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Installation of the GNU C library is relatively simple.
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.
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 section 'Installing GNU CC' in Using and Porting GNU CC, for a full description of standard GNU configuration
names.
The GNU C Library currently supports configurations that match the following patterns:
sparc-sun-sunos4.n m68k-hp-bsd4.3 m68k-sun-sunos4.n m68k-sony-bsd4.3 mips-dec-ultrix4.n i386-bsd4.3 i386-sysv i386-sysv4
While no other configurations are supported, there are handy aliases for these few. (These aliases work in other GNU software as well.)
sun4-sunos4.n hp320-bsd4.3 sun3-sunos4.n news decstation-ultrix i386-svr4
Here are some options that you should specify (if appropriate) when
you run configure:
ld to link programs with
the GNU C Library. (We strongly recommend that you do.)
gas, when
building the GNU C Library. On some systems, the library may not build
properly if you do not use gas.
Use this option if your computer lacks hardware floating point support.
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 ../hp320 cd ../hp320 ../src/configure hp320-bsd4.3
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.
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.)
The current release of the C library contains some header files that the compiler normally provides: `stddef.h', `stdarg.h', and several files with names of the form `va-machine.h'. The versions of these files that came with older releases of GCC do not work properly with the GNU C library. The `stddef.h' file in release 2.2 and later of GCC is correct. If you have release 2.2 or later of GCC, use its version of `stddef.h' instead of the C library's. To do this, put the line `override stddef.h =' in `configparms'. The other files are corrected in release 2.3 and later of GCC. `configure' will automatically detect whether the installed `stdarg.h' and `va-machine.h' files are compatible with the C library, and use its own if not.
There is a potential problem with the size_t type and versions of
GCC prior to release 2.4. ANSI C requires that size_t always be
an unsigned type. For compatibility with existing systems' header
files, GCC defines size_t in `stddef.h' to be whatever type
the system's `sys/types.h' defines it to be. Most Unix systems
that define size_t in `sys/types.h', define it to be a
signed type. Some code in the library depends on size_t being an
unsigned type, and will not work correctly if it is signed.
The GNU C library code which expects size_t to be unsigned is
correct. The definition of size_t as a signed type is incorrect.
We plan that in version 2.4, GCC will always define size_t as an
unsigned type, and the `fixincludes' script will massage the
system's `sys/types.h' so as not to conflict with this.
In the meantime, we work around this problem by telling GCC explicitly
to use an unsigned type for size_t when compiling the GNU C
library. `configure' will automatically detect what type GCC uses
for size_t arrange to override it if necessary.
To build the library, type make lib. This will produce a lot of
output, some of which looks like errors from make (but isn't).
Look for error messages from make containing `***'. Those
indicate that something is really wrong. Using the `-w' option to
make may make the output easier to understand (this option tells
make to print messages telling you what subdirectories it is
working on).
To install the library and header files, type make install, after
setting the installation directories in `configparms'. This will
build things if necessary, before installing them.
There are probably bugs in the GNU C library. 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.
If you think you have found some way in which the GNU C library does not conform to the ANSI and POSIX standards (see section 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, use, or the documentation, please report those as well.
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, `stdio' has all the standard I/O 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
headers
routines
aux
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
others
install-lib
install-data
install
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 `Makeconfig'.
distribute
distribute if there are files used in an unusual way
that should go into the distribution.
generated
extra-objs
others or tests.
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 The 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/inetand `unix/Implies' contains:
posix
So the final list is `unix/bsd/vax unix/bsd vax 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. `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 section Error Reporting.
A source file is known to be system-dependent by its having a version in `generic' or `stub'; every system-dependent function should have either a generic or stub implementation (there is no point in having both).
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':
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
Use this when there are whole new sets of routines 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.
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.
Here is the complete list of directories that would be tried for the configuration `sparc-sun-sunos4.1':
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/sparc unix/bsd/sun unix/bsd/sunos4.1/sparc unix/bsd/sunos4.1 unix/bsd/sunos4/sparc unix/bsd/sunos4 unix/bsd/sparc unix/bsd sun/sunos4.1/sparc sun/sunos4.1 sun/sunos4/sparc sun/sunos4 sun/sparc sun sunos4.1/sparc sunos4.1 sunos4/sparc sunos4 sparc
Different machine architectures are generally 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.
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'.
socket and 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, `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 almost entirely by Roland McGrath. Some parts of the library were contributed by other people.
getopt function and related code were written by
Richard Stallman, David J. MacKenzie, and Roland McGrath.
All code incorporated from 4.4 BSD is under the following copyright:
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.
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 ANSI C standard,
but the functional code is Berkeley's.
qsort was written by Michael J. Haertel.
qsort was written
by Douglas C. Schmidt.
malloc, realloc and
free and related code were written by Michael J. Haertel.
memcpy,
strlen, etc.) were written by
Granlund.
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 to
Software Distribution Coordinator School of Computer Science Carnegie Mellon University Pittsburgh PA 15213-3890or `Software.Distribution@CS.CMU.EDU' any improvements or extensions that they make and grant Carnegie Mellon the rights to redistribute these changes.
mips-dec-ultrix4)
was contributed by Brendan Kehoe and Ian Lance Taylor.
crypt and related functions were
contributed by Michael Glad.
ftw function was contributed by Ian Lance Taylor.
mktime function was contributed by Noel Cragg.
i386-sequent-bsd) was contributed by Jason Merrill.
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