libiberty.texi

理解和实践操作系统的一本好书

\input texinfo  @c -*-texinfo-*-
@c %**start of header
@setfilename libiberty.info
@settitle @sc{gnu} libiberty
@c %**end of header

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@dircategory GNU libraries
@direntry
* Libiberty: (libiberty).          Library of utility functions which
                                   are missing or broken on some systems.
@end direntry

@macro libib
@code{libiberty}
@end macro

@c The edition date is written in three locations.  Search for 'thedate'.
@ifinfo
This manual describes the GNU @libib library of utility subroutines.
This edition accompanies GCC 3, September 2001.

Copyright @copyright{} 2001 Free Software Foundation, Inc.

      Permission is granted to copy, distribute and/or modify this document
      under the terms of the GNU Free Documentation License, Version 1.2
      or any later version published by the Free Software Foundation;
      with no Invariant Sections, with no Front-Cover Texts, and with no
      Back-Cover Texts.  A copy of the license is included in the
      section entitled ``GNU Free Documentation License''.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries a copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).

@end ignore
@end ifinfo


@c The edition date is written in three locations.  Search for 'thedate'.
@titlepage
@title @sc{gnu} libiberty
@subtitle September 2001
@subtitle for GCC 3
@author Phil Edwards et al.
@page


@vskip 0pt plus 1filll
Copyright @copyright{} 2001 Free Software Foundation, Inc.

      Permission is granted to copy, distribute and/or modify this document
      under the terms of the GNU Free Documentation License, Version 1.2
      or any later version published by the Free Software Foundation;
      with no Invariant Sections, with no Front-Cover Texts, and with no
      Back-Cover Texts.  A copy of the license is included in the
      section entitled ``GNU Free Documentation License''.

@end titlepage
@contents
@page

@ifnottex
@node    Top,Using,,
@top     Introduction

The @libib{} library is a collection of subroutines used by various
GNU programs.  It is available under the Library General Public
License; for more information, see @ref{Library Copying}.

@c The edition date is written in three locations.  Search for 'thedate'.
This edition accompanies GCC 3, September 2001.

@end ifnottex

@menu
* Using::              How to use libiberty in your code.

* Overview::           Overview of available function groups.

* Functions::          Available functions, macros, and global variables.

* Obstacks::           Object Stacks.

* Licenses::           The various licenses under which libiberty sources are
                       distributed.

* Index::              Index of functions and categories.
@end menu

@node Using
@chapter Using
@cindex using libiberty
@cindex libiberty usage
@cindex how to use

@c THIS SECTION IS CRAP AND NEEDS REWRITING BADLY.

To date, @libib{} is generally not installed on its own.  It has evolved
over years but does not have its own version number nor release schedule.

Possibly the easiest way to use @libib{} in your projects is to drop the
@libib{} code into your project's sources, and to build the library along
with your own sources; the library would then be linked in at the end.  This
prevents any possible version mismatches with other copies of libiberty
elsewhere on the system.

Passing @option{--enable-install-libiberty} to the @command{configure}
script when building @libib{} causes the header files and archive library
to be installed when @kbd{make install} is run.  This option also takes
an (optional) argument to specify the installation location, in the same
manner as @option{--prefix}.

For your own projects, an approach which offers stability and flexibility
is to include @libib{} with your code, but allow the end user to optionally
choose to use a previously-installed version instead.  In this way the
user may choose (for example) to install @libib{} as part of GCC, and use
that version for all software built with that compiler.  (This approach
has proven useful with software using the GNU @code{readline} library.)

Making use of @libib{} code usually requires that you include one or more
header files from the @libib{} distribution.  (They will be named as
necessary in the function descriptions.)  At link time, you will need to
add @option{-liberty} to your link command invocation.


@node Overview
@chapter Overview

Functions contained in @libib{} can be divided into three general categories.


@menu
* Supplemental Functions::       Providing functions which don't exist
                                 on older operating systems.

* Replacement Functions::        These functions are sometimes buggy or
                                 unpredictable on some operating systems.

* Extensions::                   Functions which provide useful extensions
                                 or safety wrappers around existing code.
@end menu

@node Supplemental Functions
@section Supplemental Functions
@cindex supplemental functions
@cindex functions, supplemental
@cindex functions, missing

Certain operating systems do not provide functions which have since
become standardized, or at least common.  For example, the Single
Unix Specification Version 2 requires that the @code{basename}
function be provided, but an OS which predates that specification
might not have this function.  This should not prevent well-written
code from running on such a system.

Similarly, some functions exist only among a particular ``flavor''
or ``family'' of operating systems.  As an example, the @code{bzero}
function is often not present on systems outside the BSD-derived
family of systems.

Many such functions are provided in @libib{}.  They are quickly
listed here with little description, as systems which lack them
become less and less common.  Each function @var{foo} is implemented
in @file{@var{foo}.c} but not declared in any @libib{} header file; more
comments and caveats for each function's implementation are often
available in the source file.  Generally, the function can simply
be declared as @code{extern}.



@node Replacement Functions
@section Replacement Functions
@cindex replacement functions
@cindex functions, replacement

Some functions have extremely limited implementations on different
platforms.  Other functions are tedious to use correctly; for example,
proper use of @code{malloc} calls for the return value to be checked and
appropriate action taken if memory has been exhausted.  A group of
``replacement functions'' is available in @libib{} to address these issues
for some of the most commonly used subroutines.

All of these functions are declared in the @file{libiberty.h} header
file.  Many of the implementations will use preprocessor macros set by
GNU Autoconf, if you decide to make use of that program.  Some of these
functions may call one another.


@menu
* Memory Allocation::            Testing and handling failed memory
                                   requests automatically.
* Exit Handlers::                Calling routines on program exit.
* Error Reporting::              Mapping errno and signal numbers to
                                   more useful string formats.
@end menu

@node Memory Allocation
@subsection Memory Allocation
@cindex memory allocation

The functions beginning with the letter @samp{x} are wrappers around
standard functions; the functions provided by the system environment
are called and their results checked before the results are passed back
to client code.  If the standard functions fail, these wrappers will
terminate the program.  Thus, these versions can be used with impunity.


@node Exit Handlers
@subsection Exit Handlers
@cindex exit handlers

The existence and implementation of the @code{atexit} routine varies
amongst the flavors of Unix.  @libib{} provides an unvarying dependable
implementation via @code{xatexit} and @code{xexit}.


@node Error Reporting
@subsection Error Reporting
@cindex error reporting

These are a set of routines to facilitate programming with the system
@code{errno} interface.  The @libib{} source file @file{strerror.c}
contains a good deal of documentation for these functions.

@c signal stuff


@node Extensions
@section Extensions
@cindex extensions
@cindex functions, extension

@libib{} includes additional functionality above and beyond standard
functions, which has proven generically useful in GNU programs, such as
obstacks and regex.  These functions are often copied from other
projects as they gain popularity, and are included here to provide a
central location from which to use, maintain, and distribute them.

@menu
* Obstacks::                     Stacks of arbitrary objects.
@end menu

@c This is generated from the glibc manual using a make-obstacks-texi.sh
@c script of Phil's.  Hope it's accurate.
@include obstacks.texi

@node Functions
@chapter Function, Variable, and Macro Listing.
@include functions.texi

@node Licenses
@appendix Licenses

@menu

* Library Copying::   The GNU Library General Public License
* BSD::               Regents of the University of California

@end menu

@c This takes care of Library Copying.  It is the copying-lib.texi from the
@c GNU web site, with its @node line altered to make makeinfo shut up.
@include copying-lib.texi

@page
@node BSD
@appendixsec BSD

Copyright @copyright{} 1990 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:

@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
[rescinded 22 July 1999]

@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

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.

@node Index
@unnumbered Index

@printindex cp

@bye