681 lines
26 KiB
Plaintext
681 lines
26 KiB
Plaintext
@section Programming Questions
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@subsection How do I contribute a package?
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If you are willing to be a package maintainer, great! We urgently need
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volunteers to prepare and maintain packages, because the priority of the
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Cygwin Team is Cygwin itself.
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The Cygwin Package Contributor's Guide at
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@file{http://cygwin.com/setup.html} details everything you need to know
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about being a package maintainer. The quickest way to get started is to
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read the @emph{Initial packaging procedure, script-based} section on
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that page. The @samp{generic-build-script} found there works well for
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most packages.
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For questions about package maintenance, use the cygwin-apps mailing
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list (start at @file{http://cygwin.com/lists.html}) @emph{after}
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searching and browsing the cygwin-apps list archives, of course. Be
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sure to look at the @emph{Submitting a package} checklist at
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@file{http://cygwin.com/setup.html} before sending an ITP (Intent To
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Package) email to cygwin-apps.
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You should also announce your intentions to the general cygwin list, in
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case others were thinking the same thing.
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@subsection How do I contribute to Cygwin?
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If you want to contribute to Cygwin itself, see
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@file{http://cygwin.com/contrib.html}.
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@subsection Why are compiled executables so huge?!?
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By default, gcc compiles in all symbols. You'll also find that gcc
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creates large executables on UNIX.
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If that bothers you, just use the 'strip' program, part of the binutils
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package. Or compile with the @samp{-s} option to gcc.
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@subsection Where is glibc?
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Cygwin does not provide glibc. It uses newlib instead, which provides
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much (but not all) of the same functionality. Porting glibc to Cygwin
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would be difficult.
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@subsection Where is Objective C?
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Objective C is not distributed with the Cygwin version of gcc, and there
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are no plans to do so. The gcc package maintainer had difficulty
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building it, and once built there were problems using it. It appears
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that there is only minimal support for the Objective C front-end in the
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main GCC distribution, anyway.
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@subsection Why does my make fail on Cygwin with an execvp error?
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First of all, if you are using @samp{make -j[N]}, then stop. It doesn't
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work well. Also beware of using non-portable shell features in your
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Makefiles (see tips at @file{http://cygwin.com/faq/faq_3.html#SEC46}).
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Errors of @samp{make: execvp: /bin/sh: Illegal Argument} or
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@samp{make: execvp: /bin/sh: Argument list too long} are often
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caused by the command-line being to long for the Windows execution model.
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To circumvent this, mount the path of the executable using the -X switch
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to enable cygexec for all executables in that folder; you will also need
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to exclude non-cygwin executables with the -x switch. Enabling cygexec
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causes cygwin executables to talk directly to one another, which increases
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the command-line limit. To enable cygexec for @samp{/bin} and
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@samp{/usr/bin}, you can use these commands in a batch file:
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@example
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mount -X -b -f c:\cygwin\bin /bin
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mount -X -b -f c:\cygwin\bin /usr/bin
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mount -x -b -f c:\cygwin\bin\strace.exe /usr/bin/strace.exe
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mount -x -b -f c:\cygwin\bin\strace.exe /bin/strace.exe
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mount -x -b -f c:\cygwin\bin\cygcheck.exe /usr/bin/cygcheck.exe
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mount -x -b -f c:\cygwin\bin\cygcheck.exe /bin/cygcheck.exe
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@end example
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Note that you must specifically exclude @code{strace} and @code{cygcheck},
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which are not linked to the Cygwin DLL.
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(See @file{http://www.cygwin.com/cygwin-ug-net/using-utils.html#mount}
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for more information.)
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@subsection Why the undefined reference to @samp{WinMain@@16}?
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If you're using @samp{gcc}, try adding an empty main() function to one
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of your sources. Or, perhaps you have @samp{-lm} too early in the
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link command line. It should be at the end:
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@example
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bash$ gcc hello.c -lm
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bash$ ./a.exe
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Hello World!
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@end example
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works, but
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@example
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bash$ gcc -lm hello.c
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/c/TEMP/ccjLEGlU.o(.text+0x10):hello.c: multiple definition of `main'
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/usr/lib/libm.a(libcmain.o)(.text+0x0):libcmain.c: first defined here
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/usr/lib/libm.a(libcmain.o)(.text+0x6a):libcmain.c: undefined reference to `WinMain@@16'
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collect2: ld returned 1 exit status
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@end example
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If you're using GCJ, you need to pass a "--main" flag:
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@example
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gcj --main=Hello Hello.java
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@end example
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@subsection How do I use Win32 API calls?
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@strong{(Please note: This section has not yet been updated for the latest
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net release.)}
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It's pretty simple actually. Cygwin tools require that you explicitly
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link the import libraries for whatever Win32 API functions that you
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are going to use, with the exception of kernel32, which is linked
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automatically (because the startup and/or built-in code uses it).
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For example, to use graphics functions (GDI) you must link
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with gdi32 like this:
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gcc -o foo.exe foo.o bar.o -lgdi32
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or (compiling and linking in one step):
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gcc -o foo.exe foo.c bar.c -lgdi32
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The following libraries are available for use in this way:
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advapi32 largeint ole32 scrnsave vfw32
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cap lz32 oleaut32 shell32 win32spl
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comctl32 mapi32 oledlg snmp winmm
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comdlg32 mfcuia32 olepro32 svrapi winserve
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ctl3d32 mgmtapi opengl32 tapi32 winspool
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dlcapi mpr penwin32 th32 winstrm
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gdi32 msacm32 pkpd32 thunk32 wow32
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glaux nddeapi rasapi32 url wsock32
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glu32 netapi32 rpcdce4 user32 wst
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icmp odbc32 rpcndr uuid
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imm32 odbccp32 rpcns4 vdmdbg
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kernel32 oldnames rpcrt4 version
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The regular setup allows you to use the option -mwindows on the
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command line to include a set of the basic libraries (and also
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make your program a GUI program instead of a console program),
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including user32, gdi32 and, IIRC, comdlg32.
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Note that you should never include -lkernel32 on your link line
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unless you are invoking ld directly. Do not include the same import
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library twice on your link line. Finally, it is a good idea to
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put import libraries last on your link line, or at least after
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all the object files and static libraries that reference them.
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The first two are related to problems the linker has (as of b18 at least)
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when import libraries are referenced twice. Tables get messed up and
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programs crash randomly. The last point has to do with the fact that
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gcc processes the files listed on the command line in sequence and
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will only resolve references to libraries if they are given after
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the file that makes the reference.
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@subsection How do I compile a Win32 executable that doesn't use Cygwin?
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The -mno-cygwin flag to gcc makes gcc link against standard Microsoft
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DLLs instead of Cygwin. This is desirable for native Windows programs
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that don't need a UNIX emulation layer.
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This is not to be confused with 'MinGW' (Minimalist GNU for Windows),
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which is a completely separate effort. That project's home page is
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@file{http://www.mingw.org/index.shtml}.
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@subsection Can I build a Cygwin program that does not require cygwin1.dll at runtime?
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No. If your program uses the Cygwin API, then your executable cannot
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run without cygwin1.dll. In particular, it is not possible to
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statically link with a Cygwin library to obtain an independent,
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self-contained executable.
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If this is an issue because you intend to distribute your Cygwin
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application, then you had better read and understand
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@file{http://cygwin.com/licensing.html}, which explains the licensing
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options. Unless you purchase a special commercial license from Red
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Hat, then your Cygwin application must be Open Source.
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@subsection Can I link with both MSVCRT*.DLL and cygwin1.dll?
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No, you must use one or the other, they are mutually exclusive.
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@subsection How do I make the console window go away?
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The default during compilation is to produce a console application.
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It you are writing a GUI program, you should either compile with
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-mwindows as explained above, or add the string
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"-Wl,--subsystem,windows" to the GCC command line.
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@subsection Why does make complain about a "missing separator"?
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This problem usually occurs as a result of someone editing a Makefile
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with a text editor that replaces tab characters with spaces. Command
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lines must start with tabs. This is not specific to Cygwin.
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@subsection Why can't we redistribute Microsoft's Win32 headers?
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Subsection 2.d.f of the `Microsoft Open Tools License agreement' looks
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like it says that one may not "permit further redistribution of the
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Redistributables to their end users". We take this to mean that we can
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give them to you, but you can't give them to anyone else, which is
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something that Red Hat can't agree to. Fortunately, we
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have our own Win32 headers which are pretty complete.
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@subsection How do I link against @samp{cygwin1.dll} with Visual Studio?
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To my knowledge, none of the Cygwin developers have done this, but we
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have this report from the mailing list that it can be done this way:
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@enumerate
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@item Use the impdef program to generate a .def file for the cygwin1.dll
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(if you build the cygwin dll from source, you will already have a def
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file)
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@example
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impdef cygwin1.dll > cygwin1.def
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@end example
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@item Use the MS VS linker (lib) to generate an import library
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@example
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lib /def=cygwin1.def /out=cygwin1.lib
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@end example
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@item Create a file "my_crt0.c" with the following contents
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@example
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#include <sys/cygwin.h>
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#include <stdlib.h>
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typedef int (*MainFunc) (int argc, char *argv[], char **env);
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void
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my_crt0 (MainFunc f)
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@{
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cygwin_crt0(f);
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@}
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@end example
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@item Use gcc in a Cygwin prompt to build my_crt0.c into a DLL
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(e.g. my_crt0.dll). Follow steps 1 and 2 to generate .def and
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.lib files for the DLL.
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@item Download crt0.c from the cygwin website and include it in
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your sources. Modify it to call my_crt0() instead of
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cygwin_crt0(). Since you are using Cygwin source code, your
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resulting program will be licensed under the GNU GPL. For more
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information, see @file{http://gnu.org/licenses/gpl-faq.html}.
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@item Build your object files using the MS VC compiler cl.
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@item Link your object files, cygwin1.lib, and my_crt0.lib (or
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whatever you called it) into the executable.
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@end enumerate
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Note that if you are using any other Cygwin based libraries
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that you will probably need to build them as DLLs using gcc and
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then generate import libraries for the MS VC linker.
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Thanks to Alastair Growcott (alastair dot growcott at bakbone dot co
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dot uk) for this tip.
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@subsection How do I link against a @samp{.lib} file?
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If your @samp{.lib} file is a normal static or import library with
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C-callable entry points, you can list @samp{foo.lib} as an object file for
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gcc/g++, just like any @samp{*.o} file. Otherwise, here are some steps:
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@enumerate
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@item Build a C file with a function table. Put all functions you intend
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to use in that table. This forces the linker to include all the object
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files from the .lib. Maybe there is an option to force LINK.EXE to
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include an object file.
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@item Build a dummy 'LibMain'.
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@item Build a .def with all the exports you need.
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@item Link with your .lib using link.exe.
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@end enumerate
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or
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@enumerate
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@item Extract all the object files from the .lib using LIB.EXE.
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@item Build a dummy C file referencing all the functions you need, either
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with a direct call or through an initialized function pointer.
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@item Build a dummy LibMain.
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@item Link all the objects with this file+LibMain.
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@item Write a .def.
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@item Link.
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@end enumerate
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You can use these methods to use MSVC (and many other runtime libs)
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with Cygwin development tools.
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Note that this is a lot of work (half a day or so), but much less than
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rewriting the runtime library in question from specs...
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Thanks to Jacob Navia (root at jacob dot remcomp dot fr) for this explanation.
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@subsection How do I build Cygwin on my own?
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First, you need to get the Cygwin source. Ideally, you should check out
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what you need from CVS (@file{http://cygwin.com/cvs.html}). This is the
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@emph{preferred method} for acquiring the sources. Otherwise, you can
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install the cygwin source package from the distribution.
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If you are trying to duplicate a cygwin release then you should just
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download the corresponding source package and use "tar xjf" to unpack
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it. This will unpack the sources into a directory named cygwin-x.y.z-n,
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where x.y.z-n correspond to the version numbering of the tar.bz2
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package.
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@example
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tar xjf cygwin-1.5.12-1-src.tar.bz2
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cd cygwin-1.5.12-1
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@end example
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You @emph{must} build cygwin in a separate directory from the source,
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so create something like a @samp{build/} directory. You will also want
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to install to a temporary location:
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@example
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mkdir build
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mkdir /install
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cd build
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(../configure --prefix=/install -v; make) >& make.out
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make install > install.log 2>&1
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@end example
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Normally, this procedure ignore errors in building the documentation.
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which requires the @samp{docbook-xml}, @samp{docbook-xsl}, and
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@samp{xmlto} packages. For more information on building the
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documentation, see the README included in the cygwin-doc package.
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To check a cygwin1.dll, run "make check" in the winsup/testsuite
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directory. If that works, install everything @emph{except} the dll (if
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you can). Then, close down all cygwin programs (including bash windows,
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inetd, etc.), save your old dll, and copy the new dll to the correct
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place. Then start up a bash window, or run a cygwin program from the
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Windows command prompt, and see what happens.
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If you get the error "shared region is corrupted" it means that two
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different versions of cygwin1.dll are running on your machine at the
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same time. Remove all but one.
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@subsection I may have found a bug in Cygwin, how can I debug it (the symbols in gdb look funny)?
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Debugging symbols are stripped from distibuted Cygwin binaries, so any
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symbols that you see in gdb are basically meaningless. It is also a good
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idea to use the latest code in case the bug has been fixed, so we
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recommend trying the latest snapshot from
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@file{http://cygwin.com/snapshots/} or build the DLL from CVS.
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To build a debugging version of the Cygwin DLL, you will need to follow
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the instructions at @file{http://cygwin.com/faq/faq_3.html#SEC102}. You
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can also contact the mailing list for pointers (a simple test case that
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demonstrates the bug is always welcome).
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@subsection How can I compile Cygwin for an unsupported platform (PowerPC, Alpha, ARM, Itanium)?
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Unfortunately, this will be difficult. Exception handling and signals
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support semantics and args have been designed for x86 so you would need
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to write specific support for your platform. We don't know of any other
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incompatibilities. Please send us patches if you do this work!
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@subsection How can I adjust the heap/stack size of an application?
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If you need to change the maximum amount of memory available to Cygwin, see
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@file{http://cygwin.com/cygwin-ug-net/setup-maxmem.html}. Otherwise,
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just pass heap/stack linker arguments to gcc. To create foo.exe with
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a heap size of 1024 and a stack size of 4096, you would invoke
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gcc as:
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@code{gcc -Wl,--heap,1024,--stack,4096 -o foo foo.c}
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@subsection How can I find out which DLLs are needed by an executable?
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@samp{objdump -p} provides this information, but is rather verbose.
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@samp{cygcheck} will do this much more concisely, and operates
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recursively, provided the command is in your path.
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Note there is currently a bug in cygcheck in that it will not report
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on a program in a Windows system dir (e.g., C:\Windows or C:\WINNT) even
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if it's in your path. To work around this, supply the full Win32 path
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to the executable, including the .exe extension:
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@example
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cygcheck c:\\winnt\\system32\\cmd.exe
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@end example
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(Note the windows path separator must be escaped if this is typed in
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bash.)
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@subsection How do I build a DLL?
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There's documentation that explains the process in the Cygwin User's
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Guide here: @file{http://cygwin.com/cygwin-ug-net/dll.html}
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@subsection How can I set a breakpoint at MainCRTStartup?
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@strong{(Please note: This section has not yet been updated for the latest
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net release.)}
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Set a breakpoint at *0x401000 in gdb and then run the program in
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question.
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@subsection How can I build a relocatable dll?
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@strong{(Please note: This section has not yet been updated for the
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latest net release. However, there was a discussion on the cygwin
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mailing list recently that addresses this issue. Read
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@file{http://cygwin.com/ml/cygwin/2000-06/msg00688.html} and
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related messages.)}
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You must execute the following sequence of five commands, in this
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order:
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@example
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$(LD) -s --base-file BASEFILE --dll -o DLLNAME OBJS LIBS -e ENTRY
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$(DLLTOOL) --as=$(AS) --dllname DLLNAME --def DEFFILE \
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--base-file BASEFILE --output-exp EXPFILE
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$(LD) -s --base-file BASEFILE EXPFILE -dll -o DLLNAME OBJS LIBS -e ENTRY
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$(DLLTOOL) --as=$(AS) --dllname DLLNAME --def DEFFILE \
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--base-file BASEFILE --output-exp EXPFILE
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$(LD) EXPFILE --dll -o DLLNAME OBJS LIBS -e ENTRY
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@end example
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In this example, $(LD) is the linker, ld.
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$(DLLTOOL) is dlltool.
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$(AS) is the assembler, as.
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DLLNAME is the name of the DLL you want to create, e.g., tcl80.dll.
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OBJS is the list of object files you want to put into the DLL.
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LIBS is the list of libraries you want to link the DLL against. For
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example, you may or may not want -lcygwin. You may want -lkernel32.
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Tcl links against -lcygwin -ladvapi32 -luser32 -lgdi32 -lcomdlg32
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-lkernel32.
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DEFFILE is the name of your definitions file. A simple DEFFILE would
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consist of ``EXPORTS'' followed by a list of all symbols which should
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be exported from the DLL. Each symbol should be on a line by itself.
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Other programs will only be able to access the listed symbols.
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BASEFILE is a temporary file that is used during this five stage
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process, e.g., tcl.base.
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EXPFILE is another temporary file, e.g., tcl.exp.
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|
|
ENTRY is the name of the function which you want to use as the entry
|
|
point. This function should be defined using the WINAPI attribute,
|
|
and should take three arguments:
|
|
int WINAPI startup (HINSTANCE, DWORD, LPVOID)
|
|
|
|
This means that the actual symbol name will have an appended @@12, so if
|
|
your entry point really is named @samp{startup}, the string you should
|
|
use for ENTRY in the above examples would be @samp{startup@@12}.
|
|
|
|
If your DLL calls any Cygwin API functions, the entry function will need
|
|
to initialize the Cygwin impure pointer. You can do that by declaring
|
|
a global variable @samp{_impure_ptr}, and then initializing it in the
|
|
entry function. Be careful not to export the global variable
|
|
@samp{_impure_ptr} from your DLL; that is, do not put it in DEFFILE.
|
|
|
|
@example
|
|
/* This is a global variable. */
|
|
struct _reent *_impure_ptr;
|
|
extern struct _reent *__imp_reent_data;
|
|
|
|
int entry (HINSTANT hinst, DWORD reason, LPVOID reserved)
|
|
@{
|
|
_impure_ptr = __imp_reent_data;
|
|
/* Whatever else you want to do. */
|
|
@}
|
|
@end example
|
|
|
|
You may put an optional `--subsystem windows' on the $(LD) lines. The
|
|
Tcl build does this, but I admit that I no longer remember whether
|
|
this is important. Note that if you specify a --subsytem <x> flag to ld,
|
|
the -e entry must come after the subsystem flag, since the subsystem flag
|
|
sets a different default entry point.
|
|
|
|
You may put an optional `--image-base BASEADDR' on the $(LD) lines.
|
|
This will set the default image base. Programs using this DLL will
|
|
start up a bit faster if each DLL occupies a different portion of the
|
|
address space. Each DLL starts at the image base, and continues for
|
|
whatever size it occupies.
|
|
|
|
Now that you've built your DLL, you may want to build a library so
|
|
that other programs can link against it. This is not required: you
|
|
could always use the DLL via LoadLibrary. However, if you want to be
|
|
able to link directly against the DLL, you need to create a library.
|
|
Do that like this:
|
|
|
|
$(DLLTOOL) --as=$(AS) --dllname DLLNAME --def DEFFILE --output-lib LIBFILE
|
|
|
|
$(DLLTOOL), $(AS), DLLNAME, and DEFFILE are the same as above. Make
|
|
sure you use the same DLLNAME and DEFFILE, or things won't work right.
|
|
|
|
LIBFILE is the name of the library you want to create, e.g.,
|
|
libtcl80.a. You can then link against that library using something
|
|
like -ltcl80 in your linker command.
|
|
|
|
@subsection How can I debug what's going on?
|
|
|
|
You can debug your application using @code{gdb}. Make sure you
|
|
compile it with the -g flag! If your application calls functions in
|
|
MS DLLs, gdb will complain about not being able to load debug information
|
|
for them when you run your program. This is normal since these DLLs
|
|
don't contain debugging information (and even if they did, that debug
|
|
info would not be compatible with gdb).
|
|
|
|
@subsection Can I use a system trace mechanism instead?
|
|
|
|
Yes. You can use the @code{strace.exe} utility to run other cygwin
|
|
programs with various debug and trace messages enabled. For information
|
|
on using @code{strace}, see the Cygwin User's Guide or the file
|
|
@code{winsup/utils/utils.sgml}.
|
|
|
|
@subsection Why doesn't gdb handle signals?
|
|
|
|
Unfortunately, there is only minimal signal handling support in gdb
|
|
currently. Signal handling only works with Windows-type signals.
|
|
SIGINT may work, SIGFPE may work, SIGSEGV definitely does. You cannot
|
|
'stop', 'print' or 'nopass' signals like SIGUSR1 or SIGHUP to the
|
|
process being debugged.
|
|
|
|
@subsection The linker complains that it can't find something.
|
|
|
|
A common error is to put the library on the command line before
|
|
the thing that needs things from it.
|
|
|
|
This is wrong @code{gcc -lstdc++ hello.cc}.
|
|
This is right @code{gcc hello.cc -lstdc++}.
|
|
|
|
@subsection I use a function I know is in the API, but I still get a link error.
|
|
|
|
@strong{(Please note: This section has not yet been updated for the latest
|
|
net release.)}
|
|
|
|
The function probably isn't declared in the header files, or
|
|
the UNICODE stuff for it isn't filled in.
|
|
|
|
@subsection Can you make DLLs that are linked against libc ?
|
|
|
|
@strong{(Please note: This section has not yet been updated for the latest
|
|
net release.)}
|
|
|
|
Yes.
|
|
|
|
@subsection Where is malloc.h?
|
|
|
|
@strong{(Please note: This section has not yet been updated for the latest
|
|
net release.)}
|
|
|
|
Include stdlib.h instead of malloc.h.
|
|
|
|
@subsection Can I use my own malloc?
|
|
|
|
If you define a function called @code{malloc} in your own code, and link
|
|
with the DLL, the DLL @emph{will} call your @code{malloc}. Needless to
|
|
say, you will run into serious problems if your malloc is buggy.
|
|
|
|
If you run any programs from the DOS command prompt, rather than from in
|
|
bash, the DLL will try and expand the wildcards on the command line.
|
|
This process uses @code{malloc} @emph{before} your main line is started.
|
|
If you have written your own @code{malloc} to need some initialization
|
|
to occur after @code{main} is called, then this will surely break.
|
|
|
|
Moreover, there is an outstanding issue with @code{_malloc_r} in
|
|
@code{newlib}. This re-entrant version of @code{malloc} will be called
|
|
directly from within @code{newlib}, by-passing your custom version, and
|
|
is probably incompatible with it. But it may not be possible to replace
|
|
@code{_malloc_r} too, because @code{cygwin1.dll} does not export it and
|
|
Cygwin does not expect your program to replace it. This is really a
|
|
newlib issue, but we are open to suggestions on how to deal with it.
|
|
|
|
@subsection Can I mix objects compiled with msvc++ and gcc?
|
|
|
|
Yes, but only if you are combining C object files. MSVC C++ uses a
|
|
different mangling scheme than GNU C++, so you will have difficulties
|
|
combining C++ objects.
|
|
|
|
@subsection Can I use the gdb debugger to debug programs built by VC++?
|
|
|
|
No, not for full (high level source language) debugging.
|
|
The Microsoft compilers generate a different type of debugging
|
|
symbol information, which gdb does not understand.
|
|
|
|
However, the low-level (assembly-type) symbols generated by
|
|
Microsoft compilers are coff, which gdb DOES understand.
|
|
Therefore you should at least be able to see all of your
|
|
global symbols; you just won't have any information about
|
|
data types, line numbers, local variables etc.
|
|
|
|
@subsection Where can I find info on x86 assembly?
|
|
|
|
CPU reference manuals for Intel's current chips are available in
|
|
downloadable PDF form on Intel's web site:
|
|
|
|
@file{http://developer.intel.com/design/pro/manuals/}
|
|
|
|
@subsection Shell scripts aren't running properly from my makefiles?
|
|
|
|
If your scripts are in the current directory, you must have @samp{.}
|
|
(dot) in your $PATH. (It is not normally there by default.) Otherwise,
|
|
you would need to add /bin/sh in front of each and every shell script
|
|
invoked in your Makefiles.
|
|
|
|
@subsection What preprocessor do I need to know about?
|
|
|
|
We use _WIN32 to signify access to the Win32 API and __CYGWIN__ for
|
|
access to the Cygwin environment provided by the dll.
|
|
|
|
We chose _WIN32 because this is what Microsoft defines in VC++ and
|
|
we thought it would be a good idea for compatibility with VC++ code
|
|
to follow their example. We use _MFC_VER to indicate code that should
|
|
be compiled with VC++.
|
|
|
|
_WIN32 is only defined when you use either the -mno-cygwin or -mwin32
|
|
gcc command line options. This is because Cygwin is supposed to be a
|
|
Unix emulation environment and defining _WIN32 confuses some programs
|
|
which think that they have to make special concessions for a Windows
|
|
environment which Cygwin handles automatically.
|
|
|
|
Note that using -mno-cygwin replaces __CYGWIN__ with __MINGW32__ as to
|
|
tell which compiler (or settings) you're running.
|
|
Check this out in detail by running, for example
|
|
|
|
@example
|
|
$ gcc -dM -E -xc /dev/null >gcc.txt
|
|
$ gcc -mno-cygwin -dM -E -xc /dev/null >gcc-mno-cygwin.txt
|
|
$ gcc -mwin32 -dM -E -xc /dev/null >gcc-mwin32.txt
|
|
@end example
|
|
Then use the diff and grep utilities to check
|
|
what the difference is.
|
|
|
|
@subsection How should I port my Unix GUI to Windows?
|
|
|
|
There are two basic strategies for porting Unix GUIs to Windows.
|
|
|
|
The first is to use a portable graphics library such as tcl/tk, X11, or
|
|
V (and others?). Typically, you will end up with a GUI on Windows that
|
|
requires some runtime support. With tcl/tk, you'll want to include the
|
|
necessary library files and the tcl/tk DLLs. In the case of X11, you'll
|
|
need everyone using your program to have an X11 server installed.
|
|
|
|
The second method is to rewrite your GUI using Win32 API calls (or MFC
|
|
with VC++). If your program is written in a fairly modular fashion, you
|
|
may still want to use Cygwin if your program contains a lot of shared
|
|
(non-GUI-related) code. That way you still gain some of the portability
|
|
advantages inherent in using Cygwin.
|
|
|
|
@subsection Why not use DJGPP ?
|
|
|
|
DJGPP is a similar idea, but for DOS instead of Win32. DJGPP uses a
|
|
"DOS extender" to provide a more reasonable operating interface for its
|
|
applications. The Cygwin toolset doesn't have to do this since all of
|
|
the applications are native WIN32. Applications compiled with the
|
|
Cygwin tools can access the Win32 API functions, so you can write
|
|
programs which use the Windows GUI.
|
|
|
|
You can get more info on DJGPP by following
|
|
@file{http://www.delorie.com/}.
|