Library Maintenance
*******************

How to Install the GNU C Library
================================

Installation of the GNU C library is relatively simple, but usually requires several GNU tools to be installed already.

To configure the GNU C library for your system, run the shell script configure with sh.  Use an argument which is the conventional GNU name for your system configuration---for example, sparc-sun-sunos4.1, for a Sun 4 running SunOS 4.1. See Installing GNU CC (Using and Porting GNU CC), for a full description of standard GNU configuration names.  If you omit the configuration name, configure will try to guess one for you by inspecting the system it is running on.  It may or may not be able to come up with a guess, and the its guess might be wrong.  configure will tell you the canonical name of the chosen configuration before proceeding.

Here are some options that you should specify (if appropriate) when you run configure:

--with-gnu-ld
     Use this option if you plan to use GNU ld to link programs with the GNU C Library.  (We strongly recommend that you do.)  This option enables use of features that exist only in GNU ld; so if you configure for GNU ld you must use GNU ld every time you link with the GNU C Library, and when building it.

--with-gnu-as
     Use this option if you plan to use the GNU assembler, gas, when building the GNU C Library.  On some systems, the library may not build properly if you do not use gas.

--with-gnu-binutils
     This option implies both --with-gnu-ld and --with-gnu-as. On systems where GNU tools are the system tools, there is no need to specify this option.  These include GNU, GNU/Linux, and free BSD systems.

--without-fp
--nfp

     Use this option if your computer lacks hardware floating-point support.

--prefix=DIRECTORY
     Install machine-independent data files in subdirectories of DIRECTORY.  (You can also set this in configparms; see below.)

--exec-prefix=DIRECTORY
     Install the library and other machine-dependent files in subdirectories of DIRECTORY.  (You can also set this in configparms; see below.)

--enable-shared
--disable-shared
     Enable or disable building of an ELF shared library on systems that support it.  The default is to build the shared library on systems using ELF when the GNU binutils are available.

--enable-profile
--disable-profile
     Enable or disable building of the profiled C library, -lc_p.  The default is to build the profiled library.  You may wish to disable it if you don't plan to do profiling, because it doubles the build time of compiling just the unprofiled static library.

--enable-omitfp
     Enable building a highly-optimized but possibly undebuggable static C library.  This causes the normal static and shared (if enabled) C libraries to be compiled with maximal optimization, including the -fomit-frame-pointer switch that makes debugging impossible on many machines, and without debugging information (which makes the binaries substantially smaller).  An additional static library is compiled with no optimization and full debugging information, and installed as -lc_g.

The simplest way to run configure is to do it in the directory that contains the library sources.  This prepares to build the library in that very directory.

You can prepare to build the library in some other directory by going to that other directory to run configure.  In order to run configure, you will have to specify a directory for it, like this:

     mkdir sun4
     cd sun4
     ../configure sparc-sun-sunos4.1

configure looks for the sources in whatever directory you specified for finding configure itself.  It does not matter where in the file system the source and build directories are---as long as you specify the source directory when you run configure, you will get the proper results.

This feature lets you keep sources and binaries in different directories, and that makes it easy to build the library for several different machines from the same set of sources.  Simply create a build directory for each target machine, and run configure in that directory specifying the target machine's configuration name.

The library has a number of special-purpose configuration parameters. These are defined in the file Makeconfig; see the comments in that file for the details.

But don't edit the file Makeconfig yourself---instead, create a file configparms in the directory where you are building the library, and define in that file the parameters you want to specify. configparms should not be an edited copy of Makeconfig; specify only the parameters that you want to override.  To see how to set these parameters, find the section of Makeconfig that says ``These are the configuration variables.'' Then for each parameter that you want to change, copy the definition from Makeconfig to your new configparms file, and change the value as appropriate for your system.

It is easy to configure the GNU C library for cross-compilation by setting a few variables in configparms.  Set CC to the cross-compiler for the target you configured the library for; it is important to use this same CC value when running configure, like this: CC=TARGET-gcc configure TARGET.  Set BUILD_CC to the compiler to use for for programs run on the build system as part of compiling the library.  You may need to set AR and RANLIB to cross-compiling versions of ar and ranlib if the native tools are not configured to work with object files for the target you configured for.

Some of the machine-dependent code for some machines uses extensions in the GNU C compiler, so you may need to compile the library with GCC. (In fact, all of the existing complete ports require GCC.)

To build the library and related programs, type make.  This will produce a lot of output, some of which may look like errors from make (but isn't).  Look for error messages from make containing ***.  Those indicate that something is really wrong.

To build and run some test programs which exercise some of the library facilities, type make check.  This will produce several files with names like PROGRAM.out.

To format the GNU C Library Reference Manual for printing, type make dvi.  You need a working TeX installation to do this.

To install the library and its header files, and the Info files of the manual, type make install.  This will build things if necessary, before installing them.  If you want to install the files in a different place than the one specified at configuration time you can specify a value for the Makefile variable install_root on the command line. This is useful to create chroot'ed environment or to prepare binary releases.

Recommended Tools to Install the GNU C Library
----------------------------------------------

We recommend installing the following GNU tools before attempting to build the GNU C library:

  * make 3.75

     You need the latest version of GNU make.  Modifying the GNU C Library to work with other make programs would be so hard that we recommend you port GNU make instead.  Really. We recommend version GNU make version 3.75.  Versions 3.76 and 3.76.1 are known to have bugs which only show up in big projects like GNU libc.

  * GCC 2.7.2

     On most platforms, the GNU C library can only be compiled with the GNU C compiler.  We recommend GCC version 2.7.2 or later; earlier versions may have problems.

  * binutils 2.8.1

     Using the GNU binutils (assembler, linker, and related tools) is preferable when possible, and they are required to build an ELF shared C library.  We recommend binutils version 2.8 or later; earlier versions are known to have problems or to not support all architectures.

  * texinfo 3.11

     To correctly translate and install the Texinfo documentation you need this version of the texinfo package.  Former versions did not understand all the tags used in the document and also the installation mechanisms for the info files was not present or worked differently.

     On some Debian Linux based systems the used install-info program works differently.  Here you have to run make like this:

          make INSTALL_INFO=/path/to/GNU/install-info install

Supported Configurations
------------------------

The GNU C Library currently supports configurations that match the following patterns:

     alpha-ANYTHING-linux
     iX86-ANYTHING-gnu
     iX86-ANYTHING-linux
     m68k-ANYTHING-linux

Former releases of this library (version 1.09.1 and perhaps earlier versions) used to run on the following configurations:

     alpha-dec-osf1
     iX86-ANYTHING-bsd4.3
     iX86-ANYTHING-isc2.2
     iX86-ANYTHING-isc3.N
     iX86-ANYTHING-sco3.2
     iX86-ANYTHING-sco3.2v4
     iX86-ANYTHING-sysv
     iX86-ANYTHING-sysv4
     iX86-force_cpu386-none
     iX86-sequent-bsd
     i960-nindy960-none
     m68k-hp-bsd4.3
     m68k-mvme135-none
     m68k-mvme136-none
     m68k-sony-newsos3
     m68k-sony-newsos4
     m68k-sun-sunos4.N
     mips-dec-ultrix4.N
     mips-sgi-irix4.N
     sparc-sun-solaris2.N
     sparc-sun-sunos4.N

Since no one has volunteered to test and fix the above configurations, these are not supported at the moment.  It's expected that these don't work anymore.  Porting the library is not hard.  If you are interested in doing a port, please contact the glibc maintainers by sending electronic mail to bug-glibc@prep.ai.mit.edu.

Each case of iX86 can be i386, i486, i586, or i686.  All of those configurations produce a library that can run on any of these processors.  The library will be optimized for the specified processor, but will not use instructions not available on all of them.

While no other configurations are supported, there are handy aliases for these few.  (These aliases work in other GNU software as well.)

     decstation
     hp320-bsd4.3 hp300bsd
     i486-gnu
     i586-linux
     i386-sco
     i386-sco3.2v4
     i386-sequent-dynix
     i386-svr4
     news
     sun3-sunos4.N sun3
     sun4-solaris2.N sun4-sunos5.N
     sun4-sunos4.N sun4

Reporting Bugs
==============

There are probably bugs in the GNU C library.  There are certainly errors and omissions in this manual.  If you report them, they will get fixed.  If you don't, no one will ever know about them and they will remain unfixed for all eternity, if not longer.

To report a bug, first you must find it.  Hopefully, this will be the hard part.  Once you've found a bug, make sure it's really a bug.  A good way to do this is to see if the GNU C library behaves the same way some other C library does.  If so, probably you are wrong and the libraries are right (but not necessarily).  If not, one of the libraries is probably wrong.

Once you're sure you've found a bug, try to narrow it down to the smallest test case that reproduces the problem.  In the case of a C library, you really only need to narrow it down to one library function call, if possible.  This should not be too difficult.

The final step when you have a simple test case is to report the bug. When reporting a bug, send your test case, the results you got, the results you expected, what you think the problem might be (if you've thought of anything), your system type, and the version of the GNU C library which you are using.  Also include the files config.status and config.make which are created by running configure; they will be in whatever directory was current when you ran configure.

If you think you have found some way in which the GNU C library does not conform to the ISO and POSIX standards (see Standards and Portability), that is definitely a bug.  Report it!

Send bug reports to the Internet address bug-glibc@prep.ai.mit.edu or the UUCP path mit-eddie!prep.ai.mit.edu!bug-glibc.  If you have other problems with installation or use, please report those as well.

If you are not sure how a function should behave, and this manual doesn't tell you, that's a bug in the manual.  Report that too!  If the function's behavior disagrees with the manual, then either the library or the manual has a bug, so report the disagreement.  If you find any errors or omissions in this manual, please report them to the Internet address bug-glibc-manual@prep.ai.mit.edu or the UUCP path mit-eddie!prep.ai.mit.edu!bug-glibc-manual.

Adding New Functions
====================

The process of building the library is driven by the makefiles, which make heavy use of special features of GNU make.  The makefiles are very complex, and you probably don't want to try to understand them. But what they do is fairly straightforward, and only requires that you define a few variables in the right places.

The library sources are divided into subdirectories, grouped by topic.

The string subdirectory has all the string-manipulation functions, math has all the mathematical functions, etc.

Each subdirectory contains a simple makefile, called Makefile, which defines a few make variables and then includes the global makefile Rules with a line like:

     include ../Rules

The basic variables that a subdirectory makefile defines are:

subdir
     The name of the subdirectory, for example stdio. This variable must be defined.

headers
     The names of the header files in this section of the library, such as stdio.h.

routines
aux
     The names of the modules (source files) in this section of the library. These should be simple names, such as strlen (rather than complete file names, such as strlen.c).  Use routines for modules that define functions in the library, and aux for auxiliary modules containing things like data definitions.  But the values of routines and aux are just concatenated, so there really is no practical difference.

tests
     The names of test programs for this section of the library.  These should be simple names, such as tester (rather than complete file names, such as tester.c).  make tests will build and run all the test programs.  If a test program needs input, put the test data in a file called TEST-PROGRAM.input; it will be given to the test program on its standard input.  If a test program wants to be run with arguments, put the arguments (all on a single line) in a file called TEST-PROGRAM.args.  Test programs should exit with zero status when the test passes, and nonzero status when the test indicates a bug in the library or error in building.

others
     The names of ``other'' programs associated with this section of the library.  These are programs which are not tests per se, but are other small programs included with the library.  They are built by make others.

install-lib
install-data
install
     Files to be installed by make install.  Files listed in install-lib are installed in the directory specified by libdir in configparms or Makeconfig (see Installation).  Files listed in install-data are installed in the directory specified by datadir in configparms or Makeconfig.  Files listed in install are installed in the directory specified by bindir in configparms or Makeconfig.

distribute
     Other files from this subdirectory which should be put into a distribution tar file.  You need not list here the makefile itself or the source and header files listed in the other standard variables. Only define distribute if there are files used in an unusual way that should go into the distribution.

generated
     Files which are generated by Makefile in this subdirectory. These files will be removed by make clean, and they will never go into a distribution.

extra-objs
     Extra object files which are built by Makefile in this subdirectory.  This should be a list of file names like foo.o; the files will actually be found in whatever directory object files are being built in.  These files will be removed by make clean. This variable is used for secondary object files needed to build others or tests.

Porting the GNU C Library
=========================

The GNU C library is written to be easily portable to a variety of machines and operating systems.  Machine- and operating system-dependent functions are well separated to make it easy to add implementations for new machines or operating systems.  This section describes the layout of the library source tree and explains the mechanisms used to select machine-dependent code to use.

All the machine-dependent and operating system-dependent files in the library are in the subdirectory sysdeps under the top-level library source directory.  This directory contains a hierarchy of subdirectories (see Hierarchy Conventions).

Each subdirectory of sysdeps contains source files for a particular machine or operating system, or for a class of machine or operating system (for example, systems by a particular vendor, or all machines that use IEEE 754 floating-point format).  A configuration specifies an ordered list of these subdirectories.  Each subdirectory implicitly appends its parent directory to the list.  For example, specifying the list unix/bsd/vax is equivalent to specifying the list unix/bsd/vax unix/bsd unix.  A subdirectory can also specify that it implies other subdirectories which are not directly above it in the directory hierarchy.  If the file Implies exists in a subdirectory, it lists other subdirectories of sysdeps which are appended to the list, appearing after the subdirectory containing the Implies file.  Lines in an Implies file that begin with a # character are ignored as comments.  For example, unix/bsd/Implies contains:

     # BSD has Internet-related things.
     unix/inet

and unix/Implies contains:

     posix

So the final list is unix/bsd/vax unix/bsd unix/inet unix posix.

sysdeps has two ``special'' subdirectories, called generic and stub.  These two are always implicitly appended to the list of subdirectories (in that order), so you needn't put them in an Implies file, and you should not create any subdirectories under them intended to be new specific categories.  generic is for things that can be implemented in machine-independent C, using only other machine-independent functions in the C library.  stub is for stub versions of functions which cannot be implemented on a particular machine or operating system.  The stub functions always return an error, and set errno to ENOSYS (Function not implemented).  See Error Reporting.

A source file is known to be system-dependent by its having a version in generic or stub; every generally-available function whose implementation is system-dependent in should have either a generic or stub implementation (there is no point in having both).  Some rare functions are only useful on specific systems and aren't defined at all on others; these do not appear anywhere in the system-independent source code or makefiles (including the generic and stub directories), only in the system-dependent Makefile in the specific system's subdirectory.

If you come across a file that is in one of the main source directories (string, stdio, etc.), and you want to write a machine- or operating system-dependent version of it, move the file into sysdeps/generic and write your new implementation in the appropriate system-specific subdirectory.  Note that if a file is to be system-dependent, it must not appear in one of the main source directories.

There are a few special files that may exist in each subdirectory of sysdeps:

Makefile

     A makefile for this machine or operating system, or class of machine or operating system.  This file is included by the library makefile Makerules, which is used by the top-level makefile and the subdirectory makefiles.  It can change the variables set in the including makefile or add new rules.  It can use GNU make conditional directives based on the variable subdir (see above) to select different sets of variables and rules for different sections of the library.  It can also set the make variable sysdep-routines, to specify extra modules to be included in the library.  You should use sysdep-routines rather than adding modules to routines because the latter is used in determining what to distribute for each subdirectory of the main source tree.

     Each makefile in a subdirectory in the ordered list of subdirectories to be searched is included in order.  Since several system-dependent makefiles may be included, each should append to sysdep-routines rather than simply setting it:

          sysdep-routines := $(sysdep-routines) foo bar

Subdirs

     This file contains the names of new whole subdirectories under the top-level library source tree that should be included for this system. These subdirectories are treated just like the system-independent subdirectories in the library source tree, such as stdio and math.

     Use this when there are completely new sets of functions and header files that should go into the library for the system this subdirectory of sysdeps implements.  For example, sysdeps/unix/inet/Subdirs contains inet; the inet directory contains various network-oriented operations which only make sense to put in the library on systems that support the Internet.

Dist

     This file contains the names of files (relative to the subdirectory of sysdeps in which it appears) which should be included in the distribution.  List any new files used by rules in the Makefile in the same directory, or header files used by the source files in that directory.  You don't need to list files that are implementations (either C or assembly source) of routines whose names are given in the machine-independent makefiles in the main source tree.

configure

     This file is a shell script fragment to be run at configuration time. The top-level configure script uses the shell . command to read the configure file in each system-dependent directory chosen, in order.  The configure files are often generated from configure.in files using Autoconf.

     A system-dependent configure script will usually add things to the shell variables DEFS and config_vars; see the top-level configure script for details.  The script can check for --with-PACKAGE options that were passed to the top-level configure.  For an option --with-PACKAGE=VALUE configure sets the shell variable with_PACKAGE (with any dashes in PACKAGE converted to underscores) to VALUE; if the option is just --with-PACKAGE (no argument), then it sets with_PACKAGE to yes.

configure.in

     This file is an Autoconf input fragment to be processed into the file configure in this subdirectory.  See Introduction (Autoconf: Generating Automatic Configuration Scripts), for a description of Autoconf.  You should write either configure or configure.in, but not both.  The first line of configure.in should invoke the m4 macro GLIBC_PROVIDES.  This macro does several AC_PROVIDE calls for Autoconf macros which are used by the top-level configure script; without this, those macros might be invoked again unnecessarily by Autoconf.

That is the general system for how system-dependencies are isolated.

Layout of the sysdeps Directory Hierarchy
-----------------------------------------

A GNU configuration name has three parts: the CPU type, the manufacturer's name, and the operating system.  configure uses these to pick the list of system-dependent directories to look for.  If the --nfp option is not passed to configure, the directory MACHINE/fpu is also used.  The operating system often has a base operating system; for example, if the operating system is sunos4.1, the base operating system is unix/bsd. The algorithm used to pick the list of directories is simple: configure makes a list of the base operating system, manufacturer, CPU type, and operating system, in that order.  It then concatenates all these together with slashes in between, to produce a directory name; for example, the configuration sparc-sun-sunos4.1 results in unix/bsd/sun/sparc/sunos4.1.  configure then tries removing each element of the list in turn, so unix/bsd/sparc and sun/sparc are also tried, among others. Since the precise version number of the operating system is often not important, and it would be very inconvenient, for example, to have identical sunos4.1.1 and sunos4.1.2 directories, configure tries successively less specific operating system names by removing trailing suffixes starting with a period.

As an example, here is the complete list of directories that would be tried for the configuration sparc-sun-sunos4.1 (without the --nfp option):

     sparc/fpu
     unix/bsd/sun/sunos4.1/sparc
     unix/bsd/sun/sunos4.1
     unix/bsd/sun/sunos4/sparc
     unix/bsd/sun/sunos4
     unix/bsd/sun/sunos/sparc
     unix/bsd/sun/sunos
     unix/bsd/sun/sparc
     unix/bsd/sun
     unix/bsd/sunos4.1/sparc
     unix/bsd/sunos4.1
     unix/bsd/sunos4/sparc
     unix/bsd/sunos4
     unix/bsd/sunos/sparc
     unix/bsd/sunos
     unix/bsd/sparc
     unix/bsd
     unix/sun/sunos4.1/sparc
     unix/sun/sunos4.1
     unix/sun/sunos4/sparc
     unix/sun/sunos4
     unix/sun/sunos/sparc
     unix/sun/sunos
     unix/sun/sparc
     unix/sun
     unix/sunos4.1/sparc
     unix/sunos4.1
     unix/sunos4/sparc
     unix/sunos4
     unix/sunos/sparc
     unix/sunos
     unix/sparc
     unix
     sun/sunos4.1/sparc
     sun/sunos4.1
     sun/sunos4/sparc
     sun/sunos4
     sun/sunos/sparc
     sun/sunos
     sun/sparc
     sun
     sunos4.1/sparc
     sunos4.1
     sunos4/sparc
     sunos4
     sunos/sparc
     sunos
     sparc

Different machine architectures are conventionally subdirectories at the top level of the sysdeps directory tree.  For example, sysdeps/sparc and sysdeps/m68k.  These contain files specific to those machine architectures, but not specific to any particular operating system.  There might be subdirectories for specializations of those architectures, such as sysdeps/m68k/68020. Code which is specific to the floating-point coprocessor used with a particular machine should go in sysdeps/MACHINE/fpu.

There are a few directories at the top level of the sysdeps hierarchy that are not for particular machine architectures.

generic
stub
     As described above (see Porting), these are the two subdirectories that every configuration implicitly uses after all others.

ieee754
     This directory is for code using the IEEE 754 floating-point format, where the C type float is IEEE 754 single-precision format, and double is IEEE 754 double-precision format.  Usually this directory is referred to in the Implies file in a machine architecture-specific directory, such as m68k/Implies.

posix
     This directory contains implementations of things in the library in terms of POSIX.1 functions.  This includes some of the POSIX.1 functions themselves.  Of course, POSIX.1 cannot be completely implemented in terms of itself, so a configuration using just posix cannot be complete.

unix
     This is the directory for Unix-like things.  See Porting to Unix. unix implies posix.  There are some special-purpose subdirectories of unix:

     unix/common
          This directory is for things common to both BSD and System V release 4. Both unix/bsd and unix/sysv/sysv4 imply unix/common.

     unix/inet
          This directory is for socket and related functions on Unix systems. The inet top-level subdirectory is enabled by unix/inet/Subdirs. unix/common implies unix/inet.

mach
     This is the directory for things based on the Mach microkernel from CMU (including the GNU operating system).  Other basic operating systems (VMS, for example) would have their own directories at the top level of the sysdeps hierarchy, parallel to unix and mach.

Porting the GNU C Library to Unix Systems
-----------------------------------------

Most Unix systems are fundamentally very similar.  There are variations between different machines, and variations in what facilities are provided by the kernel.  But the interface to the operating system facilities is, for the most part, pretty uniform and simple.

The code for Unix systems is in the directory unix, at the top level of the sysdeps hierarchy.  This directory contains subdirectories (and subdirectory trees) for various Unix variants.

The functions which are system calls in most Unix systems are implemented in assembly code in files in sysdeps/unix.  These files are named with a suffix of .S; for example, __open.S.  Files ending in .S are run through the C preprocessor before being fed to the assembler.

These files all use a set of macros that should be defined in sysdep.h.  The sysdep.h file in sysdeps/unix partially defines them; a sysdep.h file in another directory must finish defining them for the particular machine and operating system variant.  See sysdeps/unix/sysdep.h and the machine-specific sysdep.h implementations to see what these macros are and what they should do.

The system-specific makefile for the unix directory (that is, the file sysdeps/unix/Makefile) gives rules to generate several files from the Unix system you are building the library on (which is assumed to be the target system you are building the library for).  All the generated files are put in the directory where the object files are kept; they should not affect the source tree itself.  The files generated are ioctls.h, errnos.h, sys/param.h, and errlist.c (for the stdio section of the library).

Contributors to the GNU C Library
=================================

The GNU C library was written originally by Roland McGrath.  Some parts of the library were contributed or worked on by other people.

  * The getopt function and related code were written by Richard Stallman, David J. MacKenzie, and Roland McGrath.

  * The merge sort function qsort was written by Michael J. Haertel.

  * The quick sort function used as a fallback by qsort was written by Douglas C. Schmidt.

  * The memory allocation functions malloc, realloc and free and related code were written by Michael J. Haertel.

  * Fast implementations of many of the string functions (memcpy, strlen, etc.) were written by Torbjorn Granlund.

  * The tar.h header file was written by David J. MacKenzie.

  * The port to the MIPS DECStation running Ultrix 4 (mips-dec-ultrix4) was contributed by Brendan Kehoe and Ian Lance Taylor.

  * The DES encryption function crypt and related functions were contributed by Michael Glad.

  * The ftw function was contributed by Ian Lance Taylor.

  * The startup code to support SunOS shared libraries was contributed by Tom Quinn.

  * The mktime function was contributed by Paul Eggert.

  * The port to the Sequent Symmetry running Dynix version 3 (i386-sequent-bsd) was contributed by Jason Merrill.

  * The timezone support code is derived from the public-domain timezone package by Arthur David Olson and his many contributors.

  * The port to the DEC Alpha running OSF/1 (alpha-dec-osf1) was contributed by Brendan Kehoe, using some code written by Roland McGrath.

  * The port to SGI machines running Irix 4 (mips-sgi-irix4) was contributed by Tom Quinn.

  * The port of the Mach and Hurd code to the MIPS architecture (mips-ANYTHING-gnu) was contributed by Kazumoto Kojima.

  * The floating-point printing function used by printf and friends and the floating-point reading function used by scanf, strtod and friends were written by Ulrich Drepper.  The multi-precision integer functions used in those functions are taken from GNU MP, which was contributed by Torbjorn Granlund.

  * The internationalization support in the library, and the support programs locale and localedef, were written by Ulrich Drepper.  Ulrich Drepper adapted the support code for message catalogs (libintl.h, etc.) from the GNU gettext package, which he also wrote.  He also contributed the catgets support and the entire suite of multi-byte and wide-character support functions (wctype.h, wchar.h, etc.).

  * The implementations of the nsswitch.conf mechanism and the files and DNS backends for it were designed and written by Ulrich Drepper and Roland McGrath, based on a backend interface defined by Peter Eriksson.

  * The port to Linux i386/ELF (i386-ANYTHING-linux) was contributed by Ulrich Drepper, based in large part on work done in Hongjiu Lu's Linux version of the GNU C Library.

  * The port to Linux/m68k (m68k-ANYTHING-linux) was contributed by Andreas Schwab.

  * Richard Henderson contributed the ELF dynamic linking code and other support for the Alpha processor.

  * David Mosberger-Tang contributed the port to Linux/Alpha (alpha-ANYTHING-linux).

  * Stephen R. van den Berg contributed a highly-optimized strstr function.

  * Ulrich Drepper contributed the hsearch and drand48 families of functions; reentrant ..._r versions of the random family; System V shared memory and IPC support code; and several highly-optimized string functions for iX86 processors.

  * The math functions are taken from fdlibm-5.1 by Sun Microsystems, as modified by J.T. Conklin, Ian Lance Taylor, Ulrich Drepper, Andreas Schwab, and Roland McGrath.

  * The libio library used to implement stdio functions on some platforms was written by Per Bothner and modified by Ulrich Drepper.

  * The Internet-related code (most of the inet subdirectory) and several other miscellaneous functions and header files have been included from 4.4 BSD with little or no modification.

     All code incorporated from 4.4 BSD is under the following copyright:

               Copyright © 1991 Regents of the University of California.
               All rights reserved.

          Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

           1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

           2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

           3. All advertising materials mentioning features or use of this software must display the following acknowledgement:

                    This product includes software developed by the University of California, Berkeley and its contributors.

           4. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

          THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

  * The random number generation functions random, srandom, setstate and initstate, which are also the basis for the rand and srand functions, were written by Earl T. Cohen for the University of California at Berkeley and are copyrighted by the Regents of the University of California.  They have undergone minor changes to fit into the GNU C library and to fit the ISO C standard, but the functional code is Berkeley's.

  * The Internet resolver code is taken directly from BIND 4.9.5, which is under both the Berkeley copyright above and also:

          Portions Copyright © 1993 by Digital Equipment Corporation.

          Permission to use, copy, modify, and distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies, and that the name of Digital Equipment Corporation not be used in advertising or publicity pertaining to distribution of the document or software without specific, written prior permission.

          THE SOFTWARE IS PROVIDED ``AS IS'' AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL DIGITAL EQUIPMENT CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

  * The code to support Sun RPC is taken verbatim from Sun's RPCSRC-4.0 distribution, and is covered by this copyright:

               Copyright © 1984, Sun Microsystems, Inc.

          Sun RPC is a product of Sun Microsystems, Inc. and is provided for unrestricted use provided that this legend is included on all tape media and as a part of the software program in whole or part.  Users may copy or modify Sun RPC without charge, but are not authorized to license or distribute it to anyone else except as part of a product or program developed by the user.

          SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.

          Sun RPC is provided with no support and without any obligation on the part of Sun Microsystems, Inc. to assist in its use, correction, modification or enhancement.

          SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC OR ANY PART THEREOF.

          In no event will Sun Microsystems, Inc. be liable for any lost revenue or profits or other special, indirect and consequential damages, even if Sun has been advised of the possibility of such damages.

               Sun Microsystems, Inc.
               2550 Garcia Avenue
               Mountain View, California  94043

  * Some of the support code for Mach is taken from Mach 3.0 by CMU, and is under the following copyright terms:

               Mach Operating System
               Copyright © 1991,1990,1989 Carnegie Mellon University
               All Rights Reserved.

          Permission to use, copy, modify and distribute this software and its documentation is hereby granted, provided that both the copyright notice and this permission notice appear in all copies of the software, derivative works or modified versions, and any portions thereof, and that both notices appear in supporting documentation.

          CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS ``AS IS'' CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.

          Carnegie Mellon requests users of this software to return to

                Software Distribution Coordinator
                School of Computer Science
                Carnegie Mellon University
                Pittsburgh PA 15213-3890

          or Software.Distribution@CS.CMU.EDU any improvements or extensions that they make and grant Carnegie Mellon the rights to redistribute these changes.