/* Provide relocatable packages.
   Copyright (C) 2003, 2005, 2008-2018 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2003.

   This program is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.
   This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.  */

#ifndef _RELOCATABLE_H
#define _RELOCATABLE_H

#ifdef __cplusplus
extern "C" {
#endif


/* This can be enabled through the configure --enable-relocatable option.  */
#if ENABLE_RELOCATABLE

/* When building a DLL, we must export some functions.  Note that because
   this is a private .h file, we don't need to use __declspec(dllimport)
   in any case.  */
#if HAVE_VISIBILITY && BUILDING_DLL
# define RELOCATABLE_DLL_EXPORTED __attribute__((__visibility__("default")))
#elif defined _MSC_VER && BUILDING_DLL
# define RELOCATABLE_DLL_EXPORTED __declspec(dllexport)
#else
# define RELOCATABLE_DLL_EXPORTED
#endif

/* Sets the original and the current installation prefix of the package.
   Relocation simply replaces a pathname starting with the original prefix
   by the corresponding pathname with the current prefix instead.  Both
   prefixes should be directory names without trailing slash (i.e. use ""
   instead of "/").  */
extern RELOCATABLE_DLL_EXPORTED void
       set_relocation_prefix (const char *orig_prefix,
                              const char *curr_prefix);

/* Returns the pathname, relocated according to the current installation
   directory.
   The returned string is either PATHNAME unmodified or a freshly allocated
   string that you can free with free() after casting it to 'char *'.  */
extern const char * relocate (const char *pathname);

/* Returns the pathname, relocated according to the current installation
   directory.
   This function sets *ALLOCATEDP to the allocated memory, or to NULL if
   no memory allocation occurs.  So that, after you're done with the return
   value, to reclaim allocated memory, you can do: free (*ALLOCATEDP).  */
extern const char * relocate2 (const char *pathname, char **allocatedp);

/* Memory management: relocate() potentially allocates memory, because it has
   to construct a fresh pathname.  If this is a problem because your program
   calls relocate() frequently or because you want to fix all potential memory
   leaks anyway, you have three options:
   1) Use this idiom:
        const char *pathname = ...;
        const char *rel_pathname = relocate (pathname);
        ...
        if (rel_pathname != pathname)
          free ((char *) rel_pathname);
   2) Use this idiom:
        char *allocated;
        const char *rel_pathname = relocate2 (..., &allocated);
        ...
        free (allocated);
   3) Think about caching the result.  */

/* Convenience function:
   Computes the current installation prefix, based on the original
   installation prefix, the original installation directory of a particular
   file, and the current pathname of this file.
   Returns it, freshly allocated.  Returns NULL upon failure.  */
extern char * compute_curr_prefix (const char *orig_installprefix,
                                   const char *orig_installdir,
                                   const char *curr_pathname);

#else

/* By default, we use the hardwired pathnames.  */
#define relocate(pathname) (pathname)
#define relocate2(pathname,allocatedp) (*(allocatedp) = NULL, (pathname))

#endif


#ifdef __cplusplus
}
#endif

#endif /* _RELOCATABLE_H */
