X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=README;h=0191f7a93eeef53463aca05e92476cc53dc8bf1f;hb=8b40415718be86c3a37388ba35804be74b8f376e;hp=72bde6dde0da6c858938293f6b81c84b0c397b88;hpb=9a21ae5eaf259e2b716e5a864e254793e2ef4e74;p=gnulib.git diff --git a/README b/README index 72bde6dde..0191f7a93 100644 --- a/README +++ b/README @@ -1,220 +1 @@ -Gnulib -====== - -Gnulib is intended to be the canonical source for most of the important -"portability" and/or common files for GNU projects. These are files -intended to be shared at the source level; Gnulib is not a library meant -to be installed and linked against. Unlike most projects, Gnulib does -not normally generate a source tarball distribution; instead, developers -should just grab modules directly from the repository. - -While portability across operating systems is not one of GNU's primary -goals, it has helped introduce many people to the GNU system, and is -worthwhile when it can be achieved at a low cost. This collection helps -lower that cost. - - -Contributing to Gnulib -====================== -All software here is Copyright (c) Free Software Foundation - you need -to have filled out an assignment form for a project that uses the -module for that contribution to be accepted here. - -If you have a piece of code that you would like to contribute, please -email bug-gnulib@gnu.org. You can review the archives, subscribe, etc., -via http://lists.gnu.org/mailman/listinfo/bug-gnulib. - -Generally we are looking for files that fulfill at least one of the -following requirements: - - * If your .c and .h files define functions that are broken or -missing on some other system, we should be able to include it. - - * If your functions remove arbitrary limits from existing -functions (either under the same name, or as a slightly different -name), we should be able to include it. - -If your functions define completely new but rarely used functionality, -you should probably consider packaging it as a separate library. - - -License -------- -Gnulib contains code both under GPL and LGPL. Because several packages -that use Gnulib are GPL, the files state they are licensed under GPL. -However, to support LGPL projects as well, you may use some of the -files under LGPL. The "License:" information in the files under -modules/ clarifies the real license that applies to the module source. - -Keep in mind that if you submit patches to files in Gnulib, you should -license them under a compatible license, which means that sometimes -the contribution will have to be LGPL, if the original file is -available under LGPL via a "License: LGPL" information in the -projects' modules/ file. - - -How to add a new module ------------------------ -* Add the header files and source files to lib/. -* If the module needs configure-time checks, write an autoconf - macro for it in m4/.m4. See m4/README for details. -* Write a module description modules/, based on modules/TEMPLATE. -* If the module contributes a section to the end-user documentation, - put this documentation in doc/.texi and add it to the "Files" - section of modules/. Most modules don't do this; they have only - documentation for the programmer (= gnulib user). Such documentation - usually goes into the lib/ source files. It may also go into doc/; - but don't add it to the module description in this case. -* Add the module to the list in MODULES.html.sh. - -You can test that a module builds correctly with: - $ ./gnulib-tool --create-testdir --dir=/tmp/testdir module1 ... moduleN - $ cd /tmp/testdir - $ ./configure && make - -Other things: -* Check the license and copyright year of headers. -* Check that the source code follows the GNU coding standards; - see . -* Add source files to config/srclist* if they are identical to upstream - and should be upgraded in gnulib whenever the upstream source changes. -* Include header files in source files to verify the function prototypes. -* Make sure a replacement function doesn't cause warnings or clashes on - systems that have the function. -* Autoconf functions can use gl_* prefix. The AC_* prefix is for - autoconf internal functions. -* Build files only if they are needed on a platform. Look at the - alloca and fnmatch modules for how to achieve this. If for some - reason you cannot do this, and you have a .c file that leads to an - empty .o file on some platforms (through some big #if around all the - code), then ensure that the compilation unit is not empty after - preprocessing. One way to do this is to #include or - before the big #if. - -Portability guidelines ----------------------- - -Gnulib code is intended to be portable to a wide variety of platforms, -not just GNU platforms. - -Many Gnulib modules exist so that applications need not worry about -undesirable variability in implementations. For example, an -application that uses the 'malloc' module need not worry about (malloc -(0)) returning NULL on some Standard C platforms; and 'time_r' users -need not worry about localtime_r returning int (not char *) on some -platforms that predate POSIX 1003.1-2001. - -Originally much of the Gnulib code was portable to ancient hosts like -4.2BSD, but it is a maintenance hassle to maintain compatibility with -unused hosts, so currently we assume at least a freestanding C89 -compiler, possibly operating with a C library that predates C89. The -oldest environment currently ported to is probably SunOS 4 + GCC 1.x, -though we haven't tested this exact combination. SunOS 4 last shipped -on 1998-09-30, and Sun dropped support for it on 2003-10-01, so at -some point we may start assuming a C89 library as well. - -Because we assume a freestanding C89 compiler, Gnulib code can include -, , , and unconditionally. It -can also include hosted headers like that were present in -Unix Version 7 and are thus widely available. Similarly, many modules -include even though it's not even in C99; that's OK -since has been around nearly forever. and - were not in Unix Version 7, so they weren't universally -available on ancient hosts, but they are both in SunOS 4 (the oldest -platform still in relatively-common use) so Gnulib assumes them now. - -Even if the include files exist, they may not conform to C89. -However, GCC has a "fixincludes" script that attempts to fix most -C89-conformance problems. So Gnulib currently assumes include files -largely conform to C89 or better. People still using ancient hosts -should use fixincludes or fix their include files manually. - -Even if the include files conform to C89, the library itself may not. -For example, SunOS 4's (free (NULL)) can dump core, so Gnulib code -must avoid freeing a null pointer, even though C89 allows it. -You can work around some of these problems by requiring the relevant -modules, e.g., the Gnulib 'free' module supplies a conforming 'free'. - -The GNU coding standards allow one departure from strict C99: Gnulib -code can assume that standard internal types like size_t are no wider -than 'long'. POSIX 1003.1-2001 and the GNU coding standards both -require 'int' to be at least 32 bits wide, so Gnulib code assumes this -as well. Gnulib code makes the following additional assumptions: - - * Signed integer arithmetic is two's complement, without runtime - overflow checking. This is the traditional behavior, and is - supported by C99 implementations that conform to ISO/IEC 10967-1 - (LIA-1) and that define signed integer types as being modulo. - - * There are no "holes" in integer values: all the bits of an integer - contribute to its value in the usual way. - - * If two nonoverlapping objects have sizes S and T represented as - size_t values, then S + T cannot overflow. This assumption is true - for all practical hosts with flat address spaces, but it is not - always true for hosts with segmented address spaces. - - * If an existing object has size S, and if T is sufficiently small - (e.g., 8 KiB), then S + T cannot overflow. Overflow in this case - would mean that the rest of your program fits into T bytes, which - can't happen in realistic flat-address-space hosts. - - * Objects with all bits zero are treated as 0 or NULL. For example, - memset (A, 0, sizeof A) initializes an array A of pointers to NULL. - - * Adding zero to a null pointer does not change the pointer. - For example, 0 + (char *) NULL == (char *) NULL. - -The above assumptions are not required by the C or POSIX standards but -hold on all practical porting targets that we're familiar with. If -you have a porting target where these assumptions are not true, we'd -appreciate hearing of any fixes. We need fixes that do not increase -runtime overhead on standard hosts and that are relatively easy to -maintain. - -With the above caveats, Gnulib code should port without problem to new -hosts, e.g., hosts conforming to C99 or to recent POSIX standards. -Hence Gnulib code should avoid using constructs (e.g., undeclared -functions return 'int') that do not conform to C99. - -High Quality -============ - -We will be developing a testsuite for these applications. The goal is -to have a 100% firm interface so that maintainers can feel free to -update to the code in CVS at *any* time and know that their -application will not break. This means that before any change can be -committed to the repository, a test suite program must be produced -that exposes the bug for regression testing. All experimental work -should be done on branches to help promote this. - -CVS -=== - -Gnulib is available for anonymous checkout. In any Bourne-shell the -following should work: - -$ cvs -d :pserver:anoncvs@cvs.gnu.org:/cvsroot/gnulib login -(Just hit Enter or Return when prompt for a password) -$ cvs -d :pserver:anoncvs@cvs.gnu.org:/cvsroot/gnulib checkout gnulib - -Gnulib is hosted on savannah.gnu.org. The project page is -http://savannah.gnu.org/projects/gnulib. - - ------ -Copyright (C) 2001, 2003, 2004, 2005, 2006 Free Software Foundation, Inc. - -This program is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2, or (at your option) -any later version. - -This program is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with this program; if not, write to the Free Software Foundation, -Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ +Please see doc/gnulib-readme.texi for basic information about Gnulib.