View source for Glibc

{{short description|GNU implementation of the standard C library}}
{{Distinguish|GLib|Gnulib}}
{{Use dmy dates|date=October 2023}}
{{lowercase title}}
{{Infobox software
| name                 = GNU C Library
| logo                 = 
| logo size            = 100px
| author               = Roland McGrath
| developer            = [[GNU Project]], most contributions by Ulrich Drepper
| released             = {{start date and age|1987}}<ref>{{cite web
 | url     = https://lwn.net/Articles/488847/
 | title     = A turning point for GNU libc
 | last     = Corbet
 | first     = Jonathan
 | date     = 28 March 2012
 | publisher     = LWN.net
 | access-date     = 5 April 2012
 | archive-date     = 23 April 2016
 | archive-url     = https://web.archive.org/web/20160423100007/https://lwn.net/Articles/488847/
 | url-status     = live
 }}</ref>
| latest release version = {{wikidata|property|preferred|references|edit|Q856089|P348|P548=Q2804309}}
| latest release date    = {{wikidata|qualifier|preferred|single|Q856089|P348|P548=Q2804309|P577}}
| latest preview version = {{wikidata|property|preferred|references|edit|Q856089|P348|P548=Q51930650}}
| latest preview date    = {{wikidata|qualifier|preferred|single|Q856089|P348|P548=Q51930650|P577}}
| programming language = [[C (programming language)|C]]
| operating system     = [[Unix-like]]
| genre                = [[Runtime library]]
| license              = 2001: [[GNU Lesser General Public License|LGPL-2.1-or-later]]{{efn|LGPL-2.1-or-later since 2001-07-06, version 2.2.4.<ref name="licensing">{{cite web
 | url      = https://sourceware.org/git/?p=glibc.git;a=blob;f=Makefile;hb=HEAD
 | title      = sourceware.org Git – glibc.git/blob – Makefile
 | quote      = LGPL-2.1-or-later in the headers
 | website      = sourceware.org
 | access-date      = 10 June 2021
 | archive-date      = 10 June 2021
 | archive-url      = https://web.archive.org/web/20210610041413/https://sourceware.org/git/?p=glibc.git;a=blob;f=Makefile;hb=HEAD
 | url-status      = live
 }}</ref><ref name="lgpl 2.0 to 2.1">{{cite web
 |url          = https://sourceware.org/git/?p=glibc.git;a=commit;h=41bdb6e20c5d2df34a740cbd70e11c05025dfd12
 |title        = sourceware.org Git – glibc.git/commit – Update to LGPL v.2.1
 |date         = 6 July 2001
 |quote        = LGPL-2.1-or-later in the headers
 |website      = sourceware.org
 |access-date  = 10 June 2021
 |archive-date = 10 June 2021
 |archive-url  = https://web.archive.org/web/20210610041423/https://sourceware.org/git/?p=glibc.git;a=commit;h=41bdb6e20c5d2df34a740cbd70e11c05025dfd12
 |url-status   = live
}}</ref>}}<br />1992: [[GNU Lesser General Public License|LGPL-2.0-or-later]]{{efn|LGPL-2.0-or-later from 1992 to 2001-07-05. Version 1.04? to 2.2.3.<ref name="glibc-1.04.tar.Z">{{cite web
 | url        = https://www.nic.funet.fi/index/gnu/funet/historical-funet-gnu-area-from-early-1990s/glib/glibc-1.04.tar.Z
 | title        = glibc-1.04.tar.Z
 | date        = 4 Sep 1992
 | access-date        = 22 December 2021
 | archive-date        = 22 December 2021
 | archive-url        = https://web.archive.org/web/20211222225512/https://www.nic.funet.fi/index/gnu/funet/historical-funet-gnu-area-from-early-1990s/glib/glibc-1.04.tar.Z
 | url-status        = live
 }}</ref><ref name="lgpl 2.0">{{cite web
 |url          = https://sourceware.org/git/?p=glibc.git;a=blob;f=Makefile;hb=28f540f45bbacd939bfd07f213bcad2bf730b1bf
 |title        = sourceware.org Git – glibc.git/commit – Initial import: Makefile
 |date         = 18 February 1995
 |quote        = LGPL-2.0-or-later in the headers
 |website      = sourceware.org
 |access-date  = 10 June 2021
 |archive-date = 10 June 2021
 |archive-url  = https://web.archive.org/web/20210610041402/https://sourceware.org/git/?p=glibc.git;a=blob;f=Makefile;hb=28f540f45bbacd939bfd07f213bcad2bf730b1bf
 |url-status   = live
}}</ref>}}
| website              = {{URL|https://www.gnu.org/software/libc/}}
}}

The '''GNU C Library''', commonly known as '''glibc''', is the [[GNU Project]] implementation of the [[C standard library]]. It provides a wrapper around the system calls of the [[Linux kernel]] and other kernels for application use. Despite its name, it now also directly supports [[C++]] (and, indirectly, other [[programming language]]s). It was started in the 1980s by the [[Free Software Foundation]] (FSF) for the [[GNU]] operating system.

glibc is [[free software]] released under the [[GNU Lesser General Public License]].<ref name="licensing"/> The GNU C Library project provides the core libraries for the GNU system, as well as many systems that use [[Linux kernel|Linux]] as the [[kernel (operating system)|kernel]]. These libraries provide critical [[API]]s including [[ISO]] [[C11 (C standard revision)|C11]], [[POSIX.1-2008]], [[Berkeley Software Distribution|BSD]], OS-specific APIs and more. These APIs include such foundational facilities as [[open (system call)|open]], [[read (system call)|read]], [[write (system call)|write]], [[malloc]], [[printf format string|printf]], [[getaddrinfo]], [[dynamic loading|dlopen]], [[pthreads|pthread_create]], [[crypt (C)|crypt]], [[login]], [[exit (system call)|exit]] and more.

==History==

<!---This version history uses dates from the ChangeLog files packaged in the 2.13 release.--->
{| class="wikitable mw-collapsible mw-collapsed"
! style="width:6%;" | Version 
! style="width:12%;" | Date 
! style="width:86%;" | Highlights 
|-
| 0.1 – 0.6 || October 1991 – February 1992 || 
|-
| 1.0 || February 1992 || 
|-
| 1.01 – 1.09.3 || March 1992 – December 1994 || 
|-
| 1.90 – 1.102 || May 1996 – January 1997 || 
|-
| 2.0 || January 1997 || 
|-
| 2.0.1 || January 1997 || 
|-
| 2.0.2 || February 1997 || 
|-
| 2.0.91 || December 1997 || 
|-
| 2.0.95 || July 1998 || 
|-
| 2.1 || February 1999 || 
|-
| 2.1.1 || March 1999 || 
|-
| 2.2 || November 2000 || 
|-
| 2.2.1 || January 2001 || 
|-
| 2.2.2 || February 2001 || 
|-
| 2.2.3 || March 2001 || 
|-
| 2.2.4 || July 2001 || 
|-
| 2.3 || October 2002 || 
|-
| 2.3.1 || October 2002 || 
|-
| 2.3.2 || February 2003 || 
|-
| 2.3.3 || December 2003 || 
|-
| 2.3.4 || December 2004 || Minimum for [[Linux Standard Base]] (LSB) 3.0 
|-
| 2.3.5 || April 2005 || 
|-
| 2.3.6 || November 2005 || 
|-
| 2.4 || March 2006 || Minimum for [[Linux Standard Base|LSB]] 4.0, initial [[inotify]] support 
|-
| 2.5 || September 2006 || Full [[inotify]] support. [[Red Hat Enterprise Linux#RHEL 5|RHEL5 end of support]] was {{start date and age |2020|11|30}} 
|-
| 2.6 || May 2007 || 
|-
| 2.7 || October 2007 || 
|-
| 2.8 || April 2008 || 
|-
| 2.9 || November 2008 || 
|-
| 2.10 || May 2009 || Minimum for [[Linux Standard Base|LSB]] 5.0. Initial [https://udrepper.livejournal.com/20948.html psiginfo] {{Webarchive|url=https://web.archive.org/web/20210919063039/https://udrepper.livejournal.com/20948.html |date=19 September 2021 }} support. 
|-
| 2.11 || October 2009 || SLES11 reached end of long-term support in [[SUSE Linux Enterprise#End-of-support schedule|March 2022]]. 
|-
| 2.12 || May 2010 || 
|-
| 2.13 || January 2011 || 
|-
| 2.14 || June 2011 || 
|-
| 2.15 || March 2012 || 
|-
| 2.16 || June 2012 || [[x32 ABI]] support, [[C11 (C standard revision)|ISO C11]] compliance, [[SystemTap]] 
|-
| 2.17 || December 2012 || [[ARMv8-A|64-bit ARM]] support 
|-
| 2.18 || August 2013 || Improved [[C++11]] support. Support for Intel [[Transactional Synchronization Extensions|TSX]] lock elision. Support for the Xilinx [[MicroBlaze]] and IBM [[POWER8]] microarchitectures. 
|-
| 2.19 || February 2014 || SystemTap probes for [[malloc]]. GNU Indirect Function (IFUNC) support for ppc32 and ppc64. New feature test macro _DEFAULT_SOURCE to replace _SVID_SOURCE and _BSD_SOURCE. Preliminary safety documentation for all functions in the manual. ABI change in ucontext and jmp_buf for s390/s390x. 
|-
| 2.20 || September 2014 || Support for file description locks 
|-
| 2.21 || February 2015 || New semaphore implementation 
|-
| 2.22 || August 2015 || Support to enable [[Google Native Client]] (NaCl), that originally ran on x86, running on [[ARMv7-A]], [[Unicode]] 7.0 
|-
| 2.23 || February 2016 || [[Unicode]] 8.0 
|-
| 2.24 || August 2016 || Some deprecated features have been removed 
|-
| 2.25 || February 2017 || The <code>getentropy</code> and <code>getrandom</code> functions, and the <code><sys/random.h></code> header file have been added. 
|-
| 2.26 || August 2017 || Improved performance (per-thread cache for malloc), Unicode 10 support 
|-
| 2.27 || February 2018 || Performance optimizations. [[RISC-V]] support. 
|-
| 2.28 || August 2018 || <code>statx</code>, <code>renameat2</code>, Unicode 11.0.0 
|-
| 2.29 || February 2019 ||
* <code>getcpu</code> wrapper
* build and install all locales as directories with files
* optimized trigonomical functions
* Transactional Lock Elision for powercp64le ABI
* posix_spawn_file_actions_addchdir_np and posix_spawn_file_actions_addfchdir_np 
* popen and system do not run atfork handlers anymore
* support for the C-SKY ABIV2 running on Linux
* strftime's default formatting of a locale's alternative year; the '_' and '-' flags can now be applied to its "%EY"<ref>{{cite web
 | url   = https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS;hb=de44ab67aa4eec369deea828733567c35a0611c0
 | title   = sourceware.org Git – glibc.git/blob – NEWS
 | access-date   = 26 April 2019
 | archive-date   = 21 March 2022
 | archive-url   = https://web.archive.org/web/20220321041644/https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS;hb=de44ab67aa4eec369deea828733567c35a0611c0
 | url-status   = live
 }}</ref>
|-
| 2.30 || August 2019 || Unicode 12.1.0, the dynamic linker accepts the <code>--preload</code> argument to preload shared objects, the <code>gettid</code> function has been added on Linux, Minguo (Republic of China) calendar support, new Japanese era added to ja_JP locale, memory allocation functions fail with total object size larger than <code>PTRDIFF_MAX</code>; {{CVE|2019-7309|2019-9169|leadout=and}} fixed<ref>{{cite web
 | url   = https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS;hb=HEAD
 | title   = sourceware.org Git – glibc.git/blob – NEWS
 | access-date   = 26 April 2019
 | archive-date   = 26 September 2019
 | archive-url   = https://web.archive.org/web/20190926020352/https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS;hb=HEAD
 | url-status   = live
 }}</ref> 
|-
| 2.31 || February 2020 || Initial [[C23 (C standard revision)|C23]] standard support 
|-
| 2.32 || August 2020 || Unicode 13.0, 'access' attribute for better warnings in GCC 10, i.e. to "help detect buffer overflows and other out-of-bounds accesses"<ref>{{Cite web|title=The GNU C Library version 2.32 is now available|url=https://sourceware.org/pipermail/libc-announce/2020/000029.html|access-date=2020-08-13|website=sourceware.org|archive-date=28 September 2020|archive-url=https://web.archive.org/web/20200928195441/https://sourceware.org/pipermail/libc-announce/2020/000029.html|url-status=live}}</ref> 
|-
| 2.33 || February 2021 || HWCAPS 
|-
| 2.34 || August 2021 || libpthread, libdl, libutil, libanl has been integrated into libc. 
|-
| 2.35 || February 2022 || Unicode 14.0, C.UTF-8 locale, restartable sequences. Removed [[Intel MPX]] support. 
|-
| 2.36 || August 2022 || 
|-
| 2.37 || February 2023 || 
|-
| 2.38 || August 2023 || The strlcpy and strlcat functions added. libmvec support for ARM64.
|-
| 2.39 || January 2024 || The stdbit.h header has been added from ISO C2X. Support for shadow stacks on x86_64, new security features, and the removal of libcrypt.
|-
| 2.40 || July 2024 || Partial support for the ISO [[C23 (C standard revision)|C23]] standard, a new tunable for the testing of {{Mono|[[setuid]]}} programs, improved 64-bit ARM vector support.
|-
| 2.41 || January 2025 || Add {{Mono|sinpi}}, {{Mono|cospi}}, {{Mono|tanpi}} functions.
|-
| 2.42 || July 2025 || New math functions, support for arbitrary baud rates in the termios.h interface, SFrame-based stack tracing.
|}

[[File:Ulrich Drepper.jpg|thumb|Ulrich Drepper in 2007, the main author of glibc]]
[[File:Linux kernel System Call Interface and glibc.svg|thumb|The GNU C Library is a wrapper around the [[system call]]s of the [[Linux kernel]].]]
[[File:Linux API and Linux ABI.svg|thumb|The [[Linux kernel]] and GNU C Library together form the [[Linux kernel interfaces#Kernel–user space API|Linux API]]. After compilation, the binaries offer an [[Application binary interface|ABI]].]]
The glibc project was initially written mostly by Roland McGrath, working for the [[Free Software Foundation]] (FSF) in the summer of 1987 as a teenager.<ref name=":0">{{cite web|url=https://lwn.net/Articles/727383/|title=Roland McGrath bows out as glibc maintainer [LWN.net]|date=2017-07-07|website=lwn.net|access-date=2017-07-08|archive-date=1 August 2020|archive-url=https://web.archive.org/web/20200801031334/https://lwn.net/Articles/727383/|url-status=live}}</ref><ref name=register>{{cite news |url=https://www.theregister.com/2017/07/10/glibc_maintainer_roland_mcgrath_steps_down/ |title=Roland McGrath steps down as glibc maintainer after 30 years |date=10 July 2017 |access-date=1 June 2024 |first=Richard |last=Chirgwin |work=[[The Register]] |publisher=Situation Publishing |archive-date=7 March 2024 |archive-url=https://web.archive.org/web/20240307163613/https://www.theregister.com/2017/07/10/glibc_maintainer_roland_mcgrath_steps_down/ |url-status=live }}</ref> In February 1988, FSF described glibc as having nearly completed the functionality required by [[ANSI C]].<ref>{{cite web | url = https://www.gnu.org/bulletins/bull4.html | title = GNU's Bulletin, vol. 1 no. 4, February, 1988 | quote = Most libraries are done. Roland McGrath [...] has a nearly complete set of ANSI C library functions. We hope they will be ready some time this spring. | access-date = 16 April 2014 | archive-date = 16 April 2016 | archive-url = https://web.archive.org/web/20160416163749/https://gnu.org/bulletins/bull4.html | url-status = live }}</ref> By 1992, it had the ANSI C-1989 and POSIX.1-1990 functions implemented and work was under way on POSIX.2.<ref>{{cite web | url = https://www.gnu.org/bulletins/bull12.html | title = GNU's Bulletin, vol. 1 no. 12 | quote = It now contains all of the ANSI C-1989 and POSIX.1-1990 functions, and work is in progress on POSIX.2 and Unix functions (BSD and System V) | access-date = 16 April 2014 | archive-date = 11 March 2016 | archive-url = https://web.archive.org/web/20160311170312/https://www.gnu.org/bulletins/bull12.html | url-status = live }}</ref> In September 1995 Ulrich Drepper made his first contribution to the glibc and by 1997 most commits were made by him. Drepper held the maintainership position for many years and until 2012 accumulated 63% of all commits to the project.<ref name=":1">{{cite web|url=https://lwn.net/Articles/488847/|title=A turning point for GNU libc|last=Corbet|first=Jonathan|date=28 March 2012|publisher=LWN.net|quote=''Of the nearly 19,000 commits found in the project's git repository (which contains changes back to 1995), over 12,000 were made by Ulrich.''|access-date=5 April 2012|archive-date=23 April 2016|archive-url=https://web.archive.org/web/20160423100007/https://lwn.net/Articles/488847/|url-status=live}}</ref>

In May 2009, glibc was migrated to a [[Git]] repository.<ref name=":1" />

In 2010, a licensing issue was resolved which was caused by the [[Sun RPC]] implementation in glibc that was not GPL [[License compatibility|compatible]]. It was fixed by re-licensing the Sun RPC components under the [[BSD licenses|BSD license]].<ref>{{Cite web|title=Glibc finally free software – The H Open: News and Features|url=http://www.h-online.com/open/news/item/Glibc-finally-free-software-1068035.html|access-date=2021-09-19|website=[[H-online]]|archive-date=21 March 2022|archive-url=https://web.archive.org/web/20220321041635/http://www.h-online.com/open/news/item/Glibc-finally-free-software-1068035.html|url-status=live}}</ref><ref>{{Cite web|last=Phipps|first=Simon|date=2010-09-02|title=Gnu/Linux: Finally, it's really free software|url=https://www.infoworld.com/article/2626417/gnu-linux--finally--it-s-really-free-software.html|access-date=2021-09-19|website=[[InfoWorld]]|language=en|archive-date=28 October 2021|archive-url=https://web.archive.org/web/20211028174447/https://www.infoworld.com/article/2626417/gnu-linux--finally--it-s-really-free-software.html|url-status=live}}</ref>

In 2014, glibc suffered from an ABI breakage bug on s390.<ref>{{Cite web |last=Corbet |first=Jonathan |title=The glibc s390 ABI break [LWN.net] |url=https://lwn.net/Articles/605607/ |access-date=2022-03-17 |website=[[LWN.net]] |archive-date=17 March 2022 |archive-url=https://web.archive.org/web/20220317160239/https://lwn.net/Articles/605607/ |url-status=live }}</ref>

In July 2017, 30 years after he started glibc, Roland McGrath announced his departure, "declaring myself maintainer emeritus and withdrawing from direct involvement in the project. These past several months, if not the last few years, have proven that you don't need me anymore".<ref name=":0" />

In 2018, maintainer Raymond Nicholson removed a joke about [[abortion]] from the glibc source code. It was restored later by Alexandre Oliva after [[Richard Stallman]] demanded to have it returned.<ref>{{Cite web |last=Claburn |first=Thomas |title=Glibc 'abortion joke' diff tiff leaves Richard Stallman miffed |url=https://www.theregister.com/2018/05/09/gnu_glic_abort_stallman/ |access-date=2023-01-17 |website=[[The Register]] |language=en |archive-date=17 January 2023 |archive-url=https://web.archive.org/web/20230117154113/https://www.theregister.com/2018/05/09/gnu_glic_abort_stallman/ |url-status=live }}</ref>

In 2021, the [[copyright]] assignment requirement to the [[Free Software Foundation]] was removed from the project.<ref>{{Cite web |last=Halfacree |first=Gareth |title=Open-source projects glibc and gnulib look to sever copyright ties with Free Software Foundation |url=https://www.theregister.com/2021/06/16/glibc_gnulib_fsf_copyright/ |access-date=2023-01-17 |website=[[The Register]] |language=en |archive-date=17 January 2023 |archive-url=https://web.archive.org/web/20230117154446/https://www.theregister.com/2021/06/16/glibc_gnulib_fsf_copyright/ |url-status=live }}</ref>

===Fork and variant<span class="anchor" id="Linux libc"></span>===
In 1994, the developers of the [[Linux kernel]] [[fork (software development)|forked]] glibc. Their fork, "Linux libc", was maintained separately until around 1998. Because the copyright attribution was insufficient, changes could not be merged back to the GNU Libc.<ref>{{Cite web|title=History of glibc and Linux libc|url=http://freesoftwaremagazine.com/articles/history_of_glibc_and_linux_libc/|access-date=2021-05-10|website=[[Free Software Magazine]]|archive-date=26 September 2021|archive-url=https://web.archive.org/web/20210926154743/http://freesoftwaremagazine.com/articles/history_of_glibc_and_linux_libc/|url-status=live}}</ref> When the FSF released glibc 2.0 in January 1997, the kernel developers discontinued Linux libc due to glibc 2.0's superior compliance with POSIX standards.<ref>{{cite web | date=24 October 2000 | title=Forking: it could even happen to you | url=https://www.linux.com/news/forking-it-could-even-happen-you/ | archive-url=https://web.archive.org/web/20090915191339/https://www.linux.com/archive/feature/3874 | archive-date=15 September 2009 | quote=the split between GNU LIBC and the Linux LIBC -- it went on for years while Linux stabilized, and then the forks re-merged into one project}}</ref> glibc 2.0 also had better [[internationalization]] and more in-depth translation, [[IPv6]] capability, 64-bit data access, facilities for multithreaded applications, future version compatibility, and the code was more portable.<ref>{{cite web | url = https://people.redhat.com/~sopwith/old/glibc-vs-libc5.html | title = A Technical Comparison of glibc 2.x With Legacy System Libraries| last = Lee | first = Elliot | date=Jul 9, 1998 |archive-url = https://web.archive.org/web/20040411191201/https://people.redhat.com/~sopwith/old/glibc-vs-libc5.html |archive-date = 11 April 2004}}</ref> The last-used version of Linux libc used the internal name ([[soname]]) {{mono|libc.so.5}}. Following on from this, glibc 2.x on Linux uses the soname {{mono|libc.so.6}}<ref>{{cite web | url = http://linuxmafia.com/faq/Licensing_and_Law/forking.html | title = Fear of Forking essay |at=6. glibc --> Linux libc --> glibc |first1=Rick |last1=Moen |date=May 20, 2021 |orig-date=14 Nov 1999 |website=linuxmafia.com |url-status=live |archive-url=https://web.archive.org/web/20231127145135/http://linuxmafia.com/faq/Licensing_and_Law/forking.html |archive-date= Nov 27, 2023 }}</ref>{{Better source needed|date=May 2021}}

In 2009, [[Debian]] and a number of [[List of Linux distributions#Debian-based|derivatives]] switched from glibc to the variant{{Refn|The eglibc developers emphasized themselves that eglibc is not a fork of glibc, but a variant, accepting patches from the upstream glibc project.<ref>{{Cite web|title=EGLIBC: FAQ|url=http://www.eglibc.org/faq|access-date=2021-09-16|website=eglibc.org|archive-date=17 March 2012|archive-url=https://web.archive.org/web/20120317051907/http://www.eglibc.org/faq|url-status=dead}}</ref>}} eglibc.<ref>{{Cite book|last=Vaduva|first=Alexandru|url=https://books.google.com/books?id=yIJcDgAAQBAJ&pg=PA24 |publisher=Packt Publishing |title=Linux : embedded development: leverage the power of Linux to develop captivating and powerful embedded Linux projects : a course in three modules|date=2016|others=Alex Gonzalez, Chris Simmonds|isbn=978-1-78712-445-5|location=Birmingham, UK|pages=24|oclc=960471438}}</ref> Eglibc was supported by a [[consortium]] consisting of [[Freescale Semiconductor|Freescale]], [[MIPS Technologies|MIPS]], [[MontaVista]] and [[Wind River Systems|Wind River]].<ref>{{Cite web|last=Stiebert|first=Julius|date=6 May 2009|title=Debian wechselt zur Eglibc|url=https://www.golem.de/0905/66930.html|access-date=2021-09-16|website=[[golem.de]]|archive-date=16 September 2021|archive-url=https://web.archive.org/web/20210916141335/https://www.golem.de/0905/66930.html|url-status=live}}</ref> It contained changes that made it more suitable for [[Embedded system|embedded usage]] and had added support for architectures that were not supported by glibc, such as the [[PowerPC e500]]. The code of eglibc was merged back into glibc at version 2.20.<ref>{{Cite book|last=Simmonds|first=Chris|title=Mastering embedded Linux programming: unleash the full potential of embedded Linux|date=2017|isbn=978-1-78728-885-0|edition=2nd|location=Birmingham, UK|pages=26|oclc=995052708}}</ref> Since 2014, eglibc is discontinued. The [[Yocto Project]] and Debian also moved back to glibc since the release of [[Debian Jessie]].<ref>{{Cite book|last=Vaduva|first=Alexandru|title=Learning embedded Linux using the Yocto project: develop powerful embedded Linux systems with the Yocto project components|date=2015|isbn=978-1-78439-519-3|location=Birmingham, UK|pages=29|oclc=914797028}}</ref>

===Steering committee===
Starting in 2001 the library's development had been overseen by a committee,<ref>{{cite web |url=https://www.gnu.org/software/libc/ |title=glibc homepage |quote=In 2001 The GNU C Library Steering Committee ..., was formed and currently consists of Mark Brown, Paul Eggert, Andreas Jaeger, Jakub Jelinek, Roland McGrath and Andreas Schwab. |access-date=16 April 2014 |archive-date=22 April 2016 |archive-url=https://web.archive.org/web/20160422061403/http://www.gnu.org/software/libc/ |url-status=live }}</ref> with Ulrich Drepper<ref>{{cite web |url=https://www.linkedin.com/in/ulrichdrepper |title=Ulrich Drepper |publisher=LinkedIn |access-date=2012-06-13 |archive-date=10 September 2014 |archive-url=https://web.archive.org/web/20140910084037/http://www.linkedin.com/in/ulrichdrepper |url-status=live }}</ref> kept as the lead contributor and maintainer. The [[steering committee]] installation was surrounded by a public controversy, as it was openly described by Ulrich Drepper as a failed [[hostile takeover]] maneuver by [[Richard Stallman]].<ref>{{Cite web|last=online|first=heise|title=Open-Source-Entwickler kritisiert Stallman|url=https://www.heise.de/newsticker/meldung/Open-Source-Entwickler-kritisiert-Stallman-48836.html|access-date=2021-09-16|website=[[heise online]]|date=19 August 2001|language=de|archive-date=16 September 2021|archive-url=https://web.archive.org/web/20210916142850/https://www.heise.de/newsticker/meldung/Open-Source-Entwickler-kritisiert-Stallman-48836.html|url-status=live}}</ref><ref>{{cite web|url=https://sourceware.org/ml/libc-hacker/2000-06/msg00180.html|title=RMS is at it again|first=Ulrich|last=Drepper|date=2000-06-26|access-date=2015-11-20|quote=''A few weeks ago RMS started the next attack on me (a single mail, followed by indirect tries to take influence, followed by another mail today). The essence is that he complains I am not following "GNU policies" and therefore have to be replaced by a steering committee of which I could be a part. Some of you (namely Roland and Andreas S.) probably know about this since he proposed both as other members of the committee. In addition there was Mark Brown listed (I know somebody of this name at IBM who would also fit in this group but I'm not sure whether it is really him.) Anyhow, I completely reject this. It is not helping at all, the opposite is true. First, I am not aware of any essential policies I'm violating. The only ones are that I'm not following orders from RMS which clearly have political intends (which is of course a sacrilege) and possibly that I do not care about Winblowz (if the latter counts at all). None of this will change in any way.''|publisher=sourceware.org|archive-date=28 December 2012|archive-url=https://web.archive.org/web/20121228210747/http://sourceware.org/ml/libc-hacker/2000-06/msg00180.html|url-status=live}}</ref><ref>{{cite web |url=https://sourceware.org/ml/libc-announce/2001/msg00000.html |title=glibc 2.2.4 |first=Ulrich |last=Drepper |date=2001-08-15 |access-date=2015-11-29 |publisher=sourceware.com |quote=''And now for some not so nice things. Stallman recently tried what I would call a hostile takeover of the glibc development. He tried to conspire behind my back and persuade the other main developers to take control so that in the end he is in control and can dictate whatever pleases him. This attempt failed but he kept on pressuring people everywhere and it got really ugly. In the end I agreed to the creation of a so-called "steering committee" (SC).'' |archive-date=9 April 2016 |archive-url=https://web.archive.org/web/20160409074117/http://sourceware.org/ml/libc-announce/2001/msg00000.html |url-status=live }}</ref><ref>[https://slashdot.org/story/01/08/19/2039211/rms-accused-of-attempting-glibc-hostile-takeover rms-accused-of-attempting-glibc-hostile-takeover] {{Webarchive|url=https://web.archive.org/web/20200801025406/https://slashdot.org/story/01/08/19/2039211/rms-accused-of-attempting-glibc-hostile-takeover |date=1 August 2020 }} on [[slashdot]].com on 19 August 2001</ref>

In March 2012, the steering committee voted to disband itself and remove Drepper in favor of a community-driven development process, with Ryan Arnold, Maxim Kuvyrkov, Joseph Myers, Carlos O'Donell, and Alexandre Oliva holding the responsibility of GNU maintainership (but no extra decision-making power).<ref>{{Cite web |title=The GNU C Library Steering Committee disbands – The H Open: News and Features |url=http://www.h-online.com/open/news/item/The-GNU-C-Library-Steering-Committee-disbands-1484707.html |access-date=2023-03-16 |website=[[Heise (company)|H-Online]] |archive-date=21 March 2023 |archive-url=https://web.archive.org/web/20230321065852/http://www.h-online.com/open/news/item/The-GNU-C-Library-Steering-Committee-disbands-1484707.html |url-status=live }}</ref><ref>{{cite web|last=McGrath|first=Roland|date=26 March 2012|title=glibc steering committee dissolving|url=https://sourceware.org/ml/libc-alpha/2012-03/msg01038.html|access-date=2012-06-13|publisher=Sourceware.org|archive-date=26 September 2019|archive-url=https://web.archive.org/web/20190926010751/http://sourceware.org/ml/libc-alpha/2012-03/msg01038.html|url-status=live}}</ref><ref>{{cite web|last=Myers|first=Joseph S.|date=26 March 2012|title=GNU C Library development and maintainers|url=https://sourceware.org/ml/libc-alpha/2012-03/msg01040.html|access-date=2012-06-13|publisher=Sourceware.org|archive-date=26 September 2019|archive-url=https://web.archive.org/web/20190926010751/http://sourceware.org/ml/libc-alpha/2012-03/msg01040.html|url-status=live}}</ref>

==Functionality==
glibc provides the functionality required by the [[Single UNIX Specification]], [[POSIX]] (1c, 1d, and 1j) and some of the functionality required by [[International Organization for Standardization|ISO]] [[C11 (C standard revision)|C11]], [[International Organization for Standardization|ISO]] [[C99]], [[Berkeley Unix]] (BSD) interfaces, the [[System V Interface Definition]] (SVID) and the [[X/Open Portability Guide]] (XPG), Issue 4.2, with all extensions common to XSI ([[X/Open System Interface]]) compliant systems along with all X/Open UNIX extensions.

In addition, glibc also provides extensions that have been deemed useful or necessary while developing [[GNU]].

===Supported hardware and kernels===
glibc is used in systems that run many different [[kernel (operating system)|kernels]] and different [[Computer hardware|hardware]] architectures. Its most common use is in systems using the [[Linux kernel]] on [[x86]] hardware, however, officially supported hardware<ref>{{cite web | url = https://sourceware.org/glibc/wiki/MAINTAINERS#Machine_maintainers | title = The GNU C Library machine maintainers. | access-date = 8 October 2015 | archive-date = 18 April 2016 | archive-url = https://web.archive.org/web/20160418170046/https://sourceware.org/glibc/wiki/MAINTAINERS#Machine_maintainers | url-status = live }}</ref> includes: [[ARM architecture|ARM]], [[ARC (processor)|ARC]], [[C-SKY]], [[DEC Alpha]], [[IA-64]], [[Motorola 68000 series|Motorola m68k]], [[MicroBlaze]], [[MIPS architecture|MIPS]], [[Nios II]], [[PA-RISC]]<!--"hppa"-->, [[PowerPC]], [[RISC-V]], [[IBM System z|s390]], [[SPARC]], and [[x86]] (old versions support [[TILE64|TILE]]). It officially supports the [[GNU Hurd|Hurd]] and [[Linux kernel|Linux]] kernels. Additionally, there are heavily patched versions that run on the kernels of [[FreeBSD]] and [[NetBSD]] (from which [[Debian gnu/kfreebsd|Debian GNU/kFreeBSD]] and [[Debian GNU/NetBSD]] systems are built, respectively), as well as a forked-version of [[OpenSolaris]].<ref>{{cite web|url=https://csclub.uwaterloo.ca/~dtbartle/opensolaris/|title=GNU/kOpenSolaris (GNU libc/base + OpenSolaris kernel)|last1=Bartley|first1=David|last2=Spang|first2=Michael|access-date=2008-12-16|archive-date=6 November 2019|archive-url=https://web.archive.org/web/20191106181358/http://csclub.uwaterloo.ca/~dtbartle/opensolaris/|url-status=dead}}</ref> It is also used (in an edited form) and named {{mono|libroot.so}} in [[BeOS]] and [[Haiku (operating system)|Haiku]].<ref>{{cite web
 | url = https://github.com/haiku/haiku/tree/master/src/system/libroot
 | title = Haiku Source
 | website = [[GitHub]]
 | quote = libroot.so is not part of GNU project and is included in Haiku source code.
 | access-date = 15 October 2014
 | archive-date = 1 May 2016
 | archive-url = https://web.archive.org/web/20160501130749/https://github.com/haiku/haiku/tree/master/src/system/libroot
 | url-status = live
 }}</ref>

===Use in small devices===
glibc has been criticized as being "[[Software bloat|bloated]]" and slower than other libraries in the past, e.g. by [[Linus Torvalds]]<ref>{{cite web|last=Torvalds|first=Linus|url=http://ecos.sourceware.org/ml/libc-alpha/2002-01/msg00079.html|title=Posting to the glibc mailing list|date=9 January 2002<!-- 19:02:37-->|access-date=22 July 2007|archive-date=12 October 2015|archive-url=https://web.archive.org/web/20151012215444/http://ecos.sourceware.org/ml/libc-alpha/2002-01/msg00079.html|url-status=live}}</ref> and [[embedded Linux]] programmers. For this reason, several [[C standard library#Implementations|alternative C standard libraries]] have been created which emphasize a smaller footprint. However, many small-device projects use GNU libc over the smaller alternatives because of its application support, standards compliance, and completeness. Examples include [[Openmoko]]<ref>{{cite web
 | url   = http://wiki.openmoko.org/wiki/OpenMoko
 | title   = OpenMoko components
 | quote   = We will use glibc (not uClibC) ... The alternatives may save more space and be more optimized, but are more likely to give us integration headaches
 | access-date   = 13 May 2008
 | archive-date   = 22 April 2016
 | archive-url   = https://web.archive.org/web/20160422073925/http://wiki.openmoko.org/wiki/Openmoko
 | url-status   = live
 }}</ref> and [[Familiar Linux]] for iPaq handhelds (when using the [[GPE Palmtop Environment|GPE]] display software).<ref>{{cite web
 | url   = https://marc.info/?l=familiar&m=118666899424374&w=2
 | title   = Re: [Familiar] Which glibc for Familiar 0.8.4&nbsp;&nbsp;?
 | quote   = Question: which version of the GLIBC was used to build the Familiar 0.8.4 ? Answer: 2.3.3
 | access-date   = 26 November 2018
 | archive-date   = 12 March 2022
 | archive-url   = https://web.archive.org/web/20220312062719/https://marc.info/?l=familiar&m=118666899424374&w=2
 | url-status   = live
 }}</ref>

===Secure string functions===
glibc does not implement bounds-checking interfaces defined in [[C11 (C standard revision)|C11]] and did not implement [[strlcpy]] and [[strlcat]]<ref>{{Cite web |last=Kerrisk |first=Michael |title=The ups and downs of strlcpy() |url=https://lwn.net/Articles/507319/ |access-date=2023-12-09 |website=[[LWN.net]] |archive-date=9 December 2023 |archive-url=https://web.archive.org/web/20231209152233/https://lwn.net/Articles/507319/ |url-status=live }}</ref><ref>{{Cite web |last=Corbet |first=Jonathan |title=Adding strlcpy() to glibc |url=https://lwn.net/Articles/612244/ |access-date=2023-12-09 |website=[[LWN.net]] |archive-date=9 December 2023 |archive-url=https://web.archive.org/web/20231209152233/https://lwn.net/Articles/612244/ |url-status=live }}</ref> until 2023 on the grounds that "in practice these functions can cause trouble, as their intended use encourages silent data truncation, adds complexity and inefficiency, and does not prevent all buffer overruns in the destinations."<ref name=":2">{{Cite web |title=FAQ |url=https://sourceware.org/glibc/wiki/FAQ#Why_no_strlcpy_.2F_strlcat.3F |access-date=2023-12-09 |website=sourceware.org |archive-date=9 December 2023 |archive-url=https://web.archive.org/web/20231209151431/https://sourceware.org/glibc/wiki/FAQ#Why_no_strlcpy_.2F_strlcat.3F |url-status=live }}</ref> The FAQ pointed out that the bounds-checking interfaces were optional in the ISO standard and that snprintf was available as an alternative.<ref name=":2" />

==Compatibility layers==
There are [[compatibility layer]]s ("[[Shim (computing)|shims]]") to allow programs written for other ecosystems to run on glibc interface offering systems. These include [[Hybris (software)|libhybris]], a compatibility layer for [[Android (OS)|Android's]] [[Bionic (software)|Bionic]], and [[Wine (software)|Wine]], which can be seen as a compatibility layer from [[Windows]] APIs to glibc and other native APIs available on Unix-like systems.

==See also==
{{Portal|Free and open-source software}}
* [[Gnulib]]
* [[Linux kernel API]]

==Notes==
{{Notelist}}

==References==
{{Reflist}}

==External links==
{{Commons category|GNU C Library}}
* {{Official website|https://www.gnu.org/software/libc/}}

{{GNU}}
{{CProLang|state=expanded}}

[[Category:C standard library]]
[[Category:Cross-platform free software]]
[[Category:Free computer libraries]]
[[Category:Free software programmed in C]]
[[Category:GNU Project software|C Library]]
[[Category:Interfaces of the Linux kernel]]
[[Category:Linux APIs]]