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content main menu main menu move to sidebar hide navigation main page contents current events random article about wikipedia contact us contribute help learn to edit community portal recent changes upload file special pages search search appearance donate create account log in personal tools donate create account log in contents move to sidebar hide top 1 original goals 2 supported architectures 3 components 4 differences from posix 5 relationship to the ndk 6 fortify source 7 controversies 8 see also 9 references 10 external links toggle the table of contents bionic software 12 languages العربية deutsch ελληνικά español فارسی bahasa indonesia 日本語 한국어 norsk bokmål русский українська 中文 edit links article talk english read edit view history tools tools move to sidebar hide actions read edit view history general what links here related changes upload file permanent link page information cite this page get shortened url switch to legacy parser print export download as pdf printable version in other projects wikidata item appearance move to sidebar hide from wikipedia the free encyclopedia c standard library for android operating system this article needs more citations please help improve this article by adding citations to reliable sources unsourced material may be challenged and removed find sources bionic software news newspapers books scholar jstor september 2025 learn how and when to remove this message bionic is an implementation of the c standard library developed by google for its android operating system it differs from the gnu c library glibc in being designed for devices with less memory and processor power than a typical linux system it is a combination of new code and code from freebsd netbsd and openbsd released under a bsd license rather than glibc which uses the gnu lesser general public license this difference was important in the early days of android when static linking was common and since bionic has its own application binary interface it cannot be replaced by a different libc without breaking all existing apps bionic is a c library for use with the linux kernel and provides libc libdl and libm libpthread functionality is part of libc not a separate library as on some other systems this differs from the bsd c libraries that bionic shares code with because they require a bsd kernel original goals edit the original publicly stated goals for bionic were the following 1 2 bsd licensed google wanted to isolate android applications from the effect of copyleft licenses to create a proprietary user space and application ecosystem 3 but android is based on the linux kernel which is subject to the copyleft gnu general public license gpl version 2 the most widespread standard c library for the linux kernel is the gnu c library glibc which is subject to the gnu lesser general public license lgpl also a copyleft license in contrast to the gpl the lgpl explicitly allows for dynamic linking but it does not allow static linking of proprietary software without providing source code or linkable object files the permissive bsd license is a non copyleft license that is compatible in both directions a bsd licensed glibc substitute could act as an isolation layer between the copyleft core kernel and the non copyleft applications and was therefore chosen by google for its bionic as a glibc substitute 4 small size bionic was much smaller than the gnu c library more importantly its memory requirements were and remain much lower speed bionic was designed for cpus at relatively low clock frequencies supported architectures edit bionic only supports linux kernels but currently supports the arm arm64 riscv64 x86 and x86 64 architectures the platform itself required armv7 with neon since marshmallow 5 though the android native development kit ndk continued to support armv5 which it called armeabi up until ndk r16 the ndk still supports armv7 though ndk r24 dropped support for non neon historically there was partial sh 4 support in the platform but no devices ever shipped and support has since been removed the ndk never supported sh 4 and mips and mips64 support were removed from the ndk in r17 components edit some parts of the libc source such as stdio are from the bsds mainly openbsd whereas others such as the pthread implementation were written from scratch the dynamic memory allocator implementation has changed over time releases predating lollipop include a single native memory allocator doug lea s dlmalloc for lollipop and marshmallow include two implementations dlmalloc and jemalloc jemalloc gives much higher performance than dlmalloc but at the cost of extra memory required for bookkeeping most devices switched to jemalloc but low memory devices did not switch away from dlmalloc for nougat through android 10 all devices use jemalloc low memory devices use a svelte configuration of jemalloc that disables the tcache to nearly match the lower memory overhead of dlmalloc while keeping most of the speed of jemalloc in android 11 the memory allocator for most devices was switched to scudo which sacrifices some of jemalloc s high performance for additional security hardening features 6 low memory devices however are still permitted to use jemalloc 7 some 64 bit devices like the nexus 9 are effectively low memory devices because of the extra space requirements of 64 bit pointers and hosting of two zygotes zygote is an android system service that is the parent of all android application processes 8 the libm source is largely freebsd s but with optimized assembler contributed by the various soc vendors the dynamic linker and libdl were written from scratch bionic doesn t include libthread_db used by gdbserver but the ndk does the android platform includes a statically linked gdbserver so that developers can use the latest gdb even on old devices since android dropped gdb support and switched to lldb this is no longer relevant in subsequent releases there is no separate libpthread libresolv or librt on android the functionality is all in libc for libpthread there is no attempt to optimize for the single threaded case because apps are in a multi threaded environment even before the first instruction of third party code is ever run the android platform uses libc for the c standard library releases up to and including lollipop used stlport the ndk historically offered stlport and gnu libstdc but those are not longer included in ndk r18 and later releases 9 note that if any native code in an android app uses c all the c must use the same stl the stl is not provided by the android os and must be bundled with each app differences from posix edit although bionic aims to implement all of c11 and posix there are still as of android 15 about 11 posix functions missing 10 from libc there are also posix functions such as the endpwent getpwent setpwent family that are inapplicable to android because it lacks a passwd database as of oreo libm is complete some functions deliberately do not conform to the posix or c standards for security reasons such as printf which does not support the n format string 11 many of the most used gnu extensions are implemented in bionic as are various bsd extensions relationship to the ndk edit platform code uses bionic directly but third party developers use the android native development kit ndk many third party developers still target older os releases which contributes to a widespread belief that bionic lacks many features gingerbread exported 803 functions from libc but oreo exports 1278 a 1 6x increase 10 historically the ndk and the platform diverged but ndk r11 and later have replaced ndk forks with their current platform equivalents this work initially focused on the gcc and clang compilers prior to ndk r14 when unified headers were first offered on an opt in basis the ndk had forked copies of the platform headers for different api levels this meant that header only fixes fixes to constant or structure definitions for example weren t available to most ndk users because they d be targeting an older api level but platform fixes were only going in to the current platform headers in the oreo development period the platform headers were annotated with api level information so that the same set of headers can be used for all api levels with only those functions available at the developer s targeted api level being visible these are the so called unified headers and have been the default since ndk r15 prior to ndk r16 the ndk linked a library called libandroid_support a to code using libc to provide functions required by libc that weren t in old os releases this wasn t the same code used by the platform and introduced numerous bugs such as breaking positional arguments to the printf family in any code that used libc from ndk r16 to r25 libandroid_support a still existed but was built directly from the then current platform source at the time each ndk was built from ndk r26 libandroid_support a is gone because all os versions still supported by the ndk contain everything needed by libc fortify source edit as of android jelly bean mr1 4 2 bionic supports similar functionality to glibc s _fortify_source 12 which is a feature where unsafe string and memory functions such as strcpy strcat and memcpy include checks for buffer overruns these checks are performed at compile time if the buffer sizes can be determined at compile time or run time otherwise because fortify relies on runtime support from libc its portability to older android releases is limited 13 the platform itself is built with _fortify_source enabled historically one of the shortcomings of fortify has been that it is closely tied with gcc which makes it very difficult to support well in other compilers like clang this meant that when android swapped to clang as its default compiler 14 bionic s fortify implementation became substantially less useful in android oreo 8 0 bionic s fortify was overhauled 15 with clang in mind resulting in fortify on clang providing an experience on par with fortify on gcc since this overhaul some checks were added above and beyond glibc s to catch code that while not necessarily causing undefined behavior is obviously incorrect because this new implementation requires no more libc support than the prior one the clang specific enhancements are available to applications targeting versions of android before oreo controversies edit for the creation of bionic google used gplv2 licensed linux kernel header files to get rid of the gpl google claimed that it cleaned the header files from any copyright able work reducing them to non copyrightable facts 16 17 linux creator linus torvalds considered google s behaviour to be acceptable 17 but google s interpretation of the gpl has been challenged for instance by raymond nimmer a law professor at the university of houston law center 18 see also edit computer programming portal free and open source software portal hybris also known as libhybris musl toybox references edit burnette ed june 4 2008 patrick brady dissects android zdnet turner david 2009 02 07 questions about bionic the name bionic comes from the fact that it is part bsd and part linux its source code consists in a mix of bsd c library pieces with custom linux specific bits used to deal with threads processes signals and a few others things android anatomy and physiology pdf p 36 archived from the original pdf on 2016 04 08 retrieved 2017 07 15 license we want to keep gpl out of user space florian mueller foss patents android 6 0 compatibility definition system hardening in android 11 android developers blog retrieved 2020 12 20 scudo android open source project retrieved 2020 12 20 zygote anatomy of android archived from the original on 2016 03 15 retrieved 2016 03 14 ndk revision history android ndk 1 2 android bionic status elliott hughes libc define to remove support for n from printf 3 android 4 2 jelly bean release notes android developers android com retrieved 2013 12 27 android 4 2 and fortify_source android security discussions retrieved 2013 12 27 android ndk changelog android ndk android googlesource com retrieved 2017 08 28 fortify in android android developers blog android developers googleblog com retrieved 2017 08 28 google android and the linux headers on theregister com 2011 1 2 android sued by microsoft not by linux archived 2016 01 13 at the wayback machine microsoft launches new android suit linus torvalds take on linux kernel headers and android on itworld march 21 2011 infringement and disclosure risk in development on copyleft platforms on ipinfoblog com by raymond nimmer 2011 external links edit google i o 2008 anatomy and physiology of an android on youtube developer home page for android android native development kit ndk home page bionic sources official repository bionic notes on elinux org v t e android android go comparison of products software development development tools official android runtime art software development kit sdk android debug bridge adb fastboot android app bundle android application package apk bionic dalvik firebase google cloud messaging gcm firebase cloud messaging fcm google mobile services gms jetpack compose native development kit ndk open accessory development kit oadk renderscript skia admob material design fonts droid roboto noto google sans google developers other openbinder apache harmony openjdk gradle gson integrated development environments ide android studio intellij idea eclipse android development tools adt mit app inventor languages databases java kotlin xml kml c c sqlite augmented virtual reality android xr cardboard daydream events communities google i o developer challenge developer lab android open source project aosp releases cupcake 1 5 donut 1 6 eclair 2 0 2 1 froyo 2 2 gingerbread 2 3 honeycomb 3 x ice cream sandwich 4 0 jelly bean 4 1 4 3 kitkat 4 4 lollipop 5 x marshmallow 6 x nougat 7 x oreo 8 x pie 9 10 11 12 13 14 15 16 17 derivatives android automotive android things tv devices android xr wear os devices pixel c pixel pixel xl 2 2 xl 3 3 xl 3a 3a xl 4 4 xl 4a 4a 5g 5 5a 6 6 pro 6a 7 7 pro 7a fold tablet 8 8 pro 8a 9 9 pro 9 pro xl 9 pro fold 9a pixel 10 10 pro 10 pro xl 10 pro fold 10a pixel 11 11 pro 11 pro xl 11 pro fold nexus one s galaxy nexus 4 10 q 5 5x 6 6p 7 2012 2013 9 player play edition htc one m7 htc one m8 lg g pad 8 3 moto g samsung galaxy s4 sony xperia z ultra android one other smartphones custom distributions alios android x86 remix os aokp baidu yi barnes noble nook calyxos coloros oxygenos realme ui copperheados emui magicos fire os flyme os grapheneos lewa os lineageos e crdroid cyanogenmod divestos iodéos kali nethunter liteos meta horizon os nokia x software platform omnirom ophone pixelexperience pixel ui replicant resurrection remix os slimroms tcl ui ubuntu for android xiaomi hyperos miui zui booting recovery booting process recovery mode twrp clockworkmod fastboot apis google maps google play services play integrity ...
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