commentary about IoTYPE() (from Nathan Torkington)

[perl5.git] / README.cygwin

If you read this file _as_is_, just ignore the funny characters you
see. It is written in the POD format (see pod/perlpod.pod) which is
specially designed to be readable as is.

=head1 NAME

README.cygwin - Perl for Cygwin

=head1 SYNOPSIS

This document will help you configure, make, test and install Perl
on Cygwin.  This document also describes features of Cygwin that will
affect how Perl behaves at runtime.

B<NOTE:> There are pre-built Perl packages available for Cygwin and a
version of Perl is provided on the Cygwin CD.  If you have no need to
customize the configuration, consider using one of these packages:

  http://cygutils.netpedia.net/

=head1 PREREQUISITES

=head2 Cygwin = GNU+Cygnus+Windows (Don't leave UNIX without it)

The Cygwin tools are ports of the popular GNU development tools for Win32
platforms.  They run thanks to the Cygwin library which provides the UNIX
system calls and environment these programs expect.  More information
about this project can be found at:

  http://sourceware.cygnus.com/cygwin/

A recent net or commercial release of Cygwin is required.

At the time this document was written, the port required recent
development snapshots that were expected to stabilize early in 2000 and
be released to the net as B21 and commercially as v1.1.

B<NOTE:> At this point, minimal effort has been made to provide
compatibility with old (beta) Cygwin releases.  The focus has been to
provide a high quality release and not worry about working around old
Cygwin bugs.  If you wish to use Perl with Cygwin B20.1 or earlier,
consider using either perl5.005_03 or perl5.005_62, which are available
in source and binary form at C<http://cygutils.netpedia.net/> or on the
Cygwin CD.  If there is significant demand, a patch kit can be developed
to port back to earlier Cygwin versions.

=head2 Compiler

A recent net or commercial release of I<gcc> is required.

At the time this document was written, I<gcc-2.95.2> was current and
could be downloaded from:

  ftp://ftp.xraylith.wisc.edu/pub/khan/gnu-win32/cygwin/gcc-2.95.2/

=head2 Cygwin Configuration

While building Perl some changes may be necessary to your Cygwin setup so
that Perl builds cleanly.  These changes are B<not> required for normal
Perl usage.

B<NOTE:> The binaries that are built will run on all Win32 versions.
They do not depend on your host system (Win9x, WinNT) or your Cygwin
configuration (I<ntea>, I<ntsec>, binary/text mounts).  The only
dependencies come from hardcoded pathnames like C</usr/local>.  However,
your host system and Cygwin configuration will affect Perl's runtime
behavior (see L</"TEST">).  Some regression tests may fail in different
ways depending on your setup.  For now, the test suite does not skip
tests that do not make sense given a particular setup.  If a test can
pass in some Cygwin setup, it is left in and explainable test failures
are documented.

=over 4

=item * C<PATH>

Set the C<PATH> environment variable so that Configure finds the Cygwin
versions of programs.  Any Windows directories should be removed or
moved to the end of your C<PATH>.

=item * F</bin/cat.exe>

There should be an instance of I<cat> in F</bin> (or F</usr/bin>).
Configure tests C<#!/bin/cat> and if it is not found, you will see
the error:

  Configure: ./try: No such file or directory

=item * F</usr/bin>

If you do not have a F</usr/bin> directory, Configure will B<not> prompt
you to install I<perl> into F</usr/bin>.

=item * I<nroff>

If you do not have I<nroff> (which is part of the I<groff> package),
Configure will B<not> prompt you to install man pages.

=item * Permissions

On WinNT with either the I<ntea> or I<ntsec> C<CYGWIN> settings, directory
and file permissions may not be set correctly.  Since the build process
creates files and directories, to be safe you may want to run a `C<chmod
-R +w *>' on the entire Perl source tree.

Also, it is a well known WinNT "feature" that files created by a login
that is a member of the I<Administrators> group will be owned by the
I<Administrators> group.  Depending on your umask, you may find that you
can not write to files that you just created (because you are no longer
the owner).  When using the I<ntsec> C<CYGWIN> setting, this is not an
issue because it "corrects" the ownership to what you would expect on
a UNIX system.

=back

=head1 CONFIGURE

The default options gathered by Configure with the assistance of
F<hints/cygwin.sh> will build a Perl that supports dynamic loading
(which requires a shared F<libperl.dll>).

This will run Configure and keep a record:

  ./Configure 2>&1 | tee log.configure

If you are willing to accept all the defaults add a B<-d> option.
However, several useful customizations are available.

=head2 Strip Binaries

It is possible to strip the EXEs and DLLs created by the build process.
The resulting binaries will be significantly smaller.  If you want the
binaries to be stripped, you can either add a B<-s> option when Configure
prompts you,

  Any additional ld flags (NOT including libraries)? [none] -s
  Any special flags to pass to gcc to use dynamic linking? [none] -s
  Any special flags to pass to ld2 to create a dynamically loaded library?
  [none] -s

or you can edit F<hints/cygwin.sh> and uncomment the relevant variables
near the end of the file.

=head2 Optional Libraries

Several Perl functions and modules depend on the existence of
some optional libraries.  Configure will find them if they are
installed in one of the directories listed as being used for library
searches.  Pre-built packages for most of these are available at
C<http://cygutils.netpedia.net/>.

=over 4

=item * C<-lcrypt>

The crypt libraries in GNU libc have been ported to Cygwin.

The DES based Ultra Fast Crypt port was done by Alexey Truhan:

  http://dome.weeg.uiowa.edu/pub/domestic/sos/cw32crypt-dist-0.tgz

NOTE: There are various export restrictions on DES implementations,
see the glibc README for more details.

The MD5 port was done by Andy Piper:

  http://dome.weeg.uiowa.edu/pub/domestic/sos/libcrypt.tgz

More information can also be found at:

  http://miracle.geol.msu.ru/sos/

=item * C<-lgdbm> (C<use GDBM_File>)

GDBM is available for Cygwin.  GDBM's ndbm/dbm compatibility feature
also makes C<NDBM_File> and C<ODBM_File> possible (although they add
little extra value).

=item * C<-ldb> (C<use DB_File>)

BerkeleyDB is available for Cygwin.  Some details can be found in
F<ext/DB_File/DB_File.pm>.

=item * C<-lcygipc> (C<use IPC::SysV>)

A port of SysV IPC is available for Cygwin.

NOTE: This has B<not> been extensively tested.  In particular,
C<d_semctl_semun> is undefined because it fails a configure test and on
Win9x the shm*() functions seem to hang.

=back

=head2 Configure-time Options

The F<INSTALL> document describes several Configure-time options.  Some of
these will work with Cygwin, others are not yet possible.  Also, some of
these are experimental.  You can either select an option when Configure
prompts you or you can define (undefine) symbols on the command line.

=over 4

=item * C<-Uusedl>

Undefining this symbol forces Perl to be compiled statically.

=item * C<-Uusemymalloc>

By default Perl uses the malloc() included with the Perl source.  If you
want to force Perl to build with the system malloc() undefine this symbol.

=item * C<-Dusemultiplicity>

Multiplicity is required when embedding Perl in a C program and using
more than one interpreter instance.  This works with the Cygwin port.

=item * C<-Duseperlio>

The PerlIO abstraction works with the Cygwin port.

=item * C<-Duse64bitint>

I<gcc> supports 64-bit integers.  However, several additional long long
functions are necessary to use them within Perl (I<{strtol,strtoul}l>).
These are B<not> yet available with Cygwin.

=item * C<-Duselongdouble>

I<gcc> supports long doubles (12 bytes).  However, several additional
long double math functions are necessary to use them within Perl
(I<{atan2,cos,exp,floor,fmod,frexp,log,modf,pow,sin,sqrt}l,strtold>).
These are B<not> yet available with Cygwin.

=item * C<-Dusethreads>

POSIX threads are B<not> yet implemented in Cygwin.

=item * C<-Duselargefiles>

Although Win32 supports large files, Cygwin currently uses 32-bit integers
for internal size and position calculations.

=back

=head2 Suspicious Warnings

You may see some messages during Configure that seem suspicious.

=over 4

=item * Whoa There

Cygwin does not yet implement chroot(), setegid() or seteuid()
functionality, but has stub functions that return C<ENOSYS>.  You will
see a message when Configure detects that its guess conflicts with the
hint file.

  *** WHOA THERE!!! ***
      The recommended value for $d_chroot on this machine was "undef"!
      Keep the recommended value? [y]

You should keep the recommended value.

=item * dlsym

I<ld2> is needed to build dynamic libraries, but it does not exist
when dlsym() checking occurs (it is not created until `C<make>' runs).
You will see the following message:

  Checking whether your dlsym() needs a leading underscore ...
  I can't compile and run the test program.
  I'm guessing that dlsym doesn't need a leading underscore.

Since the guess is correct, this is not a problem.

=item * Win9x and d_eofnblk

Win9x does not correctly report C<EOF> with a non-blocking read on a
closed pipe.  You will see the following messages:

  But it also returns -1 to signal EOF, so be careful!
  WARNING: you can't distinguish between EOF and no data!

  *** WHOA THERE!!! ***
      The recommended value for $d_eofnblk on this machine was "define"!
      Keep the recommended value? [y]

At least for consistency with WinNT, you should keep the recommended
value.

=item * Checking how std your stdio is...

Configure reports:

  Your stdio doesn't appear very std.

This is correct.

=item * Compiler/Preprocessor defines

The following error occurs because of the Cygwin C<#define> of
C<_LONG_DOUBLE>:

  Guessing which symbols your C compiler and preprocessor define...
  try.c:3847: parse error

This failure does not seem to cause any problems.

=back

=head1 MAKE

Simply run make and wait:

  make 2>&1 | tee log.make

=head2 Warnings

Warnings like these are normal:

  warning: overriding commands for target <file>
  warning: ignoring old commands for target <file>

  Warning: no export definition file provided
  dllwrap will create one, but may not be what you want

=head2 ld2

During `C<make>', I<ld2> will be created and installed in your $installbin
directory (where you said to put public executables).  It does not
wait until the `C<make install>' process to install the I<ld2> script,
this is because the remainder of the `C<make>' refers to I<ld2> without
fully specifying its path and does this from multiple subdirectories.
The assumption is that $installbin is in your current C<PATH>.  If this
is not the case or if you do not have an I<install> program, `C<make>'
will fail at some point.  If this happens, just manually copy I<ld2>
from the source directory to someplace in your C<PATH>.

=head1 TEST

There are two steps to running the test suite:

  make test 2>&1 | tee log.make-test

  cd t;./perl harness 2>&1 | tee ../log.harness

The same tests are run both times, but more information is provided when
running as `C<./perl harness>'.

Test results vary depending on your host system and your Cygwin
configuration.  It is possible that Cygwin will pass all the tests,
but it is more likely that some tests will fail for one of these reasons.

=head2 File Permissions

UNIX file permissions are based on sets of mode bits for
{read,write,execute} for each {user,group,other}.  By default Cygwin only
tracks the Win32 readonly attribute represented as the UNIX file user
write bit (files are always readable, files are executable if they have
a F<.{com,bat,exe}> extension or begin with C<#!>, directories are always
readable and executable).  On WinNT with the I<ntea> C<CYGWIN> setting,
the remaining mode bits are stored as extended attributes.  On WinNT
with the I<ntsec> C<CYGWIN> setting, permissions use the standard WinNT
security descriptors and access control lists.  Without one of these
options, these tests will fail:

  Failed Test           List of failed
  ------------------------------------
  io/fs.t               5, 7, 9-10
  lib/anydbm.t          2
  lib/db-btree.t        20
  lib/db-hash.t         16
  lib/db-recno.t        18
  lib/gdbm.t            2
  lib/ndbm.t            2
  lib/odbm.t            2
  lib/sdbm.t            2
  op/stat.t             9, 20 (.tmp not an executable extension)

=head2 Hard Links

FAT partitions do not support hard links (whereas NTFS does), in which
case Cygwin implements link() by copying the file.  These tests will fail:

  Failed Test           List of failed
  ------------------------------------
  io/fs.t               4
  op/stat.t             3

=head2 Filetime Granularity

On FAT partitions the filetime granularity is 2 seconds.  The following
test will fail:

  Failed Test           List of failed
  ------------------------------------
  io/fs.t               18

=head2 Tainting Checks

When Perl is running in taint mode, C<$ENV{PATH}> is considered tainted
and not used, so DLLs not in the default system directories will not
be found.  While the tests are running you will see warnings popup from
the system with messages like:

  Win9x
    Error Starting Program
    A required .DLL file, CYGWIN1.DLL, was not found

  WinNT
    perl.exe or sh.exe - Unable to Locate DLL
    The dynamic link library cygwin1.dll could not be found in the
      specified path ...

Just click OK and ignore them.  When running `C<make test>', 2 popups
occur.  During `C<./perl harness>', 4 popups occur.  Also, these tests
will fail:

  Failed Test           List of failed
  ------------------------------------
  op/taint.t            1, 3, 31, 37

Alternatively, you can copy F<cygwin1.dll> into one of the Windows system
directories (although, this is B<not> recommended).

=head2 /etc/group

Cygwin does not require F</etc/group>, in which case the F<op/grent.t>
test will be skipped.  The check performed by F<op/grent.t> expects to
see entries that use the members field, otherwise this test will fail:

  Failed Test           List of failed
  ------------------------------------
  op/grent.t            1

=head2 Unexplained Failures

Any additional tests that fail are likely due to bugs in Cygwin or the
optional libraries.  It is expected that by the time of the next net
release most of these will be solved so they are not described here.

=head2 Script Portability

Cygwin does an outstanding job of providing UNIX-like semantics on
top of Win32 systems.  However, in addition to the items noted above,
there are some differences that you should know about.  This is only a
very brief guide to portability, more information can be found in the
Cygwin documentation.

=over 4

=item * Pathnames

Cygwin pathnames can be separated by forward (F</>) or backward (F<\>)
slashes.  They may also begin with drive letters (F<C:>) or Universal
Naming Codes (F<//UNC>).  DOS device names (F<aux>, F<con>, F<prn>,
F<com*>, F<lpt?>) are invalid as base filenames.  However, they can be
used in extensions (e.g., F<hello.aux>).  Names may not contain these
characters:

  : * ? " < > |

File names are case insensitive, but case preserving.  With the I<mixed>
C<CYGWIN> setting, file names are mixed-case (although, directory names
remain case insensitive).

The I<mixed> setting is only available with the "coolview" version of
F<cygwin1.dll> provided by Sergey Okhapkin at:

  ftp://ftp.franken.de/pub/win32/develop/gnuwin32/cygwin/porters/Okhapkin_Sergey/

=item * Text/Binary

When a file is opened it is in either text or binary mode.  In text mode
a file is subject to CR/LF/Ctrl-Z translations.  With Cygwin, the default
mode for an open() is determined by the mode of the mount that underlies
the file.  Perl provides a binmode() function to set binary mode on files
that otherwise would be treated as text.  sysopen() with the C<O_TEXT>
flag sets text mode on files that otherwise would be treated as binary:

    sysopen(FOO, "bar", O_WRONLY|O_CREAT|O_TEXT)

lseek(), tell() and sysseek() only work with files opened in binary mode.

The text/binary issue is covered at length in the Cygwin documentation.

=item * F<.exe>

The Cygwin stat() makes the F<.exe> extension transparent by looking for
a F<foo.exe> when you ask for F<foo> (unless a F<foo> also exists).
Cygwin does not require a F<.exe> extension, but I<gcc> adds it
automatically when building a program.  However, when accessing an
executable as a normal file (e.g., I<install> or I<cp> in a makefile)
the F<.exe> is not transparent.

NOTE: There is a version of I<install> that understands the F<.exe>
semantics, it can be found at:

  ftp://ftp.franken.de/pub/win32/develop/gnuwin32/cygwin/porters/Humblet_Pierre_A/

=item * chown()

On WinNT with the I<ntsec> C<CYGWIN> setting, chown() can change a file's
user and group IDs.  In all other configurations chown() is a no-op,
although this is appropriate on Win9x since there is no security model.

=item * Miscellaneous

File locking using the C<F_GETLK> command to fcntl() is a stub that
returns C<ENOSYS>.

Win9x can not rename() an open file (although WinNT can).

=back

=head1 INSTALL

This will install Perl, including man pages.

  make install | tee log.make-install

NOTE: If C<STDERR> is redirected `C<make install>' will B<not> prompt
you to install I<perl> into F</usr/bin>.

You may need to be I<Administrator> to run `C<make install>'.  If you
are not, you must have write access to the directories in question.

Information on installing the Perl documentation in HTML format can be
found in the F<INSTALL> document.

=head1 MANIFEST

These are the files in the Perl release that contain references to Cygwin.
These very brief notes attempt to explain the reason for all conditional
code.  Hopefully, keeping this up to date will allow the Cygwin port to
be kept as clean as possible.

=over 4

=item Documentation

  INSTALL README.cygwin
  Changes Changes5.005 Changes5.004
  AUTHORS MAINTAIN MANIFEST README.win32
  pod/perl.pod pod/perlfaq3.pod pod/perlhist.pod pod/perlmodlib.pod
  pod/perlport.pod pod/perltoc.pod pod/perl5004delta.pod

=item Build, Configure, Make, Install

  cygwin/Makefile.SHs
  cygwin/ld2.in
  cygwin/perlld.in
  ext/IPC/SysV/hints/cygwin.pl
  ext/NDBM_File/hints/cygwin.pl
  ext/ODBM_File/hints/cygwin.pl
  hints/cygwin.sh
  Configure             - help finding hints from uname,
                          shared libperl required for dynamic loading
  Makefile.SH           - linklibperl
  Porting/patchls       - cygwin in port list
  installman            - man pages with :: translated to .
  installperl           - install dll/ld2/perlld, install to pods
  makedepend.SH         - uwinfix

=item Tests

  t/io/tell.t           - binmode
  t/lib/glob-basic.t    - Win32 directory list access differs from read mode
  t/op/magic.t          - $^X/symlink WORKAROUND, s/.exe//
  t/op/stat.t           - no /dev, skip Win32 ftCreationTime quirk
                          (cache manager sometimes preserves ctime of file
                          previously created and deleted), no -u (setuid)

=item Compiled Perl Source

  EXTERN.h              - __declspec(dllimport)
  XSUB.h                - __declspec(dllexport)
  cygwin/cygwin.c       - os_extras (getcwd)
  perl.c                - os_extras
  perl.h                - binmode
  doio.c                - win9x can not rename a file when it is open
  pp_sys.c              - do not define h_errno
  mg.c                  - environ WORKAROUND
  unixish.h             - environ WORKAROUND
  util.c                - environ WORKAROUND

=item Compiled Module Source

  ext/POSIX/POSIX.xs    - tzname defined externally
  ext/SDBM_File/sdbm/pair.c
                        - EXTCONST needs to be redefined from EXTERN.h
  ext/SDBM_File/sdbm/sdbm.c
                        - binary open

=item Perl Modules/Scripts

  lib/Cwd.pm            - hook to internal Cwd::cwd
  lib/ExtUtils/MakeMaker.pm
                        - require MM_Cygwin.pm
  lib/ExtUtils/MM_Cygwin.pm
                        - canonpath, cflags, manifypods, perl_archive
  lib/File/Spec/Unix.pm - preserve //unc
  lib/perl5db.pl        - use stdin not /dev/tty
  utils/perlcc.PL       - DynaLoader.a in compile, -DUSEIMPORTLIB
  utils/perldoc.PL      - version comment

=back

=head1 BUGS

Upon each start, I<make> warns that a rule for F<perlmain.o> is overridden
(but there seems to be no better solution than adding an explicit define).

`C<make clean>' does not remove library F<.def> and F<.exe.stackdump>
files.

The I<ld2> script contains references to the source directory.  You should
change these to C</usr/local/bin> (or whatever) after install.

=head1 AUTHORS

Charles Wilson E<lt>cwilson@ece.gatech.eduE<gt>,
Eric Fifer E<lt>efifer@sanwaint.comE<gt>,
alexander smishlajev E<lt>als@turnhere.comE<gt>,
Steven Morlock E<lt>newspost@morlock.netE<gt>,
Sebastien Barre E<lt>Sebastien.Barre@utc.frE<gt>,
Teun Burgers E<lt>burgers@ecn.nlE<gt>.

=head1 HISTORY

Last updated: 1 March 2000