1/* Provide relocatable packages.
2 Copyright (C) 2003, 2005, 2008-2019 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 General Public License as published by
7 the Free Software Foundation; either version 3 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 General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17
18#ifndef _RELOCATABLE_H
19#define _RELOCATABLE_H
20
21#ifdef __cplusplus
22extern "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 "/"). */
45extern 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 *'. */
53extern const char * relocate (const char *pathname);
54
55/* Returns the pathname, relocated according to the current installation
56 directory.
57 This function sets *ALLOCATEDP to the allocated memory, or to NULL if
58 no memory allocation occurs. So that, after you're done with the return
59 value, to reclaim allocated memory, you can do: free (*ALLOCATEDP). */
60extern const char * relocate2 (const char *pathname, char **allocatedp);
61
62/* Memory management: relocate() potentially allocates memory, because it has
63 to construct a fresh pathname. If this is a problem because your program
64 calls relocate() frequently or because you want to fix all potential memory
65 leaks anyway, you have three options:
66 1) Use this idiom:
67 const char *pathname = ...;
68 const char *rel_pathname = relocate (pathname);
69 ...
70 if (rel_pathname != pathname)
71 free ((char *) rel_pathname);
72 2) Use this idiom:
73 char *allocated;
74 const char *rel_pathname = relocate2 (..., &allocated);
75 ...
76 free (allocated);
77 3) Think about caching the result. */
78
79/* Convenience function:
80 Computes the current installation prefix, based on the original
81 installation prefix, the original installation directory of a particular
82 file, and the current pathname of this file.
83 Returns it, freshly allocated. Returns NULL upon failure. */
84extern char * compute_curr_prefix (const char *orig_installprefix,
85 const char *orig_installdir,
86 const char *curr_pathname);
87
88#else
89
90/* By default, we use the hardwired pathnames. */
91#define relocate(pathname) (pathname)
92#define relocate2(pathname,allocatedp) (*(allocatedp) = NULL, (pathname))
93
94#endif
95
96
97#ifdef __cplusplus
98}
99#endif
100
101#endif /* _RELOCATABLE_H */
102