Guido U. Draheim <firstname.lastname@example.org>
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guidod's Miscellaneous (released)
checker whether the current system is sensitive to -Ddefines making
off_t having different types/sizes. Automatically define a config.h
symbol LARGEFILE_SENSITIVE if that is the case, otherwise leave
everything as is.
This macro builds on top of AC_SYS_LARGEFILE to detect whether
special options are neede to make the code use 64bit off_t - in
many setups this will also make the code use 64bit off_t
The common use of a LARGEFILE_SENSITIVE config.h-define is to
rename exported functions, usually adding a 64 to the original
function name. Such renamings are only needed on systems being both
(a) 32bit off_t by default and (b) implementing large.file
extensions (as for unix98).
a renaming section could look like this:
#if defined LARGEFILE_SENSITIVE && _FILE_OFFSET_BITS+0 == 64
#define zzip_open zzip_open64
#define zzip_seek zzip_seek64
for libraries, it is best to take advantage of the prefix-config.h
macro, otherwise you want to export a renamed LARGEFILE_SENSITIVE
in an installed header file. -> see AX_PREFIX_CONFIG_H
# we know about some internals of ac_sys_largefile here...
AC_MSG_CHECKING(whether system differentiates 64bit off_t by defines)
if test ".$ac_cv_sys_file_offset_bits$ac_cv_sys_large_files" != ".nono"
[whether the system defaults to 32bit off_t but can do 64bit when requested])