Glibc

File:Ulrich Drepper.jpg

File:Linux kernel System Call Interface and glibc.svgs of the Linux kernel.]]

File:Linux API and Linux ABI.svg and GNU C Library together form the Linux API. After compilation, the binaries offer an 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.{{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}}{{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 }} In February 1988, FSF described glibc as having nearly completed the functionality required by ANSI C.{{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 }} By 1992, it had the ANSI C-1989 and POSIX.1-1990 functions implemented and work was under way on POSIX.2.{{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 }} 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.{{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}}

In May 2009 glibc was migrated to a Git repository.

In 2010, a licensing issue was resolved which was caused by the Sun RPC implementation in glibc that was not GPL compatible. It was fixed by re-licensing the Sun RPC components under the BSD license.{{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}}{{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}}

In 2014, glibc suffered from an ABI breakage bug on s390.{{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 }}

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".

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.{{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 }}

In 2021, the copyright assignment requirement to the Free Software Foundation was removed from the project.{{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 }}

In 1994, the developers of the Linux kernel 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.{{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}} 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.{{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}} glibc 2.0 also had better internationalisation and more in-depth translation, IPv6 capability, 64-bit data access, facilities for multithreaded applications, future version compatibility, and the code was more portable.{{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}} 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}}{{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 }}{{Better source needed|date=May 2021}}

In 2009, Debian and a number of 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.{{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}}}} eglibc.{{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}} Eglibc was supported by a consortium consisting of Freescale, MIPS, MontaVista and Wind River.{{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}} It contained changes that made it more suitable for 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.{{Cite book|last=Simmonds|first=Chris|url=https://www.worldcat.org/oclc/995052708|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}} Since 2014, eglibc is discontinued. The Yocto Project and Debian also moved back to glibc since the release of Debian Jessie.{{Cite book|last=Vaduva|first=Alexandru|url=https://www.worldcat.org/oclc/914797028|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}}

Starting in 2001 the library's development had been overseen by a committee,{{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 }} with Ulrich Drepper{{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 }} 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.{{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}}{{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}}{{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 }}[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

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).{{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=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 }}{{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}}{{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}}

glibc provides the functionality required by the Single UNIX Specification, POSIX (1c, 1d, and 1j) and some of the functionality required by ISO C11, 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.

glibc is used in systems that run many different kernels and different hardware architectures. Its most common use is in systems using the Linux kernel on x86 hardware, however, officially supported hardware{{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 }} includes: ARM, ARC, C-SKY, DEC Alpha, IA-64, Motorola m68k, MicroBlaze, MIPS, Nios II, PA-RISC, PowerPC, RISC-V, s390, SPARC, and x86 (old versions support TILE). It officially supports the Hurd and Linux kernels. Additionally, there are heavily patched versions that run on the kernels of FreeBSD and NetBSD (from which Debian GNU/kFreeBSD and Debian GNU/NetBSD systems are built, respectively), as well as a forked-version of OpenSolaris.{{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}} It is also used (in an edited form) and named {{mono|libroot.so}} in BeOS and Haiku.{{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

}}

glibc has been criticized as being "bloated" and slower than other libraries in the past, e.g. by Linus Torvalds{{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|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}} and embedded Linux programmers. For this reason, several 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{{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

}} and Familiar Linux for iPaq handhelds (when using the GPE display software).{{cite web

| url = https://marc.info/?l=familiar&m=118666899424374&w=2

| title = Re: [Familiar] Which glibc for Familiar 0.8.4  ?

| 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

}}

glibc does not implement bounds-checking interfaces defined in C11 and did not implement strlcpy and strlcat{{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 }}{{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 }} 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."{{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 }} The FAQ pointed out that the bounds-checking interfaces were optional in the ISO standard and that snprintf was available as an alternative.

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

{{Portal|Free and open-source software}}

• Gnulib
• Linux kernel API

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