@chapter Question and Answers

@section Where can I get more information?

@subsection Where's the documentation?

There are links to quite a lot of it on the main gnu-win32 WWW page:
@file{http://www.cygnus.com/misc/gnu-win32/}
Be sure to at least read the Release Notes on the main WWW page, if
there are any.

Tool-specific information can be found here:
@file{http://www.cygnus.com/pubs/gnupro}

@subsection How can I get on the gnu-win32 mailing list?

You can get on the gnu-win32 mailing list by sending mail
to
        gnu-win32-request@@cygnus.com

with a message body of:

@example
        subscribe gnu-win32  <your-email-address-here>
@end example

where <your-email-address-here> is your email address.

You can get off the mailing list by sending mail to

        gnu-win32-request@@cygnus.com

with a message body of:

@example
        unsubscribe gnu-win32 <your-email-address-here>
@end example

Note that because mail sometimes takes a day or two to get delivered to
the list, there is often a lag of a day or two before you stop receiving
messages after an unsubscribe request is made.

There's an archive of the mailing list in

@file{http://www.cygnus.com/ml/gnu-win32}

@subsection Why won't you/the mailing list answer my questions?

Perhaps your question has an answer that's already in the FAQ.
Perhaps nobody has time to answer your question.  Perhaps nobody
knows the answer...

@section Installation and Setup

@subsection Help! I haven't created /tmp and tools are behaving strangely!

Many Unix tools (bash, byacc, etc.) expect that /tmp always exists.
This is not guaranteed in Win32 land.  You should create /tmp or "mount"
the directory of your choice to /tmp to avoid this problem.

@subsection Why does bash spew out "49054596: No such file or directory"?

Are you sure you created a /tmp?  As of beta 18, bash will warn if
it doesn't find a /tmp.

@subsection My path has filenames containing spaces in it

This is not supported by Cygwin32.  You should change your path
so it does not contain spaces.

@subsection Where did my mount points go?

Earlier releases stored mount points in the registry under
"Cygnus Support".  This changed to "Cygnus Solutions" starting
with beta 18.  Either use a registry editor (regedit under NT)
to rename the old entry or just redo your mount points and the
cygwin.dll will automatically create the new one for you.

@subsection Why is the install of the tools failing?

If you are getting an error message saying "The decompression of
%s failed.  There may no be enough free disk space in the TEMP directory.",
read on.

InstallShield has a bug where it fails with this message if there
are more than a certain number of files in your TEMP directory.
You can also get this message if you have files in your TEMP dir
named the same thing InstallShield wishes to name its files (probably
from past runs of other InstallShield install scripts) which it cannot,
for some reason, write over.  Perhaps this will be fixed in a future
release of InstallShield.

Until then, clearing out your TEMP directory entirely should do it.
That will get rid of any files with conflicting names and solve the
"too many files" problem as well.

@subsection I'm having basic problems with find.  Why?

Make sure you are using the find that came with the gnu-win32 tools
and that you aren't picking up the Win32 find command instead.  You
can verify that you are getting the right one by doing a "type find"
in bash.

@subsection How do I set /etc up?

If you want a valid /etc set up (so "ls -l" will display correct
user information for example) and if you are running NT (preferably
with an NTFS file system), you should just need to create the /etc
directory on the filesystem mounted as / and then use mkpasswd and
mkgroup to create /etc/passwd and /etc/group respectively.  Since
Windows 95's Win32 API is less complete, you're out of luck if you're
running Windows 95!

@subsection Bash says that it can't vfork (or just hangs).  Why?

Most often this is because it can't find itself in the path.  Make sure
that your path includes the directory where bash lives, before you start
it.  Also make sure you have a copy of bash installed as /bin/sh.exe.

If you get errors like 'no such file or directory' when you're trying
to run a shell script, which you know is there, then your problem
probably that bash can't find @code{/bin/sh}.

@subsection Why is gcc failing?

If the error is "gcc: installation problem, cannot exec `cpp':
No such file or directory", the GCC_EXEC_PREFIX environment variable
hasn't been set correctly.  If this your problem, you should
go read the README.txt that accompanied this release since there
are other things like creating /tmp that you may not have done
either.  You should not need to set GCC_EXEC_PREFIX if you installed
the tools in the default location.

@subsection Why is make behaving badly?

The make included in beta 19 and later defaults to a win32 mode in
which backslashes in filenames are permitted and cmd.exe/command.com
is used as the sub-shell.  In this mode, escape characters aren't
allowed among other restrictions.  For this reason, you must set
the environment variable MAKE_MODE to UNIX to run make on ordinary Unix
Makefiles.  Here is the full scoop:

MAKE_MODE selects between native Win32 make mode (the default) and
a Unix mode where it behaves like a Unix make.  The Unix mode does
allow specifying Win32-style paths but only containing forward slashes
as the path separator.  The path list separator character is a colon
in Unix mode.

Win32 mode expects path separators to be either / or \.  Thus no
Unix-style \s as escape are allowed.  Win32 mode also uses
cmd.exe/command.com as the subshell which means "copy" and "del"
(and other shell builtins) will work.  The path list separator
character is semi-colon in Win32 mode.  People who want an nmake-like
make might want to use this mode but no one should expect Unix
Makefiles to compile in this mode.  That is why the default b19
install sets MAKE_MODE to UNIX.

@subsection GDB from beta 19 won't run!  What's wrong?

If the error says "Tcl_Init failed: Can't find a usable init.tcl...",
then your TCL_LIBRARY environment variable is probably set wrong.
If you installed the distribution in g:\cygnus\b19, TCL_LIBRARY should
be set to G:/cygnus/b19/share/tcl8.0, using all forward slashes.

If the error says "Unable to find main.tcl...", your GDBTK_LIBRARY
environment variable isn't a valid path.  If you installed the
distribution in g:\cygnus\b19, GDBTK_LIBRARY should be set to
G:/cygnus/b19/share/gdbtcl with all forward slashes.

If the error says something like "invalid command name
'create_command_window'", your GDBTK_LIBRARY environment
variable probably contains backslashes instead of all
forward slashes.

If you installed the tools in the default install location you should not
need to set any of these environment variables.

@section Using GNU-Win32 Releases

@subsection Why aren't man, less, groff, etc. included in the betas?

For obvious reasons, it isn't feasible for us to maintain and provide
binary distributions of every tool ported to work with the Cygwin32
tools.  Instead I think Cygnus should concentrate its efforts on the
core development tools.  Perhaps V or wxwin should count?
It's likely that less and a man command will get added once we
get them working to our satisfaction.

Other tools that have been ported should have their changes added to
the official releases so they can be compiled straight from normal
sources for that tool.  In cases where that isn't possible, someone
else (possibly Cygnus if that made sense) could maintain the diffs and
have them up for ftp.  Maybe we could keep a list of such tools on the
gnu-win32 Web site...

@subsection Where I can I find "which"?

While we don't include a which command, you can use the bash built
in "type" command which does something fairly similar.

@subsection What does "mount failed: Device or resource busy" mean?

This usually means that you are trying to mount to a location
already in use by mount.  For example, if c: is mounted as '/'
and you try to mount d: there as well, you will get this error
message.  First "umount" the old location, then "mount" the new one and
you should have better luck.

@subsection How do you share files between Unix and NT?

During development, we have both Unix boxes running Samba and
NT/Windows 95 dual-boot machines.  We often build with cross-compilers
under Unix and copy binaries and source to the NT/Win 95 system
or just toy with them directly off the Samba-mounted partition.
While the tools should work fine with NTFS, we usually use the FAT
filesystem so we can also access the files under Windows 95.

@subsection How can I access other drives?

Since beta 16, you can refer to random drive letters in your
paths.  To do an "ls" on drive letter a:, do the following:

@example
bash$ ls //a/
@end example

Or you can use the "mount" command to mount it so you can refer
to it with only single slashes:

@example
bash$ mount a:/ /mnt/floppy
bash$ ls /mnt/floppy
....
@end example

If you want to write to the raw device, then use @code{/dev/fd0} for
drive A or @code{/dev/fd1} for drive B.

e.g.
@example
bash$ tar cf /dev/fd0 *.exe
bash$ tar tvf /dev/fd0
....
@end example

Note that you can also access UNC paths in the standard way.  Because of
the drive letter shortcut mentioned above, machine names in UNC paths
must be more than one character long.

@subsection How can I get at other disks?

You can mount them using the 'mount' command.  Eg, to get to a share

@example
$ mount i:/a /a
$ mount 
i:\a on /a type dos (normal)
c:\ on / type dos (normal)
@end example

This is done with textual substitution whenever a file is opened.
So if you're going to do @code{ls /a/bar} on a mount like the above
the guts will turn that into @code{ls i:/a/bar}.

Note that you only need to mount drives once.  The mapping is kept
in the registry so mounts stay valid pretty much indefinitely.
You can only get rid of them with umount (or the registry editor).

The '-b' option mounts in binary mode.

If you want to put the release onto a drive that's not drive 'C', then you
@emph{have} to use the @code{mount} command if you want to make progress.

Eg, assume that you've installed the tree into @code{f:/fish}, so that
the binaries live in @code{f:/fish/bin} etc.
@example
$ mount f:/fish /usr
@end example
This means that when you type @code{ls /usr/bin}, cygwin.dll will look in
@code{f:/fish/bin}.

@subsection Are mixed-case filenames possible with GNU-Win32?

Several Unix programs expect to be able to use to filenames
spelled the same way, but with different case.  A prime example
of this is perl's configuration script, which wants @code{Makefile} and
@code{makefile}.  WIN32 can't tell the difference between files with
just different case, so the configuration fails.

In releases prior to beta 16, mount had a special mixed case option
which renamed files in such a way as to allow mixed case filenames.
We chose to remove the support when we rewrote the path handling
code for beta 16.

@subsection When it hangs, how do I get it back?

Sometimes the tools will just stop, (easy to do if you try and read a
file called aux.sh).  To get your world back, hit ^C to return to
bash or the cmd prompt.

If you start up another shell, and applications don't run, it's a good
bet that the hung process is still running somewhere.

If you have pview, fire it up and kill it. (if it's the aux
thing, then the app might well be cp).  If you don't have
pview or an equivalent then you'll probably have to log out.

@subsection Why the weird directory structure?

Why are cpp.exe, cc1.exe, etc., not in the bin directory?

Why more than one lib and include directory?
H-i386-cygwin32\lib\gcc-lib\...\cygnus-2.7.2-960712\include
x86-cygwin32\include
x86-cygwin32\H-i386-cygwin32\i386-cygwin32\include

This way multiple releases for different hosts and targets can all
coexist in the same tree.  H-i386-cygwin32 means hosted on
i386-cygwin32, common files shared by all hosts are in the top level
directories, target-specific files are in the
H-i386-cygwin32/i386-cygwin32
directory, etc...

If you had a server sharing files to a ppc NT machine and an x86 NT
machine, you could have both an H-i386-cygwin32 and an
H-powerpcle-cygwin32 directory without having to duplicate the top level
files that are the same for both hosts.  If you built and installed an
i386-cygwin32 x m68k-coff cross-compiler (I'm not sure if this is
possible yet, just an example), you would have an
H-i386-cygwin32/m68k-aout with its target-specific files and some
m68k-aout- prefixed binaries in H-i386-cygwin32/bin.

Normally we also have another higher level directory that identifies the
release.  If/when multiple gnuwin32 releases can coexist with different
dll versions, you might have
gnuwin32/b16/H-i386-cygwin32
gnuwin32/b17/H-i386-cygwin32
...

In any case, this does add complexity to the directory structure but
it's worth it for people with more complex installations.

@subsection Do anti-virus programs like gnu-win32?

One person reported that McAfee VirusScan for NT (and others?) is
incompatible with gnu-win32.  This is because it tries to scan the
newly loaded shared memory in the cygwin.dll, which can cause fork()s
to fail, wreaking havoc on many of the tools.

@subsection Why can't I run bash as a shell under NT Emacs?

Place the following code in your startup file and try again:

@smallexample
(load "comint")
(fset 'original-comint-exec-1 (symbol-function 'comint-exec-1))
(defun comint-exec-1 (name buffer command switches)
  (let ((binary-process-input t)
        (binary-process-output nil))
    (original-comint-exec-1 name buffer command switches)))
@end smallexample

@subsection Are GNU-WIN32 and CYGWIN32 deliberately lame names?

We're trying to phase out GNU-WIN32 in the source, because
of two pretty good reasons - a) it's not all GNU code and b)
it doesn't present a WIN32 API.

We're using cygwin32 as the configuration cookie for the moment.
But this may be changed if a better name becomes available.

There is some logic in this naming scheme.  The entire suite of tools
is referred to as 'gnu-win32', and the library/API which
they run on is the Cygwin32 API.  One day, someone else may write
some more code - for example, maybe 'bsd-win32'.  It would still
run on top of the Cygwin32 API.

@subsection Where did the man/info pages go?

In order to save space and download times, we have stopped providing
the man/info files for the tools with the binary install since we are
not yet providing a man page or info reader.  Both types of
documentation are available in a tar file available from the project ftp
site.  Or consult the online documentation over the WWW.

@subsection Where can I download the config files for other processor types?

In order to save space and download times, we have stripped config
directories for processors other than the x86 from the sources available
from the project ftp site.  If you would like to rebuild the tools for
other hosts, you should obtain the latest sources for each tool in
question from the Free Software Foundation (FSF).

@subsection Why do I get a message saying Out of Queue slots?

"Out of queue slots!" generally occurs when you're trying to remove
many files that you do not have permission to remove (either because
you don't have permission, they are opened exclusively, etc).  What
happens is gnuwin32 queues up these files with the supposition that it
will be possible to delete these files in the future.  Assuming that
the permission of an affected file does change later on, the file will
be deleted as requested.  However, if too many requests come in to
delete inaccessible files, the queue overflows and you get the message
you're asking about.  Usually you can remedy this with a quick chmod,
close of a file, or other such thing.  (Thanks to Larry Hall for
this explanation).

@subsection Why don't symlinks work on samba-mounted filesystems?

Symlinks are marked with "system" file attribute.  Samba does not support
this attribute.

@section Cygwin32 API Questions

@subsection How does everything work?

There's a C library which provides a Unix-style API.  The
applications are linked with it and voila - they run on Windows.

The aim is to add all the goop necessary to make your apps run on
Windows into the C library.  Then your apps should run on Unix and
Windows with no changes at the source level.

The C library is in a DLL, which makes basic applications quite small.
And it allows painless upgrades to the Win32/Unix translation layer,
providing that dll changes stay backward-compatible.

@subsection Are development snapshots for the Cygwin32 library available?

Yes, they're made whenever sizable changes are made to the Cygwin32
library (usually roughly on a weekly basis, depending on a number of
things).  They are only intended for those people who wish to contribute
code to the project.  If you aren't going to be happy debugging problems
in a buggy snapshot, avoid these and wait for a real release.  The
snapshots are available from ftp.cygnus.com in /pub/noer/winsup-snapshot.

@subsection Is the Cygwin32 library multi-thread-safe?

Unfortunately no.  We want to make it so eventually but it will take
some doing.  The minimalist package (mingw32) available
from the main project web site appears to be multi-thread safe.

Cygwin32 is not multi-thread-safe because:

1) Newlib (out libc/libm) isn't reentrant (although it almost is).
This would have to be fixed or we would have to switch to a libc/libm
that is reentrant.

2) Cygwin32 locks shared memory areas (shared by multiple processes),
but the per-process data is not locked.  Thus, different threads in a
multi-threaded application would have access to it and give rise to
nasty race-conditions.

The minimalist (mingw32) package is multi-thread-safe because that
configuration doesn't use Cygwin32 or newlib.  Instead, it uses
Microsoft libraries which are multi-thread-safe for the most part.  So
as long as the programmer avoids Microsoft APIs that aren't
multi-thread-safe (most are ok), they should be fine.

@subsection Why are some things supported under NT that aren't under 95?

Windows 95: n.
32 bit extensions and a graphical shell for a 16 bit patch to an
8 bit operating system originally coded for a 4 bit microprocessor,
written by a 2 bit company that can't stand 1 bit of competition.

But seriously, Windows 95 lacks most of the security-related calls and
has several other deficiencies with respect to its version of the Win32
API.  See the calls.texinfo document for more information as to what
is not supported in Win 95.

@subsection How is fork() implemented?

Cygwin32 fork() essentially works like a non-copy on write version
of fork() (like old Unix versions used to do).  Because of this it
can be a little slow.  In most cases, you are better off using the
spawn family of calls if possible.

Here's how fork works as of beta 18:

Parent initializes a space in the Cygwin process
table for child.  Parent creates child suspended using Win32 CreateProcess
call, giving the same path it was invoked with itself.  Parent
calls setjmp to save its own context and then sets a pointer to this
in the Cygwin32 shared memory area (shared among all Cygwin32 tasks).
Parent fills in the childs .data and .bss subsections by copying from
its own address space into the suspended child's address space.
Parent then starts the child.  Parent waits on mutex for child to get
to safe point.  Child starts and discovers if has been forked and
then longjumps using the saved jump buffer.  Child sets mutex parent
is waiting on and then blocks on another mutex waiting for parent to
fill in its stack and heap.  Parent notices child is in safe area,
copies stack and heap from itself into child, releases the mutex
the child is waiting on and returns from the fork call.  Child wakes
from blocking on mutex, recreates any mmapped areas passed to it via
shared area and then returns from fork itself.

@subsection How does wildcarding (globbing) work?

If an application using CYGWIN.DLL starts up, and can't find the
@code{PID} environment variable, it assumes that it has been started
from the a DOS style command prompt.  This is pretty safe, since the
rest of the tools (including bash) set PID so that a new process knows
what PID it has when it starts up.

If the DLL thinks it has come from a DOS style prompt, it runs a
`globber' over the arguments provided on the command line.  This means
that if you type @code{LS *.EXE} from DOS, it will do what you might
expect.

Beware: globbing uses @code{malloc}.  If your application defines
@code{malloc}, that will get used.  This may do horrible things to you.

@subsection How do symbolic links work?

CYGWIN.DLL generates link files with a magic header.  When 
you open a file or directory that is a link to somewhere else, it
opens the file or directory listed in the magic header.  Because we
don't want to have to open every referenced file to check symlink
status, Cygwin32 marks symlinks with the system attribute.  Files
without the system attribute are not checked.  Because remote samba
filesystems do not support the system attribute, symlinks do not work
on network drives.

@subsection Is ITIMER_VIRTUAL supported?

Nope, not yet.  If anyone knows how to implement this, please contact
us.

@subsection Why do some files, which are not executables have the 'x' type.

When working out the unix-style attribute bits on a file, the library
has to fill out some information not provided by the WIN32 API.  

It guesses that files ending in .exe and .bat are executable, as are
ones which have a "#!" as their first characters.

@subsection How secure is Cygwin32 in a multi-user environment?

Cygwin32 is not secure in a multi-user environment.  For
example if you have a long running daemon such as "inetd"
running as admin while ordinary users are logged in, or if
you have a user logged in remotely while another user is logged
into the console, one cygwin client can trick another into
running code for it.  In this way one user may gain the
priveledge of another cygwin program running on the machine.
This is because cygwin has shared state that is accessible by 
all processes.

(Thanks to Tim Newsham (newsham@@lava.net) for this explanation).

@subsection How do the net-related functions work?

The network support in cygwin32 is supposed to provide the Unix API, not
the winsock API.

There are differences between the semantics of functions with the same
name under the API.

E.g., the select system call on Unix can wait on a standard file handles
and handles to sockets.  The select call in winsock can only wait on
sockets.  Because of this, cygwin.dll does a lot of nasty stuff behind
the scenes, trying to persuade various winsock/win32 functions to do what
a Unix select would do.

If you are porting an application which already uses winsock, then
using the net support in cygwin32 is wrong.

But you can still use native winsock, and use cygwin32.  The functions
which cygwin.dll exports are called 'cygwin32_<name>'.  There
are a load of defines which map the standard Unix names to the names
exported by the dll - check out include/netdb.h:

@example
..etc..
void		cygwin32_setprotoent (int);
void		cygwin32_setservent (int);
void		cygwin32_setrpcent (int);
..etc..
#ifndef __INSIDE_CYGWIN_NET__
#define endprotoent cygwin32_endprotoent 
#define endservent cygwin32_endservent 
#define endrpcent  cygwin32_endrpcent  
..etc..
@end example

The idea is that you'll get the Unix->cygwin32 mapping if you include
the standard Unix header files.  If you use this, you won't need to
link with libwinsock.a - all the net stuff is inside the dll.

The mywinsock.h file is a standard winsock.h which has been hacked to
remove the bits which conflict with the standard Unix API, or are
defined in other headers.  E.g., in mywinsock.h, the definition of
struct hostent is removed.  This is because on a Unix box, it lives in
netdb.  It isn't a good idea to use it in your applications.

As of the b19 release, this information may be slightly out of date.

@subsection I don't want Unix sockets, how do I use normal Win32 winsock?

To use the vanilla Win32 winsock, you just need to #define Win32_Winsock
and #include "windows.h" at the top of your source file(s).  You'll also
want to add -lwsock32 to the compiler's command line so you link against
libwsock32.a.

@subsection What version numbers are associated with Cygwin32?

There is a cygwin.dll major version number that gets incremented
every time we make a new gnu-win32 beta release available.  This
corresponds to the name of the release (e.g. beta 19's major
number is "19").

There is also a cygwin.dll minor version number.  If we release
an update of the library for an existing release, the minor number
would be incremented.

"uname -v" prints the cygwin.dll version numbers as major.minor.

Finally there is a Cygwin32 registry version number which only
changes when incompatible changes are made to the way Cygwin32
uses the registry.  This has been "B15.0" since the beta 16 release.

@section Programming Questions

@subsection Why the undefined reference to "WinMain@@16"?

Try adding an empty main() function to one of your sources.

@subsection How do I use Win32 API calls?

It's pretty simple actually.  GNU-Win32 requires that you explicitly
link the import libraries for whatever Win32 API functions that you
are going to use, with the exception of kernel32, which is linked
automatically (because the startup and/or built-in code uses it).

For example, to use graphics functions (GDI) you must link
with gdi32 like this:

gcc -o foo.exe foo.o bar.o -lgdi32

or (compiling and linking in one step):

gcc -o foo.exe foo.c bar.c -lgdi32

The following libraries are available for use in this way:

advapi32  largeint  ole32     scrnsave  vfw32
cap       lz32      oleaut32  shell32   win32spl
comctl32  mapi32    oledlg    snmp      winmm
comdlg32  mfcuia32  olepro32  svrapi    winserve
ctl3d32   mgmtapi   opengl32  tapi32    winspool
dlcapi    mpr       penwin32  th32      winstrm
gdi32     msacm32   pkpd32    thunk32   wow32
glaux     nddeapi   rasapi32  url       wsock32
glu32     netapi32  rpcdce4   user32    wst
icmp      odbc32    rpcndr    uuid
imm32     odbccp32  rpcns4    vdmdbg
kernel32  oldnames  rpcrt4    version

The regular setup allows you to use the option -mwindows on the
command line to include a set of the basic libraries (and also
make your program a GUI program instead of a console program),
including user32, gdi32 and, IIRC, comdlg32.

Note that you should never include -lkernel32 on your link line
unless you are invoking ld directly.  Do not include the same import
library twice on your link line.  Finally, it is a good idea to
put import libraries last on your link line, or at least after
all the object files and static libraries that reference them.

The first two are related to problems the linker has (as of b18 at least)
when import libraries are referenced twice.  Tables get messed up and
programs crash randomly.  The last point has to do with the fact that
gcc processes the files listed on the command line in sequence and
will only resolve references to libraries if they are given after
the file that makes the reference.

@subsection How do I make the console window go away?

The default during compilation is to produce a console application.
It you are writing a GUI program, you should either compile with
-mwindows as explained above, or add the string
"-Wl,--subsystem,windows" to the GCC commandline.

@subsection Why can't we redistribute Microsoft's Win32 headers?

Subsection 2.d.f of the `Microsoft Open Tools License agreement' looks like
it says that can not "permit further redistribution of the
Redistributables to their end users".  We take this to mean that we can
give them to you, but you can't give them to anyone else, which is
something that Cygnus can't agree to.  Fortunately, we have our own
Win32 headers which are pretty complete.

@subsection How do I link against .lib files?

1. Build a C file with a function table. In that table you should
put all functions you want to use. This is to force the linker
to include all the object files from the .lib. Maybe there is
an option to force LINK.EXE to include an object file.
2. Build a dummy 'LibMain'
3. Build a .def with all the exports you need
4. Link with your .lib using link.exe.

or

1. Extract all the object files from the .lib using LIB.EXE
2. Build a dummy C file referencing all the functions you need.
Either with a direct call or with an initialized function pointer.
3. Build a dummy LibMain
4. Link all the objects with this file+LibMain.
5. Write a .def.
6. Link.

You can use these methods to use MSVC (and many other runtime libs)
with gnu-win32 development tools.

Note that this is a lot of work (half a day or so), but much less than
rewriting the runtime library in question from specs...

(thanks to Jacob Navia (root@@jacob.remcomp.fr) for this explanation)

@subsection How do I rebuild the tools on my NT box?

Assuming that you have the src installed as /src, will build in
the directory /obj, and want to install the tools in /install:

@example
bash
cd /obj
/src/configure --prefix=/install -v > configure.log 2>&1
make > make.log 2>&1
make install > install.log 2>&1
@end example

@subsection How can I compile a powerpc NT toolchain?

Unfortunately, this will be difficult.  It hasn't been built for
some time (late 1996) since Microsoft has dropped development of
powerpc NT.  Exception handling/signals support semantics/args have been
changed for x86 and not updated for ppc so the ppc specific support would
have to be rewritten.  We don't know of any other incompatibilities.
Please send us patches if you do this work!

@subsection How can I compile an Alpha NT toolchain?

We have not ported the tools to Alpha NT and do not have plans to
do so at the present time.  We would be happy to add support
for Alpha NT if someone contributes the changes to us.

@subsection How can I adjust the heap/stack size of an application?

Pass heap/stack linker arguments to gcc.  To create foo.exe with
a heap size of 1024 and a stack size of 4096, you would invoke
gcc as:

@code{gcc -Wl,--heap,1024,--stack,4096 -o foo foo.c}

@subsection How can I find out which dlls are needed by an executable?

objdump -p provides this information.

@subsection How do I build a DLL?

There's documentation that explains the process on the main gnu-win32
project web page (http://www.cygnus.com/misc/gnu-win32).

@subsection How can I set a breakpoint at MainCRTStartup?

Set a breakpoint at *0x401000 in gdb and then run the program in
question.

@subsection How is the DOS/Unix CR/LF thing handled?

By default, tools that deal with binaries (e.g. objdump) operate in unix
binary mode and tools that deal with text files (e.g. bash) operate in
text mode.

You can enable the DOS CR/LF end of line in a text file mode by
setting fmode_binary setting in the registry to 0.  I've tried to keep
the file types 'natural'.  By default a file is opened in text mode.
This can be changed by adding @code{O_BINARY} to the second argument of
an @code{open} call, or @code{"b"} to second argument of an
@code{fopen} call.  You can also call @code{setmode (fd, O_BINARY)}.

@code{lseek} now only works in binary mode.

@subsection How can I build a relocatable dll?

You must execute the following sequence of five commands, in this
order:

@example
$(LD) -s --base-file BASEFILE --dll -o DLLNAME OBJS LIBS -e ENTRY

$(DLLTOOL) --as=$(AS) --dllname DLLNAME --def DEFFILE \
        --base-file BASEFILE --output-exp EXPFILE

$(LD) -s --base-file BASEFILE EXPFILE -dll -o DLLNAME OBJS LIBS -e ENTRY

$(DLLTOOL) --as=$(AS) --dllname DLLNAME --def DEFFILE \
	--base-file BASEFILE --output-exp EXPFILE

$(LD) EXPFILE --dll -o DLLNAME OBJS LIBS -e ENTRY
@end example

In this example, $(LD) is the linker, ld.

$(DLLTOOL) is dlltool.

$(AS) is the assembler, as.

DLLNAME is the name of the DLL you want to create, e.g., tcl80.dll.

OBJS is the list of object files you want to put into the DLL.

LIBS is the list of libraries you want to link the DLL against.  For
example, you may or may not want -lcygwin.  You may want -lkernel32.
Tcl links against -lcygwin -ladvapi32 -luser32 -lgdi32 -lcomdlg32
-lkernel32.

DEFFILE is the name of your definitions file.  A simple DEFFILE would
consist of ``EXPORTS'' followed by a list of all symbols which should
be exported from the DLL.  Each symbol should be on a line by itself.
Other programs will only be able to access the listed symbols.

BASEFILE is a temporary file that is used during this five stage
process, e.g., tcl.base.

EXPFILE is another temporary file, e.g., tcl.exp.

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 cygwin32 functions, the entry function will need
to initialize the cygwin32 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.  At the most basic level, you can set the @code{STRACE}
environment variable to @code{1}, and get a whole load of
debug information on your screen whenever a Cygwin32 app runs.
This is an especially useful tool to use when tracking bugs down
inside the Cygwin32 library.  @code{STRACE} can be set to different
values to achieve different amounts of granularity.  You can set it
to @code{0x10} for information about syscalls or @code{0x800} for
signal/process handling-related info, to name two.  The strace
mechanism is well documented in the Cygwin32 library sources in the
file @code{winsup/include/sys/strace.h}.

@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.

The function probably isn't declared in the header files, or
the UNICODE stuff for it isn't filled in.

@subsection Can you make dll's that are linked against libc ?

Yes.

@subsection Where is malloc.h?

Include stdlib.h instead of malloc.h.

@subsection Can I mix objects compiled with msvc++ and gcc?

Yes, this should work, as long as you are dealing with C object
files.  MSVC C++ uses a different mangling scheme than GNU C++, so
you may 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/242691.HTM}

@subsection Shell scripts aren't running properly from my makefiles?

You need to have . (dot) in your $PATH.  You should NOT need to add
/bin/sh in front of each and every shell script invoked in your
Makefiles.

@subsection Why did we change the preprocessor defines in beta 16?

They were too confusing and very well defined prior to this release.
Now there's _WIN32 for access to the Win32 API and __CYGWIN32__ for
access to the cygwin32 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++.

@subsection What is V?

(excerpted from @file{http://www.cs.unm.edu/~wampler/aboutv.html})

V is a portable C++ GUI Framework intended to develop a wide variety of
applications on different graphical interface platforms. While it is
probably not suitable for developing state-of-the art commercial
applications with all the latest interface components, it is very
complete and suitable for a large majority of custom GUI applications.
Applications developed using V will have the look and feel of the native
platform, yet will be portable across platforms.

Most standard GUI objects are supported by V, including windows with
menus, status bars, tool bars, and a drawing canvas; modal and modeless
dialogs with the most common controls (buttons, lists, labels, text
entry, check and radio buttons, etc.); and portable printing support.

...

V is also an excellent tool for developing many custom applications. It
is a suitable tool for research labs, small custom software shops,
engineering firms, or individuals that need to develop an application
that needs a graphical user interface, especially for multiple
platforms. Because of its design, V is far easier to learn and use than
the native GUI tool kits. It is also easier to learn than larger
frameworks such as MFC or OWL.  Since it is freeware, licensed under the
GNU Library General Public License, it will always be available with its
source code for public use.

For more information, please check out the V WWW page at
@file{http://www.cs.unm.edu/~wampler/vgui/vgui.html}.

@subsection Why not use DJGPP ?

DJGPP is a similar idea, but for DOS instead of Win95 and Windows NT.
DJGPP uses a "DOS extender" to provide a more reasonable operating
interface for its applications.  GNU-WIN32 doesn't have to do that as
all the applications are native WIN32.   GNU-WIN32 can call all the
Win32 API functions, so you can write programs which use the Windows
GUI.  Perhaps one day GNU-WIN32 will run on the Alpha and MIPS
processors as well.

You can get more info on DJGPP by following
@file{http://www.delorie.com}.
