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/* Provide relocatable packages.
Copyright (C) 2003, 2005, 2008-2017 Free Software Foundation, Inc.
Written by Bruno Haible <>, 2003.
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU Library General Public License as published
by the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this program; if not, see <>. */
#ifdef __cplusplus
extern "C" {
/* This can be enabled through the configure --enable-relocatable option. */
/* 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. */
# define RELOCATABLE_DLL_EXPORTED __attribute__((__visibility__("default")))
#elif defined _MSC_VER && BUILDING_DLL
# define RELOCATABLE_DLL_EXPORTED __declspec(dllexport)
/* 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 "/"). */
set_relocation_prefix (const char *orig_prefix,
const char *curr_prefix);
/* Returns the pathname, relocated according to the current installation
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
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);
/* By default, we use the hardwired pathnames. */
#define relocate(pathname) (pathname)
#define relocate2(pathname,allocatedp) (*(allocatedp) = NULL, (pathname))
#ifdef __cplusplus
#endif /* _RELOCATABLE_H */