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Zack Weinberg ea1bd74def New string function explicit_bzero (from OpenBSD).
explicit_bzero(s, n) is the same as memset(s, 0, n), except that the
compiler is not allowed to delete a call to explicit_bzero even if the
memory pointed to by 's' is dead after the call.  Right now, this effect
is achieved externally by having explicit_bzero be a function whose
semantics are unknown to the compiler, and internally, with a no-op
asm statement that clobbers memory.  This does mean that small
explicit_bzero operations cannot be expanded inline as small memset
operations can, but on the other hand, small memset operations do get
deleted by the compiler.  Hopefully full compiler support for
explicit_bzero will happen relatively soon.

There are two new tests: test-explicit_bzero.c verifies the
visible semantics in the same way as the existing test-bzero.c,
and tst-xbzero-opt.c verifies the not-being-optimized-out property.
The latter is conceptually based on a test written by Matthew Dempsky
for the OpenBSD regression suite.

The crypt() implementation has an immediate use for this new feature.
We avoid having to add a GLIBC_PRIVATE alias for explicit_bzero
by running all of libcrypt's calls through the fortified variant,
__explicit_bzero_chk, which is in the impl namespace anyway.  Currently
I'm not aware of anything in libc proper that needs this, but the
glue is all in place if it does become necessary.  The legacy DES
implementation wasn't bothering to clear its buffers, so I added that,
mostly for consistency's sake.

	* string/explicit_bzero.c: New routine.
	* string/test-explicit_bzero.c, string/tst-xbzero-opt.c: New tests.
	* string/Makefile (routines, strop-tests, tests): Add them.
	* string/test-memset.c: Add ifdeffage for testing explicit_bzero.
	* string/string.h [__USE_MISC]: Declare explicit_bzero.

	* debug/explicit_bzero_chk.c: New routine.
	* debug/Makefile (routines): Add it.
	* debug/tst-chk1.c: Test fortification of explicit_bzero.
	* string/bits/string3.h: Fortify explicit_bzero.

	* manual/string.texi: Document explicit_bzero.
	* NEWS: Mention addition of explicit_bzero.

	* crypt/crypt-entry.c (__crypt_r): Clear key-dependent intermediate
	data before returning, using explicit_bzero.
	* crypt/md5-crypt.c (__md5_crypt_r): Likewise.
	* crypt/sha256-crypt.c (__sha256_crypt_r): Likewise.
	* crypt/sha512-crypt.c (__sha512_crypt_r): Likewise.

	* include/string.h: Redirect internal uses of explicit_bzero
	to __explicit_bzero_chk[_internal].
	* string/Versions [GLIBC_2.25]: Add explicit_bzero.
	* debug/Versions [GLIBC_2.25]: Add __explicit_bzero_chk.
	* sysdeps/arm/nacl/libc.abilist
	* sysdeps/unix/sysv/linux/aarch64/libc.abilist
	* sysdeps/unix/sysv/linux/alpha/libc.abilist
	* sysdeps/unix/sysv/linux/arm/libc.abilist
	* sysdeps/unix/sysv/linux/hppa/libc.abilist
	* sysdeps/unix/sysv/linux/i386/libc.abilist
	* sysdeps/unix/sysv/linux/ia64/libc.abilist
	* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
	* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
	* sysdeps/unix/sysv/linux/microblaze/libc.abilist
	* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
	* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
	* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
	* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
	* sysdeps/unix/sysv/linux/nios2/libc.abilist
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
	* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
	* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
	* sysdeps/unix/sysv/linux/sh/libc.abilist
	* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
	* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
	* sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
	* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
	* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist:
	Add entries for explicit_bzero and __explicit_bzero_chk.
2016-12-16 16:21:54 -05:00
argp Installed-header hygiene (BZ#20366): Simple self-contained fixes. 2016-09-23 08:43:55 -04:00
assert Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
benchtests Improve strtok and strtok_r performance. Instead of calling strpbrk which 2016-12-14 15:12:18 +00:00
bits Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
catgets Fix building glibc master with NDEBUG and --with-cpu. 2016-03-15 23:23:24 -04:00
conform Enable linknamespace testing for libdl and libcrypt. 2016-11-16 22:47:57 +00:00
crypt New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
csu Remove __libc_csu_irel declaration 2016-09-10 15:50:53 +05:30
ctype Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
debug New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
dirent support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
dlfcn support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
elf support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
gmon Installed-header hygiene (BZ#20366): obsolete BSD u_* types. 2016-09-23 08:43:56 -04:00
gnulib Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
grp Don't install the internal header grp-merge.h 2016-07-18 09:33:21 -03:00
gshadow Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
hesiod hesiod: Avoid heap overflow in get_txt_records [BZ #20031] 2016-05-02 16:04:32 +02:00
hurd hurd: fix using hurd.h in C++ programs 2016-12-04 23:18:32 +01:00
iconv gconv.h: fix build with GCC 7 2016-11-06 21:33:10 +01:00
iconvdata gconv: Adjust GBK to support the Euro sign 2016-11-29 18:35:21 +01:00
include New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
inet inet: Make IN6_IS_ADDR_UNSPECIFIED etc. usable with POSIX [BZ #16421] 2016-12-09 11:27:44 +01:00
intl hurd: fix pathconf visibility 2016-09-18 23:45:12 +02:00
io support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
libidn Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
libio support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
locale Bug 20729: Include libc-internal.h where required. 2016-10-31 16:46:57 -04:00
localedata localedata: GBK: add mapping for 0x80->Euro sign [BZ #20864] 2016-11-26 17:20:22 -05:00
login 2016-06-11 Paul Pluzhnikov <ppluzhnikov@google.com> 2016-06-11 14:50:16 -07:00
mach Fix old-style function definition 2016-09-20 23:10:51 +02:00
malloc support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
manual New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
math Define FE_SNANS_ALWAYS_SIGNAL. 2016-12-16 18:03:25 +00:00
mathvec Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
misc Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
nis Installed-header hygiene (BZ#20366): Simple self-contained fixes. 2016-09-23 08:43:55 -04:00
nptl nptl/tst-cancel7: Add missing case label 2016-12-13 09:26:20 +01:00
nptl_db Remove cached PID/TID in clone 2016-11-24 19:38:51 -02:00
nscd Fix incorrect double-checked locking related to _res_hconf.initialized. 2016-08-18 20:53:37 +02:00
nss Fix incorrect double-checked locking related to _res_hconf.initialized. 2016-08-18 20:53:37 +02:00
po Update PO files. 2016-08-04 11:41:27 -04:00
posix support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
pwd Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
resolv Bug 20729: Fix build failures on ppc64 and other arches. 2016-11-02 13:01:36 -04:00
resource Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
rt support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
scripts Make build-many-glibcs.py flush stdout before execv. 2016-12-16 16:17:13 +00:00
setjmp Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
shadow Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
signal Installed-header hygiene (BZ#20366): time.h types. 2016-09-23 08:43:56 -04:00
socket Installed-header hygiene (BZ#20366): conditionally defined structures. 2016-09-23 08:43:56 -04:00
soft-fp [soft-fp] Add support for various half-precision conversion routines. 2016-09-21 21:02:54 +00:00
stdio-common Fix crypt snprintf namespace (bug 20829). 2016-11-16 22:46:48 +00:00
stdlib Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
streams Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
string New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
sunrpc Fix build-and-build-again bug in sunrpc tests. 2016-11-14 14:25:11 -05:00
support Fix assertion failure on test timeout 2016-12-15 17:25:12 +01:00
sysdeps New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
sysvipc Installed-header hygiene (BZ#20366): time.h types. 2016-09-23 08:43:56 -04:00
termios Declare tcgetsid for XPG4 (bug 20055). 2016-05-11 18:05:37 +00:00
time support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
timezone Remove mention of checktab.awk in timezone/README. 2016-03-14 14:11:51 -04:00
wcsmbs Add tst-wcstod-round 2016-08-19 11:17:07 -05:00
wctype Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
.gitattributes Assume __NR_openat is always defined 2016-03-23 23:35:08 +01:00
.gitignore Add *.pyc to .gitignore 2015-05-18 15:26:26 +05:30
BUGS
CONFORMANCE Move __STDC_* predefined macros from features.h to stdc-predef.h. 2012-02-22 12:53:04 +00:00
COPYING Update to latest versions of GPL-2.0 and LGPL-2.1 2013-09-09 12:52:48 +10:00
COPYING.LIB Update to latest versions of GPL-2.0 and LGPL-2.1 2013-09-09 12:52:48 +10:00
ChangeLog New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
ChangeLog.1
ChangeLog.2
ChangeLog.3
ChangeLog.4
ChangeLog.5
ChangeLog.6 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.7 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.8 ChangeLog: change Winblowz to Windows 2016-08-10 00:49:28 +08:00
ChangeLog.9
ChangeLog.10 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.11 ChangeLog: change Winblowz to Windows 2016-08-10 00:49:28 +08:00
ChangeLog.12 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.13
ChangeLog.14 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.15
ChangeLog.16 Fix typo in name 2012-06-21 16:45:27 +02:00
ChangeLog.17 Revert "Sun agreed to a change of the license for the RPC code to a BSD-like license." 2010-06-27 19:34:03 -07:00
ChangeLog.old-ports Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-aarch64 Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-aix Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-alpha Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-am33 Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-arm Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-cris Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-hppa Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-ia64 Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-linux-generic Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-m68k Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-microblaze Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-mips Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-powerpc Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
ChangeLog.old-ports-tile Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory. 2014-04-30 10:40:29 -07:00
INSTALL Add pretty printers for the NPTL lock types 2016-12-08 18:59:02 +05:30
LICENSES Expand LICENSES file. 2012-12-05 21:56:15 +00:00
Makeconfig Expose linking against libsupport as make dependency 2016-12-13 07:58:41 +01:00
Makefile Installed header hygiene (BZ#20366): Test of installed headers. 2016-09-23 08:43:56 -04:00
Makefile.in New make target to only build benchmark binaries 2016-04-20 10:23:28 +05:30
Makerules Install libm.a as linker script (bug 20539). 2016-12-08 17:25:59 +03:00
NAMESPACE
NEWS New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
README Require Linux 3.2 except on x86 / x86_64, 3.2 headers everywhere. 2016-02-24 17:15:12 +00:00
README.pretty-printers Add pretty printers for the NPTL lock types 2016-12-08 18:59:02 +05:30
Rules Expose linking against libsupport as make dependency 2016-12-13 07:58:41 +01:00
WUR-REPORT * posix/unistd.h (setuid, setreuid, seteuid, setresuid): 2012-08-01 18:12:58 +02:00
abi-tags Add arm-nacl port. 2015-04-17 09:02:19 -07:00
aclocal.m4 Rename localedir to complocaledir (bug 14259). 2015-11-27 10:22:38 -05:00
config.h.in Add configure check to test if gcc supports attribute ifunc. 2016-10-07 10:02:59 +02:00
config.make.in Bug 20918 - Building with --enable-nss-crypt fails tst-linkall-static 2016-12-02 15:39:09 -05:00
configure Bug 20918 - Building with --enable-nss-crypt fails tst-linkall-static 2016-12-02 15:39:09 -05:00
configure.ac Bug 20918 - Building with --enable-nss-crypt fails tst-linkall-static 2016-12-02 15:39:09 -05:00
cppflags-iterator.mk
extra-lib.mk support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
extra-modules.mk Remove NOT_IN_libc 2014-11-24 15:03:45 +05:30
gen-locales.mk Split locale generation snippet into a separate file 2015-05-13 13:05:28 +05:30
libc-abis A few more archs have IFUNC support. 2010-03-17 02:43:12 -07:00
o-iterator.mk
shlib-versions This is update for configure, build and install of vector math library. 2015-05-14 18:07:06 +03:00
test-skeleton.c support: Introduce new subdirectory for test infrastructure 2016-12-09 08:18:27 +01:00
version.h Open development for 2.25. 2016-08-01 23:00:21 -04:00

README

This directory contains the sources of the GNU C Library.
See the file "version.h" for what release version you have.

The GNU C Library is the standard system C library for all GNU systems,
and is an important part of what makes up a GNU system.  It provides the
system API for all programs written in C and C-compatible languages such
as C++ and Objective C; the runtime facilities of other programming
languages use the C library to access the underlying operating system.

In GNU/Linux systems, the C library works with the Linux kernel to
implement the operating system behavior seen by user applications.
In GNU/Hurd systems, it works with a microkernel and Hurd servers.

The GNU C Library implements much of the POSIX.1 functionality in the
GNU/Hurd system, using configurations i[4567]86-*-gnu.  The current
GNU/Hurd support requires out-of-tree patches that will eventually be
incorporated into an official GNU C Library release.

When working with Linux kernels, this version of the GNU C Library
requires Linux kernel version 3.2 or later on all architectures except
i[4567]86 and x86_64, where Linux kernel version 2.6.32 or later
suffices.

Also note that the shared version of the libgcc_s library must be
installed for the pthread library to work correctly.

The GNU C Library supports these configurations for using Linux kernels:

	aarch64*-*-linux-gnu
	alpha*-*-linux-gnu
	arm-*-linux-gnueabi
	hppa-*-linux-gnu	Not currently functional without patches.
	i[4567]86-*-linux-gnu
	x86_64-*-linux-gnu	Can build either x86_64 or x32
	ia64-*-linux-gnu
	m68k-*-linux-gnu
	microblaze*-*-linux-gnu
	mips-*-linux-gnu
	mips64-*-linux-gnu
	powerpc-*-linux-gnu	Hardware or software floating point, BE only.
	powerpc64*-*-linux-gnu	Big-endian and little-endian.
	s390-*-linux-gnu
	s390x-*-linux-gnu
	sh[34]-*-linux-gnu
	sparc*-*-linux-gnu
	sparc64*-*-linux-gnu
	tilegx-*-linux-gnu
	tilepro-*-linux-gnu

If you are interested in doing a port, please contact the glibc
maintainers; see http://www.gnu.org/software/libc/ for more
information.

See the file INSTALL to find out how to configure, build, and install
the GNU C Library.  You might also consider reading the WWW pages for
the C library at http://www.gnu.org/software/libc/.

The GNU C Library is (almost) completely documented by the Texinfo manual
found in the `manual/' subdirectory.  The manual is still being updated
and contains some known errors and omissions; we regret that we do not
have the resources to work on the manual as much as we would like.  For
corrections to the manual, please file a bug in the `manual' component,
following the bug-reporting instructions below.  Please be sure to check
the manual in the current development sources to see if your problem has
already been corrected.

Please see http://www.gnu.org/software/libc/bugs.html for bug reporting
information.  We are now using the Bugzilla system to track all bug reports.
This web page gives detailed information on how to report bugs properly.

The GNU C Library is free software.  See the file COPYING.LIB for copying
conditions, and LICENSES for notices about a few contributions that require
these additional notices to be distributed.  License copyright years may be
listed using range notation, e.g., 1996-2015, indicating that every year in
the range, inclusive, is a copyrightable year that would otherwise be listed
individually.