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The GNU C Library version 2.29 is now available
- From: Siddhesh Poyarekar <siddhesh at sourceware dot org>
- To: libc-alpha at sourceware dot org
- Date: Fri, 1 Feb 2019 01:00:13 +0530
- Subject: The GNU C Library version 2.29 is now available
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:
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
* Optimized generic exp, exp2, log, log2, pow, sinf, cosf, sincosf and
* 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
* 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
In both popen and system there is no direct access to user-defined
* 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
* 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
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
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
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.
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:
Albert ARIBAUD (3ADEV)
Andreas K. Hüttel
David S. Miller
Dmitry V. Levin
Gabriel F. T. Gomes
Ilya Yu. Malakhov
Rafael Avila de Espindola
Sergi Almacellas Abellana
Tulio Magno Quites Machado Filho