From patchwork Wed Mar 22 12:55:03 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zack Weinberg X-Patchwork-Id: 19696 Received: (qmail 96830 invoked by alias); 22 Mar 2017 12:55:08 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 96809 invoked by uid 89); 22 Mar 2017 12:55:06 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-25.0 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RP_MATCHES_RCVD, SPF_PASS autolearn=ham version=3.3.2 spammy=odds, communication X-HELO: mailbackend.panix.com From: Zack Weinberg To: libc-alpha@sourceware.org Subject: [PATCH 1/2] Remove _IO_MTSAFE_IO from public headers. Date: Wed, 22 Mar 2017 08:55:03 -0400 Message-Id: <20170322125504.4863-2-zackw@panix.com> In-Reply-To: <20170322125504.4863-1-zackw@panix.com> References: <20170322125504.4863-1-zackw@panix.com> MIME-Version: 1.0 _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 +++++++++++++++++-------- libio/libio.h | 31 +++++++++++++------------------ sysdeps/generic/stdio-lock.h | 1 + sysdeps/nptl/stdio-lock.h | 1 + 4 files changed, 32 insertions(+), 26 deletions(-) diff --git a/include/libio.h b/include/libio.h index 97fc5b548b..d2fa796758 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 diff --git a/libio/libio.h b/libio/libio.h index 2241c1471d..518ffd8e44 100644 --- a/libio/libio.h +++ b/libio/libio.h @@ -143,10 +143,9 @@ struct _IO_jump_t; struct _IO_FILE; -/* Handle lock. */ -#ifdef _IO_MTSAFE_IO -/* _IO_lock_t defined in internal headers during the glibc build. */ -#else +/* During the build of glibc itself, _IO_lock_t will already have been + defined by internal headers. */ +#ifndef _IO_lock_t_defined typedef void _IO_lock_t; #endif @@ -441,20 +440,16 @@ extern void _IO_flockfile (_IO_FILE *) __THROW; extern void _IO_funlockfile (_IO_FILE *) __THROW; extern int _IO_ftrylockfile (_IO_FILE *) __THROW; -#ifdef _IO_MTSAFE_IO -# define _IO_peekc(_fp) _IO_peekc_locked (_fp) -# 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) -#else -# define _IO_peekc(_fp) _IO_peekc_unlocked (_fp) -# define _IO_flockfile(_fp) /**/ -# define _IO_funlockfile(_fp) /**/ -# define _IO_ftrylockfile(_fp) /**/ -# define _IO_cleanup_region_start(_fct, _fp) /**/ -# define _IO_cleanup_region_end(_Doit) /**/ -#endif /* !_IO_MTSAFE_IO */ +#define _IO_peekc(_fp) _IO_peekc_unlocked (_fp) +#define _IO_flockfile(_fp) /**/ +#define _IO_funlockfile(_fp) /**/ +#define _IO_ftrylockfile(_fp) /**/ +#ifndef _IO_cleanup_region_start +#define _IO_cleanup_region_start(_fct, _fp) /**/ +#endif +#ifndef _IO_cleanup_region_end +#define _IO_cleanup_region_end(_Doit) /**/ +#endif extern int _IO_vfscanf (_IO_FILE * __restrict, const char * __restrict, _IO_va_list, int *__restrict); diff --git a/sysdeps/generic/stdio-lock.h b/sysdeps/generic/stdio-lock.h index 532bb5f23f..763c7d465a 100644 --- a/sysdeps/generic/stdio-lock.h +++ b/sysdeps/generic/stdio-lock.h @@ -22,6 +22,7 @@ #include __libc_lock_define_recursive (typedef, _IO_lock_t) +#define _IO_lock_t_defined 1 /* We need recursive (counting) mutexes. */ #ifdef _LIBC_LOCK_RECURSIVE_INITIALIZER diff --git a/sysdeps/nptl/stdio-lock.h b/sysdeps/nptl/stdio-lock.h index 35d6ce0a29..df749062ea 100644 --- a/sysdeps/nptl/stdio-lock.h +++ b/sysdeps/nptl/stdio-lock.h @@ -27,6 +27,7 @@ #define _IO_lock_inexpensive 1 typedef struct { int lock; int cnt; void *owner; } _IO_lock_t; +#define _IO_lock_t_defined 1 #define _IO_lock_initializer { LLL_LOCK_INITIALIZER, 0, NULL }