root/maint/gnulib/lib/relocatable.h

/* */

INCLUDED FROM

   1 /* Provide relocatable packages.
   2    Copyright (C) 2003, 2005, 2008-2021 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2003.
   4 
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9 
  10    This file 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 <https://www.gnu.org/licenses/>.  */
  17 
  18 #ifndef _RELOCATABLE_H
  19 #define _RELOCATABLE_H
  20 
  21 #include <stdlib.h>
  22 
  23 #ifdef __cplusplus
  24 extern "C" {
  25 #endif
  26 
  27 
  28 /* This can be enabled through the configure --enable-relocatable option.  */
  29 #if ENABLE_RELOCATABLE
  30 
  31 /* When building a DLL, we must export some functions.  Note that because
  32    this is a private .h file, we don't need to use __declspec(dllimport)
  33    in any case.  */
  34 #if HAVE_VISIBILITY && BUILDING_DLL
  35 # define RELOCATABLE_DLL_EXPORTED __attribute__((__visibility__("default")))
  36 #elif defined _MSC_VER && BUILDING_DLL
  37 # define RELOCATABLE_DLL_EXPORTED __declspec(dllexport)
  38 #else
  39 # define RELOCATABLE_DLL_EXPORTED
  40 #endif
  41 
  42 /* Sets the original and the current installation prefix of the package.
  43    Relocation simply replaces a pathname starting with the original prefix
  44    by the corresponding pathname with the current prefix instead.  Both
  45    prefixes should be directory names without trailing slash (i.e. use ""
  46    instead of "/").  */
  47 extern RELOCATABLE_DLL_EXPORTED void
  48        set_relocation_prefix (const char *orig_prefix,
  49                               const char *curr_prefix);
  50 
  51 /* Returns the pathname, relocated according to the current installation
  52    directory.
  53    The returned string is either PATHNAME unmodified or a freshly allocated
  54    string that you can free with free() after casting it to 'char *'.  */
  55 extern const char * relocate (const char *pathname);
  56 
  57 /* Returns the pathname, relocated according to the current installation
  58    directory.
  59    This function sets *ALLOCATEDP to the allocated memory, or to NULL if
  60    no memory allocation occurs.  So that, after you're done with the return
  61    value, to reclaim allocated memory, you can do: free (*ALLOCATEDP).  */
  62 extern const char * relocate2 (const char *pathname, char **allocatedp);
  63 
  64 /* Memory management: relocate() potentially allocates memory, because it has
  65    to construct a fresh pathname.  If this is a problem because your program
  66    calls relocate() frequently or because you want to fix all potential memory
  67    leaks anyway, you have three options:
  68    1) Use this idiom:
  69         const char *pathname = ...;
  70         const char *rel_pathname = relocate (pathname);
  71         ...
  72         if (rel_pathname != pathname)
  73           free ((char *) rel_pathname);
  74    2) Use this idiom:
  75         char *allocated;
  76         const char *rel_pathname = relocate2 (..., &allocated);
  77         ...
  78         free (allocated);
  79    3) Think about caching the result.  */
  80 
  81 /* Convenience function:
  82    Computes the current installation prefix, based on the original
  83    installation prefix, the original installation directory of a particular
  84    file, and the current pathname of this file.
  85    Returns it, freshly allocated.  Returns NULL upon failure.  */
  86 extern char * compute_curr_prefix (const char *orig_installprefix,
  87                                    const char *orig_installdir,
  88                                    const char *curr_pathname)
  89   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE;
  90 
  91 #else
  92 
  93 /* By default, we use the hardwired pathnames.  */
  94 #define relocate(pathname) (pathname)
  95 #define relocate2(pathname,allocatedp) (*(allocatedp) = NULL, (pathname))
  96 
  97 #endif
  98 
  99 
 100 #ifdef __cplusplus
 101 }
 102 #endif
 103 
 104 #endif /* _RELOCATABLE_H */

/* */