Installation of the GNU C library is relatively simple, but usually requires several GNU tools to be installed already. (see section Recommended Tools to Install the GNU C Library, below.)
To configure the GNU C library for your system, run the shell script
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 section `Installing GNU CC' in 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
ldto 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
ldyou must use GNU
ldevery time you link with the GNU C Library, and when building it.
gas, when building the GNU C Library. On some systems, the library may not build properly if you do not use
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
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
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
RANLIB to cross-compiling versions
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
containing `***'. Those indicate that something is really wrong.
To build and run some test programs which exercise some of the library
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
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
We recommend installing the following GNU tools before attempting to build the GNU C library:
make3.75 You need the latest version of GNU
make. Modifying the GNU C Library to work with other
makeprograms would be so hard that we recommend you port GNU
makeinstead. Really. We recommend version GNU
makeversion 3.75. Versions 3.76 and 3.76.1 are known to have bugs which only show up in big projects like GNU
binutils2.8.1 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
binutilsversion 2.8 or later; earlier versions are known to have problems or to not support all architectures.
texinfo3.11 To correctly translate and install the Texinfo documentation you need this version of the
texinfopackage. 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-infoprogram works differently. Here you have to run make like this:
make INSTALL_INFO=/path/to/GNU/install-info install
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 firstname.lastname@example.org.
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
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 section Standards and Portability), that is definitely a bug. Report it!
Send bug reports to the Internet address email@example.com 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 firstname.lastname@example.org or the UUCP path mit-eddie!prep.ai.mit.edu!bug-glibc-manual.
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:
The basic variables that a subdirectory makefile defines are:
routinesfor modules that define functions in the library, and
auxfor auxiliary modules containing things like data definitions. But the values of
auxare just concatenated, so there really is no practical difference.
install-dataare installed in the directory specified by `datadir' in `configparms' or `Makeconfig'. Files listed in
installare installed in the directory specified by `bindir' in `configparms' or `Makeconfig'.
distributeif there are files used in an unusual way that should go into the distribution.
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 section Layout of the `sysdeps' Directory Hierarchy).
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:
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
ENOSYS (Function not
implemented). See section 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':
makeconditional 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
makevariable `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
.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'.
m4macro `GLIBC_PROVIDES'. This macro does several
AC_PROVIDEcalls 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. The next section explains how to decide what directories in `sysdeps' to use. section Porting the GNU C Library to Unix Systems, has some tips on porting the library to Unix variants.
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.
floatis IEEE 754 single-precision format, and
doubleis 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'.
socketand related functions on Unix systems. The `inet' top-level subdirectory is enabled by `unix/inet/Subdirs'. `unix/common' implies `unix/inet'.
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).
The GNU C library was written originally by Roland McGrath. Some parts of the library were contributed or worked on by other people.
getoptfunction and related code were written by Richard Stallman, David J. MacKenzie, and Roland McGrath.
qsortwas written by Michael J. Haertel.
qsortwas written by Douglas C. Schmidt.
freeand related code were written by Michael J. Haertel.
strlen, etc.) were written by .
mips-dec-ultrix4) was contributed by Brendan Kehoe and Ian Lance Taylor.
cryptand related functions were contributed by Michael Glad.
ftwfunction was contributed by Ian Lance Taylor.
mktimefunction was contributed by Paul Eggert.
i386-sequent-bsd) was contributed by Jason Merrill.
alpha-dec-osf1) was contributed by Brendan Kehoe, using some code written by Roland McGrath.
mips-sgi-irix4) was contributed by Tom Quinn.
mips-anything-gnu) was contributed by Kazumoto Kojima.
printfand friends and the floating-point reading function used by
strtodand friends were written by Ulrich Drepper. The multi-precision integer functions used in those functions are taken from GNU MP, which was contributed by .
localedef, were written by Ulrich Drepper. Ulrich Drepper adapted the support code for message catalogs (`libintl.h', etc.) from the GNU
gettextpackage, which he also wrote. He also contributed the
catgetssupport and the entire suite of multi-byte and wide-character support functions (`wctype.h', `wchar.h', etc.).
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.
m68k-anything-linux) was contributed by Andreas Schwab.
drand48families of functions; reentrant `...
_r' versions of the
randomfamily; System V shared memory and IPC support code; and several highly-optimized string functions for ix86 processors.
fdlibm-5.1by Sun Microsystems, as modified by J.T. Conklin, Ian Lance Taylor, Ulrich Drepper, Andreas Schwab, and Roland McGrath.
libiolibrary used to implement
stdiofunctions on some platforms was written by Per Bothner and modified by Ulrich Drepper.
Copyright (C) 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:
- Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
- 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.
- 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.
- 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.
initstate, which are also the basis for the
srandfunctions, 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.
Portions Copyright (C) 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.
Copyright (C) 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
Mach Operating System Copyright (C) 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 toSoftware 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.
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