 | Level: Introductory Cameron Laird (claird@phaseit.net), Vice president, Phaseit, Inc.
30 Jan 2003 Xmingwin makes it practical to generate Windows programs from a Linux server. This column gives a recipe for setting up Xmingwin, and outlines the most important reasons for doing so.
I do much of my Window development on Linux hosts, even
when working in C. This installment of Server clinic tells how
you can, too, and why you might want to add
mingw32-gcc source.c -o executable.exe
to your usual repertoire of gcc source.c -o
executable.
Automate chores with UNIX
Several of 2002's most popular Server clinic columns explained
how to manage common desktop technologies, including PDF and DOC files, from
servers. In one sense, this is the aim of many products and books,
including WINE, VMware, and Linux in the Workplace. They all
advertise the ability to replicate familiar desktop experiences from a
Linux host. The Resources section, below, gives references to these alternatives and suggests where each best applies.
This column consistently handles such subjects from a different angle,
though. The point this month is not to imitate Windows, but to automate
the production of Windows deliverables with open source tools. Mingwin
(also Mingw, Mingw32, and so on), the MINimalist Gnu for WINdows, fits
this description. Mingwin is adevelopment suite for Windows, roughly
comparable to Visual C++ or Borland's Delphi. Unlike the latter two,
Mingwin's distinction is that it provides a UNIX-like environment
under Windows. As it's based on the standard GNU compiler gcc,
Mingwin also supports work in C++,
Fortran, and other closely-related languages. It doesn't supply
the baroquely integrated development environments (IDEs) common in Windows
development shops. Instead, Mingwin's rich toolchest of robust utilities
performs basic development operations: compilation, linking,
and so on. All these are flexible and programmable, though, in
the usual UNIX spirit.
Why does Server clinic take such an "old-fashioned" approach?
Often I work with applications required to run equally under UNIX,
Windows, and other OSes. It multiplies my productivity to be able to
generate all deliverables from a single source set. By keeping sources on
a Linux server, for example, and automatically cross-generating, I
eliminate a whole layer of "Is it OK to re-boot? Are my file systems
compatible? Has the project structure changed? ..." puzzles that seem to
slow some development laboratories. Every developer change in my systems
leads either to production of all deliverables, for all platforms, or an
explicit error message. This immediate feedback prevents most surprises
of the, "Well, we thought it was OK last week" sort.
If you, too, want to concentrate more on progress and less on platform
hand-holding, you'll like Xmingwin. Xmingwin is my label for, "Mingwin
run as a cross-generating application." Be aware: you'll also see it
spelled as "cross Mingw32," "Xmingw32," or other variations. Usage isn't
well standardized at this point. Recall that Mingwin installs on a
Windows host and gives a UNIX interface; Xmingwin "retracts" that so that
its operation is the same as on Windows, and it produces the same
Windows-ready output but from a UNIX installation.
Installation is straightforward. I make a point of saying this,
because I came across quite an assortment of correct, muddy, and
misleading advice when I first worked with Xmingwin. Start with simple
steps. For a basic x86-based Linux launch to your Xmingwin career, use a
comprehensive bundle (see Resources for a link).
Unzip and unpack it:
Listing 1. Unpack sequence for Xmingwin bundle
INSTALLATION=/tmp/experiment
cd $INSTALLATION
bunzip2 mingw-cross.tar.bz2
tar xvf mingw-cross.tar
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That's enough to start productive cross-generation work. While there
are the usual thousands of possible variations standard for Linux
developer tools -- link at different optimization levels, port to a
different hardware variety of Linux, and so on -- a basic Xmingwin
installation should take you a long way.
Use Xmingwin for cross generation
Add the distribution's bin directory to your
PATH. Some developers favor schemes of linking
or symbolic linking, so that they can type gcc at the command prompt, and have that resolve to,
for example, /tmp/experiment/bin/mingw32-gcc.
My own preference is to have gcc always mean
the native compiler, and I explicitly invoke or configure mingw32-gcc as I need.
The first test of your new installation should be simply to ask it its
version: mingw32-gcc -v. It's likely to
report something like:
gcc version 2.95.3 20010315 (release)
Next, try the canonical "sanity test" -- write:
Listing 2. Source code for minimal "hello, world"
#include <stdio.h>
int main(int argc, char *argv[])
{
puts("It works!");
}
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and compile it with:
Listing 3. Sample generation sequence for simple source
WORKING=/tmp
INSTALLATION=/tmp/experiment
PATH="$PATH:$INSTALLATION/bin"
export PATH=$PATH:$INSTALLATION/bin
cc -o $WORKING/minimal $WORKING/minimal.c
mingw32-gcc -I$INSTALLATION/mingw32/include \
-o $WORKING/minimal.exe $WORKING/minimal.c
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This script gives you a Linux application /tmp/minimal and its Windows twin /tmp/minimal.exe. Transfer the latter to a
convenient Windows host, and you'll find it executes just as any other
well-behaved Windows application.
Background
And now you're in business. The Xmingwin/bin directory includes not just
a cross-compiler, but cross-linker, cross-library-manager, and almost two
dozen related tools for common developer operations. With a bit of
practice, you can generate deliverables for Windows just as easily as you
currently do for Linux, probably from the same Makefiles you're already using.
That's a lot of progress from 1998, when Colin Peters created the first
Mingwin compiler. At that point, his version of gcc ran in the Cygnus
environment. The evolution continued when Jan-Jaap van der Heijden
re-hosted Mingwin as a native Windows application, and expanded Mingwin to
include all GNU binutils and make; later, Mumit Khan extended these
achievements with more Windows intimacy, including better
Win32api binding.
GUIs and Win32-specific functionality is one focus for Mingwin; you
can read more about that in Resources below, especially Khan's.
Server clinic's emphasis is on applications that work on both Linux
or Windows. My own development of that sort is split about equally
between portable "pure C," and Critcl used for cross development.
Critcl is a fascinating extension to the Tcl programming language.
Critcl starts by doing for Tcl roughly what Brian Ingerson's Inline does
for Perl: allows "foreign" languages -- C, in this case, but in principle
you might want SQL, assembler, or even wilder combinations -- to be
embedded in the source of a host language. This provides advantages that it
will take an entire future column to describe. The point for now is that
Critcl inventor Jean-Claude Wippler has polished his creation sufficiently
to make cross-generation easy. The result: a single source base is
sufficient to generate both Tcl and C object code for both the host and
cross environment, without any need to write make files or figure out
linkage arguments. Critcl allows me to automate and finish challenging
jobs far, far faster than conventional "by-hand" approaches.
Conclusion
But I digress: we'll talk more about Critcl in a future column. In the
meantime, I'm interested in whether Xmingwin is as much a boon to you as
it has been for me. Do your DLLs (Windows-specific, dynamically-loaded
libraries, most often) work properly for you? More broadly, is
development with just high-level Linux-hosted languages such as Python, Ruby,
Tcl, Perl, REBOL, and so, going the way you want? Do you ever find you
know of a job your Linux servers need done, but not how to do it, or even
which language to use? Join us in the Scripting clinic discussion forum (click Discuss at the top or bottom of the article) to share your experiences.
Thanks to personal acquaintances Steve Landers, Rolf Ade, and Mo
DeJong, among those who helped start me with XMingw32, and my
congratulations to the MinGW team for the success and maturity of their
achievement.
Resources - Participate in the discussion forum.
- Check out the other installments of Server clinic.
- Check out the Debian project, where you can download version 3.2-1 of mingw32 as an
installable Debian package.
- "The Unix Guide to
Defenestration" is a book that preaches a UNIX-oriented approach to
data-center management. Its case studies bear on the motivations and
practices that make Mingwin interesting.
- VMware is a commercial product that offers,
among other variations, a virtual Windows host within a
Linux session. Many developers with cross-platform responsibilities find
VMware enormously helpful for its ability to share hardware and
file-system resources between operating systems. A modest laptop can, for
example, simultaneously appear to be a Windows and a Linux machine. VMware
does not, however, particularly support automation of Windows in a UNIX
style.
- WINE is an almost decade-old
project to define a compatibility layer for Windows applications
implemented on other operating systems, principally Linux. Although most
WINE energy goes into games and office automation, it's possible to use
Windows developers tool such as Visual C++ through WINE.
- CrossOver Office is CodeWeavers' proprietary WINE
descendant.
- Win4Lin 4.0 emulates at a lower level than WINE. This proprietary
product of NeTraverse hosts an
entire Windows95 or Windows98 instance as a Linux process. If you're happy with VMware, you
might find Win4Lin even more satisfying for common uses, at a lower license cost.
- Nicholas Petreley judiciously compares "Win4lin vs.
VMware" in a 2000 article. Note that Win4lin installation has
generally improved since his tests.
- Linux in the
Workplace is the most technically accurate description of the use
of Linux as a desktop for office automation.
- Cygwin, MKS Inc., and U/Win are
essentially UNIX compatibility packages that allow UNIX applications and
processes to be hosted on Windows.
- This
XMingw32 README explains XMingw32 generation and installation.
- Inline is a special module that
lets Perl programmers include functionality coded in C or other languages.
- Critcl does much the same for
Tcl, but extends the interfaces so they work across versions, operating
systems, and other boundaries.
- RubyInline
is Ruby's equivalent to Inline.
- Find more resources for Linux developers in the developerWorks Linux zone. The developerWorks Java zone also focuses on cross-platform programming.
About the author | | |
Cameron is a full-time consultant for Phaseit, Inc., who writes and
speaks frequently on Open Source and other technical topics. You can
contact Cameron at claird@phaseit.net.
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