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More header large file flexibility and comment cleanup for dual mode.

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Now mpg123.h listens to MPG123_NO_LARGENAME and MPG123_LARGESUFFIX. That gives a way to hack around any automatism... you might also want to #define off_t for special purpose (to get the 64 bit off_t API on 32 bit systems without having _FILE_OFFSET_BITS in place).



git-svn-id: svn://scm.orgis.org/mpg123/trunk@2677 35dc7657-300d-0410-a2e5-dc2837fedb53
This commit is contained in:
thor
2010-05-16 10:39:37 +00:00
parent d1d9cc7d90
commit 692d34e8f6
1 changed files with 16 additions and 16 deletions
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32
src/libmpg123/mpg123.h.in
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@@ -43,25 +43,25 @@
New approach: When the app defines _FILE_OFFSET_BITS, it wants non-default large file support,
and thus functions with added suffix (mpg123_open_64).
Any mismatch will be caught at link time because of the _FILE_OFFSET_BITS setting used when
building libmpg123.
building libmpg123. Plus, there's dual mode large file support in mpg123 since 1.12 now.
Link failure is not the expected outcome of any half-sane usage anymore.
Thinking about offering wrappers for non-largefile-aware apps (mpg123_open wrapping over mpg123_open_64, using 32 bit off_t):
This would need more pervasive changes in libmpg123, including figuring out how to properly handle file descriptors being handed to mpg123_open_fd.
And frankly, I would like to avoid that complication. You can have multiple builds of libmpg123, after all -- with and without large file support.
More complication: What about client code defining _LARGEFILE64_SOURCE?
I only thought about _FILE_OFFSET_BITS. Dammit!
Perhaps make a new mpg123 API after all, avoiding off_t this time and
just cautioning apps about using mpg123_open_fd?
More complication: What about client code defining _LARGEFILE64_SOURCE? It might want direct access to the _64 functions, along with the ones without suffix. Well, that's possible now via defining MPG123_NO_LARGENAME and MPG123_LARGESUFFIX, respectively, for disabling or enforcing the suffix names.
*/
#if (defined _FILE_OFFSET_BITS)
/* Need some trickery to concatenate the value of the given macro.
To make it clear:
When _FILE_OFFSET_BITS is 64, the function names get _64 appended. */
#define MPG123_ADDSUFFIX_REALLY(func, suffix) func ## _ ## suffix
#define MPG123_ADDSUFFIX(func, suffix) MPG123_ADDSUFFIX_REALLY(func, suffix)
#define MPG123_LARGENAME(func) MPG123_ADDSUFFIX(func, _FILE_OFFSET_BITS)
/*
Now, the renaming of large file aware functions.
By default, it appends underscore _FILE_OFFSET_BITS (so, mpg123_seek_64 for mpg123_seek), if _FILE_OFFSET_BITS is defined. You can force a different suffix via MPG123_LARGESUFFIX (that must include the underscore), or you can just disable the whole mess by defining MPG123_NO_LARGENAME.
*/
#if (!defined MPG123_NO_LARGENAME) && ((defined _FILE_OFFSET_BITS) || (defined MPG123_LARGESUFFIX))
/* Need some trickery to concatenate the value(s) of the given macro(s). */
#define MPG123_MACROCAT_REALLY(a, b) a ## b
#define MPG123_MACROCAT(a, b) MPG123_MACROCAT_REALLY(a, b)
#ifndef MPG123_LARGESUFFIX
#define MPG123_LARGESUFFIX MPG123_MACROCAT(_, _FILE_OFFSET_BITS)
#endif
#define MPG123_LARGENAME(func) MPG123_MACROCAT(func, MPG123_LARGESUFFIX)
#define mpg123_open MPG123_LARGENAME(mpg123_open)
#define mpg123_open_fd MPG123_LARGENAME(mpg123_open_fd)