4229 mdb hangs on exit when long umem cache names exist
Reviewed by: Robert Mustacchi <rm@joyent.com>

*** 21,32 ****
   */
  /*
   * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
! 
! #pragma ident   "%Z%%M% %I%     %E% SMI"
  
  #include <mdb/mdb_debug.h>
  #include <mdb/mdb_string.h>
  #include <mdb/mdb_modapi.h>
  #include <mdb/mdb_err.h>
--- 21,33 ----
   */
  /*
   * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
! /*
!  * Copyright (c) 2013 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
!  */
  
  #include <mdb/mdb_debug.h>
  #include <mdb/mdb_string.h>
  #include <mdb/mdb_modapi.h>
  #include <mdb/mdb_err.h>
*** 36,46 ****
  #define NV_NAME(v) \
          (((v)->v_flags & MDB_NV_EXTNAME) ? (v)->v_ename : (v)->v_lname)
  
  #define NV_SIZE(v) \
          (((v)->v_flags & MDB_NV_EXTNAME) ? sizeof (mdb_var_t) : \
!         sizeof (mdb_var_t) + MDB_NV_NAMELEN - 1)
  
  #define NV_HASHSZ       211
  
  static size_t
  nv_hashstring(const char *key)
--- 37,47 ----
  #define NV_NAME(v) \
          (((v)->v_flags & MDB_NV_EXTNAME) ? (v)->v_ename : (v)->v_lname)
  
  #define NV_SIZE(v) \
          (((v)->v_flags & MDB_NV_EXTNAME) ? sizeof (mdb_var_t) : \
!         sizeof (mdb_var_t) + strlen((v)->v_lname))
  
  #define NV_HASHSZ       211
  
  static size_t
  nv_hashstring(const char *key)
*** 64,87 ****
  
  static mdb_var_t *
  nv_var_alloc(const char *name, const mdb_nv_disc_t *disc,
          uintmax_t value, uint_t flags, uint_t um_flags, mdb_var_t *next)
  {
!         size_t nbytes = (flags & MDB_NV_EXTNAME) ? sizeof (mdb_var_t) :
!             (sizeof (mdb_var_t) + MDB_NV_NAMELEN - 1);
  
!         mdb_var_t *v = mdb_alloc(nbytes, um_flags);
  
          if (v == NULL)
                  return (NULL);
  
          if (flags & MDB_NV_EXTNAME) {
                  v->v_ename = name;
!                 v->v_lname[0] = 0;
          } else {
!                 (void) strncpy(v->v_lname, name, MDB_NV_NAMELEN - 1);
!                 v->v_lname[MDB_NV_NAMELEN - 1] = '\0';
                  v->v_ename = NULL;
          }
  
          v->v_uvalue = value;
          v->v_flags = flags & ~(MDB_NV_SILENT | MDB_NV_INTERPOS);
--- 65,96 ----
  
  static mdb_var_t *
  nv_var_alloc(const char *name, const mdb_nv_disc_t *disc,
          uintmax_t value, uint_t flags, uint_t um_flags, mdb_var_t *next)
  {
!         size_t nbytes;
!         mdb_var_t *v;
  
!         if (flags & MDB_NV_EXTNAME)
!                 nbytes = sizeof (mdb_var_t);
!         else
!                 nbytes = sizeof (mdb_var_t) + strlen(name);
! 
!         v = mdb_alloc(nbytes, um_flags);
  
          if (v == NULL)
                  return (NULL);
  
          if (flags & MDB_NV_EXTNAME) {
                  v->v_ename = name;
!                 v->v_lname[0] = '\0';
          } else {
!                 /*
!                  * We don't overflow here since the mdb_var_t itself has
!                  * room for the trailing \0.
!                  */
!                 (void) strcpy(v->v_lname, name);
                  v->v_ename = NULL;
          }
  
          v->v_uvalue = value;
          v->v_flags = flags & ~(MDB_NV_SILENT | MDB_NV_INTERPOS);