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authorZack Weinberg <zackw@panix.com>2017-03-01 08:17:07 -0500
committerZack Weinberg <zackw@panix.com>2017-05-11 19:14:11 -0400
commit171199159214f2f548132a98988435f9a450d3ef (patch)
tree8d64c85952231bad3eb928b2c8dba653441aec3e
parent31073a53d8ff1e8bac53e34cb626dae5aa6ce69c (diff)
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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.
-rw-r--r--ChangeLog14
-rw-r--r--include/libio.h25
-rw-r--r--libio/libio.h31
-rw-r--r--sysdeps/generic/stdio-lock.h1
-rw-r--r--sysdeps/nptl/stdio-lock.h1
5 files changed, 46 insertions, 26 deletions
diff --git a/ChangeLog b/ChangeLog
index 8d2cfed6067..b08ac488ffd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2017-05-11 Zack Weinberg <zackw@panix.com>
+
+ * 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.
+
2016-05-10 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* sysdeps/powerpc/powerpc32/backtrace.c (is_sigtramp_address): Use
diff --git a/include/libio.h b/include/libio.h
index 97fc5b548b9..d2fa7967586 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 2241c1471db..518ffd8e44f 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 532bb5f23f3..763c7d465aa 100644
--- a/sysdeps/generic/stdio-lock.h
+++ b/sysdeps/generic/stdio-lock.h
@@ -22,6 +22,7 @@
#include <libc-lock.h>
__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 35d6ce0a292..df749062eac 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 }