197 @@
+/* mgetgroups.c -- return a list of the groups a user or current process is in
+
+   Copyright (C) 2007-2023 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/>.  */
+
+/* Extracted from coreutils' src/id.c. */
+
+#include <config.h>
+
+#include "mgetgroups.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#if HAVE_GETGROUPLIST
+# include <grp.h>
+#endif
+
+#include "getugroups.h"
+#include "xalloc-oversized.h"
+
+/* Work around an incompatibility of OS X 10.11: getgrouplist
+   accepts int *, not gid_t *, and int and gid_t differ in sign.  */
+#if 4 < __GNUC__ + (3 <= __GNUC_MINOR__) || defined __clang__
+# pragma GCC diagnostic ignored "-Wpointer-sign"
+#endif
+
+static gid_t *
+realloc_groupbuf (gid_t *g, size_t num)
+{
+  if (xalloc_oversized (num, sizeof *g))
+    {
+      errno = ENOMEM;
+      return NULL;
+    }
+
+  return realloc (g, num * sizeof *g);
+}
+
+/* Like getugroups, but store the result in malloc'd storage.
+   Set *GROUPS to the malloc'd list of all group IDs of which USERNAME
+   is a member.  If GID is not -1, store it first.  GID should be the
+   group ID (pw_gid) obtained from getpwuid, in case USERNAME is not
+   listed in the groups database (e.g., /etc/groups).  If USERNAME is
+   NULL, store the supplementary groups of the current process, and GID
+   should be -1 or the effective group ID (getegid).  Upon failure,
+   don't modify *GROUPS, set errno, and return -1.  Otherwise, return
+   the number of groups.  The resulting list may contain duplicates,
+   but adjacent members will be distinct.  */
+
+int
+mgetgroups (char const *username, gid_t gid, gid_t **groups)
+{
+  int max_n_groups;
+  int ng;
+  gid_t *g;
+
+#if HAVE_GETGROUPLIST
+  /* We prefer to use getgrouplist if available, because it has better
+     performance characteristics.
+
+     In glibc 2.3.2, getgrouplist is buggy.  If you pass a zero as the
+     length of the output buffer, getgrouplist will still write to the
+     buffer.  Contrary to what some versions of the getgrouplist
+     manpage say, this doesn't happen with nonzero buffer sizes.
+     Therefore our usage here just avoids a zero sized buffer.  */
+  if (username)
+    {
+      enum { N_GROUPS_INIT = 10 };
+      max_n_groups = N_GROUPS_INIT;
+
+      g = realloc_groupbuf (NULL, max_n_groups);
+      if (g == NULL)
+        return -1;
+
+      while (1)
+        {
+          gid_t *h;
+          int last_n_groups = max_n_groups;
+
+          /* getgrouplist updates max_n_groups to num required.  */
+          ng = getgrouplist (username, gid, g, &max_n_groups);
+
+          /* Some systems (like Darwin) have a bug where they
+             never increase max_n_groups.  */
+          if (ng < 0 && last_n_groups == max_n_groups)
+            max_n_groups *= 2;
+
+          if ((h = realloc_groupbuf (g, max_n_groups)) == NULL)
+            {
+              free (g);
+              return -1;
+            }
+          g = h;
+
+          if (0 <= ng)
+            {
+              *groups = g;
+              /* On success some systems just return 0 from getgrouplist,
+                 so return max_n_groups rather than ng.  */
+              return max_n_groups;
+            }
+        }
+    }
+  /* else no username, so fall through and use getgroups. */
+#endif
+
+  max_n_groups = (username
+                  ? getugroups (0, NULL, username, gid)
+                  : getgroups (0, NULL));
+
+  /* If we failed to count groups because there is no supplemental
+     group support, then return an array containing just GID.
+     Otherwise, we fail for the same reason.  */
+  if (max_n_groups < 0)
+    {
+      if (errno == ENOSYS && (g = realloc_groupbuf (NULL, 1)))
+        {
+          *groups = g;
+          *g = gid;
+          return gid != (gid_t) -1;
+        }
+      return -1;
+    }
+
+  if (max_n_groups == 0 || (!username && gid != (gid_t) -1))
+    max_n_groups++;
+  g = realloc_groupbuf (NULL, max_n_groups);
+  if (g == NULL)
+    return -1;
+
+  ng = (username
+        ? getugroups (max_n_groups, g, username, gid)
+        : getgroups (max_n_groups - (gid != (gid_t) -1),
+                                g + (gid != (gid_t) -1)));
+
+  if (ng < 0)
+    {
+      /* Failure is unexpected, but handle it anyway.  */
+      free (g);
+      return -1;
+    }
+
+  if (!username && gid != (gid_t) -1)
+    {
+      *g = gid;
+      ng++;
+    }
+  *groups = g;
+
+  /* Reduce the number of duplicates.  On some systems, getgroups
+     returns the effective gid twice: once as the first element, and
+     once in its position within the supplementary groups.  On other
+     systems, getgroups does not return the effective gid at all,
+     which is why we provide a GID argument.  Meanwhile, the GID
+     argument, if provided, is typically any member of the
+     supplementary groups, and not necessarily the effective gid.  So,
+     the most likely duplicates are the first element with an
+     arbitrary other element, or pair-wise duplication between the
+     first and second elements returned by getgroups.  It is possible
+     that this O(n) pass will not remove all duplicates, but it is not
+     worth the effort to slow down to an O(n log n) algorithm that
+     sorts the array in place, nor the extra memory needed for
+     duplicate removal via an O(n) hash-table.  Hence, this function
+     is only documented as guaranteeing no pair-wise duplicates,
+     rather than returning the minimal set.  */
+  if (1 < ng)
+    {
+      gid_t first = *g;
+      gid_t *next;
+      gid_t *groups_end = g + ng;
+
+      for (next = g + 1; next < groups_end; next++)
+        {
+          if (*next == first || *next == *g)
+            ng--;
+          else
+            *++g = *next;
+        }
+    }
+
+  return ng;
+}