Linux从用户层到内核层系列 - GNU系列之glibc介绍
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最近写程序的时候突然想到一个问题，我们在做内核开发的时候很少使用到C库函数，在linux kernel中使用到C库的几个重要的地方如系统启动时候的标准输入输出，scsi驱动部分还有就是linux/tools。我们修改内核代码的时候都使用内核自身提供的函数接口或者变量，我们可以直接调用系统提供的API，在我们做应用层开发的时候我们却大量的使用了libc，libc和内核开发出来的接口是如何衔接起来的呢？libc对kernel提供的接口是如何封装的？从用户层调用的libc如何映射到系统中断向量表中？glibc系列文章将逐一弄明白这写问题。磨刀不误砍柴功，首先从glibc说起。
说明：对于glibc的介绍没有比GNU官方Web介绍更为简洁和明了的了。由于原文没有太难的英文词汇和复杂的语法，就不再翻译了。
文章引用自GNU官网：http://www.gnu.org/software/libc/index.html
Overview
Any Unix-like operating system needs a C library: the library which defines the ``system calls'' and other basic facilities such as open, malloc, printf, exit...
The GNU C Library is used as the C library in the GNU systems and most systems with the Linux kernel.
Project Goals
The GNU C Library is primarily designed to be aportable 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.
Current Status
The current stable version of glibc is 2.17. See the NEWS file in the glibc sources for more information.
Latest News
2012-12-25: glibc 2.17 released.
2012-06-30: glibc 2.16 released.
2012-03-21: glibc 2.15 released.
2011-06-07: glibc 2.14 released.
2011-02-04: glibc 2.13 released.
History
The history of Unix and various standards determine much of the interface of the C library. In general the GNU C Library supports the ISO C and POSIX standards. We also try to support the features of popular Unix variants (including BSD and System V) when those do not conflict with the standards. Different compatibility modes (selectable when you compile an application) allow the peaceful coexistence of compatibility support for different varieties of Unix.
People
The GNU C Library is currently maintained by a community of developers many of which are listed on the MAINTAINERS page of the project wiki.
Many others have contributed in large amounts as documented in the glibc Contributors.
Thank you to all who have contributed, either in bug reports, or by answering a question, your help is appreciated.