striconveh: Don't malloc memory if the result buffer is sufficient.

[gnulib.git] / lib / mgetgroups.c

diff --git a/lib/mgetgroups.c b/lib/mgetgroups.c
index 5ca450f..76474c2 100644 (file)
--- a/lib/mgetgroups.c
+++ b/lib/mgetgroups.c
@@ -1,6 +1,6 @@
 /* mgetgroups.c -- return a list of the groups a user or current process is in
 
-   Copyright (C) 2007-2009 Free Software Foundation, Inc.
+   Copyright (C) 2007-2010 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
@@ -141,7 +141,8 @@ mgetgroups (char const *username, gid_t gid, gid_t **groups)
 
   ng = (username
         ? getugroups (max_n_groups, g, username, gid)
-        : getgroups (max_n_groups, g + (gid != (gid_t) -1)));
+        : getgroups (max_n_groups - (gid != (gid_t) -1),
+                                g + (gid != (gid_t) -1)));
 
   if (ng < 0)
     {
@@ -175,19 +176,20 @@ mgetgroups (char const *username, gid_t gid, gid_t **groups)
      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.  */
-  {
-    gid_t first = *g;
-    gid_t *next;
-    gid_t *sentinel = g + ng;
-
-    for (next = g + 1; next < sentinel; next++)
-      {
-        if (*next == first || *next == *g)
-          ng--;
-        else
-          *++g = *next;
-      }
-  }
+  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;
 }