From 171199159214f2f548132a98988435f9a450d3ef Mon Sep 17 00:00:00 2001 From: Zack Weinberg Date: Wed, 1 Mar 2017 08:17:07 -0500 Subject: Remove _IO_MTSAFE_IO from public headers. _IO_MTSAFE_IO controls whether stdio is *built* with support for multithreading. In the distant past it might also have worked as a feature selection macro, allowing library *users* to select thread-safe or lock-free stdio at application build time, I haven't done the archaeology. Nowadays, defining _IO_MTSAFE_IO while using the installed headers, or in _ISOMAC mode, will cause libio.h to throw syntax errors. This patch removes _IO_MTSAFE_IO from the public headers (specifically, from libio/libio.h). The most important thing it controlled in there was whether libio.h defines _IO_lock_t itself or expects stdio-lock.h to have done it, and we do still need a inter-header communication macro for that, because stdio-lock.h can only define _IO_lock_t as a typedef. I've invented _IO_lock_t_defined, which is defined by both versions of stdio-lock.h. _IO_MTSAFE_IO also controlled the definitions of a handful of macros that _might_ count as part of the public libio.h interface. They are now unconditionally given their non-_IO_MTSAFE_IO definition in libio/libio.h, and include/libio.h redefines them with the _IO_MTSAFE_IO definition. This should minimize the odds of breaking old software that actually uses those macros. I suspect that this entire mechanism is vestigial, and that glibc won't build anymore if you *don't* define _IO_MTSAFE_IO, but that's another patchset. The bulk of libio.h is internal-use-only stuff that no longer makes sense to expose (libstdc++ gave up on making a FILE the same object as a C++ filebuf *decades* ago) but that, too, is another patchset. * libio/libio.h: Condition dummy definition of _IO_lock_t on _IO_lock_t_defined, not _IO_MTSAFE_IO. Unconditionally use the non-_IO_MTSAFE_IO definitions for _IO_peekc, _IO_flockfile, _IO_funlockfile, and _IO_ftrylockfile. Only define _IO_cleanup_region_start and _IO_cleanup_region_end if not already defined. * include/libio.h: If _IO_MTSAFE_IO is defined, redefine _IO_peekc, _IO_flockfile, _IO_funlockfile, and _IO_ftrylockfile appropriately. * sysdeps/generic/stdio-lock.h, sysdeps/nptl/stdio-lock.h: Define _IO_lock_t_defined after defining _IO_lock_t. --- include/libio.h | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) (limited to 'include') diff --git a/include/libio.h b/include/libio.h index 97fc5b5..d2fa796 100644 --- a/include/libio.h +++ b/include/libio.h @@ -21,16 +21,25 @@ libc_hidden_proto (_IO_sgetn) libc_hidden_proto (_IO_vfprintf) libc_hidden_proto (_IO_vfscanf) -#if defined _IO_MTSAFE_IO && _IO_lock_inexpensive +#ifdef _IO_MTSAFE_IO +# undef _IO_peekc # undef _IO_flockfile -# define _IO_flockfile(_fp) \ - if (((_fp)->_flags & _IO_USER_LOCK) == 0) \ - _IO_lock_lock (*(_fp)->_lock) # undef _IO_funlockfile -# define _IO_funlockfile(_fp) \ - if (((_fp)->_flags & _IO_USER_LOCK) == 0) \ - _IO_lock_unlock (*(_fp)->_lock) -#endif +# undef _IO_ftrylockfile + +# define _IO_peekc(_fp) _IO_peekc_locked (_fp) +# if _IO_lock_inexpensive +# define _IO_flockfile(_fp) \ + if (((_fp)->_flags & _IO_USER_LOCK) == 0) _IO_lock_lock (*(_fp)->_lock) +# define _IO_funlockfile(_fp) \ + if (((_fp)->_flags & _IO_USER_LOCK) == 0) _IO_lock_unlock (*(_fp)->_lock) +# else +# define _IO_flockfile(_fp) \ + if (((_fp)->_flags & _IO_USER_LOCK) == 0) _IO_flockfile (_fp) +# define _IO_funlockfile(_fp) \ + if (((_fp)->_flags & _IO_USER_LOCK) == 0) _IO_funlockfile (_fp) +# endif +#endif /* _IO_MTSAFE_IO */ #endif #endif -- cgit v1.1