lib/relocatable.h

   1 /* Provide relocatable packages.
   2    Copyright (C) 2003, 2005, 2008-2017 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2003.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as published by
   7    the Free Software Foundation; either version 2.1 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _RELOCATABLE_H
  19 #define _RELOCATABLE_H
  20
  21 #ifdef __cplusplus
  22 extern "C" {
  23 #endif
  24
  25
  26 /* This can be enabled through the configure --enable-relocatable option.  */
  27 #if ENABLE_RELOCATABLE
  28
  29 /* When building a DLL, we must export some functions.  Note that because
  30    this is a private .h file, we don't need to use __declspec(dllimport)
  31    in any case.  */
  32 #if HAVE_VISIBILITY && BUILDING_DLL
  33 # define RELOCATABLE_DLL_EXPORTED __attribute__((__visibility__("default")))
  34 #elif defined _MSC_VER && BUILDING_DLL
  35 # define RELOCATABLE_DLL_EXPORTED __declspec(dllexport)
  36 #else
  37 # define RELOCATABLE_DLL_EXPORTED
  38 #endif
  39
  40 /* Sets the original and the current installation prefix of the package.
  41    Relocation simply replaces a pathname starting with the original prefix
  42    by the corresponding pathname with the current prefix instead.  Both
  43    prefixes should be directory names without trailing slash (i.e. use ""
  44    instead of "/").  */
  45 extern RELOCATABLE_DLL_EXPORTED void
  46        set_relocation_prefix (const char *orig_prefix,
  47                               const char *curr_prefix);
  48
  49 /* Returns the pathname, relocated according to the current installation
  50    directory.
  51    The returned string is either PATHNAME unmodified or a freshly allocated
  52    string that you can free with free() after casting it to 'char *'.  */
  53 extern const char * relocate (const char *pathname);
  54
  55 /* Memory management: relocate() potentially allocates memory, because it has
  56    to construct a fresh pathname.  If this is a problem because your program
  57    calls relocate() frequently, think about caching the result.  Or free the
  58    return value if it was different from the argument pathname.  */
  59
  60 /* Convenience function:
  61    Computes the current installation prefix, based on the original
  62    installation prefix, the original installation directory of a particular
  63    file, and the current pathname of this file.
  64    Returns it, freshly allocated.  Returns NULL upon failure.  */
  65 extern char * compute_curr_prefix (const char *orig_installprefix,
  66                                    const char *orig_installdir,
  67                                    const char *curr_pathname);
  68
  69 #else
  70
  71 /* By default, we use the hardwired pathnames.  */
  72 #define relocate(pathname) (pathname)
  73
  74 #endif
  75
  76
  77 #ifdef __cplusplus
  78 }
  79 #endif
  80
  81 #endif /* _RELOCATABLE_H */