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diff --git a/lib/elstring.h b/lib/elstring.h
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+/* Length/String string handling -- header
+ * Copyright (C) 2009 Chris Hall (GMCH), Highwayman
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra 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 2, or (at your
+ * option) any later version.
+ *
+ * GNU Zebra 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 GNU Zebra; see the file COPYING.  If not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef _ZEBRA_ELSTRING_H
+#define _ZEBRA_ELSTRING_H
+
+#include "misc.h"
+
+/*==============================================================================
+ * This is some very simple support for strings which are Length/Body
+ * objects.
+ *
+ * NB: this object knows NOTHING about memory allocation etc.  The objective
+ *     is the simplest possible encapsulation of strings which are NOT '\0'
+ *     terminated.
+ *
+ * NB: this object knows NOTHING about whether there is a '\0' beyond the
+ *     'len' of the string.
+ */
+struct elstring
+{
+  union
+  {
+    void*       v ;     /* may be NULL iff len == 0             */
+    const void* cv ;
+  } body ;
+
+  ulen  len ;
+} ;
+
+typedef struct elstring  elstring_t[1] ;
+typedef struct elstring* elstring ;
+
+/* Setting an elstring object to all zeros is enough to initialise it to
+ * an empty string.
+ */
+enum { ELSTRING_INIT_ALL_ZEROS = true } ;
+
+#define ELSTRING_INIT { { { NULL }, 0 } }
+
+/*==============================================================================
+ * Pointer pair and unsigned pointer pair and const versions.
+ */
+struct pp
+{
+  char*   p ;
+  char*   e ;
+} ;
+typedef struct pp  pp_t[1] ;
+typedef struct pp* pp ;
+
+struct cpp
+{
+  const char*   p ;
+  const char*   e ;
+} ;
+typedef struct cpp  cpp_t[1] ;
+typedef struct cpp* cpp ;
+
+/*==============================================================================
+ * NULLs for all types of pp and for els
+ */
+Inline void pp_null(pp p)   { p->p = p->e = NULL ; } ;
+Inline void cpp_null(cpp p) { p->p = p->e = NULL ; } ;
+
+Inline void els_null(elstring els) { els->body.v = NULL ; els->len = 0 ; } ;
+
+/*==============================================================================
+ * Access functions.
+ */
+
+Inline void* els_body(elstring els) ;
+Inline void* els_body_nn(elstring els) ;
+Inline ulen els_len(elstring els) ;
+Inline ulen els_len_nn(elstring els) ;
+Inline void* els_end(elstring els) ;
+Inline void* els_end_nn(elstring els) ;
+
+Inline void els_pp(pp p, elstring els) ;
+Inline void els_pp_nn(pp p, elstring els) ;
+Inline void els_cpp(cpp p, elstring els) ;
+Inline void els_cpp_nn(cpp p, elstring els) ;
+
+Inline void*
+els_body(elstring els)
+{
+  return (els != NULL) ? els_body_nn(els)  : NULL ;
+} ;
+
+Inline void*
+els_body_nn(elstring els)
+{
+  return els->body.v ;
+} ;
+
+Inline ulen
+els_len(elstring els)
+{
+  return (els != NULL) ? els_len_nn(els) : 0 ;
+} ;
+
+Inline ulen
+els_len_nn(elstring els)
+{
+  return els->len ;
+} ;
+
+Inline void*
+els_end(elstring els)
+{
+  return (els != NULL) ? els_end_nn(els) : NULL ;
+} ;
+
+Inline void*
+els_end_nn(elstring els)
+{
+  return (void*)((char*)els->body.v + els->len);
+} ;
+
+Inline void
+els_pp(pp p, elstring els)
+{
+  if (els != NULL)
+    els_pp_nn(p, els) ;
+  else
+    pp_null(p) ;
+} ;
+
+Inline void
+els_pp_nn(pp p, elstring els)
+{
+  p->p = els->body.v ;
+  p->e = p->p + els->len ;
+} ;
+
+Inline void
+els_cpp(cpp p, elstring els)
+{
+  if (els != NULL)
+    els_cpp_nn(p, els) ;
+  else
+    cpp_null(p) ;
+} ;
+
+Inline void
+els_cpp_nn(cpp p, elstring els)
+{
+  p->p = els->body.cv ;
+  p->e = p->p + els->len ;
+} ;
+
+/*==============================================================================
+ * All so simple that most is implemented as Inline
+ */
+
+extern elstring els_init_new(elstring els) ;
+extern elstring els_new(void) ;
+extern elstring els_free(elstring els) ;
+
+extern int els_cmp(elstring a, elstring b) ;
+extern int els_nn_cmp(const void* ap, ulen al, const void* bp, ulen bl) ;
+extern int els_cmp_word(elstring a, elstring w) ;
+extern int els_cmp_sig(elstring a, elstring b) ;
+extern bool els_equal(elstring a, elstring b) ;
+extern bool els_substring(elstring a, elstring b) ;
+
+/*------------------------------------------------------------------------------
+ * Set elstring value from ordinary string.
+ *
+ * NB: elstring MUST NOT be NULL.
+ *
+ * NB: treats str == NULL as a zero length string.
+ *
+ * NB: sets "term" unless str == NULL.
+ */
+Inline void
+els_set_nn(elstring els, const void* str)
+{
+  els->body.cv = str ;
+  els->len     = (str != NULL) ? strlen(str) : 0 ;
+} ;
+
+/*------------------------------------------------------------------------------
+ * Set elstring value from ordinary string.
+ *
+ * Creates elstring object if required (ie if els == NULL).
+ *
+ * See: els_set_nn.
+ */
+Inline elstring
+els_set(elstring els, const void* str)
+{
+  if (els == NULL)
+    els = els_new() ;
+
+  els_set_nn(els, str) ;
+
+  return els ;
+} ;
+
+/*------------------------------------------------------------------------------
+ * Set elstring value from body + length.
+ *
+ * NB: sets term = false.
+ *
+ * NB: elstring MUST NOT be NULL.
+ *
+ * NB: treats str == NULL as a zero length string.
+ */
+Inline void
+els_set_n_nn(elstring els, const void* body, ulen len)
+{
+  els->body.cv = body ;
+  els->len     = len ;
+} ;
+
+/*------------------------------------------------------------------------------
+ * Set elstring value from body + length.
+ *
+ * Creates elstring object if required (ie if els == NULL).
+ *
+ * See els_set_n_nn.
+ */
+Inline elstring
+els_set_n(elstring els, const void* body, ulen len)
+{
+  if (els == NULL)
+    els = els_new() ;
+
+  els_set_n_nn(els, body, len) ;
+
+  return els ;
+} ;
+
+/*------------------------------------------------------------------------------
+ * Clear contents of an elstring (if any)
+ *
+ * NB: it is the callers responsibility to free the contents of the elstring.
+ *     if that is required, before freeing the elstring itself.
+ */
+Inline void
+els_clear(elstring els)
+{
+  if (els != NULL)
+    {
+      els->body.v  = NULL ;
+      els->len     = 0 ;
+    } ;
+} ;
+
+/*------------------------------------------------------------------------------
+ * Set elstring 'len'.
+ *
+ * NB: it is the caller's responsibility to set a valid body !!
+ *
+ * NB: elstring MUST NOT be NULL.
+ */
+Inline void
+els_set_len_nn(elstring els, ulen len)
+{
+  els->len     = len ;
+} ;
+
+/*------------------------------------------------------------------------------
+ * Set elstring body.
+ *
+ * NB: it is the caller's responsibility to set a valid body !!
+ *
+ * NB: it is the caller's responsibility to set a valid 'len'.
+ *
+ * NB: elstring MUST NOT be NULL.
+ */
+Inline void
+els_set_body_nn(elstring els, const void* body)
+{
+  els->body.cv  = body ;
+} ;
+
+#endif /* _ZEBRA_ELSTRING_H */