mirror of git://sourceware.org/git/glibc.git
Make _REENTRANT and _THREAD_SAFE aliases for _POSIX_C_SOURCE=199506L.
For many years, the only effect of these macros has been to make unistd.h declare getlogin_r. _POSIX_C_SOURCE >= 199506L also causes this function to be declared. However, people who don't carefully read all the headers might be confused into thinking they need to define _REENTRANT for any threaded code (as was indeed the case a long time ago). Therefore, remove __USE_REENTRANT, and make _REENTRANT and _THREAD_SAFE into synonyms for _POSIX_C_SOURCE=199506L. This will only affect programs that don't select a higher conformance level some other way. For instance, -std=c89 -D_REENTRANT will see a change in visible declarations, but -std=c99 -D_POSIX_C_SOURCE=200809L -D_REENTRANT won't, and -D_REENTRANT all by itself also won't, because _DEFAULT_SOURCE implies _POSIX_C_SOURCE > 199506. * include/features.h: Remove __USE_REENTRANT. Treat _REENTRANT and _THREAD_SAFE the same as _POSIX_C_SOURCE=199506L, if a higher POSIX conformance level has not been selected by other macros. * NEWS, manual/creature.texi: Document this change. * posix/unistd.h, posix/bits/unistd.h: Don't check __USE_REENTRANT. * include/libc-symbols.h: Don't define _REENTRANT. * scripts/check-installed-headers.sh: Don't undefine _REENTRANT.
This commit is contained in:
Zack Weinberg
parent
3d6bfcace1
commit
c03073774f
13
NEWS
13
NEWS
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@ -22,6 +22,19 @@ Version 2.25
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from that TS. Note that most features from that TS are not supported by
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the GNU C Library.
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* The nonstandard feature selection macros _REENTRANT and _THREAD_SAFE are
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now treated as compatibility synonyms for _POSIX_C_SOURCE=199506L.
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Since the GNU C Library defaults to a much newer revision of POSIX, this
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will only affect programs that specifically request an old conformance
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mode. For instance, a program compiled with -std=c89 -D_REENTRANT will
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see a change in the visible declarations, but a program compiled with
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just -D_REENTRANT, or -std=c99 -D_POSIX_C_SOURCE=200809L -D_REENTRANT,
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will not.
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Some C libraries once required _REENTRANT and/or _THREAD_SAFE to be
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defined by all multithreaded code, but glibc has not required this for
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many years.
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* The inclusion of <sys/sysmacros.h> by <sys/types.h> is deprecated. This
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means that in a future release, the macros “major”, “minor”, and “makedev”
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will only be available from <sys/sysmacros.h>.
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@ -24,10 +24,13 @@
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__STRICT_ANSI__ ISO Standard C.
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_ISOC99_SOURCE Extensions to ISO C89 from ISO C99.
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_ISOC11_SOURCE Extensions to ISO C99 from ISO C11.
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__STDC_WANT_LIB_EXT2__ Extensions to ISO C99 from TR 27431-2:2010.
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__STDC_WANT_IEC_60559_BFP_EXT__ Extensions to ISO C11 from TS 18661-1:2014.
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__STDC_WANT_IEC_60559_FUNCS_EXT__ Extensions to ISO C11 from
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TS 18661-4:2015.
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__STDC_WANT_LIB_EXT2__
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Extensions to ISO C99 from TR 27431-2:2010.
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__STDC_WANT_IEC_60559_BFP_EXT__
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Extensions to ISO C11 from TS 18661-1:2014.
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__STDC_WANT_IEC_60559_FUNCS_EXT__
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Extensions to ISO C11 from TS 18661-4:2015.
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_POSIX_SOURCE IEEE Std 1003.1.
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_POSIX_C_SOURCE If ==1, like _POSIX_SOURCE; if >=2 add IEEE Std 1003.2;
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if >=199309L, add IEEE Std 1003.1b-1993;
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@ -45,10 +48,12 @@
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_GNU_SOURCE All of the above, plus GNU extensions.
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_DEFAULT_SOURCE The default set of features (taking precedence over
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__STRICT_ANSI__).
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_REENTRANT Select additionally reentrant object.
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_THREAD_SAFE Same as _REENTRANT, often used by other systems.
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_FORTIFY_SOURCE If set to numeric value > 0 additional security
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measures are defined, according to level.
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_FORTIFY_SOURCE Add security hardening to many library functions.
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Set to 1 or 2; 2 performs stricter checks than 1.
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_REENTRANT, _THREAD_SAFE
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Obsolete; equivalent to _POSIX_C_SOURCE=199506L.
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The `-ansi' switch to the GNU C compiler, and standards conformance
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options such as `-std=c99', define __STRICT_ANSI__. If none of
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@ -86,7 +91,6 @@
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__USE_MISC Define things from 4.3BSD or System V Unix.
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__USE_ATFILE Define *at interfaces and AT_* constants for them.
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__USE_GNU Define GNU extensions.
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__USE_REENTRANT Define reentrant/thread-safe *_r functions.
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__USE_FORTIFY_LEVEL Additional security measures used, according to level.
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The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
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@ -130,7 +134,6 @@
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#undef __USE_MISC
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#undef __USE_ATFILE
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#undef __USE_GNU
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#undef __USE_REENTRANT
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#undef __USE_FORTIFY_LEVEL
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#undef __KERNEL_STRICT_NAMES
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@ -253,6 +256,7 @@
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# undef _POSIX_C_SOURCE
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# define _POSIX_C_SOURCE 200809L
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#endif
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#if ((!defined __STRICT_ANSI__ \
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|| (defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >= 500)) \
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&& !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE)
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@ -269,6 +273,19 @@
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# define __USE_POSIX_IMPLICITLY 1
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#endif
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/* Some C libraries once required _REENTRANT and/or _THREAD_SAFE to be
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defined in all multithreaded code. GNU libc has not required this
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for many years. We now treat them as compatibility synonyms for
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_POSIX_C_SOURCE=199506L, which is the earliest level of POSIX with
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comprehensive support for multithreaded code. Using them never
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lowers the selected level of POSIX conformance, only raises it. */
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#if ((!defined _POSIX_C_SOURCE || (_POSIX_C_SOURCE - 0) < 199506L) \
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&& (defined _REENTRANT || defined _THREAD_SAFE))
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# define _POSIX_SOURCE 1
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# undef _POSIX_C_SOURCE
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# define _POSIX_C_SOURCE 199506L
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#endif
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#if (defined _POSIX_SOURCE \
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|| (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 1) \
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|| defined _XOPEN_SOURCE)
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@ -351,10 +368,6 @@
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# define __USE_GNU 1
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#endif
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#if defined _REENTRANT || defined _THREAD_SAFE
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# define __USE_REENTRANT 1
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#endif
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#if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 0
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# if !defined __OPTIMIZE__ || __OPTIMIZE__ <= 0
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# warning _FORTIFY_SOURCE requires compiling with optimization (-O)
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@ -52,8 +52,6 @@
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/* Enable declarations of GNU extensions, since we are compiling them. */
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#define _GNU_SOURCE 1
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/* And we also need the data for the reentrant functions. */
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#define _REENTRANT 1
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#include <config.h>
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@ -219,15 +219,11 @@ cause them to be disabled.
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@comment GNU
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@defvr Macro _REENTRANT
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@defvrx Macro _THREAD_SAFE
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If you define one of these macros, reentrant versions of several functions get
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declared. Some of the functions are specified in POSIX.1c but many others
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are only available on a few other systems or are unique to @theglibc{}.
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The problem is the delay in the standardization of the thread safe C library
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interface.
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These macros are obsolete. They have the same effect as defining
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@code{_POSIX_C_SOURCE} with the value @code{199506L}.
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Unlike on some other systems, no special version of the C library must be
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used for linking. There is only one version but while compiling this
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it must have been specified to compile as thread safe.
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Some very old C libraries required one of these macros to be defined
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for basic functionality (e.g.@: @code{getchar}) to be thread-safe.
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@end defvr
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We recommend you use @code{_GNU_SOURCE} in new programs. If you don't
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@ -302,7 +302,7 @@ __NTH (ttyname_r (int __fd, char *__buf, size_t __buflen))
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}
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#if defined __USE_REENTRANT || defined __USE_POSIX199506
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#ifdef __USE_POSIX199506
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extern int __getlogin_r_chk (char *__buf, size_t __buflen, size_t __nreal)
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__nonnull ((1));
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extern int __REDIRECT (__getlogin_r_alias, (char *__buf, size_t __buflen),
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@ -849,7 +849,7 @@ extern int tcsetpgrp (int __fd, __pid_t __pgrp_id) __THROW;
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This function is a possible cancellation point and therefore not
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marked with __THROW. */
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extern char *getlogin (void);
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#if defined __USE_REENTRANT || defined __USE_POSIX199506
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#ifdef __USE_POSIX199506
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/* Return at most NAME_LEN characters of the login name of the user in NAME.
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If it cannot be determined or some other error occurred, return the error
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code. Otherwise return 0.
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@ -143,7 +143,6 @@ EOF
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inappropriate for this test. */
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#undef _LIBC
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#undef _GNU_SOURCE
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#undef _REENTRANT
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/* The library mode is selected here rather than on the command line to
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ensure that this selection wins. */
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$expanded_lib_mode
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