(i[34]86sol2): New abbrev for i[34]86-unknown-solaris2.

[kopensolaris-gnu/glibc.git] / manual / maint.texi

@c \input /gd/gnu/doc/texinfo
@c This is for making the `INSTALL' file for the distribution.
@c Makeinfo ignores it when processing the file from the include.
@setfilename INSTALL

@node Maintenance, Copying, Library Summary, Top
@appendix Library Maintenance

@menu
* Installation::          How to configure, compile and
                             install the GNU C library.
* Reporting Bugs::        How to report bugs (if you want to
                             get them fixed) and other troubles
                             you may have with the GNU C library.
* Source Layout::         How to add new functions or header files
                             to the GNU C library.
* Porting::               How to port the GNU C library to
                             a new machine or operating system.
* Contributors::          Contributors to the GNU C Library.
@end menu

@node Installation
@appendixsec How to Install the GNU C Library
@cindex installing the library

Installation of the GNU C library is relatively simple.

You need the latest version of GNU @code{make}.  Modifying the GNU C
Library to work with other @code{make} programs would be so hard that we
recommend you port GNU @code{make} instead.  @strong{Really.}@refill

To configure the GNU C library for your system, run the shell script
@file{configure} with @code{sh}.  Use an argument which is the
conventional GNU name for your system configuration---for example,
@samp{sparc-sun-sunos4.1}, for a Sun 4 running Sunos 4.1.
@xref{Installation, Installation, Installing GNU CC, gcc.info, 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:

@example
sparc-sun-sunos4.@var{n}
m68k-hp-bsd4.3
m68k-sun-sunos4.@var{n}
m68k-sony-bsd4.3
mips-dec-ultrix4.@var{n}
i386-bsd4.3
i386-sysv
i386-sysv4
@end example

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

@example
sun4-sunos4.@var{n}
hp320-bsd4.3
sun3-sunos4.@var{n}
news
decstation-ultrix
i386-svr4
@end example

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

@table @samp
@item --with-gnu-ld
Use this option if you plan to use GNU @code{ld} to link programs with
the GNU C Library.  (We strongly recommend that you do.)

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

@c extra blank line makes it look better
@item --nfp

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

@item --prefix=@var{directory}
Install machine-independent data files in subdirectories of
@file{@var{directory}}.  (You can also set this in @file{configparms};
see below.)

@item --exec_prefix=@var{directory}
Install the library and other machine-dependent files in subdirectories
of @file{@var{directory}}.  (You can also set this in
@file{configparms}; see below.)
@end table

The simplest way to run @code{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 @code{configure}.  In order to run
configure, you will have to specify a directory for it, like this:

@example
mkdir ../hp320
cd ../hp320
../src/configure hp320-bsd4.3
@end example

@noindent
@code{configure} looks for the sources in whatever directory you
specified for finding @code{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 @code{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 @code{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 @file{Makeconfig}; see the comments in
that file for the details.

But don't edit the file @file{Makeconfig} yourself---instead, create a
file @file{configparms} in the directory where you are building the
library, and define in that file the parameters you want to specify.
@file{configparms} should @strong{not} be an edited copy of
@file{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: @file{stddef.h}, @file{stdarg.h}, and
several files with names of the form @file{va-@var{machine}.h}.  The
versions of these files that came with older releases of GCC do not work
properly with the GNU C library.  The @file{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 @file{stddef.h} instead of the C library's.  To
do this, put the line @w{@samp{override stddef.h =}} in
@file{configparms}.  The other files are corrected in release 2.3 and
later of GCC.  If you release 2.3 or later of GCC, use its
@file{stdarg.h} and @file{va-@var{machine}.h} files instead of the C
library's.  To do this, put the line @w{@samp{override stdarg.h =}} in
@file{configparms}.

There is a potential problem with the @code{size_t} type and versions of
GCC prior to release 2.4.  ANSI C requires that @code{size_t} always be
an unsigned type.  For compatibility with existing systems' header
files, GCC defines @code{size_t} in @file{stddef.h} to be whatever type
the system's @file{sys/types.h} defines it to be.  Most Unix systems
that define @code{size_t} in @file{sys/types.h}, define it to be a
signed type.  Some code in the library depends on @code{size_t} being an
unsigned type, and will not work correctly if it is signed.

The GNU C library code which expects @code{size_t} to be unsigned is
correct.  The definition of @code{size_t} as a signed type is incorrect.
We plan that in version 2.4, GCC will always define @code{size_t} as an
unsigned type, and the @file{fixincludes} script will massage the
system's @file{sys/types.h} so as not to conflict with this.

In the meantime, the way to work around this problem is to tell GCC
explicitly to use an unsigned type for @code{size_t} when you compile
the GNU C library.  You can do this by compiling with
@samp{-D__SIZE_TYPE__='unsigned long int'}.  You can either put this
into the GCC @file{specs} file to affect all compilations using GCC, or
specify the flag just to compile the C library, with this line in
@file{configparms}:

@example
# Be sure to remember the 's to quote the spaces from the shell.
defines := -D__SIZE_TYPE__='unsigned long int'
@end example

@noindent
When you do this, the current version of GCC
will give you the annoying warning:

@example
*Initialization*:1: warning: `__SIZE_TYPE__' redefined
@end example

@noindent
It is safe to ignore this warning.  Version 2.3 of GCC is supposed to
fix this bug (the spurious warning---the type of @code{size_t} will not
be fixed until 2.4).

To build the library, type @code{make lib}.  This will produce a lot of
output, some of which looks like errors from @code{make} (but isn't).
Look for error messages from @code{make} containing @samp{***}.  Those
indicate that something is really wrong.  Using the @samp{-w} option to
@code{make} may make the output easier to understand (this option tells
@code{make} to print messages telling you what subdirectories it is
working on).@refill

To install the library and header files, type @code{make install}, after
setting the installation directories in @file{configparms}.  This will
build things if necessary, before installing them.@refill

@node Reporting Bugs
@appendixsec Reporting Bugs
@cindex reporting bugs

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.

@ignore @c this makes no sense for `INSTALL' before the manual is out. --rm
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.
@end ignore

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

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

@node Source Layout
@appendixsec Adding New Functions

The process of building the library is driven by the makefiles, which
make heavy use of special features of GNU @code{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 @file{string} subdirectory has all the string-manipulation
functions, @file{stdio} has all the standard I/O functions, etc.

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

@example
include ../Rules
@end example

@noindent
The basic variables that a subdirectory makefile defines are:

@table @code
@item subdir
The name of the subdirectory, for example @file{stdio}.
This variable @strong{must} be defined.

@item headers
The names of the header files in this section of the library,
such as @file{stdio.h}.

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

@item tests
The names of test programs for this section of the library.  These
should be simple names, such as @samp{tester} (rather than complete file
names, such as @file{tester.c}).  @w{@samp{make tests}} will build and
run all the test programs.  If a test program needs input, put the test
data in a file called @file{@var{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 @file{@var{test-program}.args}.@refill

@item 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
@w{@samp{make others}}.@refill

@item install-lib
@itemx install-data
@itemx install
Files to be installed by @w{@samp{make install}}.  Things listed in
@samp{install-lib} are installed in the directory specified by
@samp{libdir} in @file{Makeconfig} (@pxref{Installation}).  Files listed
in @code{install-data} are installed in the directory specified by
@samp{datadir} in @file{configparms} or @file{Makeconfig}.  Files listed
in @code{install} are installed in the directory specified by
@samp{bindir} in @file{Makeconfig}.@refill

@item 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 @code{distribute} if there are files used in an unusual way
that should go into the distribution.
@end table

@node Porting
@appendixsec 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 @file{sysdeps} under the top-level
library source directory.  This directory contains a hierarchy of
subdirectories (@pxref{Hierarchy Conventions}).

Each subdirectory of @file{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 @file{unix/bsd/vax} is equivalent to specifying the
list @file{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 @file{Implies} exists in a
subdirectory, it lists other subdirectories of @file{sysdeps} which are
appended to the list, appearing after the subdirectory containing the
@file{Implies} file.  Lines in an @file{Implies} file that begin with a
@samp{#} character are ignored as comments.  For example,
@file{unix/bsd/Implies} contains:@refill
@example
# BSD has Internet-related things.
unix/inet
@end example
@noindent
and @file{unix/Implies} contains:
@example
posix
@end example

@noindent
So the final list is @file{unix/bsd/vax unix/bsd vax unix/inet unix posix}.

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

A source file is known to be system-dependent by its having a version in
@file{generic} or @file{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
(@file{string}, @file{stdio}, etc.), and you want to write a machine- or
operating system-dependent version of it, move the file into
@file{sysdeps/generic} and write your new implementation in the
appropriate system-specific subdirectory.  Note that if a file is to be
system-dependent, it @strong{must not} appear in one of the main source
directories.@refill

There are a few special files that may exist in each subdirectory of
@file{sysdeps}:

@table @file
@item Makefile
A makefile for this machine or operating system, or class of machine or
operating system.  This file is included by the library makefile
@file{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 @code{make}
conditional directives based on the variable @samp{subdir} (see above) to
select different sets of variables and rules for different sections of
the library.  It can also set the @code{make} variable
@samp{sysdep-routines}, to specify extra modules to be included in the
library.  You should use @samp{sysdep-routines} rather than adding
modules to @samp{routines} because the latter is used in determining
what to distribute for each subdirectory of the main source tree.@refill

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 @samp{sysdep-routines}
rather than simply setting it:

@example
sysdep-routines := $(sysdep-routines) foo bar
@end example

@item 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 @file{stdio} and
@file{math}.

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
@file{sysdeps} implements.  For example,
@file{sysdeps/unix/inet/Subdirs} contains @file{inet}; the @file{inet}
directory contains various network-oriented operations which only make
sense to put in the library on systems that support the Internet.@refill

@item Dist
This file contains the names of files (relative the the subdirectory of
@file{sysdeps} in which it appears) which should be included in the
distribution.  List any new files used by rules in the @file{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.
@end table

That is the general system for how system-dependencies are isolated.
@iftex
The next section explains how to decide what directories in
@file{sysdeps} to use.  @ref{Porting to Unix}, has some tips on porting
the library to Unix variants.
@end iftex

@menu
* Hierarchy Conventions::       The layout of the @file{sysdeps} hierarchy.
* Porting to Unix::             Porting the library to an average
                                   Unix-like system.
@end menu

@node Hierarchy Conventions
@appendixsubsec The Layout of the @file{sysdeps} Directory Hierarchy

A GNU configuration name has three parts: the CPU type, the
manufacturer's name, and the operating system.  @file{configure} uses
these to pick the list of system-dependent directories to look for.  If
the @samp{--nfp} option is @emph{not} passed to @file{configure}, the
directory @file{@var{machine}/fpu} is also used.  The operating system
often has a @dfn{base operating system}; for example, if the operating
system is @samp{sunos4.1}, the base operating system is @samp{unix/bsd}.
The algorithm used to pick the list of directories is simple:
@file{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 @w{@samp{sparc-sun-sunos4.1}}
results in @file{unix/bsd/sun/sparc/sunos4.1}.  @file{configure} then
tries removing each element of the list in turn, so
@file{unix/bsd/sparc} and @file{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 @file{sunos4.1.1} and @file{sunos4.1.2} directories,
@file{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 @samp{sparc-sun-sunos4.1}:

@example
@group
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
@end group
@end example

Different machine architectures are generally at the top level of the
@file{sysdeps} directory tree.  For example, @w{@file{sysdeps/sparc}}
and @w{@file{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 @w{@file{sysdeps/m68k/68020}}. Code which is
specific to the floating-point coprocessor used with a particular
machine should go in @w{@file{sysdeps/@var{machine}/fpu}}.

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

@table @file
@item generic
@itemx stub
As described above (@pxref{Porting}), these are the two subdirectories
that every configuration implicitly uses after all others.

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

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

@item unix
This is the directory for Unix-like things.  See @xref{Porting to Unix}.
@file{unix} implies @file{posix}.

@item 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 @file{sysdeps} hierarchy, parallel to @file{unix} and @file{mach}.
@end table

@node Porting to Unix
@appendixsubsec 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 @file{unix}, at the top
level of the @file{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 @file{sysdeps/unix}.  These
files are named with a suffix of @samp{.S}; for example,
@file{__open.S}.  Files ending in @samp{.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
@file{sysdep.h}.  The @file{sysdep.h} file in @file{sysdeps/unix}
partially defines them; a @file{sysdep.h} file in another directory must
finish defining them for the particular machine and operating system
variant.  See @file{sysdeps/unix/sysdep.h} and the machine-specific
@file{sysdep.h} implementations to see what these macros are and what
they should do.@refill

The system-specific makefile for the @file{unix} directory,
@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 @emph{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 @file{ioctls.h}, @file{errnos.h}, @file{sys/param.h}, and
@file{errlist.c} (for the @file{stdio} section of the library).

@ignore
@c This section might be a good idea if it is finished,
@c but there's no point including it as it stands. --rms
@c @appendixsec Compatibility with Traditional C

@c ??? This section is really short now.  Want to keep it? --roland

Although the GNU C library implements the ANSI C library facilities, you
@emph{can} use the GNU C library with traditional, ``pre-ANSI'' C
compilers.  However, you need to be careful because the content and
organization of the GNU C library header files differs from that of
traditional C implementations.  This means you may need to make changes
to your program in order to get it to compile.
@end ignore

@node Contributors
@appendixsec Contributors to the GNU C Library

The GNU C library was written almost entirely by Roland McGrath.
Some parts of the library were contributed by other people.

@itemize @bullet
@item
The @code{getopt} function and related code were written by
@w{Richard Stallman}, @w{David J. MacKenzie}, and @w{Roland McGrath}.

@item
Most of the math functions are taken from 4.4 BSD; they have been
modified only slightly to work with the GNU C library.  The
Internet-related code (most of the @file{inet} subdirectory) and several
other miscellaneous functions and header files have been included with
little or no modification.

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

@quotation
@display
Copyright @copyright{} 1991 Regents of the University of California.
All rights reserved.
@end display

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

@enumerate
@item
Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
@item
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.
@item
All advertising materials mentioning features or use of this software
must display the following acknowledgement:
@quotation
        This product includes software developed by the University of
        California, Berkeley and its contributors.
@end quotation
@item
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.
@end enumerate

@sc{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.}
@end quotation

@item
The random number generation functions @code{random}, @code{srandom},
@code{setstate} and @code{initstate}, which are also the basis for the
@code{rand} and @code{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.@refill

@item
The merge sort function @code{qsort} was written by Michael J. Haertel.

@item
The quick sort function used as a fallback by @code{qsort} was written
by Douglas C. Schmidt.

@item
The memory allocation functions @code{malloc}, @code{realloc} and
@code{free} and related code were written by Michael J. Haertel.

@item
Fast implementations of many of the string functions (@code{memcpy},
@code{strlen}, etc.) were written by
@tex
Torbj\"orn
@end tex
@ifinfo
Torbjorn
@end ifinfo
Granlund.@refill

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

@quotation
@display
Mach Operating System
Copyright @copyright{} 1991,1990,1989 Carnegie Mellon University
All Rights Reserved.
@end display

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.

@sc{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

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

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

@item
The @file{tar.h} header file was written by David J. MacKenzie.

@item
The port to the MIPS DECStation running Ultrix 4 was contributed by
Brendan Kehoe and Ian Lance Taylor.

@item
The DES encryption function @code{crypt} and related functions were
contributed by Michael Glad.

@item
The @code{ftw} function was contributed by Ian Lance Taylor.

@item
The code to support SunOS shared libraries was contributed by Tom Quinn.
@end itemize

@c @bye