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The GNU C Library version 2.26 is now available

Item posted by Siddhesh Poyarekar <siddhesh> on Wed 02 Aug 2017 02:47:12 PM UTC.

The GNU C Library

The GNU C Library version 2.26 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

Packages for the 2.26 release may be downloaded from:

The mirror list is at

NEWS for version 2.26

Major new features:

  no locks and therefore significantly accelerates the fast path to allocate
  and free small amounts of memory. Refilling an empty cache requires
  the underlying arena. Performance measurements show significant gains in a
  wide variety of user workloads. Workloads were captured using a special
  instrumented malloc and analyzed with a malloc simulator. Contributed by
  DJ Delorie with the help of Florian Weimer, and Carlos O'Donell.

  transliteration tables are all updated to Unicode 10.0.0, using
  generator scripts contributed by Mike FABIAN (Red Hat).
  These updates cause user visible changes, especially the changes in
  wcwidth for many emoji characters cause problems when emoji sequences
  are rendered with pango, see for example:

  Rules of Hungarian Orthography, 12th edition" (Bug 18934).  Contributed by
  Egmont Koblinger.

  - The GNU C Library will now detect when /etc/resolv.conf has been
    modified and reload the changed configuration.  The new resolver option
    “no-reload” (RES_NORELOAD) disables this behavior.

  - The GNU C Library now supports an arbitrary number of search domains
    (configured using the “search” directive in /etc/resolv.conf);
    previously, there was a hard limit of six domains.  For backward
    compatibility, applications that directly modify the ‘_res’ global
    object are still limited to six search domains.

  - When the “rotate” (RES_ROTATE) resolver option is active, the GNU C
    Library will now randomly pick a name server from the configuration as a
    starting point.  (Previously, the second name server was always used.)

  behavior of the GNU C Library using the GLIBC_TUNABLES environment

  to the product of two sizes, with a guaranteed clean failure upon integer
  overflow in the multiplication.  Originally from OpenBSD, contributed by
  Dennis Wölfing and Rüdiger Sonderfeld.

  These are extended versions of preadv and pwritev, respectively, taking an
  additional flags argument.  The set of supported flags depends on the
  running kernel; full support currently requires kernel 4.7 or later.

  create a new session ID for the spawned process.  This feature is
  scheduled to be added to the next major revision of POSIX; for the time
  being, it is available under _GNU_SOURCE.

  supported operating systems.  In this context, it will only define the
  Exxxx constants, as preprocessor macros expanding to integer literals.

  128-bit floating point as defined by ISO/IEC/IEEE 60559:2011 (IEEE
  754-2008) and ISO/IEC TS 18661-3:2015.  Contributed by Paul E. Murphy,
  Gabriel F. T. Gomes, Tulio Magno Quites Machado Filho, and Joseph Myers.

  To compile programs that use this feature, the compiler must support
  128-bit floating point with the type name _Float128 (as defined by TS
  18661-3) or __float128 (the nonstandard name used by GCC for C++, and for
  C prior to version 7).  GNU_SOURCE or __STDC_WANT_IEC_60559_TYPES_EXT_
  must be defined to make the new interfaces visible.

  The new functions and macros correspond to those present for other
  floating-point types (except for a few obsolescent interfaces not
  supported for the new type), with F128 or f128 suffixes; for example,
  strtof128, HUGE_VAL_F128 and cosf128.  Following TS 18661-3, there are no
  printf or scanf formats for the new type; the strfromf128 and strtof128
  interfaces should be used instead.

Deprecated and removed features, and other changes affecting compatibility:

  now be equivalent to a C11 atomic store with release memory order to the
  spin lock's memory location.  Previously, several (but not all)
  architectures used stronger synchronization (e.g., containing what is
  often called a full barrier).  This change can improve performance, but
  may affect odd fringe uses of spin locks that depend on the previous
  behavior (e.g., using spin locks as atomic variables to try to implement
  Dekker's mutual exclusion algorithm).


  will only be built and installed when the GNU C Library is configured with
  --enable-obsolete-rpc.  This allows alternative RPC implementations, such
  as TIRPC or rpcsvc-proto, to be used.

  libnss_compat, are deprecated, and will not be built or installed by

  The NIS(+) support library, libnsl, is also deprecated.  By default, a
  compatibility shared library will be built and installed, but not headers
  or development libraries. Only a few NIS-related programs require this
  library.  (In particular, the GNU C Library has never required programs
  that use 'gethostbyname' to be linked with libnsl.)

  Replacement implementations based on TIRPC, which additionally support
  IPv6, are available from <>.  The configure
  option --enable-obsolete-nsl will cause libnsl's headers, and the NIS(+)
  name service modules, to be built and installed.

  support is enabled, the configured recursive resolver must support EDNS.
  (Responding to EDNS-enabled queries with responses which are not
  EDNS-enabled is fine, but FORMERR responses are not.)

  servers have not supported this opcode for a long time.

  exported by accident.

  as this kind of optimization is better done by the compiler.  The macros
  __USE_STRING_INLINES and __NO_STRING_INLINES no longer have any effect.

  use <locale.h> instead.  If you have a specific need for the definition of
  locale_t with no other declarations, please contact and explain.

  free instead.

  the C++ name mangling for interfaces involving this type.

  the C++ name mangling for interfaces involving this type.

  the name struct fpregset.  On Nios II GNU/Linux, the mcontext_t type no
  longer has the name struct mcontext.  On SPARC GNU/Linux, the struct
  mc_fq, struct rwindow, struct fpq and struct fq types are no longer
  defined in sys/ucontext.h, the mc_fpu_t type no longer has the name struct
  mc_fpu, the gwindows_t type no longer has the name struct gwindows and the
  fpregset_t type no longer has the name struct fpu.  This changes the C++
  name mangling for interfaces involving those types.

  synced with the kernel:

      are not supported on this architecture and have been removed.

      PTRACE_DISABLE_TE and PTRACE_TE_ABORT_RAND have been added.

  Programs that assume the GET/SETREGS ptrace requests are universally
  available will now fail to build, instead of malfunctioning at runtime.

Changes to build and runtime requirements:

  supported by that kernel.  (This is a change from version 2.25 only for
  x86-32 and x86-64.)

  Library.  On powerpc64le, GCC 6.2 or later is required.

  Older GCC versions and non-GNU compilers are still supported when
  compiling programs that use the GNU C Library.  (We do not know exactly
  how old, and some GNU extensions to C may be de facto required.  If you
  are interested in helping us make this statement less vague, please

Security related changes:

  to avoid fragmentation-based spoofing attacks (CVE-2017-12132).

  mode to guard against local privilege escalation attacks

  called on a corrupt stack and a backtrace is unreliable on a corrupt stack

has been
  fixed (CVE-2017-12133).


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
Akhilesh Kumar
Alan Modra
Alexey Neyman
Andreas Schwab
Arjun Shankar
Benjamin Cama
Carlos O'Donell
Chris Leonard
Christian Borntraeger
Christian Brauner
Christopher Chittleborough
Chung-Lin Tang
DJ Delorie
Dennis Wölfing
Dmitry Bilunov
Dmitry V. Levin
Egmont Koblinger
Eyolf Østrem
Florian Weimer
Gabriel F. T. Gomes
Gordana Cmiljanovic
H.J. Lu
Ihar Hrachyshka
Ivo Raisr
Jiong Wang
John David Anglin
Joseph Myers
Justus Winter
Kir Kolyshkin
Marko Myllynen
Massimeddu Cireddu
Matthew Krupcale
Mike Frysinger
Mousa Moradi
Nathan Rossi
Paul Clarke
Paul E. Murphy
Paul Eggert
Peng Wu
Phil Blundell
Prakhar Bahuguna
Rabin Vincent
Rafal Luzynski
Rajalakshmi Srinivasaraghavan
Rical Jasan
Rogerio A. Cardoso
Samuel Thibault
Santhosh Thottingal
Siddhesh Poyarekar
Slava Barinov
Stefan Liebler
Steve Ellcey
Sunyeop Lee
Szabolcs Nagy
Thorsten Kukuk
Tulio Magno Quites Machado Filho
Uros Bizjak
Vladimir Mezentsev
Wainer dos Santos Moschetta
Wilco Dijkstra
Wladimir J. van der Laan
Yury Norov
Zack Weinberg

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