The GNU C Library
=================

The GNU C Library version 2.29 is now available.

The GNU C Library is used as *the* C library in the GNU system and
in GNU/Linux systems, as well as many other systems that use Linux
as the kernel.

The GNU C Library is primarily designed to be a portable
and high performance C library.  It follows all relevant
standards including ISO C11 and POSIX.1-2008.  It is also
internationalized and has one of the most complete
internationalization interfaces known.

The GNU C Library webpage is at http://www.gnu.org/software/libc/

Packages for the 2.29 release may be downloaded from:
        http://ftpmirror.gnu.org/libc/
        http://ftp.gnu.org/gnu/libc/

The mirror list is at http://www.gnu.org/order/ftp.html

NEWS for version 2.29
====================

* The getcpu wrapper function has been added, which returns the currently
  used CPU and NUMA node.  This function is Linux-specific.

* A new convenience target has been added for distribution maintainers
  to build and install all locales as directories with files.  The new
  target is run by issuing the following command in your build tree:
  'make localedata/install-locale-files', with an optional DESTDIR
  to set the install root if you wish to install into a non-default
  configured location.

* Optimized generic exp, exp2, log, log2, pow, sinf, cosf, sincosf and tanf.

* The reallocarray function is now declared under _DEFAULT_SOURCE, not just
  for _GNU_SOURCE, to match BSD environments.

* For powercp64le ABI, Transactional Lock Elision is now enabled iff kernel
  indicates that it will abort the transaction prior to entering the kernel
  (PPC_FEATURE2_HTM_NOSC on hwcap2).  On older kernels the transaction is
  suspended, and this caused some undefined side-effects issues by aborting
  transactions manually.  Glibc avoided it by abort transactions manually on
  each syscall, but it lead to performance issues on newer kernels where the
  HTM state is saved and restore lazily (the state being saved even when the
  process actually does not use HTM).

* The functions posix_spawn_file_actions_addchdir_np and
  posix_spawn_file_actions_addfchdir_np have been added, enabling
  posix_spawn and posix_spawnp to run the new process in a different
  directory.  These functions are GNU extensions.  The function
  posix_spawn_file_actions_addchdir_np is similar to the Solaris function
  of the same name.

* The popen and system do not run atfork handlers anymore (BZ#17490).
  Although it is a possible POSIX violation, the POSIX rationale in
  pthread_atfork documentation regarding atfork handlers is to handle
  inconsistent mutex state after a fork call in a multi-threaded process.
  In both popen and system there is no direct access to user-defined mutexes.

* Support for the C-SKY ABIV2 running on Linux has been added.  This port
  requires at least binutils-2.32, gcc-9.0, and linux-4.20.  Two ABIs are
  supported:
    - C-SKY ABIV2 soft-float little-endian
    - C-SKY ABIV2 hard-float little-endian

* strftime's default formatting of a locale's alternative year (%Ey)
  has been changed to zero-pad the year to a minimum of two digits,
  like "%y".  This improves the display of Japanese era years during
  the first nine years of a new era, and is expected to be harmless
  for all other locales (only Japanese locales regularly have
  alternative year numbers less than 10).  Zero-padding can be
  overridden with the '_' or '-' flags (which are GNU extensions).

* As a GNU extension, the '_' and '-' flags can now be applied to
  "%EY" to control how the year number is formatted; they have the
  same effect that they would on "%Ey".

Deprecated and removed features, and other changes affecting compatibility:

* The glibc.tune tunable namespace has been renamed to glibc.cpu and the
  tunable glibc.tune.cpu has been renamed to glibc.cpu.name.

* The type of the pr_uid and pr_gid members of struct elf_prpsinfo, defined
  in <sys/procfs.h>, has been corrected to match the type actually used by
  the Linux kernel.  This affects the size and layout of that structure on
  MicroBlaze, MIPS (n64 ABI only), Nios II and RISC-V.

* For the MIPS n32 ABI, the type of the pr_sigpend and pr_sighold members of
  struct elf_prstatus, and the pr_flag member of struct elf_prpsinfo,
  defined in <sys/procfs.h>, has been corrected to match the type actually
  used by the Linux kernel.  This affects the size and layout of those
  structures.

* An archaic GNU extension to scanf, under which '%as', '%aS', and '%a[...]'
  meant to scan a string and allocate space for it with malloc, is now
  restricted to programs compiled in C89 or C++98 mode with _GNU_SOURCE
  defined.  This extension conflicts with C99's use of '%a' to scan a
  hexadecimal floating-point number, which is now available to programs
  compiled as C99 or C++11 or higher, regardless of _GNU_SOURCE.

  POSIX.1-2008 includes the feature of allocating a buffer for string input
  with malloc, using the modifier letter 'm' instead.  Programs using
  '%as', '%aS', or '%a[...]' with the old GNU meaning should change to
  '%ms', '%mS', or '%m[...]' respectively.  Programs that wish to use the
  C99 '%a' no longer need to avoid _GNU_SOURCE.

  GCC's -Wformat warnings can detect most uses of this extension, as long
  as all functions that call vscanf, vfscanf, or vsscanf are annotated with
  __attribute__ ((format (scanf, ...))).

Changes to build and runtime requirements:

* Python 3.4 or later is required to build the GNU C Library.

* On most architectures, GCC 5 or later is required to build the GNU C
  Library.  (On powerpc64le, GCC 6.2 or later is still required, as before.)

  Older GCC versions and non-GNU compilers are still supported when
  compiling programs that use the GNU C Library.

Security related changes:

  CVE-2018-19591: A file descriptor leak in if_nametoindex can lead to a
  denial of service due to resource exhaustion when processing getaddrinfo
  calls with crafted host names.  Reported by Guido Vranken.

  CVE-2019-6488: On x32, the size_t parameter may be passed in the lower
  32 bits of a 64-bit register with with non-zero upper 32 bit.  When it
  happened, accessing the 32-bit size_t value as the full 64-bit register
  in the assembly string/memory functions would cause a buffer overflow.
  Reported by H.J. Lu.

  CVE-2016-10739: The getaddrinfo function could successfully parse IPv4
  addresses with arbitrary trailing characters, potentially leading to data
  or command injection issues in applications.

Release Notes
=============

https://sourceware.org/glibc/wiki/Release/2.29

Contributors
============

This release was made possible by the contributions of many people.
The maintainers are grateful to everyone who has contributed
changes or bug reports.  These include:

Adhemerval Zanella
Albert ARIBAUD (3ADEV)
Alexandra Hájková
Andreas K. Hüttel
Andreas Schwab
Anton Youdkevitch
Arjun Shankar
Assaf Gordon
Aurelien Jarno
Carlos O'Donell
Charles-Antoine Couret
DJ Delorie
Darius Rad
David S. Miller
Dmitry V. Levin
Florian Weimer
Fredrik Noring
Gabriel F. T. Gomes
H.J. Lu
Ilya Leoshkevich
Ilya Yu. Malakhov
Istvan Kurucsai
Jim Wilson
Joseph Myers
Justus Winter
Kemi Wang
Leonardo Sandoval
Mao Han
Martin Jansa
Martin Kuchta
Martin Sebor
Mingli Yu
Moritz Eckert
PanderMusubi
Paul Clarke
Paul Eggert
Paul Pluzhnikov
Pochang Chen
Rafael Avila de Espindola
Rafael Ávila de Espíndola
Rafal Luzynski
Rajalakshmi Srinivasaraghavan
Rogerio Alves
Samuel Thibault
Sergi Almacellas Abellana
Siddhesh Poyarekar
Stefan Liebler
Steve Ellcey
Szabolcs Nagy
TAMUKI Shoichi
Tobias Klauser
Tulio Magno Quites Machado Filho
Uroš Bizjak
Wilco Dijkstra
Zack Weinberg
Zong Li

Open master branch for glibc 2.30 development

The GNU C Library
=================

The GNU C Library version 2.30 is now available.

The GNU C Library is used as *the* C library in the GNU system and
in GNU/Linux systems, as well as many other systems that use Linux
as the kernel.

The GNU C Library is primarily designed to be a portable
and high performance C library.  It follows all relevant
standards including ISO C11 and POSIX.1-2017.  It is also
internationalized and has one of the most complete
internationalization interfaces known.

The GNU C Library webpage is at http://www.gnu.org/software/libc/

Packages for the 2.30 release may be downloaded from:
        http://ftpmirror.gnu.org/libc/
        http://ftp.gnu.org/gnu/libc/

The mirror list is at http://www.gnu.org/order/ftp.html

NEWS for version 2.30
=====================

Major new features:

* Unicode 12.1.0 Support: Character encoding, character type info, and
  transliteration tables are all updated to Unicode 12.1.0, using
  generator scripts contributed by Mike FABIAN (Red Hat).

* The dynamic linker accepts the --preload argument to preload shared
  objects, in addition to the LD_PRELOAD environment variable.

* The twalk_r function has been added.  It is similar to the existing
  twalk function, but it passes an additional caller-supplied argument
  to the callback function.

* On Linux, the getdents64, gettid, and tgkill functions have been added.

* Minguo (Republic of China) calendar support has been added as an
  alternative calendar for the following locales: zh_TW, cmn_TW, hak_TW,
  nan_TW, lzh_TW.

* The entry for the new Japanese era has been added for ja_JP locale.

* Memory allocation functions malloc, calloc, realloc, reallocarray, valloc,
  pvalloc, memalign, and posix_memalign fail now with total object size
  larger than PTRDIFF_MAX.  This is to avoid potential undefined behavior with
  pointer subtraction within the allocated object, where results might
  overflow the ptrdiff_t type.

* The dynamic linker no longer refuses to load objects which reference
  versioned symbols whose implementation has moved to a different soname
  since the object has been linked.  The old error message, symbol
  FUNCTION-NAME, version SYMBOL-VERSION not defined in file DSO-NAME with
  link time reference, is gone.

* Add new POSIX-proposed pthread_cond_clockwait, pthread_mutex_clocklock,
  pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock and sem_clockwait
  functions.  These behave similarly to their "timed" equivalents, but also
  accept a clockid_t parameter to determine which clock their timeout should
  be measured against.  All functions allow waiting against CLOCK_MONOTONIC
  and CLOCK_REALTIME.  The decision of which clock to be used is made at the
  time of the wait (unlike with pthread_condattr_setclock, which requires
  the clock choice at initialization time).

* On AArch64 the GNU IFUNC resolver call ABI changed: old resolvers still
  work, new resolvers can use a second argument which can be extended in
  the future, currently it contains the AT_HWCAP2 value.

Deprecated and removed features, and other changes affecting compatibility:

* The copy_file_range function fails with ENOSYS if the kernel does not
  support the system call of the same name.  Previously, user space
  emulation was performed, but its behavior did not match the kernel
  behavior, which was deemed too confusing.  Applications which use the
  copy_file_range function can no longer rely on glibc to provide a fallback
  on kernels that do not support the copy_file_range system call, and if
  this function returns ENOSYS, they will need to use their own fallback.
  Support for copy_file_range for most architectures was added in version
  4.5 of the mainline Linux kernel.

* The functions clock_gettime, clock_getres, clock_settime,
  clock_getcpuclockid, clock_nanosleep were removed from the librt library
  for new applications (on architectures which had them).  Instead, the
  definitions in libc will be used automatically, which have been available
  since glibc 2.17.

* The obsolete and never-implemented XSI STREAMS header files <stropts.h>
  and <sys/stropts.h> have been removed.

* Support for the "inet6" option in /etc/resolv.conf and the RES_USE_INET6
  resolver flag (deprecated in glibc 2.25) have been removed.

* The obsolete RES_INSECURE1 and RES_INSECURE2 option flags for the DNS stub
  resolver have been removed from <resolv.h>.

* With --enable-bind-now, installed programs are now linked with the
  BIND_NOW flag.

* Support for the PowerPC SPE ISA extension (powerpc-*-*gnuspe*
  configurations) has been removed, following the deprecation of this
  subarchitecture in version 8 of GCC, and its removal in version 9.

* On 32-bit Arm, support for the port-based I/O emulation and the <sys/io.h>
  header have been removed.

* The Linux-specific <sys/sysctl.h> header and the sysctl function have been
  deprecated and will be removed from a future version of glibc.
  Application should directly access /proc instead.  For obtaining random
  bits, the getentropy function can be used.

Changes to build and runtime requirements:

* GCC 6.2 or later is required to build the GNU C Library.

  Older GCC versions and non-GNU compilers are still supported when
  compiling programs that use the GNU C Library.

Security related changes:

  CVE-2019-7309: x86-64 memcmp used signed Jcc instructions to check
  size.  For x86-64, memcmp on an object size larger than SSIZE_MAX
  has undefined behavior.  On x32, the size_t argument may be passed
  in the lower 32 bits of the 64-bit RDX register with non-zero upper
  32 bits.  When it happened with the sign bit of RDX register set,
  memcmp gave the wrong result since it treated the size argument as
  zero.  Reported by H.J. Lu.

  CVE-2019-9169: Attempted case-insensitive regular-expression match
  via proceed_next_node in posix/regexec.c leads to heap-based buffer
  over-read.  Reported by Hongxu Chen.

The following bugs are resolved with this release:

  [2872] locale: Transliteration Cyrillic -> ASCII fails
  [6399] libc: gettid() should have a wrapper
  [16573] malloc: mtrace hangs when MALLOC_TRACE is defined
  [16976] glob: fnmatch unbounded stack VLA for collating symbols
  [17396] localedata: globbing for locale by [[.collating-element.]]
  [18035] dynamic-link: pldd does no longer work, enters infinite loop
  [18465] malloc: memusagestat is built using system C library
  [18830] locale: iconv -c -f ascii with >buffer size worth of input before
    invalid input drops valid char
  [20188] nptl: libpthread IFUNC resolver for vfork can lead to crash
  [20568] locale: Segfault with wide characters and setlocale/fgetwc/UTF-8
  [21897] localedata: Afar locales: Fix mon, abmon, and abday
  [22964] localedata: The Japanese Era name will be changed on May 1, 2019
  [23352] malloc: __malloc_check_init still defined in public header
    malloc.h.
  [23403] nptl: Wrong alignment of TLS variables
  [23501] libc: nftw() doesn't return dangling symlink's inode
  [23733] malloc: Check the count before calling tcache_get()
  [23741] malloc: Missing __attribute_alloc_size__ in many allocation
    functions
  [23831] localedata: nl_NL missing LC_NUMERIC thousands_sep
  [23844] nptl: pthread_rwlock_trywrlock results in hang
  [23983] argparse: Missing compat versions of argp_failure and argp_error
    for long double = double
  [23984] libc: Missing compat versions of err.h and error.h functions for
    long double = double
  [23996] localedata: Dutch salutations
  [24040] libc: riscv64: unterminated call chain in __thread_start
  [24047] network: libresolv should use IP_RECVERR/IPV6_RECVERR to avoid
    long timeouts
  [24051] stdio: puts and putchar ouput to _IO_stdout instead of stdout
  [24059] nss: nss_files: get_next_alias calls fgets_unlocked without
    checking for NULL.
  [24114] regex: regexec buffer read overrun in "grep -i
    '\(\(\)*.\)*\(\)\(\)\1'"
  [24122] libc: Segfaults if 0 returned from la_version
  [24153] stdio: Some input functions do not react to stdin assignment
  [24155] string: x32 memcmp can treat positive length as 0 (if sign bit in
    RDX is set) (CVE-2019-7309)
  [24161] nptl: __run_fork_handlers self-deadlocks in malloc/tst-mallocfork2
  [24164] libc: Systemtap probes need to use "nr" constraint on 32-bit Arm,
    not the default "nor"
  [24166] dynamic-link: Dl_serinfo.dls_serpath[1] in dlfcn.h causes UBSAN
    false positives, change to modern flexible array
  [24180] nptl: pthread_mutex_trylock does not use the correct order of
    instructions while maintaining the robust mutex list due to missing
    compiler barriers.
  [24194] librt: Non-compatibility symbols for clock_gettime etc. cause
    unnecessary librt dependencies
  [24200] localedata: Revert first_weekday removal in en_IE locale
  [24211] nptl: Use-after-free in Systemtap probe in pthread_join
  [24215] nptl: pthread_timedjoin_np should be a cancellation point
  [24216] malloc: Check for large bin list corruption when inserting
    unsorted chunk
  [24228] stdio: old x86 applications that use legacy libio crash on exit
  [24231] dynamic-link: [sparc64] R_SPARC_H34 implementation falls through
    to R_SPARC_H44
  [24293] localedata: Missing Minguo calendar support for TW locales
  [24296] localedata: Orthographic mistakes in 'day' and 'abday' sections in
    tt_RU (Tatar) locale
  [24307] localedata: Update locale data to Unicode 12.0.0
  [24323] dynamic-link: dlopen should not be able open PIE objects
  [24335] build: "Obsolete types detected" with Linux 5.0 headers
  [24369] localedata: Orthographic mistakes in 'mon' and 'abmon' sections in
    tt_RU (Tatar) locale
  [24370] localedata: Add lang_name for tt_RU locale
  [24372] locale: Binary locale files are not architecture independent
  [24394] time: strptime %Ey mis-parses final year of era
  [24476] dynamic-link: __libc_freeres triggers bad free in libdl if dlerror
    was not used
  [24506] dynamic-link: FAIL: elf/tst-pldd with --enable-hardcoded-path-in-
    tests
  [24531] malloc: Malloc tunables give tcache assertion failures
  [24532] libc: conform/arpa/inet.h failures due to linux kernel 64-bit
    time_t changes
  [24535] localedata: Update locale data to Unicode 12.1.0
  [24537] build: nptl/tst-eintr1 test case can hit task limits on some
    kernels and break testing
  [24544] build: elf/tst-pldd doesn't work if you install with a --prefix
  [24556] build: [GCC 9] error: ‘%s’ directive argument is null
    [-Werror=format-overflow=]
  [24570] libc: alpha: compat msgctl uses __IPC_64
  [24584] locale: Data race in __wcsmbs_clone_conv
  [24588] stdio: Remove codecvt vtables from libio
  [24603] math: sysdeps/ieee754/dbl-64/branred.c is slow when compiled with
    -O3 -march=skylake
  [24614] localedata: nl_NL LC_MONETARY doesn't match CLDR 35
  [24632] stdio: Old binaries which use freopen with default stdio handles
    crash
  [24640] libc: __ppc_get_timebase_freq() always return 0 when using static
    linked glibc
  [24652] localedata: szl_PL spelling correction
  [24695] nss: nss_db: calling getpwent after endpwent crashes
  [24696] nss: endgrent() clobbers errno=ERRNO for 'group: db files' entry
    in /etc/nsswitch.conf
  [24699] libc: mmap64 with very large offset broken on MIPS64 n32
  [24740] libc: getdents64 type confusion
  [24741] dynamic-link: ld.so should not require that a versioned symbol is
    always implemented in the same library
  [24744] libc: Remove copy_file_range emulation
  [24757] malloc: memusagestat is linked against system libpthread
  [24794] libc: Partial test suite run builds corrupt test-in-container
    testroot

Release Notes
=============

https://sourceware.org/glibc/wiki/Release/2.30

Contributors
============

This release was made possible by the contributions of many people.
The maintainers are grateful to everyone who has contributed
changes or bug reports.  These include:

Adam Maris
Adhemerval Zanella
Alexandra Hájková
Andreas K. Hüttel
Andreas Schwab
Anton Youdkevitch
Aurelien Jarno
Carlos O'Donell
DJ Delorie
Daniil Zhilin
David Abdurachmanov
David Newall
Dmitry V. Levin
Egor Kobylkin
Felix Yan
Feng Xue
Florian Weimer
Gabriel F. T. Gomes
Grzegorz Kulik
H.J. Lu
Jan Kratochvil
Jim Wilson
Joseph Myers
Maciej W. Rozycki
Mao Han
Mark Wielaard
Matthew Malcomson
Mike Crowe
Mike FABIAN
Mike Frysinger
Mike Gerow
PanderMusubi
Patsy Franklin
Paul A. Clarke
Paul Clarke
Paul Eggert
Paul Pluzhnikov
Rafal Luzynski
Richard Henderson
Samuel Thibault
Siddhesh Poyarekar
Stan Shebs
Stefan Liebler
Szabolcs Nagy
TAMUKI Shoichi
Tobias Klauser
Tulio Magno Quites Machado Filho
Uros Bizjak
Vincent Chen
Vineet Gupta
Wilco Dijkstra
Wolfram Sang
Yann Droneaud
Zack Weinberg
mansayk
marxin

Open master branch for glibc 2.30 development.

The GNU C Library
=================

The GNU C Library version 2.31 is now available.

The GNU C Library is used as *the* C library in the GNU system and
in GNU/Linux systems, as well as many other systems that use Linux
as the kernel.

The GNU C Library is primarily designed to be a portable
and high performance C library.  It follows all relevant
standards including ISO C11 and POSIX.1-2017.  It is also
internationalized and has one of the most complete
internationalization interfaces known.

The GNU C Library webpage is at http://www.gnu.org/software/libc/

Packages for the 2.31 release may be downloaded from:
        http://ftpmirror.gnu.org/libc/
        http://ftp.gnu.org/gnu/libc/

The mirror list is at http://www.gnu.org/order/ftp.html

NEWS for version 2.31
=====================

Major new features:

* The GNU C Library now supports a feature test macro _ISOC2X_SOURCE to
  enable features from the draft ISO C2X standard.  Only some features from
  this draft standard are supported by the GNU C Library, and as the draft
  is under active development, the set of features enabled by this macro is
  liable to change.  Features from C2X are also enabled by _GNU_SOURCE, or
  by compiling with "gcc -std=gnu2x".

* The <math.h> functions that round their results to a narrower type now
  have corresponding type-generic macros in <tgmath.h>, as defined in TS
  18661-1:2014 and TS 18661-3:2015 as amended by the resolution of
  Clarification Request 13 to TS 18661-3.

* The function pthread_clockjoin_np has been added, enabling join with a
  terminated thread with a specific clock.  It allows waiting against
  CLOCK_MONOTONIC and CLOCK_REALTIME.  This function is a GNU extension.

* New locale added: mnw_MM (Mon language spoken in Myanmar).

* The DNS stub resolver will optionally send the AD (authenticated data) bit
  in queries if the trust-ad option is set via the options directive in
  /etc/resolv.conf (or if RES_TRUSTAD is set in _res.options).  In this
  mode, the AD bit, as provided by the name server, is available to
  applications which call res_search and related functions.  In the default
  mode, the AD bit is not set in queries, and it is automatically cleared in
  responses, indicating a lack of DNSSEC validation.  (Therefore, the name
  servers and the network path to them are treated as untrusted.)

Deprecated and removed features, and other changes affecting compatibility:

* The totalorder and totalordermag functions, and the corresponding
  functions for other floating-point types, now take pointer arguments to
  avoid signaling NaNs possibly being converted to quiet NaNs in argument
  passing.  This is in accordance with the resolution of Clarification
  Request 25 to TS 18661-1, as applied for C2X.  Existing binaries that pass
  floating-point arguments directly will continue to work.

* The obsolete function stime is no longer available to newly linked
  binaries, and its declaration has been removed from <time.h>.
  Programs that set the system time should use clock_settime instead.

* We plan to remove the obsolete function ftime, and the header <sys/timeb.h>,
  in a future version of glibc.  In this release, the header still exists
  but calling ftime will cause a compiler warning.  All programs should use
  gettimeofday or clock_gettime instead.

* The gettimeofday function no longer reports information about a
  system-wide time zone.  This 4.2-BSD-era feature has been deprecated for
  many years, as it cannot handle the full complexity of the world's
  timezones, but hitherto we have supported it on a best-effort basis.
  Changes required to support 64-bit time_t on 32-bit architectures have
  made this no longer practical.

  As of this release, callers of gettimeofday with a non-null 'tzp' argument
  should expect to receive a 'struct timezone' whose tz_minuteswest and
  tz_dsttime fields are zero.  (For efficiency reasons, this does not always
  happen on a few Linux-based ports.  This will be corrected in a future
  release.)

  All callers should supply a null pointer for the 'tzp' argument to
  gettimeofday.  For accurate information about the time zone associated
  with the current time, use the localtime function.

  gettimeofday itself is obsolescent according to POSIX.  We have no plans
  to remove access to this function, but portable programs should consider
  using clock_gettime instead.

* The settimeofday function can still be used to set a system-wide time
  zone when the operating system supports it.  This is because the Linux
  kernel reused the API, on some architectures, to describe a system-wide
  time-zone-like offset between the software clock maintained by the kernel,
  and the "RTC" clock that keeps time when the system is shut down.

  However, to reduce the odds of this offset being set by accident,
  settimeofday can no longer be used to set the time and the offset
  simultaneously.  If both of its two arguments are non-null, the call
  will fail (setting errno to EINVAL).

  Callers attempting to set this offset should also be prepared for the call
  to fail and set errno to ENOSYS; this already happens on the Hurd and on
  some Linux architectures.  The Linux kernel maintainers are discussing a
  more principled replacement for the reused API.  After a replacement
  becomes available, we will change settimeofday to fail with ENOSYS on all
  platforms when its 'tzp' argument is not a null pointer.

  settimeofday itself is obsolescent according to POSIX.  Programs that set
  the system time should use clock_settime and/or the adjtime family of
  functions instead.  We may cease to make settimeofday available to newly
  linked binaries after there is a replacement for Linux's time-zone-like
  offset API.

* SPARC ISA v7 is no longer supported.  v8 is still supported, but only if
  the optional CAS instruction is implemented (for instance, LEON processors
  are still supported, but SuperSPARC processors are not).

  As the oldest 64-bit SPARC ISA is v9, this only affects 32-bit
  configurations.

* If a lazy binding failure happens during dlopen, during the execution of
  an ELF constructor, the process is now terminated.  Previously, the
  dynamic loader would return NULL from dlopen, with the lazy binding error
  captured in a dlerror message.  In general, this is unsafe because
  resetting the stack in an arbitrary function call is not possible.

* For MIPS hard-float ABIs, the GNU C Library will be configured to need an
  executable stack unless explicitly configured at build time to require
  minimum kernel version 4.8 or newer.  This is because executing
  floating-point branches on a non-executable stack on Linux kernels prior to
  4.8 can lead to application crashes for some MIPS configurations. While
  currently PT_GNU_STACK is not widely used on MIPS, future releases of GCC are
  expected to enable non-executable stack by default  with PT_GNU_STACK by
  default and is thus likely to trigger a crash on older kernels.

  The GNU C Library can be built with --enable-kernel=4.8.0 in order to keep a
  non-executable stack while dropping support for older kernels.

* System call wrappers for time system calls now use the new time64 system
  calls when available. On 32-bit targets, these wrappers attempt to call
  the new system calls first and fall back to the older 32-bit time system
  calls if they are not present.  This may cause issues in environments
  that cannot handle unsupported system calls gracefully by returning
  -ENOSYS. Seccomp sandboxes are affected by this issue.

Changes to build and runtime requirements:

* It is no longer necessary to have recent Linux kernel headers to build
  working (non-stub) system call wrappers on all architectures except 64-bit
  RISC-V.  64-bit RISC-V requires a minimum kernel headers version of 5.0.

* The ChangeLog file is no longer present in the toplevel directory of the
  source tree.  ChangeLog files are located in the ChangeLog.old directory as
  ChangeLog.N where the highest N has the latest entries.

Security related changes:

  CVE-2019-19126: ld.so failed to ignore the LD_PREFER_MAP_32BIT_EXEC
  environment variable during program execution after a security
  transition, allowing local attackers to restrict the possible mapping
  addresses for loaded libraries and thus bypass ASLR for a setuid
  program.  Reported by Marcin Kościelnicki.

The following bugs are resolved with this release:

  [12031] localedata: iconv -t ascii//translit with Greek characters
  [15813] libc: Multiple issues in __gen_tempname
  [17726] libc: [arm, sparc] profil_counter should be compat symbol
  [18231] libc: ipc_perm struct's mode member has wrong type in sys/ipc.h
  [19767] libc: vdso is not used with static linking
  [19903] hurd: Shared mappings not being inherited by children processes
  [20358] network: RES_USE_DNSSEC sets DO; should also have a way to set AD
  [20839] dynamic-link: Incomplete rollback of dynamic linker state on
    linking failure
  [23132] localedata: Missing transliterations in Miscellaneous Mathematical
    Symbols-A/B Unicode blocks
  [23518] libc: Eliminate __libc_utmp_jump_table
  [24026] malloc: malloc_info() returns wrong numbers
  [24054] localedata: Many locales are missing date_fmt
  [24214] dynamic-link: user defined ifunc resolvers may run in ldd mode
  [24304] dynamic-link: Lazy binding failure during ELF
    constructors/destructors is not fatal
  [24376] libc: RISC-V symbol size confusion with _start
  [24682] localedata: zh_CN first weekday should be Monday per GB/T
    7408-2005
  [24824] libc: test-in-container does not install charmap files compatible
    with localedef
  [24844] regex: regex bad pointer / leakage if malloc fails
  [24867] malloc: Unintended malloc_info formatting changes
  [24879] libc: login: utmp alarm timer can arrive after lock acquisition
  [24880] libc: login: utmp implementation uses struct flock with fcntl64
  [24882] libc: login: pututline uses potentially outdated cache
  [24899] libc: Missing nonstring attributes in <utmp.h>, <utmpx.h>
  [24902] libc: login: Repeating pututxline on EINTR/EAGAIN causes stale
    utmp entries
  [24916] dynamic-link: [MIPS] Highest EI_ABIVERSION value not raised to
    ABSOLUTE ABI
  [24930] dynamic-link: dlopen of PIE executable can result in
    _dl_allocate_tls_init assertion failure
  [24950] localedata: Top-of-tree glibc does not build with top-of-tree GCC
    (stringop-overflow error)
  [24959] time: librt IFUNC resolvers for clock_gettime and clock_*
    functions other  can lead to crashes
  [24967] libc: jemalloc static linking causes runtime failure
  [24986] libc: alpha: new getegid, geteuid and getppid syscalls used
    unconditionally
  [25035] libc: sbrk() failure handled poorly in tunables_strdup
  [25087] dynamic-link: ldconfig mishandles unusual .dynstr placement
  [25097] libc: new -Warray-bounds with GCC 10
  [25112] dynamic-link: dlopen must not make new objects accessible when it
    still can fail with an error
  [25139] localedata: Please add the new mnw_MM locale
  [25149] regex: Array bounds violation in proceed_next_node
  [25157] dynamic-link: Audit cookie for the dynamic loader is not
    initialized correctly
  [25189] libc: glibc's __glibc_has_include causes issues with clang
    -frewrite-includes
  [25194] malloc: malloc.c: do_set_mxfast incorrectly casts the mallopt
    value to an unsigned
  [25204] dynamic-link: LD_PREFER_MAP_32BIT_EXEC not ignored in setuid
    binaries (CVE-2019-19126)
  [25225] libc: ld.so fails to link on x86 if GCC defaults to -fcf-
    protection
  [25226] string: strstr: Invalid result if needle crosses page on s390-z15
    ifunc variant.
  [25232] string: <string.h> does not enable const correctness for strchr et
    al. for Clang++
  [25233] localedata: Consider "." as the thousands separator for sl_SI
    (Slovenian)
  [25241] nptl: __SIZEOF_PTHREAD_MUTEX_T defined twice for x86
  [25251] build: Failure to run tests when CFLAGS contains -DNDEBUG.
  [25271] libc: undeclared identifier PTHREAD_MUTEX_DEFAULT when compiling
    with -std=c11
  [25323] localedata: km_KH: d_t_fmt contains "m" instead of "%M"
  [25324] localedata: lv_LV: d_t_fmt contains suspicious words in the time
    part
  [25396] dynamic-link: Failing dlopen can leave behind dangling GL
    (dl_initfirst) link map pointer
  [25401] malloc: pvalloc must not have __attribute_alloc_size__
  [25423] libc: Array overflow in backtrace on powerpc
  [25425] network: Missing call to __resolv_context_put in
    getaddrinfo.c:gethosts

Release Notes
=============

https://sourceware.org/glibc/wiki/Release/2.31

Contributors
============

This release was made possible by the contributions of many people.
The maintainers are grateful to everyone who has contributed
changes or bug reports.  These include:

Adhemerval Zanella
Alexandra Hájková
Alistair Francis
Andreas Schwab
Andrew Eggenberger
Arjun Shankar
Aurelien Jarno
Carlos O'Donell
Chung-Lin Tang
DJ Delorie
Dmitry V. Levin
Dragan Mladjenovic
Egor Kobylkin
Emilio Cobos Álvarez
Emilio Pozuelo Monfort
Feng Xue
Florian Weimer
Gabriel F. T. Gomes
Gustavo Romero
H.J. Lu
Ian Kent
James Clarke
Jeremie Koenig
John David Anglin
Joseph Myers
Kamlesh Kumar
Krzysztof Koch
Leandro Pereira
Lucas A. M. Magalhaes
Lukasz Majewski
Marcin Kościelnicki
Matheus Castanho
Mihailo Stojanovic
Mike Crowe
Mike FABIAN
Niklas Hambüchen
Paul A. Clarke
Paul Eggert
Petr Vorel
Rafal Luzynski
Rafał Lużyński
Rajalakshmi Srinivasaraghavan
Raoni Fassina Firmino
Richard Braun
Samuel Thibault
Sandra Loosemore
Siddhesh Poyarekar
Stefan Liebler
Svante Signell
Szabolcs Nagy
Talachan Mon
Thomas Schwinge
Tim Rühsen
Tulio Magno Quites Machado Filho
Wilco Dijkstra
Xuelei Zhang
Zack Weinberg
liqingqing

Open master branch for 2.32 development