lib/check-version.c

   1 /* check-version.h --- Check version string compatibility.
   2    Copyright (C) 1998-2006, 2008-2017 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Simon Josefsson.  This interface is influenced by
  18    gcry_check_version from Werner Koch's Libgcrypt.  Paul Eggert
  19    suggested the use of strverscmp to simplify implementation. */
  20
  21 #include <config.h>
  22
  23 #include <stddef.h>
  24 #include <string.h>
  25
  26 /* Get specification. */
  27 #include "check-version.h"
  28
  29 /* Check that the version of the library (i.e., the CPP symbol VERSION)
  30  * is at minimum the requested one in REQ_VERSION (typically found in
  31  * a header file) and return the version string.  Return NULL if the
  32  * condition is not satisfied.  If a NULL is passed to this function,
  33  * no check is done, but the version string is simply returned.
  34  */
  35 const char *
  36 check_version (const char *req_version)
  37 {
  38   if (!req_version || strverscmp (req_version, VERSION) <= 0)
  39     return VERSION;
  40
  41   return NULL;
  42 }